Qayoom2021_Article_AssessmentOfPotentialRisksOfHe.pdf

Vol.:(0123456789)
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International Journal of Environmental Science and Technology
https://doi.org/10.1007/s13762-021-03612-8
ORIGINAL PAPER
Assessment of potential risks of heavy metals from wastewater
treatment plants of Srinagar city, Kashmir
U. Qayoom1
· S. U. Bhat1
· I. Ahmad2
· A. Kumar3
Received: 3 February 2021 / Revised: 10 June 2021 / Accepted: 14 August 2021
© Islamic Azad University (IAU) 2021
Abstract
Globally an enormous amount of sewage and sludge is being generated which has turned out to be a major environmental
threat due to the associated risks arising from heavy metals. In this context the present study aimed to assess the concen-
tration of heavy metals in sewage and sludge from wastewater treatment plants located around Dal Lake of Srinagar city.
Aluminum, iron, zinc, lead, copper, mercury, arsenic, cadmium and chromium were determined using atomic absorption
spectrophotometer. Certain key physico-chemical characteristics of sewage in raw and effluent were also evaluated. Health
risk assessment using non-carcinogenic and carcinogenic risk revealed suitability of sludge in agriculture which till now
remain a neglected resource in the city. Principal component analysis showed that the maximum variability in the data was
reflected from sludge samples, whereas correlation among physico-chemical parameters and heavy metals revealed influence
of ionic properties of wastewater on heavy metal distribution. While concentration of heavy metals was within the discharge
standards, physico-chemical parameters like total suspended solids, ammonia, biochemical oxygen demand and total phos-
phorus were exceeding the standards meant for effluent disposal. This is one of the unique situations wherein the waste water
from the entire city is discharged into Dal Lake without subjecting to advanced treatment. Since the lake is directly linked
with supply chain of food and water, continuous discharge of heavy metals have the potential to build up toxicity and cause
harm to the lake biota and public health thereof.
Keywords Heavy metals · Carcinogenic · Dal Lake · Effluent · Waste water
Introduction
Pollution due to heavy metals has gradually increased
during the past few years (Khelifi et al. 2019; Deng
et al. 2019) due to the rapid pace of urbanization and
industrial development (Solgi et al. 2012). Owing to
their toxicity, bioaccumulation and persistent nature
heavy metals have received great attention (Ouyang et al.
2018; Ali et al. 2019; Dash et al. 2021) and their moni-
toring has become a useful indicator of the influence of
anthropogenic activities on the environment (Chuan and
Yunus 2019; Mehana et al. 2020). Pollution of water bod-
ies by heavy metals is an emerging phenomena world-
wide as it can cause ecotoxicological problems and sev-
eral other health effects (Cunningham et al. 2019; Pinto
et al. 2019; Cabral Pinto et al. 2019; Magd et al. 2021; Yu
et al. 2021). Treated effluents from wastewater treatment
plants (WWTP's) are potential sources of heavy metals
which gradually accumulate in the environment (Busetti
et al. 2005; Topal et al. 2020; Mkhinini et al. 2020). Waste-
water treatment generates large volumes of sludge which
contains several harmful constituents removed during
the treatment (Laura et al. 2020; Latosinska et al. 2021;
Kumar et al. 2021a; Singh et al. 2021; Kumar and Amit
2021; Tavker et al. 2021). Lately there has been a grow-
ing concern regarding wastewater treatment and sludge
disposal across the world and its management has been
Editorial Responsibility: Gobinath Ravindran.
* S. U. Bhat
samiullah@kashmiruniversity.ac.in
1
Department of Environmental Science, School of Earth
and Environmental Sciences, University of Kashmir,
Srinagar 190006, India
2
Division of Genetics and Biotechnology, Faculty of Fisheries,
SKUAST-K, Srinagar 190006, Kashmir, India
3
School of Hydrology and Water Resources,
Nanjing University of Information Science
and Technology, Nanjing 210044, Jiangsu Province,
People’s Republic of China

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a serious issue among all the stakeholders like operators,
regulators, scientific community and politicians (LeBlanc
et al. 2008). Due to the presence of heavy metals, sludge
is associated with several health risks in humans (Harrison
et al. 1999; Mudho and Kumar 2013), while on the other
hand it is a resource which needs to be exploited to its
best (Rios et al. 2012; Latare et al. 2014; Cantinho et al.
2016). After the biological or chemical stabilization of
sludge it is referred as biosolids (Metcalf 1979) and the
nutrients present in biosolid make it a valuable resource
for use in agriculture (Romanos et al. 2021). It contains
most of the nitrogen derived from excreta, organic matter
and nutrients which upon treatment in a biological WWTP
generates additional organic matter. Wastewater sludge
consists of various nutrients required for plant growth.
It contains 1–8% nitrogen (N), 0.5–5% phosphorus (P)
and < 1% potassium (K) (LeBlanc et al. 2008). Various
other components of sludge like organic matter, micronu-
trients, trace elements and microbes supplement the soil
and improve its properties (Rios et al. 2012; Latare et al.
2014; Riaz et al. 2018a; Cai et al. 2019). Land application
of sludge decreases bulk density, increases water holding
capacity, improves aeration, root penetration and enhances
soil microbial activity (Kukal et al. 2012; Wolna-Maruwka
et al. 2018). Application of sludge in agriculture is being
employed in many countries as an effective method to
deal with its large quantities (Turek et al. 2019; Saha et al.
2017a, b; Zdeb et al. 2020). In India about 38,354 million
liters of sewage and an equivalent amount of sludge is
being generated (Kaur et al. 2012) which despite having
high nutrient potential is disposed mainly through inciner-
ation and land filling (Saha et al. 2017a, b). In China more
than 80% of sludge generated is disposed of via improper
dumping, while remaining is disposed in sanitary landfill
followed by land application (Yang et al. 2015). In con-
trast, European Union (EU) countries utilize around 37%
of sludge generated in agriculture, while in USA the cor-
responding figure is 60% (Olofsson et al. 2012). In Medi-
terranean countries 40% of sludge generated is used as soil
amendment (Milieu 2010). However, land application of
sludge is associated with certain ill effects. Contamination
of soil with pathogens, harmful organic compounds and
dispersal of heavy metals from sludge into soil, water and
air (Przewrocki et al. 2004; Kapanen 2013) restricts its use
as fertilizer (Riaz et al. 2020). Elevated level of heavy met-
als is harmful to living organisms (Chipasa 2003). Various
metals being non-biodegradable accumulate in water and
soil from where they enter food chain and bioconcentrate
in living organisms, thereby affecting public health (Zhang
et al. 2017; Liu et al. 2018; Riaz et al. 2018b). Humans
are exposed to these contaminants through several routes
like dermal, ingestion and inhalation (Cabral Pinto et al.
2017; Lu et al. 2011; Khalili et al. 2019) which initiates
several health risks in them (Karim and Qureshi 2013;
Guo et al. 2012).
Urban wastewater containing heavy metals is considered
as an important source of water as well as soil pollution (da
Silva et al. 2007), and their distribution to various environ-
mental compartments, especially aquatic ecosystems, has
put a great deal of pressure on the self-purifying capacity
of water bodies (Susarla et al. 2002). Heavy metals com-
prise one of the most toxic pollutants in aquatic ecosystems
(Aguilar et al. 2020) due to the detrimental impacts they
display in aquatic biota (Ashraj 2005; Cruz-guzmán et al.
2006; Vosyliene and Jankaite 2006; Farombi et al. 2007).
Adverse effects of heavy metals are well documented, and
lately humans have been exposed toward them, especially
in developing countries (Duruibe et al. 2007; Jaishankar
et al. 2014; Tchounwou et al. 2012; Akoto et al. 2019).
Apart from their impacts on living organisms, higher lev-
els of heavy metal in wastewater inhibit microbial activity
effecting wastewater treatment processes like nitrification,
denitrification (Braam and Klapwijk 1981; Waara 1992) and
increase in its treatment cost (Akpor et al. 2014).
Contamination of lakes due to heavy metals is an emerg-
ing environmental problem due to which several lakes like
Shahpura Lake, India; Lake Erie, North America; Lake
Taihu, China; and Lake Manzala, Egypt, have been effected.
Inland waters in Kashmir ranging from wetlands to lakes
and reservoirs offer various ecosystem services including a
source of water for irrigation and drinking purposes for the
entire population (Yaseen and Bhat 2021). Lakes in Kash-
mir have witnessed tremendous anthropogenic pressures
from various sources like urbanization (Rashid et al. 2017),
entry of untreated sewage (Parvaiz and Bhat 2014; Dar et al.
2020a), eutrophication (Romshoo and Muslim 2011; Dar
et al. 2020a), catchment scale land use changes (Rather
et al. 2016; Dar et al. 2020b), sediment load (Rashid and
Aneaus 2019) which deteriorates their water quality (Vass
1980; Najar and Khan 2012; Bhat and Pandit 2014) and
adversely impacts aquatic life (Khan et al. 2004; Zutshi and
Gopal 2000). However, recent reports on heavy metal con-
centration from water and macrophytes (Ahmad et al. 2014,
2016; Showqi et al. 2018) from the region have generated
a concern despite Srinagar city being outside the contours
of industrialization. Since most of the WWTPs for munici-
pal sewage treatment processes are not designed to remove
heavy metals which can cause secondary environmental
pollution (Cantinho et al. 2016), sewage treatment plants
(STP’s) located in Srinagar city discharge their effluents into
Dal Lake, while the sludge generated is being dumped at a
landfill site located close to the foreshore road surrounding
the lake (Figs. 1, 2). Occasionally the sludge is also dumped
along the banks of the lake damaging its aesthetic value
(Lone et al. 2013). Water quality is being a prerequisite for
sustainable water and sanitation in Sustainable Development

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Goal (SDG) no. 6 and is also equally important for many
other SDGs related to health, food security and biodiversity.
Growing population, urbanization and change in lifestyle
have resulted in increase in the quality as well as volume
of sewage in the cities, thereby having a potential to trigger
nutrient and biological hazards in aquatic systems (Gupta
et al. 2018). The opinion of considering STP’s as ‘end-of
pipe solution’ has changed, and now it is viewed as a flex-
ible treatment system that can provide opportunity of water,
nutrients and energy reuse (Iacovidou et al. 2012). Many
countries have passed legislation regarding use of biosolids
in agriculture which is no longer regarded as waste (Chris-
todoulou and Stamatelatou 2016). Sewage generation of
Srinagar city is estimated to be 170MLD against which the
installed treatment capacity is only 54.2MLD leaving a defi-
cit of about 116 MLD unattended (Qayoom et al. 2020). This
emerging scenario if allowed to remain for a longer period of
time is surely going to change the lake characteristics which
will defeat the purpose of having STPs around Dal Lake.
This is partly due to lack of adequate treatment capacity and
partly due to the efficiency issues of already installed STPs.
In this scenario it was thought worthwhile to conduct the
present study in order to evaluate the heavy metal content in
sewage as well as sludge generated from two WWTPs based
on FAB (fluidized aerobic bioreactor) and SBR (sequential
batch reactor) technologies in Srinagar city. As the receiving
water body, i.e., Dal Lake, is a source of food and water for
a large proportion of local population, this study will offer
some insights on the efficiency of the STPs and also the haz-
ards associated with heavy metal which has every potential
to change the lake ecology.
Materials and methods
Description of study area
The study was conducted at Hazratbal
(34 °08ʹ06ʺN–74 °50ʹ29ʺE) and Nallah Amir Khan (34°06
ʹ49.4ʺN–074 °49ʹ36.4ʺ) STP’s based on FAB (7.5 MLD)
Fig. 1 Location of various STP’s and landfill site around Dal Lake in Kashmir Valley

1 3
and SBR (5.4MLD) technologies, respectively. Sludge gen-
erated during wastewater treatment in these STP’s is col-
lected with the help of sludge sumps and directed toward
sludge thickeners which increase its consistency. Dewater-
ing polyelectrolyte (DWP) is also added which removes
excess water from sludge after which it is disposed in the
landfill site. These STPs have been commissioned around
Dal Lake with an aim to treat the sewage generated within
the city prior to its subsequent discharge into the lake. Dal
Lake (34°5ʹ–34°9 ʹ N and 74°49ʹ–74°53ʹ E) is an urban lake
located in the northeast of Srinagar with an area of about
24 km2
(Rashid et al. 2017). Being one of the most well-
recognized tourist spot throughout the world, Dal Lake is
very popular due to the presence of houseboats and shikara
boats within the lake. For nearly a century these houseboats
have attracted the attention of millions of tourists through-
out the world (Yousuf and Ali 2018). These houseboats act
merely as hotels for many tourists who reside in them, while
many others prefer to enjoy shikar ride in the lake. Tourist
inflow to the lake is quite large and a source of revenue for
the state as well as local population. Besides, many ecosys-
tem services like vegetables, fish, drinking water, livelihood,
recreation, culture value and aesthetics are obtained from the
lake (Kawoosa 2017; Nengroo et al. 2017; Khanday et al.
2018; Dar et al. 2020c). Thus the lake has great socioeco-
nomic importance for the people of Srinagar city.
Sampling and analysis
Samples were collected over a period of two years, once
during the summer of 2017 and once during winter of 2018.
Sampling of sewage was done at the inlet and outlet of both
the STP’s in clean plastic bottles while sludge samples were
collected in clean polyethylene bags and brought to the labo-
ratory for further analysis. Acid digestion of sludge was done
using the method given in USEPA (2012). Sludge samples
were air-dried and crushed using mortar and pestle to obtain
smaller fractions which were sieved using a mesh size of
2 mm. The process of crushing and sieving was repeated
until fine powder of sludge was obtained and larger impuri-
ties like pebbles, etc., were separated. For acid digestion 1
gm of powdered sludge was added with 10 ml of 1:1
HNO3
and refluxed (10–15 min) at 95 °C. After cooling 5 ml of
concentrated HNO3 was added and refluxed (30 min) till no
brown fumes were generated. Heating was continued (2 h)
and prior to cooling the samples were added with 2 ml water
and 3 ml of 30%
H2O2 which was kept adding in 1 ml of
aliquots upto a maximum of 10 ml, and again sample was
heated (2 h). After peroxide digestion samples were cooled
and 10 ml of HCl was added to them and heated slowly
(15 min). Digested samples after cooling were filter through
a 0.45-µm filter, transferred to a volumetric flask and raised
to 50 ml with deionized water. Acid digestion of sewage was
done as per nitric acid-sulfuric acid digestion method given
in APHA (2005). To 50 ml of sewage sample, 5 ml of conc.
HNO3 was added and slowly boiled on a hot plate till it was
evaporated to 15–20 ml. After this 5 ml conc.
HNO3 and
10 ml conc.
H2SO4 were added, cooling the flask between
additions. Evaporation was continued till dense white fumes
of SO3 started appearing and solution became clear. The
samples were cooled and raised upto 50 ml with deionized
water. For calibration, working standards of the metals to be
analyzed were prepared freshly by diluting the stock solu-
tion. For quality control, blank and replicates were used in
order to assess the precision and bias during the analysis.
Metals like cadmium (Cd), iron (Fe), lead (Pb), zinc (Zn),
Fig. 2 a–c Landfill site near foreshore road around Dal Lake in Srina-
gar city of Kashmir

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chromium (Cr), aluminum (Al) and copper (Cu) were ana-
lyzed on flame mode, while mercury (Hg) and arsenic (As)
were analyzed on graphite mode using Atomic Absorption
Spectrophotometer (AAS-800) PerkinElmer, USA.
Physico-chemical parameters of sewage were analyzed
monthly for a period of one year from June 2017 to May
2018, and analysis was carried out as per the standard meth-
ods given in APHA (2005). In situ measurements of water
temperature (WT), pH, conductivity (EC), total dissolved
solids (TDS) were carried out with a multi-parameter probe
(Eutech PCSTEST35-01 × 441,506) calibrated with stand-
ard solutions. Turbidity was determined by microprocessor
turbidity meter (Labtronics). Physico-chemical parameters
that were analyzed by titrimetric method included: total
alkalinity (TA)–phenolphthalein, chloride
(Cl−
)–argento-
metric, free carbon dioxide (FCD)–titrimetric, total hard-
ness (TH), calcium hardness (CaH) and magnesium hardness
(MgH)–EDTA titrimetric and dissolved oxygen (DO)–Win-
kler Azide modification. The parameters that were ana-
lyzed spectrophotometrically using Motras Scientific, UV
Visible Spectrophotometer, include: ammonical nitrogen
(NH3-N)–phenate method, nitrite nitrogen
(NO2-N)–sul-
fanilamide, nitrate nitrogen
(NO3-N)–salicylate method,
total phosphorus (TP) and ortho phosphate phosphorus
(PO4
2—
P)–ascorbic acid method, sulfate
(SO4
−2
)–turbi-
dimetric method, silicate–molybdosilicate and total iron
(Fe)–phenanthroline method, chemical oxygen demand
(COD) was determined by open reflux method, while
CBOD5 (carbonaceous biochemical oxygen demand) was
determined by five-day incubation method. Univariate (cor-
relation matrix and one-way ANOVA) statistical analysis
was performed on the data using statistical software Minitab
18, and multivariate statistical technique, i.e., PCA (princi-
pal component analysis), was carried out using R software
(R Core Team 2013).
Health risk assessment (HRA)
HRA was used to estimate potential health risks caused by
contaminants present in environment (Mckenzie et al. 2012)
using risk assessment methods given by USEPA (1989,
2001). In order to estimate the exposure of humans toward
the containments (USEPA 1997) average daily dose (ADD)
via inhalation, ingestion and dermal pathways were calcu-
lated using the following equations:
ADD (ingest) =
C × IRingest × EF × ED
BW × AT
× CF
ADD(inhale) =
C × InhR × EF × ED
PWF × BW × AT
× CF
The values of various parameters used in the above
equations are given in Table 1
Non-carcinogenic (Cu, Zn, Hg, Pb and Cr) risk of indi-
vidual heavy metals was computed by means of hazard
quotient (HQ), while cumulative non-carcinogenic risk of
all heavy metals via all pathways was expressed as haz-
ard index (HI) (Li et al. 2014; Arnous and Hassan 2015;
Praveena et al. 2015; Pan et al. 2016) using the following
equations:
where reference dose values (RfD mg.
kg−1
.d−1
), i.e., maxi-
mum acceptable concentration of heavy metals which pos-
sess no harm on human health, are: 0.004 (Cu), 0.300 (Zn),
0.0001 (Hg), 0.038 (Pb) and 0.005 (Cr) (USEPA 2002).
Carcinogenic risk (CR) of As and Cd (Li et al. 2014;
Yang et al. 2014a, b) was calculated using the following
equation:
where slope factor (SF kg.d.mg−1
) is the dose at which
humans could get cancer and its values for As and Cd are
1.5 and 6.1, respectively (USEPA 2002).
ADD (dermal) =
C × SA × AFsi ABS × EF × ED
BW × AT
× CF
HQ =
ADD
RfD
HI
∑
HQ
CR = ADD × SF
Table 1 Parameters and their values used for estimation of ADD via
ingestion, inhalation and dermal route (USEPA 2002)
Parameter Symbol Unit Value
Mean concentration of
heavy metals in the
sludge sample
C mg kg−1
–
Ingestion rate of heavy
metals
IRingest mg/day 100 (adults)
Exposure frequency EF days year−1
350
Exposure duration ED years 24 (adults)
Average body weight BW kg 62.65
Average time AT days 8760 non-cancer
25,550 for cancer
Conversion factor CF kg/mg 1 × 10−6
Inhalation rate of heavy
metals
InhR m3
. day−1
20m3
.day−1
(adults)
Particle emission factor PEF m3
.kg−1
1.36 × 109
m3
/kg
Surface area of the skin SA cm2
/event 5700
Skin adherence factor AFsoil mg/cm2
0.07
Dermal absorption
factor
ABS mg/cm2
0.001 (non-cancer)
0.03 (for cancer)

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Results and discussion
Sewage and sludge
Among various heavy metals found in sewage As, Cd,
Cr, Cu, Hg, Pb and Zn are considered potentially toxic.
Their high concentration can cause acute or chronic health
effects in humans and carcinogenicity, bioaccumulation
and phytotoxicity in plants (EC 2001). Fe reported high-
est concentration in sewage due to its extensive use in
several household substances like food contents, food col-
oring agents, iron and steel products, pipes, paints and
cosmetic items (Tjadraatmadja and Diaper 2006 and Riaz
et al. 2020) besides combined sewer systems receive run-
off containing Fe as one of the abundant elements in the
environment (Lester 1987). Pb appeared second highest
after Fe resulting from old pipelines of water and sewer-
age conducts (Meinzinger and Oldenburg 2009). This was
followed by Al which was contributed mainly from food
additives, drinking water, aluminum foil, aluminum cook-
ware, cans and ceramics (Baby et al. 2010). In addition to
this, Al in the present study is derived from the use of poly
aluminum chloride (PAC) meant for phosphorus removal
during wastewater treatment. Approximately 40 kg of PAC
is added to the wastewater per day which becomes a sig-
nificant source of Al in the receiving water body. Al is
considered as extremely toxic metal for plants, animals
and humans. Several toxic metals like Pb, Al, Cu, Hg and
As are linked to major neurological diseases in humans
like Parkinson’s disease and Alzheimer’s disease (Gorell
et al. 1999; Ashok et al. 2015; Cabral Pinto et al. 2015;
Ahlskog 2016). Exposure toward Al has been found to be
responsible for brain aging (Bondy 2014). High concentra-
tion of Al in the lake can result in osmoregulatory failure
in aquatic animals like fishes (Rosseland et al. 1990). It
has the potential to bind with fish gills causing several
kinds of diseases, suffocation and ultimately death (Exley
et al. 1991), change in blood plasma levels and decrease in
nutrient intake at gills (Nilsen et al. 2010). Heavy metals
tend to accumulate more in the sediments as compared
to water column (Tuikka et al. 2011). More than 90% of
heavy metals in aquatic environment are being retained by
suspended solids and sediments (Zahra et al. 2014). More
residence time of water in lakes results in the accumula-
tion of heavy metals in biota (Yang et al. 2018), while a
significant portion finds its way into the sediments (Varol
2011). Cd and Cr are added to wastewater from household
cleaning agents, feces, food products, washing of metal-
lic utensils and stainless steel (Sorme and Lagerkvist
2002; Van de Velden et al. 2008 and Houhou et al. 2009).
Besides washing powders and detergents use phosphates as
softeners containing Cd as an impurity (Comber and Gunn
1996; Jenkins 1998). Similarly, tap water, food, detergents,
personal care products and plumbing are the main sources
of Cu and Zn in WWTP (Ustun 2009; Houhou et al. 2009
and Rule et al. 2006). Hg was present in less concentration
and its source in wastewater is thermostats, thermometers
and dental amalgam (Omura et al. 1996; O Brien 2001 and
Baby et al. 2010). Least concentration was recorded by As
which is added from medicines, glass, washing products,
paints and pigments (Jenkins and Russell 1994; Thornton
2001; Tjadraatmadja and Diaper 2006 and Ismail et al.
2013). Heavy metals like Cd, Pb and Hg are found to be
more toxic toward humans and animals, while Cu and Zn
manifest there harmful effects more in plants (Latosinska
et al. 2021). Prolonged exposure toward As, Cd and Pb can
cause several forms of cancer (Zhou 2015), developmen-
tal and neurological disorders in humans (Iwegbue et al.
2016; Massadeh et al. 2017). Long-term exposure to Cu
can lead to lung cancer (Luo et al. 2019; Ren et al. 2019),
while Cr can cause gastrointestinal disorders and even
death (Janus and Krajnc 1990). Hg has carcinogenic and
neurotoxic properties with ability to accumulate in living
organisms which gradually increase in food web (Watras et
al. 1998; Jardine et al. 2013). Cd is ubiquitous and persis-
tent in environment (García-Esquinas et al. 2020) which
has been recognized as a carcinogen with several health
risk (Wallace and Djordjevic 2020). Heavy metals being
high-risk pollutants have detrimental impacts on human
health (Tan et al. 2020). Several studies suggest that they
contribute in carcinogenesis by inducing tumors (Wallace
and Djordjevic 2020). Due to the absence of industries in
the region low concentration of heavy metals was observed
which was contributed entirely from the domestic sources
(Aonghusa and Gray 2002; Rule et al. 2006; Sun et al.
2009; Cheng et al. 2014). Concentration of metals in the
influent of FAB and SBR followed the order: Fe > Pb >
Al > Cd > Cr > Zn > Cu > Hg > As. ANOVA displayed
insignificant variation in the concentration of heavy met-
als (sewage and sludge) between both the seasons. While
most of the heavy metals displayed insignificant reduc-
tion between raw and effluent, significant reduction was
recorded in case of Zn due to its absorption on oxides,
organics and residual portion (Brummer 1986), resulting
in its reduction from the effluent. Significant reduction in
the concentration of Fe and Cu in the effluent was due to
their use by microorganisms for carrying out their activi-
ties and functions (Chanpiwat 2008) (Table 2).
Removal of metals from the wastewater is mostly
because of their partitioning with the solid phase during
treatment which retains a significant portion of metals
entering the waste stream (Cantinho et al. 2016). Among
various metals studied Al accumulated highest in sludge,
while Hg and As accumulated least (Fig. 3). The use of

1 3
PAC in WWTP’s yield sludge rich in Al referred as poly
aluminum water treatment sludge. Although concentration
of Zn was low in sewage, it accumulated in considerable
amount in sludge due to its occlusion and co-precipitation
along with Fe and Al (Rosazlin et al. 2007; Riaz et al.
2020). Moreover, Zn remains absorbed on oxides, organ-
ics and residual portion (Brummer 1986), resulting in its
increased retention in sludge. Similarly, Cu was present
in less concentration in sewage, but due to its affinity with
organic matter (Kabata-Pendias and Pendias, 2002) it
accumulated in considerable amount in sludge. Several
researchers have found it mainly associated with organic
fraction (Kabata-Pendias and Pendias 2002; Rosazlin et al.
2007; Hanay et al. 2008). Pb was second highest metal
present in sewage but accumulated least in sludge due to
the presence of insoluble salts like phosphates resulting
in its immobility (Walker 2003). Besides pH also governs
its distribution in various sections of sewage and sludge
(Sungur et al. 2015). Concentration of various metals in
sludge followed the order: Al > Fe > Zn > Cu > Cr > Pb
> Cd > As = Hg. A similar trend of heavy metals in the
sludge was reported by Tella et al. (2013) and Cheng et al.
(2014). A comparison of our results with studies carried
out in different parts of the world (Table 3) revealed high
concentrations of Cd, As and Hg in the sludge of other
countries as compared to the values obtained in our study.
Concentration of Pb, Cu, Zn and Cr in our study was rela-
tively similar with the values reported in other parts of the
world. Overall, heavy metal concentration varied across
the world due to differences in the characteristics of waste-
water. Among heavy metals Cd, As and Hg are considered
as most toxic metals, and their low values in the present
study are an indication of relatively safe sludge with least
harm on humans or environment.
Physico‑chemical parameters
Analysis of various physico-chemical parameters in the
wastewater provided information regarding the quality of
the effluent produced within the WWTP’s which finds its
way into the Dal Lake. ANOVA of physico-chemical param-
eters revealed significant variation (P < 0.05) in pH, TDS,
TSS, salinity, TA, TH, CH, DO,
CBOD5, COD,
NH3-N, TP
and silicate during treatment. Parameters like TSS, BOD,
NH3-N and TP which are of paramount importance with
regard to the health of receiving water body were exceeding
the discharge standards meant for effluent disposal (Table 4).
High concentration of TSS in the effluent results in several
direct and indirect effects like reduced sunlight penetration,
harmful effects on fish and toxicity from contaminants which
remain adhered to particles (Horner et al. 1994). DO is an
important parameter which indicates health of the water
body. Oxygen demanding wastes deteriorate DO levels in
the receiving water body which effect water quality as well
as biodiversity (Suthar et al. 2010). Further, concentration
of NO3-N in the effluent (FAB, 0.12 mg/l; SBR, 0.22 mg/l)
was higher in comparison with raw (P > 0.05) due to the pro-
cess of nitrification taking place within the treatment facility,
whereby NH3-N is oxidized to
NO3-N (Tallec et al. 2006).
NH3-N and
NO3-N are principal forms of nitrogen (Hurse
and Connor 1999), and in the presence of oxygen
NH3-N is
converted into
NO3-N creating low dissolved oxygen condi-
tions in surface waters (Kurosu 2001; Sabalowsky 1999).
Besides NH3-N is considered toxic for fish and other forms
of aquatic life (CDC, 2002). Phosphorus being an essential
Table 2 Results of ANOVA in FAB and SBR
Values in italics indicates significance; ns indicates non-significant
FAB
Heavy metal Cd Cu Cr Zn Fe Pb Al Hg As
F 8.34 33.92 0.51 1 69.47 1.43 0.98 12.90 0.91
P value 0.10 ns 0.02 0.54 ns 0.42 ns 0.01 0.35 ns 0.42 ns 0.070 ns 0.44 ns
SBR
F 3.42 0.38 0.45 88.36 5.83 9.98 3.24 0.46 0.17
P value 0.206 ns 0.59 ns 0.57 ns 0.01 0.13 ns 0.08 ns 0.21 ns 0.56 ns 0.72 ns
Results of seasonal variation
FAB SBR
Sewage Sludge Sewage Sludge
F 0.23 0.02 0.07 0.03
P value 0.63 ns 0.88 ns 0.79 ns 0.86 ns

1 3
Fig. 3 a–j Concentration of heavy metals at inlet and outlet of both STP’s during summer of 2017 and winter of 2018

1 3
constituent of living organisms remains in balance under
natural conditions. Many problems like eutrophication occur
when input of phosphorus is higher than the required amount
which living organisms can assimilate (Rybicki 1997).
NO3-N along with phosphorus are referred as nutrients
which are linked with the process of eutrophication which
is known to occur in inland water bodies. Extensive algal
growth (Department of Natural Science 2006), destabilized
Table 3 Concentration of heavy metals in sludge of various countries of the world
Cd Pb Cu Zn Cr Ni Mn As Hg
Present study 0.55 37 346 1674 65 – – 0.14 0.151
Pakistan 1.88 61.31 – – 3150.1 – – 8.11 – Riaz et al. 2020
Italy 1.357 70.69 456.6 1260.8 39.58 31.21 – – 0.58 Rizzardini et al. 2014
Iran 4.1 169 330 1908 213 110 – – – Nafez et al. 2015
Portugal 1.0 < 5.6 140.8 757.2 < 5.6 22.6 – – < 1.3 Alvarenga et al. 2015
Brazil 1.6 26.3 202 690 260 54.6 – – – Moretti et al. 2016
Egypt 4.0 750.0 538.0 1204.0 – 81.0 – – – Ashmawy et al. 2012
Japan 73.02 122.14 415.00 750.65 150.18 638.56 – – – Shi et al. 2013
France 0.60 19.7 149 548 27.6 26.4 – – – Tella et al. 2013
Poland 3.5 167.8 216.4 1477.6 44.5 23.5 – – 0.8 Tüfenkçi et al. 2006
Turkey 0.55 – 198 860 30.6 38.5 390 – – Latare et al.2014
Spain – 26.44 – 544.01 24.10 8.04 – – – Hernández–Sánchez et al. 2017
China 3.88 112.2 499.1 2088 259.2 166.9 – 25.23 3.18 Yang et al. 2014a, b
Venezuela 6.8 304.29 226.01 1474.79 72.81 76.46 – – – Garcia et al. 2006
Tunisia 3.3 325 278 410 52 44 – – – Achiba et al. 2009
Greece 1.2 191 599 729 134 – – – – Manios et al. 2003
Austria 0.82 38.3 166 683 30.6 25.6 – – – Sager 2007
India 16 340.5 1434.5 2164 – 168 – – – Kandpal et al. 2004
Malaysia 8 10 80 200 500 – – – – Haroun et al. 2009
Table 4 Mean values of various physico-chemical parameters in raw and treated effluent during June 2017 to May 2018 along with statistical
analysis
FAB P value SBR P value Discharge
standards
Raw Treated Raw Treated
pH 6.63 ± 0.32 7.26 ± 0.26 0.000 6.99 ± 0.34 7.21 ± 0.34 0.000 5–9
EC ( µScm−1
) 806.33 ± 83.73 751.33 ± 84.84 0.08 ns 1004.50 ± 97.73 978.58 ± 91.65 0.18 ns –
TDS (mg/l) 595.08 ± 62.57 547.00 ± 63.31 0.011 736.67 ± 71.59 714.67 ± 70.59 0.208 ns –
TSS (mg/l) 468.83 ± 69.13 245.58 ± 63.97 0.000 364.92 ± 118.71 163.92 ± 69.40 0.000 100
Salinity (mg/l) 375.92 ± 53.40 331.58 ± 51.22 0.018 505.75 ± 43.40 485.67 ± 46.33 0.227 ns –
Cl (mg/l) 44.33 ± 11.80 37.58 ± 13.17 0.456 ns 55.67 ± 16.07 50.25 ± 16.37 0.265 ns –
TA (mg/l) 29.25 ± 3.62 23.92 ± 4.83 0.000 35.17 ± 3.74 31.00 ± 1.35 0.000 –
TH (mg/l) 279.53 ± 47.85 245.32 ± 37.56 0.001 357.07 ± 62.25 336.28 ± 59.02 0.087 ns –
CH (mg/l) 140.70 ± 33.39 115.59 ± 31.95 0.018 160.37 ± 35.80 141.80 ± 34.14 0.064 ns –
MH (mg/l) 141.43 ± 47.80 125.45 ± 41.16 0.747 ns 196.81 ± 50.93 182.78 ± 50.59 0.506 ns –
DO (mg/l) 0.13 ± 0.46 3.79 ± 0.85 0.00 0.00 4.31 ± 1.31 0.00 –
CBOD5 (mg/l) 118.75 ± 5.59 52.33 ± 13.81 0.000 120.75 ± 6.66 48.58 ± 6.05 0.000 40
COD (mgO2/l) 156.67 ± 16.70 109.17 ± 14.43 0.000 146.67 ± 14.35 110.00 ± 18.59 0.000 120
NH3–N (mg/l) 4.14 ± 0.62 1.83 ± 0.90 0.000 3.76 ± 0.91 2.58 ± 0.80 0.000 1
NO3–N (mg/l) 0.12 ± 0.04 0.12 ± 0.07 0.625 ns 0.17 ± 0.05 0.22 ± 0.06 0.381 ns 10
TP (mg/l) 3.13 ± 0.66 1.66 ± 0.46 0.000 2.49 ± 0.88 1.92 ± 0.79 0.040 1
SO4
−2
(mg/l) 237.09 ± 51.47 189.77 ± 53.90 0.023 251.33 ± 79.36 231.21 ± 82.15 0.405 ns –
Silicate (mg/l) 23.43 ± 3.21 14.18 ± 2.33 0.000 21.73 ± 2.81 17.51 ± 3.43 0.000 –

1 3
aquatic ecosystem (Morrison et al. 2001), change in physical
and chemical properties of water (Indira and Sivaji, 2006;
Krishnan et al. 2007a, b), creation of de-oxygenated dead
zones (Corcoran et al. 2010), deterioration of economic ser-
vices and impairing of aesthetic values (Igbinosa and Okoh
2009) are some of the hazards of disposing partially treated
sewage in water bodies.
Health risk assessment
Results of ADD intake of heavy metals via ingestion, inhala-
tion and dermal routes along with the values of non-carci-
nogenic and carcinogenic risk are presented in Tables 5 and
6. HQ and HI are an indication of non-carcinogenic risk
or chronic toxicity due to exposure to heavy metals (Duan
et al. 2017). Values > 1 indicate chances of non-carcinogenic
effect on humans, while values < 1 are an indication of safer
levels. However, our findings revealed that the heavy metals
in sludge of FAB and SBR do not pose any non-carcinogenic
risk to the human health since the values of HQ and HI
were < 1. Similarly carcinogenic risk depicts the possibility
of individual to develop cancer over a lifetime due to expo-
sure to some cancer-inducing substances (EPA 2016). For
a single metal the range for CR set by EPA is 1 ×
10–4
to
1 × 10–6
. Values < 1 × 10–6
depict inconsequential cancer
risk, while values > 1 × 10–4
are considered unacceptable and
none of the sludge samples from the STP’s were exceeding
the set standard. The acceptable level for sum of all heavy
metals via all exposure pathways is 1 ×
10–5
which was not
surpassed by any of the two heavy metals, i.e., Cd and As
in FAB (4.63 × 10–6
) as well as SBR (3.79 ×
10–6
). Several
studies suggest that some heavy metals are carcinogenic or
contribute in carcinogenesis by inducing tumors (Wallace
and Djordjevic 2020). Prolonged exposure to heavy metals
like As and Cd causes several forms of cancer (Zhou 2015)
including skin cancer (Tseng et al. 1968), lung cancer (Obiri
et al. 2010), developmental and neurological disorders in
humans (Iwegbue et al. 2016; Massadeh et al. 2017). Cd
is ubiquitous (García-Esquinas et al. 2020) and persistent
in environment which has been recognized as a carcinogen
with several health risks (Wallace and Djordjevic 2020;
Kumar et al. 2021b). Prolonged exposure of humans toward
Table 5 ADD values of heavy
metals in sludge
FAB HQ dermal SBR HQ dermal
ADD ingest ADD inhale ADD ingest ADD inhale
Cu 5.77 × 10–4
8.48 × 10–14
0.2 × 10–5
4.82 × 10–4
7 × 10–14
0.1 × 10–5
Cr 1.06 × 10–4
1.55 × 10–14
0.04 × 10–4
9.5 × 10–5
1.3 × 10–14
0.03 × 10–4
Zn 2.6 × 10–3
3.83 × 10–13
1 × 10–5
2.51 × 10–3
3.6 × 10–13
1 × 10–5
Fe 6.06 × 10–3
8.91 × 10–13
2.4 × 10–5
6.51 × 10–3
9.5 × 10–13
2.5 × 10–5
Pb 5.7 × 10–5
0.8 × 10–14
0.02 × 10–4
5.6 × 10–5
0.8 × 10–14
0.02 × 10–4
Al 6.18 × 10–3
9.09 × 10–13
2.4 × 10–5
6.51 × 10–3
9.5 × 10–13
2.5 × 10–5
Hg 2 × 10–7
2 × 10–8
8 × 10–9
2.6 × 10–7
3 × 10–8
1 × 10–9
As 7 × 10–8
1.1 × 10–8
9 × 10–9
6 × 10–8
1 × 10–8
8 × 10–9
Cd 6.5 × 10–7
5 × 10–8
4 × 10–8
4.5 × 10–7
3 × 10–8
2 × 10–8
Table 6 Values of non-carcinogenic and carcinogenic risk of heavy metals
FAB SBR
HQ ingest HQ inhale HQ dermal HI HQ ingest HQ inhale HQ dermal HI
Cu 1.44 × 10–1
2.12 × 10–11
1.6 × 10–4
1.44 × 10–1
1.2 × 10–1
1.7 × 10–11
0.8 × 10–4
1.2 × 10–1
Cr 2.12 × 10–2
3.10 × 10–12
5.33 × 10–2
7.45 × 10–2
1.9 × 10–2
2.6 × 10–12
4 × 10–1
4.19 × 10–1
Zn 0.8 × 10–2
1.2 × 10–12
– 8 × 10–3
0.8 × 10–2
1.2 × 10–12
– 8 × 10–3
Pb 1.5 × 10–3
2.1 × 10–13
3.8 × 10–3
5.3 × 10–3
1.4 × 10–3
2.1 × 10–13
3.8 × 10–3
5.2 × 10–3
Hg 2.0 × 10–3
2.0 × 10–4
2.6 × 10–5
2.22 × 10–3
2.6 × 10–3
3.0 × 10–4
3.3 × 10–6
2.9 × 10–3
HI 2.34 × 10–1
5.55 × 10–1
FAB SBR
RISK ingest RISK inhale RISK dermal CR RISK ingest RISK inhale RISK dermal CR
Cd 3.96 × 10–6
3.05 × 10–7
2.44 × 10–7
4.5 × 10–6
2.74 × 10–6
1.83 × 10–7
1.22 × 10–7
3.04 × 10–6
As 1.05 × 10–7
1.65 × 10–8
1.35 × 10–8
1.35 × 10–7
6.75 × 10–7
4.5 × 10–8
3 × 10–8
7.5 × 10–7
CR 4.63 × 10–6
3.79 × 10–6

1 3
Cd can cause irritation of upper respiratory tract, metallic
taste in the mouth, cough and chest pains (Foulkes 1990;
Shakah and Smith 1976). Elevated levels of Cd in human
body can cause toxicity to kidney, skeletal system, hyperten-
sion and cardiovascular disease (Obiri et al. 2010). Being
one of the most toxic heavy metals Pb ingestion via food
chain caused potential hazards in humans and its elevated
levels in blood affects postnatal growth, behavior and cogni-
tive performances. In adults it causes central nervous sys-
tem, cardiovascular, fertility and kidney problems (Kumar
et al. 2020a).
Statistical analysis
PCA was carried out on heavy metal data set and PCs
(principal components) with eigen values greater than one
were retained. First PC alone contributed to maximum
variance, i.e., 96.837%, while the second PC was associ-
ated with least variance, i.e., 2.479%. A biplot comprises
of overlaid scores and loadings along with variables and
samples on the same figure. Summer samples of sludge,
i.e., FABsS and SBRsS, represented maximum variability
and were positioned close to correlation circle followed
by SBRsW and FABsW. This was due to more wastewater
generation during summer as compared to winter, resulting
in more accumulation of metals in sludge. The results are
in agreement with García-Delgado et al. (2007) in WWTP
of Spain. FABsS was characterized by Cu and As, while
SBRsW and FABsW were characterized by Cd, Cr, Pb,
Fe, Zn and Al. Similarly, SBRsS was characterized by Hg
(Fig. 4). Correlation matrix displayed the effect of some
water quality parameters on the availability of heavy met-
als in wastewater. A negative correlation heavy metals
were observed with EC, TDS and salinity in FAB, while
a negative correlation of heavy metals was observed with
salinity in SBR. High concentration of ions in the solution
has an inhibitory effect on the concentration of metals in
solid phase. Increase in amount of suspended solids results
in the decrease in concentration of heavy metals as a result
of their uptake by solid particulates (Huang and Wang
2001). However, a positive correlation of hardness with
heavy metals was observed in both the WWTP (Tables 7
and 8) due to the presence of certain dissolved metals con-
tributing to hardness (Sengupta 2013).
Fig. 4 Biplot, scree plot and PC loading of heavy metals from sewage treatment plants

1 3
Metal concentration was low and within the discharge
standards meant for disposal in inland water body in the case
of sewage and for agriculture application in case of sludge
(Table 9). Yet their impact even in lower concentration in
sewage and sludge and that of exceeding key parameters for
effluents should be a worry because of toxicity levels which
can interfere with ecological processes of the lake, thereby
affecting well-being of the society from the public health
perspective. Nowadays heavy metal contamination of soil
has become a key priority for researchers globally due to
Table 7 Correlation matrix (Pearson) among various parameters of wastewater and heavy metals in FAB STP
Values in italics are different from 0 with a significant alpha level = 0.05 for “*” and 0.01 for “**”
Cd Cr Cu Zn Fe Pb Al Hg As
pH –0.415 – 0.503 – 0.534 – 0.444 – 0.429 – 0.565 – 0.411 – 0.366 – 0.541
EC – 0.963** – 0.94** – 0.867 – 0.951** – 0.959** – 0.943** – 0.964** – 0.97** – 0.857*
TDS – 0.883* – 0.835* – 0.759 – 0.864* – 0.875* – 0.809* – 0.885** – 0.9** – 0.747
TSS – 0.279 – 0.197 – 0.129 – 0.25 – 0.266 – 0.141 – 0.283 – 0.319 – 0.117
Salinity – 0.929** – 0.884** – 0.815 – 0.913** – 0.923** – 0.859* – 0.931** – 0.943** – 0.803*
Cl – 0.325 – 0.322 – 0.386 – 0.346 – 0.328 – 0.202 – 0.328 – 0.296 – 0.387
TA 0.034 0.113 0.111 0.049 0.042 0.216 0.029 0.007 0.118
TH 0.853* 0.92** 0.955 0.885** 0.865* 0.914** 0.851* 0.798* 0.959**
DO – 0.284 – 0.377 – 0.412 – 0.314 – 0.298 – 0.446 – 0.279 – 0.235 – 0.421
CH 0.403 0.401 0.472 0.423 0.411 0.329 0.403 0.375 0.472
MH 0.582 0.648 0.629 0.598 0.587 0.699 0.579 0.548 0.632
NH3– N (mg/l) 0.089 0.185 0.298 0.137 0.108 0.191 0.085 0.021 0.311
NO3– N (mg/l) – 0.297 – 0.204 – 0.075 – 0.249 – 0.28 – 0.229 – 0.3 – 0.363 – 0.058
TP – 0.413 – 0.342 – 0.284 – 0.389 – 0.401 – 0.279 – 0.416 – 0.442 – 0.273
BOD – 0.017 0.082 0.189 0.029 0.003 0.101 − 0.021 − 0.08 0.202
COD 0.213 0.291 0.189 0.237 0.226 0.361 0.208 0.174 0.328
SO4
−2
(mg/l) − 0.616 − 0.562 − 0.474 − 0.591 − 0.605 − 0.539 − 0.619 − 0.644 − 0.463
Silicate 0.414 0.507 0.575 0.454 0.431 0.536 0.41 0.352 0.585
Table 8 Correlation matrix (Pearson) among various parameters of wastewater and heavy metals in SBR STP
Values in italics are different from 0 with a significant alpha level = 0.05 for “*” and 0.01 for “**”
Cd Cr Cu Zn Fe Pb Al Hg As
pH – 0.713 – 0.791 – 0.647 – 0.755 – 0.721 – 0.761 – 0.723 – 0.75 – 0.667
EC – 0.324 – 0.236 – 0.324 – 0.306 – 0.324 – 0.333 – 0.321 – 0.314 – 0.331
TDS – 0.52 – 0.438 – 0.519 – 0.496 – 0.519 – 0.477 – 0.517 – 0.504 – 0.526
TSS – 0.428 – 0.337 – 0.437 – 0.398 – 0.425 – 0.26 – 0.425 – 0.405 – 0.44
Salinity – 0.92** – 0.865 – 0.932** – 0.866* – 0.915** – 0.8* – 0.914** – 0.873* – 0.934**
Cl – 0.358 – 0.375 – 0.43 – 0.27 – 0.345 – 0.146 – 0.346 – 0.271 – 0.404
TA – 0.191 – 0.203 – 0.186 – 0.185 – 0.193 – 0.327 – 0.189 – 0.188 – 0.19
TH 0.932** 0.965 0.888** 0.939** 0.935** 0.905** 0.936** 0.939** 0.904**
DO – 0.18 – 0.241 – 0.095 – 0.26 – 0.194 – 0.478 – 0.192 – 0.257 – 0.123
CH 0.489 0.572 0.455 0.508 0.492 0.462 0.495 0.502 0.462
MH 0.692 0.639 0.663 0.688 0.695 0.749 0.692 0.695 0.679
NH3-N (mg/l) 0.873* 0.92 0.782 0.934** 0.883* 0.908** 0.886** 0.93** 0.813*
NO3-N (mg/l) – 0.373 – 0.356 – 0.281 – 0.453 – 0.387 – 0.546 – 0.386 – 0.454 – 0.316
TP – 0.526 – 0.438 – 0.533 – 0.492 – 0.524 – 0.499 – 0.521 – 0.5 – 0.538
BOD – 0.033 0.057 – 0.149 0.093 – 0.014 0.287 – 0.013 0.085 – 0.114
COD 0.44 0.512 0.33 0.537 0.456 0.696 0.456 0.533 0.366
SO4
−2
(mg/l) – 0.601 – 0.509 – 0.628 – 0.543 – 0.596 – 0.547 – 0.592 – 0.553 – 0.626
Silicate 0.076 0.168 − 0.013 0.166 0.09 0.354 0.09 0.16 0.013

1 3
health hazards associated with it. Heavy metals even at low
concentrations enter food chain and manifest its effects in
humans (Kumar et al. 2020b). Humans are exposed to heavy
metals mostly via food consumption, which constitute 90%
of metal intake (Ametepey et al. 2018; Pajevic et al. 2018).
Several kinds of food obtained from the lake like Schizo-
thorax, Carp and Nelumbo stem which are locally known
as “Nadru” are among the relished foods in Kashmir. Con-
sumption of food from the lake contaminated with heavy
metals can threaten food security and health of the com-
munity as a whole. Thus, there is an urgent need to frame a
management strategy for sludge generated from the STP’s
which will ensure its proper handling and usage. Mainly,
WWTP operators and transporters are exposed to the associ-
ated health risks of sludge and should be well versed to deal
with it. Public perception especially those of farmers has an
important role in utilization of sludge in agriculture. It is
usually discarded as a harmful waste which has originated
from excreta without considering the benefits it could pro-
vide and requires a change in perception. Being a valuable
organic supplement in agriculture its effective utilization can
be very beneficial for farmers and will also provide eco-
nomic assistance to the concerned authorities by providing
the cost involved in its transportation. Further, there is a
need to determine the optimum rate of sludge application
so as to prevent accumulation of heavy metals in soil as
well as plants.
Conclusion
Some of the critical parameters like TSS, BOD,
NH3-N
and TP were exceeding the standards in both the STP’s
which has every potential to change the Dal Lake ecol-
ogy and endangers the public health on a long-term basis.
A considerable portion of heavy metals like Pb, Zn and
Cu gets accumulated in the sludge irrespective of their
concentration in sewage. Concentration of heavy metals
in sewage in both the STPs was found to be within the set
limits. It was found to be suitable for agricultural applica-
tion with least non-carcinogenic or carcinogenic risk to
humans. Being directly linked with supply chain of food
and water, a new line of research is urgently needed to
evaluate comprehensively the impact of likely buildup of
Al in various compartments of the Dal Lake like water,
sediment, plants, fish, etc. The continuous use of alu-
minum on long-term basis in STPs can lead to aluminum
toxicity of Dal Lake biota.
Acknowledgements The authors are highly thankful to the Department
of Environmental Science, University of Kashmir, for providing the
necessary laboratory facilities, and the first author also acknowledges
financial assistance through University Research Scholarship scheme to
carry out this research work. Thanks are also to USIC (University Sci-
ence Instrumentation Centre), University of Kashmir, for the analysis
of heavy metals. The authors are also thankful to Lakes and Waterways
Development Authority (LAWDA), Govt. of Jammu and Kashmir, for
giving permission of sampling from the STP’s.
Author’s contributions Research study was conceived and designed by
second author, while the first author has carried out the sampling in the
field and conducted analysis and survey related to the work under the
guidance of the second author. Third and fourth authors have contrib-
uted in the preparation of the draft manuscript. All the authors equally
contributed in editing, reviewing and approved the final manuscript.
Funding Not applicable.
Declarations
Conflict of interest The authors hereby declare there is no conflict of
interest in the study.
Ethical approval Research ethics stand adhered while submitting the
manuscript.
Consent to publish All the authors approved the manuscript to be
published.
Human and animal rights This article does not contain any studies with
human participants performed by any of the authors.
Table 9 Mean effluent values of various heavy metals in sewage and sludge along with their discharge standards
s Heavy metal Effluent (FAB)
(ppm/ppb*)
Effluent (SBR)
(ppm/ppb*)
Discharge stand-
ards (ppm/ppb*)
Sludge (FAB)
(mg kg−1
d. w)
Sludge (SBR)
(mg kg−1
d. w)
Ceiling concentration limits
(CCL) EPA (mg
kg−1
d. w)
1 Cd 0.05 ± 0.002 0.05 ± 0.009 1.0 0.65 ± 0.07 0.45 ± 0.07 85
2 Cu 0.01 ± 0.001 0.01 ± 0.002 3.0 377 ± 163.7 315 ± 63.6 4300
3 Cr 0.03 ± 0.02 0.03 ± 0.026 2.0 69 ± 12.1 62 ± 7.85 3000
4 Zn 0.02 ± 0.002 0.02 ± 0.002 1.5 1706 ± 196.5 1641 ± 452.5 7500
5 Fe 0.02 ± 0.006 0.16 ± 0.098 – 3959 ± 215.6 4255 ± 243.9 –
6 Pb 0.06 ± 0.024 0.20 ± 0.007 1.0 37.4 ± 3.1 36.7 ± 2.12 840
7 Al 0.07 ± 0.007 0.07 ± 0.002 – 4041 ± 86.9 4257 ± 287.7 –
8 Hg 0.01 ± 0.002* 0.01 ± 0.007* 0.01* 0.132 ± 0.01 0.171 ± 0.04 57
9 As 0.01 ± 0.003* 0.01 ± 0.004* 0.2* 0.15 ± 0.07 0.13 ± 0.02 75

1 3
Data availability The data sets generated during and/or analyzed dur-
ing the current study are available from the corresponding author on
reasonable request.
References
Achiba WB, Gabteni N, Lakhdar A, Du Laing G, Verloo M, Jedidi
N, Gallali T (2009) Effects of 5-year application of municipal
solid waste compost on the distribution and mobility of heavy
metals in a Tunisian calcareous soil. Agric Ecosyst Environ
30(3–4):156–163. https://doi.org/10.1016/j.agee.2009.01.001
Aguilar MI, Lloréns M, Fernández-Garrido JM, Pérez-Marín AB,
Ortuño JF, Meseguer VF (2020) Heavy metals effect on the het-
erotrophic activity of activated sludge. Int J Environ Sci Technol
12:1–8. https://doi.org/10.1007/s13762-020-02704-1
Ahlskog JE (2016) New and appropriate goals for parkinson disease
physical therapy. JAMA Neurol 73(3):269–270
Ahmad SS, Reshi ZA, Shah MA, Rashid I, Ara R, Andrabi SM (2014)
Phytoremediation potential of Phragmites australis in Hokersar
wetland-a Ramsar site of Kashmir Himalaya. Int J Phytoreme-
diation 16(12):1183–1191. https://doi.org/10.1080/15226514.
2013.821449
Ahmad SS, Reshi ZA, Shah MA, Rashid I, Ara R, Andrabi SM (2016)
Heavy metal accumulation in the leaves of Potamogeton natans
and Ceratophyllum demersum in a Himalayan RAMSAR site:
management implications. Wetlands Ecol Manage 24(4):469–
475. https://doi.org/10.1007/s11273-015-9472-9
Akoto O, Gyimah E, Zhan Z, Xu H, Nimako C (2019) Evaluation of
health risks associated with trace metal exposure in water from
the Barekese reservoir in Kumasi, Ghana. Human Ecol Risk
Assess: Int J. https://doi.org/10.1080/10807039.2018.1559033
Akpor OB, Ohiobor GO, Olaolu DT (2014) Heavy metal pollutants
in wastewater effluents: sources, effects and remediation. Adv
Biosci Bioeng 2(4):37–43. https://doi.org/10.11648/j.abb.20140
204.11
Ali H, Khan E, Ilahi I (2019) Environmental chemistry and ecotoxi-
cology of hazardous heavy metals: environmental persistence,
toxicity, and bioaccumulation. J Chem 35:879
Alvarenga P, Mourinha C, Farto M, Santos T, Palma P, Sengo J, Morais
MC, Cunha-Queda C (2015) Sewage sludge, compost and other
representative organic wastes as agricultural soil amendments:
benefits versus limiting factors. Waste Manage 40:44–52
Ametepey ST, Cobbina SJ, Akpabey FJ, Duwiejuah AB, Abuntori ZN
(2018) Health risk assessment and heavy metal contamination
levels in vegetables from Tamale Metropolis, Ghana. Int J Food
Contam 5(1):1–8
Aonghusa CN, Gray NF (2002) Laundry detergents as a source of
heavy metals in Irish domestic wastewater. J Environ Sci Health,
Part A 37(1):1–6
APHA (2005) American Public Health Association/American Water
Works Association/Water Environment Federation. Standard
Methods for the Examination of Water and Wastewater
21st
edn,
Washington DC, USA.
Arnous MO, Hassan MA (2015) Heavy metals risk assessment in
water and bottom sediments of the eastern part of Lake Man-
zala, Egypt, based on remote sensing and GIS. Arabian J Geosci
8(10):7899–7918. https://doi.org/10.1007/s12517-014-1763-6
Ashmawy AM, Ibrahim HS, Moniem SMA, Saleh TS (2012) Immobi-
lization of some metals in contaminated by zeolite prepared from
local materials. Toxicol Environ Chem 94(9):1657–1669. https://
doi.org/10.1080/02772248.2012.727819
Ashok A, Rai NK, Tripathi S, Bandyopadhyay S (2015) Exposure to
As-, Cd-, and Pb-mixture induces Aβ, amyloidogenic APP pro-
cessing and cognitive impairments via oxidative stress-dependent
neuroinflammation in young rats. Toxicol Sci 143(1):64–80
Ashraj W (2005) Accumulation of heavy metals in kidney and heart
tissues of Epinephelus microdon fish from the Arabian Gulf.
Environ Monit Assess 101(1–3):311–316. https://doi.org/10.
1007/s10661-005-0298-4
Baby J, Raj JS, Biby ET, Sankarganesh P, Jeevitha MV, Ajisha SU,
Rajan SS (2010) Toxic effect of heavy metals on aquatic envi-
ronment. Int J Biol Chem Sci. https://doi.org/10.4314/ijbcs.v4i4.
62976
Bhat SA, Pandit AK (2014) Surface water quality assessment of Wular
Lake, a Ramsar site in Kashmir Himalaya, using discriminant
analysis and WQI. J Ecosyst. https://doi.org/10.1155/2014/
724728
Bondy SC (2014) Prolonged exposure to low levels of aluminum leads
to changes associated with brain aging and neurodegeneration.
Toxicology 315:1–7
Braam F, Klapwijk A (1981) Effect of copper on nitrification in acti-
vated sludge. Water Res 15(9):1093–1098. https://doi.org/10.
1016/0043-1354(81)90077-4
Brummer GW (1986) Heavy metals species, mobility and availabil-
ity in soils. In: Bernard M, Brinckman FE, Sadler PJ (eds) The
importance of chemical speciation in environment processes.
Springer-Verlag, Berlin
Busetti F, Badoer S, Cuomo M, Rubino B, Traverso P (2005) Occur-
rence and removal of potentially toxic metals and heavy metals
in the wastewater treatment plant of Fusina (Venice, Italy). Indus
Eng Chem Res 44(24):9264–9272
Cabral Pinto M, Silva M, Ferreira da Silva EA, Marinho-Reis AP
(2017) The cancer and non-cancer risk of Santiago Island (Cape
Verde) population due to potential toxic elements exposure from
soils. Geosciences 7(3):78
Cabral Pinto M, Marinho-Reis P, Almeida A, Pinto E, Neves O, Inácio
M, Moreira PI (2019) Links between cognitive status and trace
element levels in hair for an environmentally exposed population:
a case study in the surroundings of the estarreja industrial area.
Int J Environ Res Pub Health 16(22):4560
Cabral Pinto M M S, Almeida A, Pinto E, Freitas S, Simões M, Diniz
L et al. (2015) Occupational and environmental exposure to Mn
in manganese mining areas (South Portugal) and the occurrence
of dementia. In 25th Alzheimer Europe Conference “Dementia:
Putting strategies and research into practice” https://hdl.handle.
net/10216/127239
Cai H, Liu J, Kuo J, Buyukada M, Evrendilek F (2019) Thermal char-
acteristics, kinetics, gas emissions and thermodynamic simula-
tions of (co-) combustions of textile dyeing sludge and waste
tea. J Clean Prod 239:118113. https://doi.org/10.1016/j.jclepro.
2019.118113
Cantinho P, Matos M, Trancoso MA, dos Santos MC (2016) Behav-
iour and fate of metals in urban wastewater treatment plants: a
review. Int J Environ Sci Technol 13(1):359–386. https://doi.org/
10.1007/s13762-015-0887-x
CDC (2002) U.S. Toxicity of Heavy Metals and Radionucleotides.
Department of Health and Human Services, Centers for Dis-
ease Control and Prevention. Savannah river-site health effects
subcommittee (SRSHES) meeting: Available from http://www.
cdc.gov/nceh/radiation/savannah/SRSHES_Toxicity_jan0 2.htm.
(Accessed on
6th
March 2020).
Chanpiwat P, Kim KW, Sthiannopkao S. Metal Contents and Its Vari-
ation in Wastewater and Sewage Sludge: A Case Study of Bang-
kok Central Wastewater Treatment Plants. In Proceedings of the
International Symposia on Geoscience Resources and Environ-
ments of Asian Terranes (GREAT 2008), 4th International Geo-
logical Correlation Programme (IGCP) (Vol. 516).

1 3
Cheng M, Wu L, Huang Y, Luo Y, Christie P (2014) Total con-
centrations of heavy metals and occurrence of antibiotics in
sewage sludges from cities throughout China. J Soils Sedim
14(6):1123–1135
Chipasa KB (2003) Accumulation and fate of selected heavy met-
als in a biological wastewater treatment system. Waste Man-
age 23(2):135–143. https://doi.org/10.1016/S0956-053X(02)
00065-X
Christodoulou A, Stamatelatou K (2016) Overview of legislation on
sewage sludge management in developed countries worldwide.
Water Sci Technol 73(3):453–462. https://doi.org/10.2166/wst.
2015.521
Chuan OM, Yunus K (2019) Sediment and organisms as marker for
metal pollution in monitoring of marine pollution. IntechOpen
Comber SDW, Gunn AM (1996) Heavy metals entering sewage-treat-
ment works from domestic sources. Water Environ J 10(2):137–
142. https://doi.org/10.1111/j.1747-6593.1996.tb00023.x
Corcoran E. (Editor), Nellemann, C., Baker, E., Bos, Robert, Osborn
D, Savelli, H (2010) Sick Water? The central role of waste-water
management in Sustainable development. UNEP and UN-HAB-
ITAT. Available at: http://www.unep.org/pdf/SickWater_screen.
pdf. (Accessed on
12th
June 2019)
Cruz-Guzmán M, Celis R, Hermosin MC, Koskinen WC, Nater EA,
Cornejo J (2006) Heavy metal adsorption by montmorillon-
ites modified with natural organic cations. Soil Sci Soc Am J
70(1):215–221. https://doi.org/10.2136/sssaj2005.0131
Cunningham PA, Sullivan EE, Everett KH, Kovach SS, Rajan A, Bar-
ber MC (2019) Assessment of metal contamination in Arabian/
Persian Gulf fish: a review. Mar Pollut Bull 143:264–283
da Silva OA, Bocio A, Trevilato TM, Takayanagui AM, Domingo JL,
Segura-Muñoz SI (2007) Heavy metals in untreated/treated urban
effluent and sludge from a biological wastewater treatment plant.
Environ Sci Pollut Res-Int 14(7):483. https://doi.org/10.1065/
espr2006.10.355
Dar SA, Bhat SU, Aneaus S, Rashid I (2020a) A geospatial approach
for limnological characterization of Nigeen Lake Kashmir Hima-
laya. Environ Monitor Assess 192(2):1–18. https://doi.org/10.
1007/s10661-020-8091-y
Dar SA, Rashid I, Bhat SU (2020b) Land system transformations
govern the trophic status of an urban wetland ecosystem: per-
spectives from remote sensing and water quality analysis. Land
Degrad Develop. https://doi.org/10.22541/au.160071436.64933
166
Dar SA, Bhat SU, Rashid I, Dar SA (2020c) Current status of wetlands
in Srinagar city: threats, management strategies, and future per-
spectives. Front Environ Sci 7:199. https://doi.org/10.3389/fenvs.
2019.00199.24
Dash S, Borah SS, Kalamdhad AS (2021) Heavy metal pollution and
potential ecological risk assessment for surficial sediments of
Deepor Beel India. Ecol Indic 122:107–265
Deng Y, Jiang L, Xu L, Hao X, Zhang S, Xu M, Zhu P, Fu S, Liang
Y, Yin H, Liu X (2019) Spatial distribution and risk assess-
ment of heavy metals in contaminated paddy fields–a case
study in Xiangtan City, southern China. Ecotoxicol Environ Saf
171:281–289
Department of Natural Science (2006) Wastewater characterization
for evaluation of biological phosphorus removal. Available
from www.dnr.state.wi.us/org/water/wm/water/wm/ww/bioph
os//into.htm.
Duan B, Zhang W, Zheng H, Wu C, Zhang Q, Bu Y (2017) Compari-
son of health risk assessments of heavy metals and as in sewage
sludge from wastewater treatment plants (WWTPs) for adults and
children in the urban district of Taiyuan, China. Int J Environ Res
Pub Health 4(10):1194. https://doi.org/10.3390/ijerph14101194
Duruibe JO, Ogwuegbu MOC, Egwurugwu JN (2007) Heavy metal
pollution and human biotoxic effects. Int J Phys Sci 2(5):112–
118. https://doi.org/10.5897/IJPS.9000289
US EPA (2001) Baseline human health risk assessment.VasquezBoule-
vardandI-70 superfund site Denver, Denver (Co).
EC (2001) Commission Regulation No. 466/2001 of 8 March 2001,
Official Journal of European Communities 1.77/1
Exley C, Chappell JS, Birchall JD (1991) A mechanism for acute alu-
minium toxicity in fish. J Theor Biol 151(3):417–428
Farombi EO, Adelowo OA, Ajimoko YR (2007) Biomarkers of oxida-
tive stress and heavy metal levels as indicators of environmental
pollution in African Catfish (Clarias gariepinus) from Nigeria
ogun river. Int J Environ Res Pub Health 4(2):158–165. https://
doi.org/10.3390/ijerph2007040011
Foulkes EC, Blanck S (1990) Acute cadmium uptake by rabbit kidneys:
mechanism and effects. Toxicol Appl Pharmacol 102(3):464–473
García H, El Zauahre M, Morán H, Acosta Y, Senior A, Fernández N
(2006) Análisis comparativo de dos técnicas de digestión para
la determinación de metales pesados en lodos residuales. Multi-
ciencias 6(3): 234–43. https://www.redalyc.org/pdf/904/90460
305.pdf
García-Delgado M, Rodríguez-Cruz MS, Lorenzo LF, Arienzo M,
Sánchez-Martín MJ (2007) Seasonal and time variability of
heavy metal content and of its chemical forms in sewage sludges
from different wastewater treatment plants. Sci Total Environ
382(1):82–92
García-Esquinas E, Carrasco-Rios M, Navas-Acien A, Ortolá R, Rod-
ríguez-Artalejo F (2020) Cadmium exposure is associated with
reduced grip strength in US adults. Environ Res 180:108819
Gorell JM, Johnson CC, Rybicki BA, Peterson EL, Kortsha GX, Brown
RRJ (1999) Occupational exposure to manganese, copper, lead,
iron, mercury and zinc and the risk of Parkinson’s disease. Neu-
rotoxicology 20:239–247
Guo G, Wu F, Xie F, Zhang R (2012) Spatial distribution and pollu-
tion assessment of heavy metals in urban soils from southwest
China. J Environ Sci 24(3):410–418. https://doi.org/10.1016/
S1001-0742(11)60762-6
Gupta M, Santoro DHD, Torfs E, Doucet J, Van Peter AA, Van-
rolleghen NG (2018) Experimental assessment an validation of
quantification method for cellulose content in muncipal waste
water and sludge. Env Sci Pollut Res 25(17):16743–13753
Hanay Ö, Hasar H, Kocer NN, Aslan S (2008) Evaluation for agricul-
tural usage with speciation of heavy metals in a municipal sew-
age sludge. Bull Environ Contam Toxicol 81(1):42–46
Haroun M, Idri A, Omar S (2009) Analysis of heavy metals during
composting of tannery sludge using physicochemical and spec-
troscopic techniques. J Hazard Matter 165:111–119. https://doi.
org/10.1016/j.jhazmat.2008.09.092
Harrison EZ, McBride MB, Bouldin DR (1999) Land application of
sewage sludges: an appraisal of the US Regulations. Internat J
Environ Pollut 11(1):1–36. https://doi.org/10.1504/IJEP.1999.
002247
Hernández-Sánchez C, Fernández AG, Galindo JM, Weller DG,
Armendáriz CR, Gironés CR, Ojeda AB, de la Torre AH (2017)
Heavy metal content in sewage sludge: a management strategy
for an ocean island. Revista De Salud Ambiental 17(1):3–9
Horner RR, Skupien JJ, Livingstone EH, Shaver HE (1994) Funda-
mentals of urban runoff management. Technical and Institutional
Issues, Terrene Institute, Washington, DC. http://agris.fao.org/
agris-search/search.do?recordID=US9536404
Houhou J, Lartiges BS, Montarges-Pelletier E, Sieliechi J, Ghanbaja J,
Kohler A (2009) Sources, nature, and fate of heavy metal-bearing
particles in the sewer system. Sci Total Environ 407(23):6052–
6062. https://doi.org/10.1016/j.scitotenv.2009.08.019

1 3
Huang CP, Wang JM (2001) Factors affecting the distribution of heavy
metals in wastewater treatment processes: role of sludge particu-
late. Water Sci Technol 44(10):47–52. https://doi.org/10.2166/
wst.2001.0577
Hurse JT, Connor AM (1999) Nitrogen removal from wastewater treat-
ment lagoons. Water Sci Technol 39(6):191–198
Iacovidou E, Ohandja DJ, Voulvoulis N (2012) Food waste codiges-
tion with sewage sludge and realising its potential in the UK. J
Environ Manage 112:267–274. https://doi.org/10.1016/j.jenvm
an.2012.07.029
Igbinosa EO, Okoh AI (2009) Impact of discharge wastewater efflu-
ents on the physico-chemical qualities of a receiving watershed
in a typical rural community. Int J Environ Sci Tech 6(2):175–
182. https://doi.org/10.1007/BF03327619
Ismail Z, Salim K, Othman SZ, Ramli AH, Shirazi SM, Karim R,
Khoo SY (2013) Determining and comparing the levels of
heavy metal concentrations in two selected urban river water.
Measurement 46(10):4135–4144. https://doi.org/10.1016/j.
measurement.2013.08.013
Iwegbue CM, Bassey FI, Obi G, Tesi GO, Martincigh BS (2016)
Concentrations and exposure risks of some metals in facial
cosmetics in Nigeria. Toxicol Rep 3:464–472. https://doi.org/
10.1016/j.toxrep.2016.04.004
Jaishankar M, Tseten T, Anbalagan N, Mathew BB, Beeregowda
KN (2014) Toxicity, mechanism and health effects of some
heavy metals. Interdiscip Toxicol 7(2):60–72. https://doi.org/
10.2478/intox-2014-0009
Janus JA (1990) Integrated Criteria Document Chromium: Effects:
Appendix to Report No. 710401002. National Institute of Pub-
lic Health and Environmental Protection.
Jardine TD, Kidd KA, O’Driscoll N (2013) Food web analysis
reveals effects of pH on mercury bioaccumulation at multiple
trophic levels in streams. Aquat Toxicol 132:46–52
Jenkins D (1998) The effect of reformulation of household powder
laundry detergents on their contribution to heavy metals levels
in wastewater. Water Environ Res 70(5):980–983. https://doi.
org/10.2175/106143098X123309
Jenkins D, Russell LL (1994) Heavy metals contribution of house-
hold washing products to municipal wastewater. Water Environ
Res 66(6):805–813. https://doi.org/10.2175/WER.66.6.7
Kabata-Pendias A, Pendias H (eds) (2002) Trace elements in soils
and plant, 3rd edn. CRC Press, Boca Raton
Kandpal G, Ram B, Srivastava PC, Singh SK (2004) Effect of metal
spiking on different chemical pools and chemically extractable
fractions of heavy metals in sewage sludge. J Hazard Mater
106(2–3):133–137. https://doi.org/10.1016/j.jhazmat.2003.
10.006
Kapanen A, Vikman M, Rajasärkkä J, Virta M, Itävaara M (2013)
Biotests for environmental quality assessment of composted
sewage sludge. Waste Manage 33(6):1451–1460. https://doi.
org/10.1016/j.wasman.2013.02.022
Karim Z, Qureshi BA (2013) Health risk assessment of heavy met-
als in urban soil of Karachi Pakistan. Hum Ecol Risk Assess
20(3):658–667. https://doi.org/10.1080/10807039.2013.
791535
Kaur R, Wani S P, Singh A K, Lal K (2012) Wastewater production,
treatment and use in India, presented at the 2nd Regional Work-
shop on Safe Use of Wastewater in Agriculture, 16–18 May,
National Report, New Delhi, India [online] http://www.ais.unwat
er.org. (Assessed on 2nd June 2021)
Kawoosa B J (2017) Dal Lake— The myth, perceptions and the reali-
ties. Jklda.org.
Khalili F, Mahvi AH, Nasseri S, Yunesian M, Yaseri M, Djahed B
(2019) Health risk assessment of dermal exposure to heavy met-
als content of chemical hair dyes. Iran J Pub Health 48(5):902
Khan MA, Shah MA, Mir SS, Bashir S (2004) The environmental
status of a Kashmir Himalayan wetland game reserve: aquatic
plant communities and eco-restoration measures. Lakes Reserv
Res Manage 9:125–132. https://doi.org/10.1111/j.1440-1770.
2004.00242.x
Khanday SA, Romshoo SA, Jehangir A, Sahay A, Chauhan P (2018)
Environmetric and GIS techniques for hydrochemical characteri-
zation of the Dal Lake, Kashmir Himalaya, India. Stoch Environ
Res Risk Assess. https://doi.org/10.1007/s00477-0181581-6
Khelifi F, Melki A, Hamed Y, Adamo P, Caporale AG (2019) Envi-
ronmental and human health risk assessment of potentially toxic
elements in soil, sediments, and ore-processing wastes from a
mining area of southwestern Tunisia. Environ Geochem Health
42:1–15
Krishnan R, Radha K, Dharmaraj BD, Kumari R (2007a) A compara-
tive study on the physicochemical and bacterial analysis of drink-
ing borewell and sewage water in the three different places of
Sivakasi. J Environ Biol 28:105–108
Krishnan RR, Dharmaraj K, Kumari BR (2007b) A comparative study
on the physicochemical and bacterial analysis of drinking, bore-
well and sewage water in the three different places of Sivakasi. J
Environ Biol 28(1):105–108
Kukal SS, Saha D, Bhowmika A, Dubey RK (2012) Water Retention
characteristics of soil bio-amendments used as growing media
in pot culture. J Appl Hort 14(2):92–97
Kumar A, Chaturvedi AK, Shabnam AA, Subrahmanyam G, Mondal
R, Gupta DK, Malyan SK, Kumar S, Khan A, Yadav KK (2020)
Lead toxicity: health hazards, influence on food chain, and sus-
tainable remediation approaches. Int J Environ Res Pub Health
17(7):2179
Kumar A, Cabral-Pinto M, Kumar M, Dinis PA (2020) Estimation of
risk to the eco-environment and human health of using heavy
metals in the Uttarakhand Himalaya. India Appl Sci 10(20):7078
Kumar A, Subrahmanyam G, Mondal R, Cabral-Pinto MMS, Shabnam
AA, Jigyasu DK, Malyan SK, Fagodiya RK, Khan SA, Yu ZG
(2021) Bio-remediation approaches for alleviation of cadmium
contamination in natural resources. Chemosphere 268:12885
Kumar A, Chaturvedi A K, Surendran U, Shabnam A A, Singh A,
Vinodakumar S N, Tamuly B, Malyan S K, Khan S A, Cabral-
Pinto M M S, Raja P (2021a) Mechanistic overview of metal
tolerance in edible plants: A physiological and molecular per-
spective. Handbook of Bioremediation, pp.23–47.
Kurosu O (2001) Nitrogen removal from wastewaters in microalgal-
bacterial-treatment ponds. Available from http://www.socrates.
berkeley.edu/es196/projects/2001fi nal/kurosu.pdf. (Assessed on
14th March 2020).
Latare AM, Kumar O, Singh SK, Gupta A (2014) Direct and residual
effect of sewage sludge on yield, heavy metals content and soil
fertility under rice-wheat system. Ecol Eng 69:17–24. https://doi.
org/10.1016/j.ecoleng.2014.03.066
Latosińska J, Kowalik R, Gawdzik J (2021) Risk Assessment of soil
contamination with heavy metals from municipal sewage sludge.
Appl Sci 11(2):548
Laura F, Tamara A, Müller A, Hiroshan H, Christina D, Serena C
(2020) Selecting sustainable 526 sewage sludge reuse options
through a systematic assessment framework: methodology and
case study in Latin America. J Clean Prod 242:118389. https://
doi.org/10.1016/j.jclepro.2019.118389
LeBlanc RJ, Matthews P, Richard RP. eds., (2008) Global atlas of
excreta, wastewater sludge, and biosolids management: moving
forward the sustainable and welcome uses of a global resource.
Un-habitat.
Lester J (1987) Heavy metals in wastewater and sludge treatment pro-
cess. CRC Press Inc, Boca Raton, pp 1–40
Li ZY, Ma ZW, van der Kuijp TJ, Yuan ZW, Huang L (2014) A review
of soil heavy metal pollution from mines in China: pollution and

1 3
health risk assessment. Sci Total Environ 468:843–853. https://
doi.org/10.1016/j.scitotenv.2013.08.090
Liu J, Zhuo Z, Xie W, Kuo J, Lu X, Buyukada M, Evrendilek F
(2018) Interaction effects of chlorine and phosphorus on ther-
mochemical behaviors of heavy metals during incineration of
sulfur-rich textile dyeing sludge. Chem Eng J 351:897–911.
https://doi.org/10.1016/j.cej.2018.06.158
Lone FA, Zaffar S, Qureshi N, Rather AQ, Kirmani NA (2013) Stud-
ies on efficacy of sewage sludge as an agricultural supplement
for the assessment of growth performance of Brinjal (Solanum
melongena var Local long). Nature Environ Pollut Technol Int
Q Scientif J 12(2):367–370
Lu Y, Yin W, Huang LB, Zhang GL, Zhao YG (2011) Assessment of
bioaccessibility and exposure risk of arsenic and lead in urban
soils of Guangzhou City, China. Environ Geochem Health
33:93–102. https://doi.org/10.1007/s10653-010-9324-8
Luo X, Ren B, Hursthouse AS, Jiang F, Deng RJ (2019) Potentially
toxic elements (PTEs) in crops, soil, and water near Xiang-
tan manganese mine, China: potential risk to health in the
foodchain. Environ Geochem Health. https://doi.org/10.1007/
s10653-019-00454-9102
Magd SA, Taha TH, Pienaar HH, Breil P, Amer RA, Namour P
(2021) Assessing heavy metal pollution hazard in sediments
of Lake Mariout. Egypt. J Afr Earth Sci 5:104116
Manios T, Stentiford E, Millner P (2003) The effect of heavy met-
als accumulation on the chlorophyll concentration of Thy-
phalatifolia plants, growing in a substrate containing sewage
sludge compost and watered with metalliferous water. Ecol Eng
20:65–74. https://doi.org/10.1016/S0925-8574(03)00004-1
Massadeh AM, El-Khateeb MY, Ibrahim SM (2017) Evaluation of
Cd, Cr, Cu, Ni, and Pb in selected cosmetic products from Jor-
danian, Sudanese, and Syrian markets. Public Health 149:130–
137. https://doi.org/10.1016/j.puhe.2017.03.015
Mckenzie LM, Witter RZ, Newman LS, Adgate JL (2012) Human
health risk assessment of air emissions from development
of unconventional natural gas resources. Sci Total Environ
424:79–87. https://doi.org/10.1016/j.scitotenv.2012.02.018
Mehana ES, Khafaga AF, Elblehi SS, El-Hack A, Mohamed E, Naiel
MA, Bin-Jumah M, Othman SI, Allam AA (2020) Biomonitor-
ing of heavy metal pollution using acanthocephalans parasite
in ecosystem: an updated overview. Animals 10(5):811
Meinzinger F, Oldenburg M (2009) Characteristics of source-sep-
arated household wastewater flows: a statistical assessment.
Water Sci Technol 59(9):1785–1791. https://doi.org/10.2166/
wst.2009.185
Metcalf L, Eddy HP, Tchobanoglous G (1979) Wastewater engineer-
ing: treatment, disposal, and reuse. McGraw-Hill, New York
Milieu Ltd, WRc, Risk and Policy Analysts Ltd (RPA) (2010) Envi-
ronmental, economic and social impacts of the use of sewage
sludge on land. Final Report, Part III: Project Interim Reports;
DG ENV.G.4./ETU/2008/0076r. http://ec.europa.eu/envir
onment/archives/waste/sludge/pdf/part_iii_report.pdf.235:
106150. Accessed 5 June 2021
Mkhinini M, Boughattas I, Alphonse V, Livet A, Gıustı-Mıller S,
Bannı M, Bousserrhıne N (2020) Heavy metal accumulation
and changes in soil enzymes activities and bacterial functional
diversity under long-term treated wastewater irrigation in East
Central region of Tunisia (Monastir governorate). Agricultural
Water Management
Moretti SML, Bertoncini EI, Vitti AC, Alleoni LRF, Abreu-Junior
CH (2016) Concentration of Cu, Zn, Ni, Cd, and Pb in soil,
sugarcane leaf and juice: residual effect of sewage sludge and
organic compost application. Environ Monit Assess 188:163–
174. https://doi.org/10.1007/s10661-016-5170-1
Morrison G, Fatoki OS, Persson L, Ekberg A (2001) Assessment of
the impact of point source pollution from the Keiskammahoek
sewage treatment plant on the Keiskamma River–pH, electri-
cal conductivity, oxygen demanding substance (COD) and
nutrients. Water SA 27(4):475–480. https://doi.org/10.4314/
wsa.v27i4.4960
Mudho A, Kumar S (2013) Effects of heavy metals as stress factors
on anaerobic digestion processes and biogas production from
biomass. Int J Environ Sci Technol 10:1383–1398
Nafez AH, Nikaeen M, Kadkhodaie S, Hatamzadeh M, Moghim S
(2015) Sewage sludge composting: quality assessment for agri-
cultural application. Environ Monit Assess 187:709–717. https://
doi.org/10.1007/s10661-015-4940-5
Najar IA, Khan AB (2012) Assessment of water quality and identifica-
tion of pollution sources of three lakes in Kashmir, India, using
multivariate analysis. Environ Earth Sci 66:2367–2378. https://
doi.org/10.1007/s12665-011-1458-1
Nengroo ZA, Bhat MS, Kuchay NA (2017) Measuring urban sprawl
of Srinagar city, Jammu and Kashmir India. J Urban Manage
6(2):45–55. https://doi.org/10.1016/j.jum.2017.08.001
Nilsen TO, Ebbesson LO, Kverneland OG, Kroglund F, Finstad B,
Stefansson SO (2010) Effects of acidic water and aluminum
exposure on gill Na+, K+-ATPase α-subunit isoforms, enzyme
activity, physiology and return rates in Atlantic salmon (Salmo
salar L.). Aquat Toxicol 97(3):250–9
O’Brien J (2001) Mercury amalgam toxicity. Life Ext Mag 7(5):43–51
Obiri S, Dodoo DK, Essumang DK, Armah FA (2010) Cancer and
non-cancer risk assessment from exposure to arsenic, copper,
and cadmium in borehole, tap, and surface water in the Obuasi
municipality Ghana. Human Ecol Risk Assess 16(3):651–665
Olofsson U, Bignert A, Haglund P (2012) Time-trends of metals and
organic contaminants in sewage sludge. Water Res 46:4841–4851
Omura Y, Shimotsuura Y, Fukuoka A, Fukuoka H, Nomoto T (1996)
Significant mercury deposits in internal organs following the
removal of dental amalgam, and development of pre-cancer on
the gingiva and the sides of the tongue and their represented
organs as a result of inadvertent exposure to strong curing light
(used to solidify synthetic dental filling material) & effective
treatment: a clinical case report, along with organ representation
areas for each tooth. Acupunct Electrother Res 21(2):133–160.
https://doi.org/10.3727/036012996816356915
Ouyang W, Wang Y, Lin C, He M, Hao F, Liu H, Zhu W (2018) Heavy
metal loss from agricultural watershed to aquatic system: a sci-
entometrics review. Sci Total Environ 637:208–220
Pajević S, Arsenov D, Nikolić N, Borišev M, Orčić D, Župunski M,
Mimica-Dukić N (2018) Heavy metal accumulation in vegeta-
ble species and health risk assessment in Serbia. Environ Monit
Assess 190(8):1–4
Pan L, Ma J, Hu Y, Su B, Fang G, Wang Y, Wang ZS, Wang L, Xiang
B (2016) Assessments of levels, potential ecological risk, and
human health risk of heavy metals in the soils from a typi-
cal county in Shanxi province, China. Environ Sci Pollut Res
23:19330–19340. https://doi.org/10.1007/s11356-016-7044-z
Parvez S, Bhat SU (2014) Searching for water quality improvement
in Dal Lake, Srinagar, Kashmir. J Himalayan Ecol Sust Dev
9:51–64
Pinto MMC, Marinho-Reis AP, Almeida A, Freitas S, Simões MR,
Diniz ML, Moreira PI (2019) Fingernail trace element content
in environmentally exposed individuals and its influence on their
cognitive status in ageing. Expo Health 11(3):181–194
Praveena SM, Ismail SNS, Aris AZ (2015) Health risk assessment
of heavy metal exposure in urban soil from Seri Kembangan
(Malaysia). Arab J Geosci 8:9753–9761. https://doi.org/10.1007/
s12517-015-1895-3
Przewrocki P, Kulczycka J, Wzorek Z, Kowalski Z, Gorazda K, Jodko
M (2004) Risk analysis of sewage sludge Poland and EU com-
parative approach. Pol J Environ Stud 13:39–59

1 3
Qayoom U, Bhat SU, Ahmad I (2020) Efficiency evaluation of sew-
age treatment technologies: Implications on aquatic ecosystem
health. J Water Health 19(1):29–46
R Core Team (2013). R: A language and environment for statistical
computing. R Foundation for Statistical Computing, Vienna,
Austria. https://www.R-project.org/.
Rashid I, Aneaus S (2019) High resolution earth observation data for
assessing the impact of land system changes on wetland health
in Kashmir Himalaya India. Arabian J Geosci 12:453. https://doi.
org/10.1007/s12517-019-4649-9
Rashid I, Romshoo SA, Amin M, Khanday SA, Chauhan P (2017)
Linking human-biophysical interactions with the trophic status
of Dal Lake, Kashmir Himalaya, India. Limnologica 62:84–96.
https://doi.org/10.1016/j.limno.2016.11.008
Rather MI, Rashid I, Shahi N, Murtaza KO, Hassan K, Yousuf AR,
Romshoo SA, Shah IY (2016) Massive land system changes
impact water quality of the Jhelum River in Kashmir Himalaya.
Environ Monit Assess 188(3):1–20. https://doi.org/10.1007/
s10661-016-5190-x
Ren Z, Xiao R, Zhang Z, Lv X, Fei X (2019) Risk assessment and
source identification of heavy metals in agricultural soil: a case
study in the coastal city of Zhejiang Province, China. Stoch Env
Res Risk Assess 33(11):2109–2118. https://doi.org/10.1007/
s00477-019-01741-8
Geoscience Resources and Environments of Asian Terranes (GREAT
2008), 4th International Geo-logical Correlation Programme
(IGCP) (Vol. 516).
Riaz U, Murtaza G, Saifullah FM (2018a) Comparable effect of com-
mercial composts on chemical properties of sandy clay loam soil
and accumulation of trace elements in soil-plant system. Int J
Agric Biol 20:85–92. https://doi.org/10.17957/IJAB/15.0433
Riaz U, Murtaza G, Saifullah FM (2018b) Influence of different sew-
age sludges and composts on growth, yield, and trace elements
accumulation in rice and wheat. Land Degrad and Dev. https://
doi.org/10.1002/ldr.2925
Riaz U, Murtaza G, Saifullah Farooq M, Aziz H, Qadir AA, Mehdi SM,
Qazi MA (2020) Chemical fractionation and risk assessment of
trace elements in sewage sludge generated from various states
of Pakistan. Environ Sci Pollut Res. https://doi.org/10.1007/
s11356-020-07795-4
Rios D, Perez C, Sandoval M (2012) Phytotoxic effect of paper pulp
sludge on Alfisol soil. J Soil Sci Plant Nutr 12:315–327. https://
doi.org/10.4067/S0718-95162012000200011
Rizzardini CB, Goi D (2014) Sustainability of domestic sewage sludge
disposal. Sustainability 6:2424–2434. https://doi.org/10.3390/
su6052424
Romanos DM, Nemer N, Khairallah Y, Abi Saab MT (2021) Applica-
tion of sewage sludge for cereal production in a Mediterranean
environment (Lebanon). Int J Recycl Org Waste Agric. https://
doi.org/10.30486/ijrowa.2021.1903739.1098
Romshoo SA, Muslim M (2011) Geospatial modeling for assessing the
nutrient load of a Himalayan lake. Environ Earth Sci 64(5):1269–
1282. https://doi.org/10.1007/s12665-011-0944-9
Rosazlin A, Che Fauziah I, Rosenani AB, Zauyah S (2007) Domes-
tic sewage sludge application to an acid tropical soil: part III.
Fractionation study of heavy metals in sewage sludge and soils
applied with sewage sludge. Malaysian J Soil Sci 11:81–95
Rosseland BO, Eldhuset TD, Staurnes M (1990) Environmental effects
of aluminium. Environ Geochem Health 12(1–2):17–27
Rule KL, Comber SD, Ross D, Thornton A, Makropoulos CK, Rau-
tiu R (2006) Diffuse sources of heavy metals entering an urban
wastewater catchment. Chemosphere 63(1):64–72. https://doi.
org/10.1016/j.chemosphere.2005.08.016
Rybicki S (1997) Advanced Wastewater Treatment Report No 1.
“Phosphorus Removal From Wastewater A Literature Review”.
Division of Water Resources Engineering, Department of Civil
and Environmental Engineering, Royal Institute of Technology.
Stockholm, Sweden.106.
Sabalowsky AR (1999) An investigation of the feasibility of nitrifica-
tion and denitrification of a complex industrial wastewater with
high seasonal temperatures. Master’s Thesis from Virginia Poly-
technic Institute and State University. Blacksburg.
Sager M (2007) Trace and nutrient elements in manure, dung and com-
post samples in Austria. Soil Biol Biochem 39(6):1383–1390.
https://doi.org/10.1016/j.soilbio.2006.12.015
Saha S, Nath Saha B, Pati S, Pal B, Chand Hazra G (2017a) Agricul-
tural use of sewage sludge in India: benefits and potential risk of
heavy metals contamination and possible remediation options—a
review. Int J Environ Technol Manag 20:183–199. https://doi.org/
10.1504/IJETM.2017.089645
Saha S, Saha BN, Pati S, Pal B, Hazra GC (2017b) Agricultural use
of sewage sludge in India: benefits and potential risk of heavy
metals contamination and possible remediation options–a review.
Int J Environ Technol Manage 20(3–4):183–199
Sengupta P (2013) Potential health impacts of hard water. Int J Prev
Med 4(8):866–875
Shaikh ZA, Smith JC (1976) The biosynthesis of metallothionein in
rat liver and kidney after administration of cadmium. Chem Biol
Interact 15(4):327–336
Shi WS, Liu CG, Ding DJ, Lei ZF, Yang YN, Feng CP, Zhang ZY
(2013) Immobilization of heavy metals in sewage sludge by using
subcritical water technology. Bioresour Technol 137:18–24
Showqi I, Lone FA, Naikoo M (2018) Preliminary assessment of heavy
metals in water, sediment and macrophyte (Lemna minor) col-
lected from Anchar Lake, Kashmir India. Appl Water Sci
8(3):80. https://doi.org/10.1007/s13201-018-0720-z
Singh J, Kumar V, Kumar P, Kumar P, Yadav KK, Cabral‐Pinto MM,
Kamyab H, Chelliapan S (2021) An experimental investigation
on phytoremediation performance of water lettuce (Pistia stra-
tiotes L.) for pollutants removal from paper mill effluent. Water
Environment Research. Feb 10.
Solgi E, Esmaili-Sari A, Riyahi-Bakhtiari A, Hadipour M (2012) Soil
contamination of metals in the three industrial estates, Arak Iran.
Bull Environ Contamin Toxicol 88(4):634–638
Sorme L, Lagerkvist R (2002) Sources of heavy metals in urban
wastewater in Stockholm. Sci Total Environ 298(1–3):131–145.
https://doi.org/10.1016/S0048-9697(02)00197-3
Sun YH, Luo YM, Wu LH, Teng Y (2009) Heavy metals concentra-
tion in sewage sludge of Yangtze River Delta. Environ Prot Sci
35:26–29
Sungur A, Soylak M, Yilmaz E (2015) Characterization of heavy metal
fractions in agricultural soils by sequential extraction procedure:
the relationship between soil properties and heavy metal frac-
tions. Soil Sedim Contam Int J 24:1–15. https://doi.org/10.1080/
15320383.2014.907238
Susarla S, Medina VF, McCutcheon SC (2002) Phytoremediation: An
ecological solution to organic chemical contamination. Ecol Eng
18(5):647–658. https://doi.org/10.1016/S0925-8574(02)00026-5

1 3
Suthar S, Sharma J, Chabukdhara M, Nema AK (2010) Water quality
assessment of river Hindon at Ghaziabad, India: impact of indus-
trial and urban wastewater. Environ Monit Assess 165(1–4):103–
112. https://doi.org/10.1007/s10661-009-0930-9
Tallec G, Garnier J, Gousailles M (2006) Nitrogen removal in a waste-
water treatment plant through biofilters: nitrous oxide emissions
during nitrification and denitrification. Bioprocess Biosyst Eng
29:323–333. https://doi.org/10.1007/s00449-006-0081-0
Tan TH, Mo KH, Ling TC, Lai SH (2020) Current development of
geopolymer as alternative adsorbent for heavy metal removal.
Environ Technol Innov 18:100684
Tavker N, Yadav VK, Yadav KK, Cabral-Pinto M, Alam J, Shukla AK,
Ali FA, Alhoshan M (2021) Removal of cadmium and chromium
by mixture of silver nanoparticles and nano-fibrillated cellulose
isolated from waste peels of citrus sinensis. Polymers 13(2):234
Tchounwou PB, Yedjou CG, Patlolla AK, Sutton DJ (2012) Heavy
metal toxicity and the environment. In Molecular, clinical and
environmental toxicology (pp. 133–164). Springer, Basel.
Tella M, Doelsch E, Letourmy P, Chataing S, Cuoq F, Bravin MN,
Saint MH (2013) Investigation of potentially toxic heavy metals
in different organic wastes used to fertilize market garden crops.
Waste Manage 33(1):184–92
Thornton I, Butler D, Docx P, Hession M, Makropoulos C, McMullen
M, Nieuwenhuijsen M, Pitman A, Rautiu R, Sawyer R, Smith S
(2001) Pollutants in urban waste water and sewage sludge. Final
report prepared for European Commission Directorate-General
Environment.
Tjadraatmadja G, Diaper C (2006) Sources of Critical Contaminants in
Domestic Wastewater: A Literature Review. Australia: CSIRO:
Water for a healthy country national research flagship.
Topal AEI, Topal M, Öbek E (2020) Assessment of heavy metal accu-
mulations and health risk potentials in tomatoes grown in the
discharge area of a municipal wastewater treatment plant. Int J
Environ Health Res 8:1–3
Tseng WP, Chu H, How SW, Fong JM, Lin CS, Yeh SHU (1968) Preva-
lence of skin cancer in an endemic area of chronic arsenicism in
Taiwan. J Natl Cancer Inst 40(3):453–463
Tufenkçi S, Turkmen O, Sonmez F, Erdinç C, Sensoy S (2006) Effects
of humic acid doses and application on the plant growth, nutrient
and heavy metal contents of lettuce grown on sewage sludge-
applied. Fresenius Environ Bull 15(4):295–300
Tuikka AI, Schmitt C, Höss S, Bandow N, Von der Ohe PC, De Zwart
D, De Deckere E, Streck G, Mothes S, Van Hattum B, Kocan A
(2011) Toxicity assessment of sediments from three European
river basins using a sediment contact test battery. Ecotoxicol
Environ Saf 74(1):123–131
Turek A, Wieczorek K, Wolf WM (2019) Digestion procedure and
determination of heavy metals in sewage sludge an analytical
problem. Sustainability 11(6):1753. https://doi.org/10.3390/
su11061753
USEPA. Risk Assessment Guidance for Superfund. Human Health
Evaluation Manual, (Part A); Office of Emergency and Remedial
Response: Washington, DC, USA, 1989.
USEPA (1997) Exposure factors handbook, volume 1: general factors.
U.S. Environmental Protection Agency, Office of Research and
Development, Washington.
USEPA (2012) METHOD 3050B. Acid digestion of sediments, sludge
and soils. http://www.epa.gov/osw/hazard/testmethods/sw846/
online/3_series.htm.
Ustun GE (2009) Occurrence and removal of metals in urban wastewa-
ter treatment plants. J Hazard Mater 172(2–3):833–838. https://
doi.org/10.1016/j.jhazmat.2009.07.073
Van de Velden M, Dewil R, Baeyens J, Josson L, Lanssens P (2008)
The distribution of heavy metals during fluidized bed combustion
of sludge (FBSC). J Hazard Matter 151(1):96–102. https://doi.
org/10.1016/j.jhazmat.2007.05.056
Varol M (2011) Assessment of heavy metal contamination in sedi-
ments of the Tigris River (Turkey) using pollution indices and
multivariate statistical techniques. J Hazard Mater 195:355–364
Vass KK (1980) On the trophic status and conservation of Kashmir
lakes. Hydrobiologia 68(1):9–15
Vosyliene MZ, Jankaite A (2006) Effect of heavy metal model mixture
on rainbow trout biological parameters. Ekologija 4:12–17
Waara KO (1992) Effects of copper, cadmium, lead and zinc on nitrate
reduction in a synthetic water medium and lake water from north-
ern Sweden. Water Res 26(3):355–364. https://doi.org/10.1016/
0043-1354(92)90032-Y
Walker DJ, Clemente R, Roig A (2003) The effects of soil amendments
on heavy metal bioavailability in two contaminated Mediterra-
nean soils. Environ Pollut 122:303–312. https://doi.org/10.1016/
S0269-7491(02)00287-7
Wallace DR, Djordjevic AB (2020) Heavy metal and pesticide expo-
sure: a mixture of potential toxicity and carcinogenicity. Curr
Opin Toxicol 19:72–79
Watras CJ, Back RC, Halvorsen S, Hudson RJM, Morrison KA, Wente
SP (1998) Bioaccumulation of mercury in pelagic freshwater
food webs. Sci Total Environ 219:183–208
Wolna-Maruwka A, Sulewska H, Niewidomska A, Panasiewicz K,
Borowiak K, Ratajczak K (2018) The influence of sewage sludge
and a consortium of aerobic microorganisms added to the soil
under a willow plantation on the biological indicators of trans-
formation of organic nitrogen compounds. Pol J Environ Stud
27(1):403–412. https://doi.org/10.15244/pjoes/74184
Yang G, Li Y, Wu L, Xie LP, Wu J (2014a) Concentration and health
risk of heavy metals in topsoil of paddy field of Chengdu Plain.
Environ Chem 33:269–275
Yang J, Lei M, Chen TB, Gao D, Zheng GD, Guo GH, Le DJ (2014b)
Current status and developing trends of the contents of heavy
metals in sewage sludges in China. Front Environ Sci Eng 8:719–
728. https://doi.org/10.1007/s11783-013-0600-6
Yang G, Zhang G, Wang H (2015) Current state of sludge produc-
tion, management, treatment and disposal in China. Water Res
78:60–73
Yang Q, Li Z, Lu X, Duan Q, Huang L, Bi J (2018) A review of soil
heavy metal pollution from industrial and agricultural regions
in China: pollution and risk assessment. Sci Total Environ
642:690–700
Yaseen T, Bhat SU (2021) Assessing the nutrient dynamics in a
Himalayan Warm Monomictic Lake. Water Air Soil Pollut
232(3):1–21
Yousuf T, Ali M (2018) Tourist Satisfaction, Environmental concerns
and tourism in and beyond Dal Lake. Kashmir J Tourism Hospit.
https://doi.org/10.4172/2167-0269.1000349
Yu H, Zhang Z, Zhang Y, Fan P, Xi B, Tan W (2021) Metal type and
aggregate microenvironment govern the response sequence of
speciation transformation of different heavy metals to microplas-
tics in soil. Sci Total Environ. 752:141956
Zahra A, Hashmi MZ, Malik RN, Ahmed Z (2014) Enrichment and
geo-accumulation of heavy metals and risk assessment of

1 3
sediments of the Kurang Nallah—feeding tributary of the Rawal
Lake Reservoir, Pakistan. Sci Total Environ 470:925–933
Zdeb M, Pawłowska M, Pacan J (2020) The Influence of anaerobic
digestion on selected heavy metals fractionation in sewage
sludge. J Ecol Eng 21(3):27–35. https://doi.org/10.12911/22998
993/118302
Zhang J, Tian Y, Li ZJ, Kong L, Yu M, Zuo W (2017) Distribution and
risk assessment of heavy metals in sewage sludge after ozona-
tion. Environ Sci Pollut Res 24:5118–5125. https://doi.org/10.
1007/s11356-016-6313-1
Zhou H (2015) Soil heavy metal pollution evaluation around mine area
with traditional and ecological assessment methods. J Geosci
Environ Prot 3(10):28. https://doi.org/10.4236/gep.2015.310005
Zutshi DP, Gopal B (2000) Himalayan lake ecosystems: current issues
and threat perceptions. Internationale Vereinigung Für Theore-
tische Und Angewandte Limnologie: Verhandlungen 27(4):2167–
2170. https://doi.org/10.1080/03680770.1998.11901622

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