Technical Paper written on Problems associated with the use of treated wastewater evaluating the literature

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University of Moratuwa – Department of Languages
EL 2710
Technical and Scientific Writing
Assignment [02]
Combining Sources (Citing and Referencing)
Student Name Reg. Number
B. V. C. M. Benaragama 170070D
Course Coordinator: Ms S U Gamage
Lecturer(s): Ms Apsara Wimalasiri
Date of Assignment: [26 November 2019]
Date of Submission: [20 December 2019]
Declaration:
I sincerely declare that this assignment is a result of my own work and is not an unethical
reproduction of someone else’s published or unpublished work. I confirm that I took genuine
efforts to complete all parts of this assignments by reflecting on and applying what I learned
and read both inside and outside the class. I further declare that the assignment submitted is
original except where source materials have been cited.
Signature of the Student:

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PROBLEMS ASSOCIATED WITH USE OF TREATED WASTEWATER
Introduction
Clean water has become a scarce resource today. According to Ritchie and Roser (2017), with
the population growth, and expansion of agricultural and industrial fields, per capita,
freshwater demand per annum has exponentially ascended over past eight decades from one
trillion to approximately four trillion cubic metres. The importance of freshwater has become
a crucial topic, and a trend has been developed to encourage the use of wastewater or treated
wastewater for possible applications. However, using wastewater directly could obviously
have negative effects on the environment and ecology. Similarly, even the use of treated
wastewater seems to have some negative effects on the environment. The suitability of
wastewater to be reused in different applications such as irrigation is still in the debate even
today due to unfavourable circumstances it could create in the ecological balance.
Raschid-Sally (2009), states that wastewater can be classified into four main groups,
depending on the source it is produced from, namely,
1. Water containing domestic effluents
2. Water from establishments and institutions (e.g.: Hospitals)
3. Industrial effluents and urban run-off
4. Water containing agricultural, horticultural, and aquacultural effluents
Domestic wastewater is separately treated depending on whether they contain faecal matter
(black water) or not (greywater);(WHO, 2006).
The type of effluents found in water and the treatments to be done depend on the source
wastewater is produced on. Hence, the situations where treated water can be used, also
primarily depend on the source of water. The treated water is released to the environment
via three different modes, namely using water for agriculture, using water aquifer refilling
and directly releasing them into freshwater bodies. Each of the above measures has its
negative and positive consequences. The purpose of this paper is to discuss the
environmental problems related to the above-mentioned measures and study the validity of
them with the support of views from the academic world.

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Uses of Treated Wastewater
Even though some studies suggest wastewater can be treated through sophisticated
procedures and can be used even for drinking, a reluctance is observed among the public to
use treated wastewater for drinking and personal hygienic activities. However, purified water
obtained from urine through complex reverse osmosis procedures is used for drinking by the
astronauts in outer space. In his report, Pescod (1992) presents a number of case studies done
around the world to check the feasibility of using treated wastewater for different
applications. Pescod also maintains that treated wastewater can be used in applications such
as irrigation and agriculture, aquifer recharge, aquaculture, as construction raw material, and
numerous other applications. For instance, figure 01 shows the types of uses obtained from
wastewater in California in 1992.
Figure 01: (Pescod, 1992)
Environmental Problems Related with the Use of Treated Wastewater for Agriculture and
Irrigation
Since centuries ago, practices have been developed to use wastewater directly on crops, for
it tends to have numerous nutrients required for the plant growth. However, with
industrialization and urbanization, more and more harmful constituents were released into
wastewater, and the attention was paid to treat the wastewater to a certain extent and use
it in agriculture and irrigation. Also as a solution for both the problems of the consequent

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freshwater stress emerged as a result of increasing human population, and increase in
wastewater volumes produced following the latter, further researches were done on how to
treat wastewater to obtain a product that can be used in agriculture and irrigation with
minimum harmful effects to the ecology. Despite the general tendency to believe that the use
of treated wastewater in agriculture could bring environmental issues, some researchers
state otherwise.
Figure 02: (Lamizana, 2006)
Two main constituents in wastewater have been specifically identified to cause critical
environmental issues when used in agriculture and irrigation, namely toxic heavy metals, and
pathogens. Despite how sophisticated the techniques used in the treatment are, there is a
possibility of the above constituents to be present is treated wastewater in considerable
amounts. Some studies suggest, when cultivated with treated wastewater, most of the plant
species have shown higher heavy metal concentrations in edible parts of the plant. In fact,
the concentration heavy metals found in some plants was high, even when the treated
wastewater used had low concentrations of heavy metals (Gupta et al., 2010). Furthermore,
it is also said in the study by Gupta et al.,(2010), “Heavy metal accumulation due to
wastewater irrigation induces physiological stress in plants and subsequent alterations in

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their biochemical composition”. The heavy metals accumulated in plants eventually transfer
through food chains, through the process called “bio-accumulation”. The toxicity of heavy
metals could affect the different organs, of different organisms, giving a detrimental blow to
balance in the biosphere (Govind and Madhuri, 2014). The Minamata disease condition that
developed in Japan in 1956 due to mercury poisoning, can be given as a very good example
of such a situation.
The second critical constituent found in treated wastewater, that could create a considerable
environmental impact is biohazardous organisms. The general method of sterilization or
disinfectant method used wastewater treatment is chlorination. However, the chlorine
treatments could be inefficient sometimes when treated wastewater contains nutrients that
could accelerate the growth of microorganism (Al-Lahham, El Assi and Fayyad, 2003). Such
microorganism could be pathogenic to animals or plants in the environment because they
could have higher propagation rates and media.
Although the above factors are addressed as detrimental issues of using treated wastewater
for agriculture and irrigation, some researchers hold completely different ideologies. They
maintain that, given the wastewater treatment is done properly under constant quality
assurance, using treated wastewater for agriculture could be an excellent solution to the
wastewater crisis. Through research, they try to prove that with controlled effluents in
wastewater the toxic heavy metal content in plants can be maintained under standard
accepted levels while increasing the yield exploiting the nutrients found wastewater (Al-
Nakshabandi et al., 1997; Al-Lahham, El Assi and Fayyad, 2003, 2007). However, the same
researchers insist that in the case of pathogenic microorganisms, it is advised not to use
treated wastewater in the cultivation of vegetables that are consumed raw.
In addition to the above two crucial factors, some minor factors such as the quality of the soil
could be affected by the use of treated wastewater for irrigation. Treated wastewater could
have dissolved solids that could change the soil chemistry making it inhabitable to soil-
dwelling macro and microorganisms. This can affect the chemical and biological balance in
the soil which might lead to leaching or infertility. Alobaidy et al., (2010) explains how such
minor factors can affect the soil chemistry and hence the flora population. According to him,
high dissolved ionic contents in water could lead to dehydration of the plant, high sodium
content can reduce soil permeability, and high chloride contents can cause defoliation.

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Ground Water and Soil Pollution
In countries located in semi-arid to arid climatic zones, the groundwater is a rare resource.
Groundwater is very important when it comes to the balance of the environment because the
flora population mainly depends on groundwater. Recently, various researches and case
studies have been done to check the possibility of groundwater aquifer refilling using treated
wastewater, and the reports predict that it is feasible but with a price of groundwater and soil
pollution.
The treated wastewater discharges into the groundwater aquifers through the soil. In most
cases, the soil layer over the aquifer acts as a filter medium called Vadose Zone. Upon
filtration depending on the capture ability of the vadose zone, the remaining effluent
substances of treated wastewater either remains in the soil or disperse into groundwater.
Either the case is, either soil pollution or groundwater pollution could take place.
Figure 03: (Ward and Dilon, 2009)
Same as in the case of using treated wastewater for agriculture and irrigation, the topic of the
practicality of recharging groundwater aquifers without causing a detrimental effect to the
environment remains in debate. In a case study done in south-central Arizona, USA, it has
been found no matter up to which the treatment has been done to wastewater used for
aquifer recharge, considerable groundwater pollution has occurred (Pescod, 1992). In his
report, Pescod (1992) mentions that most of the faecal coliform present in treated
wastewater was “removed in the top metre of the vadose zone but some penetrated to the
aquifer”. This is a serious issue because the purest water is found in the groundwater aquifers
which are polluted in this case. The industries related to bottled water and beverages depend

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on groundwater aquifers, which will be affected in this case. I addition to that, the heavy
metals and such chemicals retained in the vadose layer will be get absorbed into plants and
invade food chains causing bioaccumulation in humans and other animals.
However it has been found by Abiye, Sulieman and Ayalew, (2009) that soil from vadose layer
can be artificially used for further purification of treated wastewater, and the clean water
obtained could be used to refill aquifers.
Surface Water Pollution
In a country where there are fertile soil and abundance of groundwater and surface water for
agriculture, treated wastewater is generally released to water bodies such as seas, lakes and
rivers. According to, the studies done by YI et al., (2008) on the Yangtze river in China, the
critical issues could arrive with time in both flowing and non-flowing water bodies. With
respect to the heavy metal accumulation, he states that, “ The concentrations of heavy metals
were 100-10,000 times higher in the river sediment than in the water”, and that, “the
concentration of heavy metals was lower in the river sediments than in the lake sediments,
while the concentration of heavy metals was higher in river water than in lake water.”
Figure 04: (YI et al., 2008)
The environmental effects brought by discharging treated wastewater are only light and
delayed versions of that occur when wastewater is directly released into water bodies. In
addition to the problems faced by flowing water bodies, non-flowing bodies such as lakes and
tanks may face eutrophication due to the nutrient added to water with the treated

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wastewater. Other than the direct discharges, the nutrients and pollutants from groundwater
and that washed-off from agricultural lands where treated wastewater has been used, can
emerge from surface water bodies causing above mentioned effects. In other words, three
modes through which treated wastewater are discharged into environments are indeed
interrelated, one can affect each other causing more serious environmental impacts.
Conclusion
With the increasing world population, the per capita production of wastewater has increased
detrimentally for past few decades. Even though the wastewater treatment procedures are
executed properly, procedures to utilize treated wastewater usefully have not been
developed significantly into practice due to the environmental problems it could cause.
Despite the fact that the environmental problems it could cause by reusing treated
wastewater are clearly considerable, some of the environmental problems seem exaggerated
unnecessarily. The approach brought by some researchers to prove that treated wastewater
can be used in proper applications showing the positive effects of reusing treated wastewater,
rather than directly disposing untreated wastewater to the environment, seems to have a
stronger rational basis.

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REFERENCES:
Abiye, T. A., Sulieman, H. and Ayalew, M. (2009) ‘Use of treated wastewater for managed
aquifer recharge in highly populated urban centers: A case study in Addis Ababa, Ethiopia’,
Environmental Geology, 58(1), pp. 55–59. doi: 10.1007/s00254-008-1490-y.
Al-Lahham, O., El Assi, N. M. and Fayyad, M. (2003) ‘Impact of treated wastewater irrigation
on quality attributes and contamination of tomato fruit’, Agricultural Water Management.
Elsevier, 61(1), pp. 51–62. doi: 10.1016/S0378-3774(02)00173-7.
Al-Lahham, O., El Assi, N. M. and Fayyad, M. (2007) ‘Translocation of heavy metals to
tomato (Solanum lycopersicom L.) fruit irrigated with treated wastewater’, Scientia
Horticulturae, 113(3), pp. 250–254. doi: 10.1016/j.scienta.2007.03.017.
Al-Nakshabandi, G. A. et al. (1997) ‘Some environmental problems associated with the use
of treated wastewater for irrigation in Jordan’, Agricultural Water Management, 34(1), pp.
81–94. doi: 10.1016/S0378-3774(96)01287-5.
Alobaidy, A. H. M. J. et al. (2010) ‘Evaluation of Treated Municipal Wastewater Quality for
Irrigation’, Journal of Environmental Protection. Scientific Research Publishing, Inc, 01(03),
pp. 216–225. doi: 10.4236/jep.2010.13026.
Govind, P. and Madhuri, S. (2014) ‘Heavy metals causing toxicity in animals and fishes’, pp.
17–23. Available at:
https://www.researchgate.net/publication/270169412_Heavy_metals_causing_toxicity_in_
animals_and_fishes (Accessed: 20 December 2019).
Gupta, S. et al. (2010) ‘Effect of wastewater irrigation on vegetables in relation to
bioaccumulation of heavy metals and biochemical changes’, Environmental Monitoring and
Assessment, 165(1–4), pp. 169–177. doi: 10.1007/s10661-009-0936-3.
Lamizana, B. (2006) Environmental Effects of Wastewater use in Agriculture & appropriate
treatment technology for reuse .
Pescod, M. B. (1992) Wastewater treatment and use in agriculture-FAO irrigation and
drainage paper 47 FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS.
Raschid-Sally, L., Jayakody, P. and International Water Management Institute. (2009) Drivers
and characteristics of wastewater agriculture in developing countries : results from a global
assessment. [International Water Management Institute].
Ritchie, H. and Roser, M. (2017) ‘Water Use and Stress’, Our World in Data.
Ward, J. and Dilon, P. (2009) Robust Design of Managed Aquifer Recharge Policy in Australia.
Available at:
https://www.researchgate.net/publication/265271534_Robust_Design_of_Managed_Aquif
er_Recharge_Policy_in_Australia/citation/download (Accessed: 20 December 2019).
WHO, W. H. O. (2006) Health Aspects of Plumbing - World Health Organization, World
Plumbing Council - Google Books. Available at:
https://books.google.lk/books?id=u6YsDwAAQBAJ&pg=PA114&lpg=PA114&dq=%22The+us

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e+of+wastewater+for+a+variety+of+purposes+is+gaining+increased+popularity+as+a+mean
s+of+preserving+scarce+freshwater+resources%22&source=bl&ots=77PA9IYxpg&sig=ACfU3
U3ldQhf5sI2OBLeluBS4hqfwYFaCA&hl=en&sa=X&ved=2ahUKEwjG-
JKfzcLmAhUGxzgGHZi_Ay4Q6AEwAHoECAoQAQ#v=onepage&q=%22The use of wastewater
for a variety of purposes is gaining increased popularity as a means of preserving scarce
freshwater resources%22&f=false (Accessed: 20 December 2019).
YI, Y. et al. (2008) ‘Sediment pollution and its effect on fish through food chain in the
Yangtze River’, International Journal of Sediment Research, 23(4), pp. 338–347. doi:
10.1016/S1001-6279(09)60005-6.