How to treat effluents from the industries. industrial wastewater treatment

1. EFFLUENT TREATMENT
Submitted by: Munawar Hussain
Roll no. 8107
Submitted to: Dr. Farhat Jabeen

2. Table of Contents
Industrial effluent treatment............................................................................................................ 2
Principle and non-principle treatment............................................................................................. 3
Need of Effluent treatment.............................................................................................................. 3
Treatment levels and mechanisms of effluent treatment ................................................................ 3
Treatment mechanisms ................................................................................................................... 3
Preliminary treatment level............................................................................................................. 4
 Screening:............................................................................................................................. 4
 Sedimentation: ..................................................................................................................... 4
 Clarification: ........................................................................................................................ 4
Effluent equalization:.................................................................................................................. 4
Primary treatment level................................................................................................................... 5
1- pH controle:.......................................................................................................................... 5
2- Chemical coagulation and flocculation:............................................................................... 5
Secondary treatment level............................................................................................................... 5
1- Biological unit process:........................................................................................................ 6
2- Aerobic processes: ............................................................................................................... 6
3- Anaerobic processes:............................................................................................................ 6
Tertiary or advanced treatment level .............................................................................................. 6
Ponds effluent treatment ................................................................................................................. 7
1- Wetlands............................................................................................................................... 8
2- Settling basins ...................................................................................................................... 9
3- Irrigation............................................................................................................................... 9
References:.................................................................................................................................... 10

3. Effluent Treatment
Definition:
Effluent treatment is a process that is designed for treatment of the waste water for its reuse or
safe disposal to the environment.
Industrial effluent treatment
Treatment of the effluent that comes from the industries.
Introduction:
Technologies involved in the effluent treatment procedure can be divided into three categories and
these are:
1- Chemical methods
2- Physical methods
3- Biological methods
Chemical methods include chemical precipitation, chemical oxidation or reduction, formation of
an insoluble gas followed by stripping, and other chemical reactions that involve exchanging or
sharing electrons between atoms.
Physical treatment methods include sedimentation, flotation, filtering, stripping, ion exchange,
adsorption and other processes that accomplish removal of dissolved and undissolved substances
without necessarily changing their chemical structure. Biological methods are those that involve
living organisms using organic or in some instances inorganic substances for food, completely
changing their chemical and physical characteristics.
Most substances found as pollutants in industrial waste waters can be categorized as to whether
chemical, physical, or biological treatment should be the most appropriate. For instance, dairy
wastewater should most appropriately be treated by biological means because the bulk of the
pollution load from a typical dairy is organic material from whole milk, which is readily
biodegradable. As a general rule, biological treatment is more economical than any other type of
treatment, when reasonably complete treatment is required, and whenever it can be made towork
successfully.

4. Principle and non-principle treatment
Most treatment technologies remove substances other than the target substances. For instance,
biological treatment can effectively remove a certain amount of metal ion from wastewater.
Because metal ions do not particularly like to be dissolved in water because they are hydrophobic,
they are driven by the second law of thermodynamics to be adsorbed on the surface of solids-just
about any solid-including activated sludge solids.
This mechanism for removing metals from wastewater is often undesirable because the presence
of metal ions in the waste sludge may render the sludge unsuitable for a desired disposal method.
In any case, biological treatment is a “principle” technology for removing organics from effluents
and its unintended removal of metal ions is a “non-principle” mechanism.
Needof Effluent treatment
The effluent treatment is needed for the following purposes:
1- It is needed for the cleaning of industrial waste and recycle it for further use.
2- It is also needed to reduce the usage of fresh or portable water in industries.
3- The effluent treatment is needed to cut the expenditure on water procurement.
4- It is very important to meet the standards for emission or discharge of environmental
pollutants from various industries set by the government and avoid hefty penalties.
5- Effluent treatment is needed to safeguard environment against pollution and contribute in
sustainable development.
Treatment levels and mechanisms of effluent treatment
Treatment levels
 Preliminary treatment
 Primary treatment
 Secondary treatment
 Tertiary treatment or advanced treatment
Treatment mechanisms
 Physical

5.  Chemical
 Biological
Preliminary treatment level
The purpose of the preliminary treatment level is the physical separation of the big sized impurities
like cloth, plastics, wood logs, paper, etc.
Common physical unit operations at preliminary level are:
 Screening: A screen with openings of uniform size is used to remove large solids such
as plastics, cloth etc. Generally maximum 10mm is used.
 Sedimentation: Physical water treatment process using gravity to remove suspended
solids from water.
 Clarification: Used for separation of solids from fluids.
Effluent equalization:
Among the most effective waste management procedures is equalization of waste stream.
Equalization can be of two types: flow equalization and constituent equalization. Flow equalization
refers to changing the variations in rate of flow throughout the processing and clean-up cycles to
a more nearly equal to the average flow rate for that period. Constituent equalization refers to the
concentration of the target pollutant in the waste stream. Throughout the 24-hour day, the
concentrations of individual constituents in a given industrial waste stream typically vary over
wide ranges as processes are started up, operated, shut down, and clean-up takes place.
Waste treatment systems that are designed for given ranges of concentrations of target pollutants
often do not perform well when those constituents are in concentrations significantly different
from design values. Equalization can be of two types
a- Online flow equalization is accomplished by allowing the waste stream to flow into a basin.
The waste is then transferred from basin to the treatment system at a constant, or more
nearly constant, rate. The basin, must be sufficiently large that it never overflows and must

6. always contain enough waste that it never becomes empty, causing the flow to the treatment
system to stop.
b- Offline flow equalization is accomplished by restricting the flow into the treatment system
by means of either a flow regulating valve or a constant speed positive displacement pump.
When there is excess waste flow, it is directed to the equalization tank. When there is
insufficient flow, it is made up from the equalization tank.
Primary treatment level
This treatment level is used for the removal of floating and settleable materials such as suspended
solids and organic matter.
Methods: both physical and chemical methods are used in this treatment level.
Chemical unit processes:
The chemical unit processes are always used with physical operations and they may also be used
with the biological treatment processes. And the chemical processes mostly use the addition of
chemicals to the wastewater to bring about changes in its quality.
Example: pH controle, coagulation, chemical precipitation and oxidation.
1- pH controle:The waste water or effluent pH is made neutral by adjusting its pH. So this
process is used to make the effluent pH neutral. In case of the effluents or wastes that have
the acidic nature or have low pH we use the basic chemicals to neutralize their pH for
example NaoH, Na2CO3, CaCO3, or calcium hydroxide. And for the alkali wastes we use
sulfuric acid and hydrochloric acid.
2- Chemical coagulation and flocculation: Coagulation means collection of the
minute particles dispersed in a liquid into a larger mass. In this process chemical coagulants
like Al2(SO4)3 that is also known as alum or Fe(SO4)3 are added to waste water to make
greater the attraction among the fine particles so that they can come together and form
larger particles called flocs.
Secondarytreatment level
Biological and chemical methods are involved in this level of treatment.

7. 1- Biologicalunit process:It is used for the removal of or reduction of the concentration
of the organic and inorganic compounds. And it can take many forms but all are based
around microorganisms, mainly bacteria.
2- Aerobic processes: Aerobic processes are those processes that take place in the
presence of the air(oxygen). It utilizes those microorganisms that which use molecular and
free oxygen to assimilate organic impurities i.e. convert them into carbon dioxide, water,
and biomass.
3- Anaerobic processes:The anaerobic processes take place in the absence of the oxygen.
These processes use microorganisms that do not use oxygen to assimilate organic
impurities and its final products are methane and biomass.
Tertiary or advanced treatment level
It is the final treatment or cleaning process that t improves the quality of the wastewater before it
is reused, recycled or discharged to the environment.
1- Alum: Alum is used to help in removing the additional phosphorus particles and group the
remaining solid particles together for easy removal in the filters.
2- Chlorine: Contact tank disinfects the tertiary treated wastewater or effluent by removing
microorganisms in treated wastewater including bacteria, viruses and parasites.
3- Remaining chlorine: The remaining chlorine is removed by adding sodium bisulphate just
before its discharged.
Effluent treatment plant operation
1- Screen chamber:
Removes relatively large solids to avoid abrasion of mechanical equipments and clogging
of hydraulic system.
2- Collection tank:
The collection tank collects the effluent water from screening chamber, stores and then
pumps it to the equalization tank.
3- Equalization tank:

8. The effluents are stored in the equalization tank from 8 to 12 hours resulting in the
homogenous mixture of effluents and helping in neutralization.
4- Flash mixer:
coagulants are added to the effluents e.g. poly electrolyte
5- Clarriflocculator:
In the clarriflocculator the water is circulated continuously by the stirrer and thus the solid
particles are settled down.
6- Aeration tank:
here the water is passed through certain staircase shape arrangements like a thin film. And
the water gets direct contact with the air to dissolve oxygen into water. Thus BOD and
COD values of water are reduced upto 90%.
7- Clarifier:
The clarifier collects the biological sludge. Here the overflowed water is called as treated
effluent and disposed out. The outlet water quality is checked to be within the accepted
limit as delineated in the norms of the bureau of Indian standards. Through pipelines, the
treated water is disposed into the environment river water, barren land, etc.
8- Sludge thickener: In the sludge thickener the inlet water consists of 60% water + 40%
solids. The effluent is passed through the centrifuge and the solids and liquids are separated
due to the centrifugal action. The sludge thickener thus reduces the water content in the
effluent to 40% water +60% solids. The effluent is then reprocessed and sludge collected
at the bottom.
9- Drying bed: The sludge is dried on the drying beds.
Ponds effluent treatment
Many techniques or schemes for using or improving effluents from ponds have been advanced
over the years to include hydroponics, irrigation, culture medium for other aquatic organisms,
wetlands, settling basins, biological filters, nutrient removal by water hyacinths or other floating
macrophytes, fluidized-bed filters, and others. The most efficient procedure appear to be irrigation,
settling basins, and wetlands. Effluents from ponds are not concentrated enough in nutrients for
use in hydroponics unless nutrient concentrations are supplemented, which may defeat the purpose
of using this procedure to treat effluents. Filter-feeding fish and mollusks and certain plants have

9. been successfully cultured in effluents, but this practice has seldom been economical, and it does
not greatly improve effluent quality. Complicated water-treatment procedures such as biological
filtration and activated sludge processes are too expensive to use with pond effluents. Also,
nutrient and organic matter concentrations in most pond effluents are too low for these treatment
procedures to be effective.
1- Wetlands
Natural wetlands and constructed wetlands can be effective in reducing nutrient and
organic matter concentrations in wastewater (Mitsch and Gosselink 1993). Wetlands act as
biological filters to remove pollutants from water, and natural and constructed wetlands
sometimes are used for treatment of agricultural, municipal, and industrial wastewaters
(Hammer 1992; Moshiri 1995). There are several advantages to wetland wastewater
treatment:
 wetlands are relatively inexpensive to build and operate.
 Chemical treatment of wastewater is eliminated
 Wetlands contribute stability to local hydrologic processes.
 Plant communities in wetlands are excellent wildlife habitat.
 The main problem with wetlands for treating aquaculture effluents is that large areas of
land may be necessary.
Process
Removal of substances from water by a wetland involves a number of processes including
 Sedimentation of suspended particles
 Filtration of suspended particles by plant materials
 Uptake of nutrients by plants and bacteria
 Decomposition of organic matter
 Denitrification
 Nitrification
 Adsorption of ions by the soil.

10. Wetlands remove large amounts of potential nutrients from the water even when vegetation is
dormant and temperature is low. Much of the observed removal during both dormant and
vegetative seasons probably occurs through nonbiological processes of sedimentation, filteration,
and soil adsorption. Reed and Brown (1992) state that only 10% of the nitrogen in the wetland
systems is removed by macrophytes and Vymazal (1988) found that periphyton can remove up to
80 % of ammonia and 70 % of phosphorus from water.
Robertson and Phillips(1995) concluded that mangrove forests could serve as filters to remove
nutrients and particulate matter from shrimp pond effluents. They made estimates of nitrogen and
phosphors loads from semi-intensive and intensive shrimp ponds and nutrient requirements for
Rhizophora-dominated mangrove forests. It was concluded that between 2 and 22 ha of mangrove
forest would be needed to remove the nutrients from effluent produced by a 1 ha shrimp pond.
However, this computation fails to account for loss of phosphorus through sedimentation and
uptake by sediment and nitrogen losses through denitrification, which are likely of much greater
magnitude than simple assimilation by growing plants. Research on the use of mangrove forest to
treat shrimp pond effluents could be fruitful. If such systems are feasible, constructed wetlands in
coastal areas could be planted with mangrove seeding to treat pond effluents and enhance
mangrove reserves.
2- Settling basins
Settling basins are easier to construct and operate than wetlands because they do not have to be
seeded with plants. Findings suggest that settling basins can be just as effective as wetlands in
improving the quality of catfish pond effluents. This results because much of phosphorus and
organic matter in pond effluents is associated with suspended matter, and the suspended matter
will quickly settle if water is held in settling basins. Boyd (1995) provided an in depth discussion
of the sedimentation process and discussed the method for computing the hydraulic residence time
for removing solids of different sizes.
3- Irrigation
In some cases, it is possible to use water from freshwater aquaculture ponds for crop irrigation.
The primary importance of irrigation to the crop would be to supplement the water supply, but the
nutrients in the pond effluent might be of minor importance to the crop. Also, solids and organic
matter in the effluent would settle out in in the field and not cause problems provided application

11. techniques and erosion control procedures prevent them from entering natural bodies of water in
runoff.
References:
1- Woodard F 1939, Industrial waste water treatment, pages 230-235.
2- S. tucker Craig and E. Boyd Claude, Pond aquaculture water quality management, pages
550-560.
3- "Battery Manufacturing Effluent Guidelines". Washington, D.C.: U.S. Environmental
Protection Agency (EPA). 2017-06-12.
4- "Lowering Cost and Waste in Flue Gas Desulfurization Wastewater Treatment". Power
Mag. Electric Power. Retrieved 6 April 2017.
5- Guide for the Application of Effluent Limitations Guidelines for the Petroleum Refining
Industry (Report). EPA. June 1985. p. 5.
6- Western Regional Aquaculture Center, University of Washington. Seattle, WA
(2001). "Settling Basin Design." Archived 2009-01-16 at the Wayback Machine WRAC
Publication No. 106.