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shamskm.com
Sewage Water Pollution and Its Environmental Effects
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Author: Md. Wasim Aktar



INTRODUCTION

India faces a turbulent water future. Unless water management practices are changed – and changed soon – India will face a severe water crisis within
the next two decades and will have neither the cash to build new infrastructure nor the water needed by its growing economy and rising population. Water
is one of the critical inputs for the sustenance of mankind. It is used both terrestrial and aquatic environment for various activities, balancing the
ecological system of global environment. Water is the important natural source, which is abundant in nature and cover about 2/3ds of earth surface.
However, only 1% of the water resource is available as fresh water (i.e., surface water-rivers, lakes, reams, and ground water) for human consumption
and other activities. The major uses of water are for irrigation (30%), thermal power plants (50%), while other uses are domestic (7%) and industrial
consumption (~12%) (A. K. De, 2002).The United Nation’s report on “Water for People, Water for Life” (the first ever UN system wide evaluation on global
water resources-2003) has put India a poor 120th for water quality among 122 nations covered. Only Belgium and Morocco are ranked worse than India.
The quality indicator value was based on quality and quantity of fresh water (especially ground water), waste water treatment facilities, legalities like
application of pollution regulations, India’s quality indicator value stood at -3.1 while for based ranked country Finland it was 1.85. The UN evaluation also
ranked India 133 in a list of 180 countries for its poor water availability (1880m3 per person per year). Kuwait was ranked the poorest on water availability.
Against the National average target of 135 lpcd of water and 180 lpcd per capita in large cities, the per capita availability is low and ranges from 165 lpcd
in a few larger town to about 50 lpcd in most smaller towns. The availability of water in urban slums is about 27 lpcd. Urbanisation has given rise to a
number of environmental problems such as water supply, wastewater generation and its collection, treatment and disposal in urban areas.  In most
cases wastewater is let out untreated and it either percolates into the ground and in turn contaminates the groundwater or is discharged into the natural
drainage system causing pollution in downstream areas. Sewage and not the industrial pollution accounts for more than 75 per cent of the surface water
contamination in India. Due to negligence, groundwater is also increasingly getting contaminated. In India less than 50% of the urban population has
access to sewage disposal system.  Most of the existing collecting systems discharge directly to the receiving water without treatment. Garbage,
domestic and otherwise, is directly dumped into water bodies or roadside, which can often be washed into streams and lakes. The municipalities
disposes off their treated or partly treated or untreated wastewater into natural drains joining rivers or lakes or used on land for irrigation or fodder
cultivation or into sea or combination of these. Toxic chemicals from sewage water transfer to plants and entire in the food chain and affect public health.
Pathogens occurring in the sewage water directly affect the mammals causing severe diseases. About 60 per cent of urban deaths in India are due to
lack of safe drinking water facilities. Further deaths due to water borne diseases are second only to malnutrition. It is estimated that around 80% of water
consumed by a household is let of to the drains of sewers as wastewater. There is substantial scope for segregated use of the water for further use for
gardening, industrial cooling, street cleaning, vehicular washing, fire fighting, irrigation, yard cleaning, fountains, recreational lakes, etc. Though methods
are available to improve the quality of recycled water to potable grade, the lack of social acceptance and prohibitive costs may prevent the adoption of
these techniques. The importance of reuse and recycling of treated sewage and industrial effluents has been realized on account of two distinct
advantages: reduction of pollution in the receiving water bodies and reduction in the requirement of fresh water for various uses. Reuse of municipal
wastewater after necessary treatment to meet industrial water requirement is being practiced in India.  

Thus, wastewater can be considered as both a resource and a problem. Wastewater and its nutrient content can be used extensively for irrigation and
other ecosystem services. Its reuse can deliver positive benefits to the farming community, society, and municipalities. However, wastewater reuse also
exacts negative externality effects on humans and ecological systems, which need to be identified and assessed. Before one can endorse wastewater
irrigation as a means of increasing water supply for agriculture, a thorough analysis must be undertaken from an economic perspective as well. In this
regard the comprehensive costs and benefits of such wastewater reuse should also be evaluated. Moreover, the economic effects of wastewater
irrigation need to be evaluated not only from the social, economic, and ecological standpoint, but also from the sustainable development perspective.  


Wastewater Characteristics

Sources of Wastewater

In general, municipal wastewater is made up of domestic wastewater, industrial wastewater, storm water, and by groundwater seepage entering the
municipal sewage network.  

1. Domestic wastewater consists of effluent discharges from households, institutions, and commercial buildings.  

2. Industrial wastewater is the effluent discharged by manufacturing units and food processing plants.  

3. Unlike in some developed cities where the systems are separate, there, the municipal sewage network also serves as the storm water sewer. Due to
defects in the sewerage system, there is groundwater seepage as well, adding to the volume of sewage to be disposed.


Composition of sewage water    

•        Organic matter

•        Nutrients (Nitrogen, Phosphorus, Potassium)

•        Inorganic matter (dissolved minerals)

•        Toxic chemicals (heavy metal and pesticides)

•        Pathogens



Table 1. Major Constituents of Typical Domestic Wastewater

Constituent        Concentration (mg/l)

              Strong        Medium        Weak

Total solids        1200        700        350

Dissolved solids  (TDS)        850        500        250

Suspended solids        350        200        100

Nitrogen (as N)        85        40        20

Phosphorus (as P)        20        10        6

Chloride        100        50        30

Alkalinity (as CaCO3)        200        100        50

Grease        150        100        50

BOD5        300        200        100

Source: UN Department of Technical Cooperation for Development (1985)


Quality parameters of importance  

Parameters of health significance

Organic chemicals usually exist in municipal wastewaters at very low concentrations and ingestion over prolonged periods would be necessary to
produce detrimental effects on human health. This is not likely to occur with agricultural/aquacultural use of wastewater, unless cross-connections with
potable supplies occur or agricultural workers are not properly instructed, and can normally be ignored. The principal health hazards associated with the
chemical constituents of wastewaters, therefore, arise from the contamination of crops or groundwaters. Hillman (1988) has drawn attention to the
particular concern attached to the cumulative poisons, principally heavy metals, and carcinogens, mainly organic chemicals. World Health Organization
guidelines for drinking water quality (WHO 1984) include limit values for the organic and toxic substances given in the table - 3 based on acceptable daily
intakes (ADI). These can be adopted directly for groundwater protection purposes but, in view of the possible accumulation of certain toxic elements in
plants (for example, cadmium and selenium) the intake of toxic materials through eating the crops irrigated with contaminated wastewater must be
carefully assessed.  


Table 2. Pollutants and contaminants in wastewater and their potential impacts  

Pollutants/

Contaminants        Parameters            Impacts

Hydrogen ion concentration                           pH        1.        Possible adverse impact on plant growth due to acidity /alkalinity.

                                                                           2.        Impact sometimes beneficial to flora  and fauna.

Suspended solids        Volatile compounds, settable, suspended and colloidal impurities        1.        Development of sludge deposit.

Dissolved inorganic substances         TDS, EC, Na, Ca, Mg, Cl and B        1.        Cause salinity and associated adverse impacts

                                                                                                                    2.        Phytotoxicity

                                                                                                                    3.        Affect permeability and soil structure

Plant food nutrients        N, P, K etc.

       1.        Excess N causes nitrogen injury, excessive vegetative growth, delayed growth season and maturity, causing economic loss of farmers.

      2.        Excessive of N and P cause excessive growth of undesirable aquatic life (eutropication)

      3.        Nitrogen leaching causes ground water pollution with adverse health and environmental impacts.

Heavy metals        Fe, Mn,  Cu, Cd, Cr, Pb, Ni, Zn, Ag, Hg etc,        1.        Accumulate in aquatic  organisms

 2.        Accumulate in sewage water irrigates soils and transfer to the plants and entire in the food chain and affect public health.

 3.        Toxic to plants and animals.

 4.        May make sewage water unsuitable for irrigation.

Pesticide residues        Both parent molecules and metabolites        1.        Ground and surface water contamination  

                                                                                                            2.        Toxicity to mammals and aquatic organisms

                                                                                                            3.         residual organic compounds

                                                                                                            4.        Green-house effect.  

Biodegradable organics        BOD,COD        1.        Depletion of D.O. in surface water.

                                                               2.        Development of septic conditions.

                                                               3.        Unsuitable habitat and Environment.

                                                              4.        Can inhibit pond-breeding amphibians.

                                                              5.        Fish death.

                                                              6.        Humus build up

Source: Asano et.al. (1985)


Table 3. Organic and inorganic constituents of drinking water of

health significance

Organic                 Organic        Inorganic

Aldrin and dieldrin        1,1 Dichlorethylene        Arsenic

Benzene        Heptachlor and heptachlor epoxide        Cadmium

Benzo-a-pyrene        Hexachlorobenzene        Chromium

Carbon tetrachloride        Lindane        Cyanide

Chlordane        Methoxychlor        Fluoride

Chloroform        Pentachlorophenol        Lead

2,4 D        Tetrachlorethylene        Mercury

DDT        2, 4, 6 Trichloroethylene        Nitrate

1,2 Dichloroethane        Trichlorophenol        Selenium

Source: WHO (1984)


Sewage water contains pathogenic microorganisms like bacteria, viruses, fungi, algal etc., having the potential risks to causes diseases can causes
immense harm to public health. The water borne diseases are typhoid, paratyphoid fevers, dysentery and cholera, polio and infectious hepatitis.  The
responsible organisms occur in the faces or urine or infected people. Where raw untreated sewage water is used to irrigate crops helminthic disease
caused by Ascaris, and Trichuris spp. as occurred in   West Germany. Melbourne, Australia and from Denmark (reported by Shuval et al. 1985) that cattle
grazing on fields freshly irrigated with raw wastewater, or drinking from raw wastewater canals or ponds, can become heavily infected with the disease
(cysticerosis).  

In India sewage farm workers exposed to raw wastewater in areas where Ancylostoma (hookworm) and Ascaris (nematode) infections are endemic have
significantly excess levels of infection with these two parasites compared with other agricultural workers in similar occupations.

From the health  point of view important microbiological parameter are coliform , fecal coliform, fecal streptococci and clostridium perfringens. Finally, in
respect of the health impact of use of wastewater in agriculture, Shuval et al. (1986) rank pathogenic agents in the order of priority shown in Table 4. They
pointed out that negative health effects were only detected in association with the use of raw or poorly-settled wastewater, while inconclusive evidence
suggested that appropriate wastewater treatment could provide a high level of health protection. high level of health protection.  



Table 4. Relative health impact of pathogenic agents

High Risk

Helminths

(Ancylostoma, Ascaris, Trichuris and Taenia)

Medium Risk

Enteric Bacteria

(Cholera vibrio, Salmonella typhosa, Shigella etc.

Low Risk

Enteric viruses

(Shuval et al. 1986)


Indicator organisms

A) Coliforms and Faecal Coliforms. The Coliform group of bacteria comprises mainly species of the genera Citrobacter, Enterobacter, Escherichia and
Klebsiella and includes Faecal Coliforms, of which Escherichia coli is the predominant species. They are   not itself harmful but presesnce of  coliform
groups of  bacteria indicate t he presence of pathogenic bacte4ria and fecal coliforms indicate  fecal contamination  and presence of enteric  pathogens
in surrounding water.    Several coliforms are able to grow out side of the intestines , specially in hot climates. Hence their enumeration is unsuitable as a
parameter. The fecal coliforms can  grow  at 44 degree C,  so E.coli, is most  s satisfactory  indicator parameter  in sewage water use.

B) Faecal Streptococci. Faecal Streptococci as an indicator in tropical conditions and especially to compare survival with that of Salmonellae.  

Clostridium perfringens. This bacterium is an exclusively faecal spore-forming anaerobe normally used to detect intermittent or previous pollution of
water, due to the prolonged survival of its spores. In sewage  water studies  it is useful as it may have survival characteristics similar to those of viruses
or even helminth eggs.

Parameters of agricultural significance

Sewage water contains soluble salts that may accumulate in the root zone with possible harmful effect on soil health and crop yield. The quality of
irrigation water is of particular importance in arid zones where extremes of temperature and low relative humidity result in high rates of evaporation, with
consequent deposition of salt which tends to accumulate in the soil profile. The physical and mechanical properties of the soil, such as dispersion of
particles, stability of aggregates, soil structure and permeability, are very sensitive to the type of exchangeable ions present in irrigation water. Thus, when
effluent use is being planned, several factors related to soil properties must be taken into consideration.  

Another aspect of agricultural concern is the effect of dissolved solids (TDS) in the irrigation water on the growth of plants. Dissolved salts increase the
osmotic potential of soil water and an increase in osmotic pressure of the soil solution increases the amount of energy which plants must expend to take
up water from the soil. As a result, respiration is increased and the growth and yield of most plants decline progressively as osmotic pressure increases.
Important Agricultural Water Quality parameters include a number of specific properties of water that are relevant in relation to the yield and quality crops,
maintenance of soil productivity and protection of the environment. These parameters mainly consist of certain physical and chemical characteristics of
the water. The primary wastewater quality parameters of importance from an agricultural viewpoint are:


Table 5. Guidelines for interpretation of water quality for irrigation

Potential irrigation problem         Units         Degree of restriction on use  

 None         Slight to moderate         Severe  

Salinity  

EC        dS/m          3.0  

TDS         mg/l          2000  

Specific ion toxicity  

Sodium (Na)  

Surface irrigation         SAR          9  

Chloride (Cl)  

Surface irrigation         me/I          10  

Boron (B)         mg/l          3.0  

Miscellaneous effects  

Nitrogen (NO3-N)         mg/l          30  

Bicarbonate (HCO3)         me/I          8.5  

pH         Normal range 6.5-8.0  

Source: FAO (1985)


A.  pH  

pH is an indicator of the acidity or basicity of water but is seldom a problem by itself. The normal pH range for irrigation water is from 6.5 to 8.4; pH values
outside this range are a good warning that the water is abnormal in quality. Normally, pH is a routine measurement in irrigation water quality
assessment.  

B. Electrical Conductivity  

Electrical conductivity is widely used to indicate the total ionized constituents of water. It is directly related to the sum of the cations (or anions). It should
be noted that the electrical conductivity of solutions increases approximately 2 percent per °C increase in temperature. The symbol ECw, is used to
represent the electrical conductivity of irrigation water and the symbol ECe is used to designate the electrical conductivity of the soil saturation extract. The
unit of electrical conductivity is deciSiemen per metre (dS/m).


C. Total Salt Concentration  

Total salt concentration (for all practical purposes, the total dissolved solids) is one of the most important agricultural water quality parameters. This is
because the salinity of the soil water is related to, and often determined by, the salinity of the irrigation water. Accordingly, plant growth, crop yield and
quality of produce are affected by the total dissolved salts in the irrigation water. Equally, the rate of accumulation of salts in the soil, or soil salinization, is
also directly affected by the salinity of the irrigation water. Total salt concentration is expressed in milligrams per litre (mg/l) or parts per million (ppm).  

D. Sodium Adsorption Ratio  

Sodium is an unique cation because of its effect on soil. When present in the soil in exchangeable form, it causes adverse physico-chemical changes in
the soil, particularly to soil structure. It has the ability to disperse soil, when present above a certain threshold value, relative to the concentration of total
dissolved salts. Dispersion of soils results in reduced infiltration rates of water and air into the soil. When dried, dispersed soil forms crusts which are
hard to till and interfere with germination and seedling emergence. Irrigation water could be a source of excess sodium in the soil solution and hence it
should be evaluated for this hazard. The most reliable index of the sodium hazard of irrigation water is the sodium adsorption ration, SAR. The sodium
adsorption ratio is defined by the formula and the ionic concentrations are expressed in me/l.  

E.  Toxic Ions  

Irrigation water that contains certain ions at concentrations above threshold values can cause plant toxicity problems. The most common phytotoxic ions
that may be present in municipal sewage and treated effluents in concentrations such as to cause toxicity are: boron (B), chloride (Cl) and sodium (Na).
Hence, the concentration of these ions will have to be determined to assess the suitability of waste-water quality for use in agriculture.  


F. Trace Elements and Heavy Metals  

A number of elements are normally present in relatively low concentrations, usually less than a few mg/l, in conventional irrigation waters and are called
trace elements. They are not normally included in routine analysis of regular irrigation water, but attention should be paid to them when using sewage
effluents, particularly if contamination with industrial wastewater discharges is suspected. These include Aluminium (Al), Beryllium (Be), Cobalt (Co),
Fluoride (F), Iron (Fe), Lithium (Li), Manganese (Mn), Molybdenum (Mo), Selenium (Se), Tin (Sn), Titanium (Ti), Tungsten (W) and Vanadium (V). Heavy
metals are a special group of trace elements which have been shown to create definite health hazards when taken up by plants. Under this group are
included, Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), Mercury (Hg) and Zinc (Zn). These are called heavy metals because in
their metallic form, their densities are greater than 4g/cc. The threshold levels of trace elements for crop production are given in Table – 6.  



Table 6. Threshold levels of trace elements for crop production  

Element        Recommended maximum concentration (mg/l)        Remarks

Al        (aluminium)        5.0        Can cause non-productivity in acid soils (pH  7.0 will precipitate the ion and eliminate any toxicity.

As        (arsenic)        0.10        Toxicity to plants varies widely, ranging from 12 mg/l for Sudan grass to less than 0.05 mg/l for rice.

Cd        (cadmium)        0.01        Toxic to beans, beets and turnips at concentrations as low as 0.1 mg/l in nutrient solutions. Conservative limits
recommended due to its potential for accumulation in plants and soils to concentrations that may be harmful to humans.

Co        (cobalt)        0.05        Toxic to tomato plants at 0.1 mg/l in nutrient solution. Tends to be inactivated by neutral and alkaline soils.

Cr        (chromium)        0.10        Not generally recognized as an essential growth element. Conservative limits recommended due to lack of knowledge on
its toxicity to plants.

Cu        (copper)        0.20        Toxic to a number of plants at 0.1 to 1.0 mg/l in nutrient solutions.

F        (fluoride)        1.0        Inactivated by neutral and alkaline soils.

Fe        (iron)        5.0        Not toxic to plants in aerated soils, but can contribute to soil acidification and loss of availability of essential phosphorus and
molybdenum. Overhead sprinkling may result in unsightly deposits on plants, equipment and buildings.

Li        (lithium)        2.5        Tolerated by most crops up to 5 mg/l; mobile in soil. Toxic to citrus at low concentrations ( 6.0 and in fine textured or organic
soils.

Source: National Academy of Sciences (1972) and Pratt (1972).



Potential impacts of wastewater in environment

This section provides the potential impacts of wastewater use in various substrates

1.        Public Health & Other living organism

2.        Crops

3.        Social Resources

4.        Ground Water resources

5.        Property values

6.        Ecological impacts

7.        Social Impacts


1. Public health& other living  organisms: Use of  untreated sewage water pose a high risk to  human health& other living organisms in all groups as it
contain pathogenic microorganisms which have the potential to cause diseases.

2. Crops

Generally speaking, wastewater (treated and untreated) is extensively used in agriculture because it is a rich source of nutrients and provides all the
moisture necessary for crop growth. Most crops give higher than potential yields with wastewater irrigation; reduce the need for chemical fertilizers,
resulting in net cost savings to farmers.

3. Soil Resources

Impact from wastewater on agricultural soil, is mainly due to the presence of high nutrient contents (Nitrogen and Phosphorus), high total dissolved
solids and other constituents such as heavy metals, which are added to the soil over time. Wastewater can also contain salts that may accumulate in the
root zone with possible harmful impacts on soil health and crop yields. The leaching of these salts below the root zone may cause soil and groundwater
pollution (Bond 1999). Prolonged use of saline and sodium rich wastewater is a potential hazard for soil as it may erode the soil structure and effect
productivity. This may result in the land use becoming non-sustainable in the long run. Wastewater induced salinity may reduce crop productivity (Kijne et
al. 1998). The net effect on growth may be a reduction in crop yields and potential loss of income to farmers. Wastewater irrigation may lead to transport
and bio-accumulate heavy metals to soils, affecting soil flora and fauna. e.g., Cd and Cu, may be redistributed by soil fauna such as earthworms (Kruse
and Barrett 1985). In general, heavy metal accumulation and translocation is more a concern in sewage sludge application than wastewater irrigation,
because sludge formed during the treatment process consists of concentrations of most heavy metals. The impact of wastewater irrigation on soil may
depend on a number of factors such as soil properties, plant characteristics and sources of wastewater.  

4. Groundwater Resources

Wastewater application has the potential to affect the quality of groundwater resources in the long run through excess nutrients and salts found in
wastewater leaching below the plant root zone. For instance the quality of groundwater would determine the magnitude of the impact from leaching of
nitrates. Groundwater constitutes a major source of potable water for many developing country communities. Hence the potential of groundwater
contamination needs to be evaluated before embarking on a major wastewater irrigation program. In addition to the accretion of salts and nitrates, under
certain conditions, wastewater irrigation has the potential to translocate pathogenic bacteria and viruses to groundwater (NRC report 1996).

Farid et al. (1993), reported that the long-term use of wastewater for crop irrigation has interestingly led to an improvement in the salinity of the
groundwater. This was offset by evidence of coliform contamination of groundwater which was also observed in Mexico (Downs et al. 1999, Gallegos et
al. 1999). A companion study (Rashed et al. 1995), reveals that in the wastewater irrigated Gabar el Asfar region, concentrations of chloride, sulfate, TDS,
and dissolved oxygen in groundwater is much higher than average concentrations in sewage effluents. The leaching and drainage of wastewater,
applied for crop irrigation, to groundwater aquifer may serve as a source of groundwater recharge. In some regions, 50-70 percent of irrigation water may
percolate to groundwater aquifer (Rashed et al. 1995).  

5. Ecological Impacts

When drainage water from wastewater irrigation schemes drains particularly into small confined lakes and water bodies and surface water, and if
phosphates in the orthophosphate form are present, the remains of nutrients may cause eutrophication (Smith et al. 1999). For example, overloading of
organic material resulting in decreases in dissolved oxygen may lead to changes in the composition of aquatic life, such as fish deaths and reduced
fishery. The eutrophication potential of wastewater irrigation can be assessed using biological indices or biomarkers, which in turn can be quantified in
monetary units using appropriate economic valuation techniques.

6. Social Impacts

In the context of this analysis social impacts are the concerns/doubts expressed by the public about wastewater irrigation. These concerns can be
classified as follows:

General concerns such as nuisance, poor environmental quality, poor hygiene, odor, noise, higher probability of accidents, etc.

Social concerns such as food safety, health and welfare, impaired quality of life, loss of property values, and sustainability of land use.

Natural resource concerns such as pollution of vital water resources, loss of fish, wildlife, exotic species, etc.

7. Economics of Wastewater Irrigation

To date, in relation to wastewater irrigation, economic analyses have been conducted with specific perspectives in mind viz that of a municipality
optimizing treatment costs, or that of farmers or a regional entity maximizing income, or that of evaluating environmental impacts.  


The researchers evaluated the effect of crop selection on cost and revenue streams and system efficiency by selecting three cropping patterns viz. reed
canary grass, alfalfa, corn and forest plantations. Wastewater can also be used for producing rapidly growing pulpwood, such as eucalyptus, on public
lands, along canal banks, roads and greenbelts etc. These plants can be harvested every 8 to 10 years to generate revenue, along with the added
advantage of working as natural air conditioners and greenhouse gas sinks, for ameliorating the highly polluted urban environments.The main benefits
from wastewater irrigation are effective water and nutrient recycling, higher crop yields, a diversified cropping pattern, and disposal cost savings. Segarra
et al. (1996), suggested that alfalfa, wheat-corn, wheat-grain sorghum, and cotton are optimal crop combinations to maximize net revenue. It, therefore,
implies that municipalities can benefit from cooperative arrangements with neighboring farmers for wastewater irrigation. A recent IWMI study (Scott et al.
2000), evaluated the economic value and risks associated with long-term use of urban wastewater for crop irrigation in Guanajuato, Mexico. The study
was conducted to predict changes in water quality under various wastewater management scenarios. The study used an opportunity cost or replacement
value approach to estimate dollar values for water and nutrient contents of wastewater. The findings suggest that wastewater is a valuable resource for
the community and wastewater reuse for irrigation is an economical alternative to expensive treatment. However, the study recognizes that there could be
negative health and environmental impacts of wastewater use, and that these impacts should be evaluated.


Waste water treatment procedure adopted in India

        Activated sludge process

        Trickling filter

        Oxidation pond and Waste stabilization pond


Status of sewage and sewage treatment in India

The total wastewater generated by 23 metropolitan cities is 9,275 mld. Out of 9,275

mld of total wastewater generated, only 31% (2,923 mld) is treated before letting out

and the rest i.e. 6,352 mld is disposed off untreated. Three cities have only primary treatment facilities and thirteen have primary and secondary treatment
facilities. In India less than 50% of the urban population has access to sewage disposal system. Most of the existing collecting systems discharge
directly to the receiving water without treatment. Garbage, domestic and otherwise, is directly dumped into water bodies or roadside, which can often be
washed into streams and lakes. This vulnerable environment requires special attention and the solution of such complex and interdisciplinary problems
call for an integrated water resources management approach.

The municipalities (governing bodies of metropolitan cities) disposes off their treated or partly treated or untreated wastewater into natural drains joining
rivers or lakes or used on land for irrigation or fodder cultivation or into sea or combination of these. In four cities, it is disposed indirectly into the
rivers/lakes, while in two cities it is disposed into sea/creek and the rest partly used for agriculture and partly disposed into rivers. It is found that in 12
metropolitan cities there is some level of organized sewage farming under the control of government or local body (CPCB, August 1997).

In India, till now very little emphasis has been laid on research on hydrology of urban

areas. Taking into account that the trends of urban population concentration increase will continue in the future, a programme for encompassing all
hydrological, ecological and socio-economic aspects of future urban planning and management needs to be taken up in right earnest. This would
require improvement in the management of existing urban drainage systems, disseminate knowledge of integrated urban water management, identify
the impact of urbanization on surface and ground water quality through point and nonpoint sources, to study impact of storm water (wastewater
discharges) on ecosystem health of receiving water courses and to establish experimental urban catchments.


Water quality guidelines

From effect of sewage water several guidelines are produced to minimize the potential risk. WHO guidelines is used on the safe use of water for
agriculture and aquaculture. The rationale behind the WHO guidelines was to develop criteria that would present the transmission of communicable
diseases   caused by microorganisms while optimizing resource conservation and recycling. Recent evidence suggest that these guidelines are used
only to crop consumers  but not necessarily farmers, farm workers and their families, thereby meeting this guidelines debatable. In order to evaluate the
financial feasibility of WHO and USEP a microbial health guidelines, Shuval et al. (1997), developed a risk assessment approach to conduct a
comparative risk analysis. Most European countries, with the exception of Germany and France, have not established any guidelines for the use of
wastewater for irrigation. The EU guidelines, when formulated, propose to cover both agronomic aspects, of soil and groundwater protection, yield
maximization, and the sanitary aspects, relating to public health protection.


Conclusion

Rapid urbanization places immense pressure on the world’s fragile and dwindling fresh water resources and over-burdened sanitation systems, leading
to environmental degradation. Thus, it is quiet justified and seems logistic to say that:   

1.        Wastewater (raw, diluted or treated) is a resource of increasing global importance.

2.        Without proper management sewage water use poses high risks to human health and cause environmental degradation Thus scientists around  
the world refocus on conserving water, recycling of water and treatment of   sewage water through sewage treatment plant.

3.        With proper management, wastewater use contributes significantly to sustaining livelihoods, food security and the quality of the environment.

Parameters for Water Quality Characterization & Standards

(Domestic Water Supply)

parameters        USPH Standard        ISI Standard

Color, odour, state        Colorless, odorless, tasteless        -

Inorganic Chemicals                 

pH        6.0-8.5        6.0-9.0

conductance        300mmho/cm        -

D.O        4.0-6.0 ppm        3.0

TDS        500        -

Suspended Solid        5.0        -

SO42-        250        100

Cl-        250        600

F-        1.5        3.0

PO43-        0.1        -

S-        0.1mg/L        -

Ammonia        0.5        -

B        1.0        -

Ca2+        100        -

Mg2+        30        -

As        0.05        0.2

Cd        0.01        -

Cr        0.05        0.05

Cu        1.0        -

Fe        Less than 0.3        -

Pb        Less than 0.05        0.01

Mn         Less than 0.05        -

Hg        0.001        -

Ag        0.05        -

U        5.0        -

Zn        5.5        -

Organics                 

COD        4.0        -

Phenols        0.001        0.005

Pesticides(total)        0.005        -

Polycyclic aromatic hydrocarbons(PAH)        0.002ppm        -

Surfactants        200        -

Biological parameters                 

Coliform cells/1000mL        100        Less than5000

Total bacteria count/100mL        1x106         

4.        Sewage treatment   cost studies shows that marginal cost are very high at   higher levels of treatment at higher levels of treatment. However, these
costs become justifiable in view of the value of the degree of water scarcity and public concern. Cost-effective and appropriate treatment suited to the end
use of wastewater, supplemented by guidelines and their application.

5.        Proposed guidelines should link heath, agriculture and environmental quality, which are implemented in a stepwise approach.

6.        Reduction of toxic contaminants in sewage water is essential by improved management practices.

7.        Where sewage water is insufficiently treated  due to lack of treatment facilities there some steps should be taken, which are

(a)    Development and application of guidelines for untreated wastewater use that will safe livelihoods, public health and the environment.

(b)   Application of appropriate irrigation, agricultural, post-harvest, and public health practices that limit risks to farming communities, vendors,         
 and  consumers.

(c)    Education and awareness programs for all stakeholders, including the public at large, to disseminate these measures.

8.        Therefore, we strongly urge policy-makers and authorities in the fields of water, agriculture, aquaculture, health, environment and urban planning,
as well as donors and the private sector to.



“ Safeguard and strengthen livelihoods and food security, mitigate health and environmental risks and conserve water resources by confronting the
realities of wastewater use in agriculture through the adoption of appropriate policies and the commitment of financial resources for policy
implementation”.  

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*Correspondence to: Md. Wasim Aktar,   e-mail id : wasim04101981@yahoo.co.in

Tel. No. +91-9474126188, Fax no. +91-33-2582 8407

Source:  
ArticlesBase.com

About the Author:
1) Md. Wasim Aktar is a Senior Research Fellow in Export Testing Laboratory, APEDA, Govt. of India, under Deptt of Agricultural Chemicals, Bidhan
Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India

2) Prof. Anjan Bhattacharyya is the Head,Deptt of Agricultural Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India
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