Raw city effluent represents the untreated sewage or waste water which normally contains plant
nutrient, toxic chemicals, organic and inorganic pollutants and pathogens. The frequency and
volume of effluents are increasing day by day due to unplanned and unchecked urbanization.
The mushroom growth of urban population and industries has absorbed the major share of fresh
water and dispose it into drains in the form of waste water. In Pakistan the bulk quantities of
effluents are mixed in nature contributed by municipal, industrial, hospital and agricultural
sectors. Composition of waste water varies depending upon the source, industries in a particular
area and living standards of inhabitants. Municipal waste effluents are constituted by the
discharge from the households, institutions and commercial buildings trash or garbage while
industrial effluents contain wastewater from industries like Tanning, Textile, Sugar, Vegetable
ghee and cooking oil, Cement, Chemical and Fertilizer industry etc. The composition of
industrial effluent contains dyes, solids, organic chemicals, heavy metals, oils, sulphates and
cyanide pollutants. Hospital effluents contain wastewater from surgical operations and
pharmaceutical disposals like diagnostic tissues, used needles and syringes, medical devices,
blood and liquid medicines while the agriculture field operation and routine operation at animal
farms are the constitute of agriculture effluent.
In Pakistan the total quantity of waste water produced 9.6 x 10 5 million gallons (4.39 x 109
m 3 /yr). The estimated volume of wastewater discharge (cusec) from different cities of Pakistan
like Lahore (3304), Faisalabad (1278), Gujranwala (312), Multan (235), Rawalpindi (171),
Sargodha (99), Sialkot (92), Gujrat (42), Shiekhupura (416), Jhang (21) and others cities
(421.60) in 2010. The Faisalabad city generates approximately 280 Million Gallons of waste
water per Day more as compared to all others cities. Annually sewage water and the total
capacity of waste water treatment plant (Chakera) contain approximately 20 Millions of Gallons
per Day. The total volume of wastewater produced by the industrial, commercial, residential
and agriculture sector is about 395, 266, 4687 and 1036 x 10 6 m 3 yr -1 respectively. Collection of
effluents and its safe disposal is the responsibility of the Water and Sanitation Agencies
(WASAs) in major cities and the Tehsil Municipal Administrations (TMAs) in developing cities
but they have failed in managing such a large quantity of uncontrolled effluents in many cities
of Pakistan like Faisalabad, Islamabad and Karachi where about less than 20% of its generated
sewerage is being treated. In Pakistan, water bodies and agricultural land are acting as the major
dumping sites of this hazardous waste water.
In Pakistan, agriculture is the biggest sector which greatly influences the socio-economic
conditions of rural community. Agriculture adds 20.9% to Gross domestic product (GDP) in
Pakistan. Water acts as the backbone of agriculture but uneven and industry tilted distribution of
fresh water has created acute shortage of good quality water. Beside this curse high prices of
fertilizers and unavailability of proper nutrients at proper time and at proper stage of crops are
also the limiting factors for the traditional agriculture. To combat with these problems, the
nutritional value and around the clock availability of wastewater has grabbed the attention of
the farmers, opting wastewater for agriculture purpose. From total waste water produced almost
30% is used for irrigating an area of about 32,500 hac in Pakistan.
This practice is reducing the cost of production of agricultural commodities, lessening the
fertilizer and water expenses. The most striving contaminants in waste water are heavy metals
sourced from different anthropogenic activities and having agriculture lands as their final
destination. These metals are non-biodegradable, having great persistence in soils. The major
portion of heavy metals remains phyto-available and has high risk to enter food chain via plants
grown on these contaminated agricultural lands. These heavy metals are carcinogenic and
patients in bulk have been reported in cancer hospitals due to outrageous heavy metals exposure
directly or indirectly. Moreover, stomach diseases, skin allergies, malaria, mental disorders and
kidney failure are other curses of this contamination. Soil contamination with heavy metals
through wastewater irrigation largely affects the biological and physical properties of soil.
Various biochemical and physiological disorders of plants are also the result heavy metals
toxicity. Disposal of untreated waste water into fresh water bodies is causing serious threat such
water borne diseases in Pakistan like diarrhea, salmonellosis, typhoid, shigellosis and gastric
ulcers. Variety of salts of nitrates and heavy metals has been reported to leach down into ground
water. Once ground water may get contaminated it is impossible to remediate it. Ground
water of the Faisalabad city is not suitable for domestic, irrigation and industrial purpose which
is creating extra pressure on utilization of fresh water. By drinking such type of contaminated
water diseases like hepatitis in Samundri, Gastroenteritis in Lahore, typhoid, kidney and
stomach problems in Faisalabad have been reported.
As water scarcity is the major issue all over the world, the survival only lies in the utilization of
fresh water wisely and in an appropriate way. Follow “more crop per drop” in all stack holder
sectors of fresh water including agriculture sector. The first step is the implementation of
existing laws and policies to giant industries to replace or make the existing treatment plants
functional. The waste water and sewerage water can be reused for agriculture sector by
remediating it using bio-sorbents, chemi-sorbents and phytoremediation. Bio-sorption is a
physiochemical method that takes place naturally in certain biomass that concentrates and binds
the solid wastes onto its cellular structure. This method makes use of peelings of vegetables,
eggshells, bones and peat etc. to act as bio-sorbents that remove the heavy metals from the
contaminated water. Scientists believe that it is an economic and environment friendly
technique to remove the heavy metals from waste water. Besides bio-sorbents, various
chemicals are being in use to treat the wastewater.
The different chemical processes such as chemical coagulation, chemical precipitation,
chemical oxidation and advanced oxidation, ion exchange and chemical neutralization and
stabilization are used to decontaminate the waste water and make it reusable. Phytoremediation
is the use of plants for the remediation purposes that act as the hyper accumulators such as
bamboo, kikar, shahtut/ mulberry, popular, neem and dharaik. In Pakistan, about 26% of
national vegetable production is irrigated with waste water. Instead of growing vegetables with
sewerage water cultivation of trees that accumulate the heavy metals will act as constrain for the
entry of heavy metals into food chain. These trees could be use for the fuel and energy
production purposes instead of food production. There is increasing understanding of “treating
to fit the purpose” and other treatment options related with water usage and water quality
objectives.
The management of wastewater through treatment has two major objectives: 1) To protect the
environment by reducing the pollution of fresh water resources, productive lands and hence
reducing health hazards. 2) To mobilize this available water resource for mitigating water
scarcity and improving crop production. Other simple option for farmers includes changes in
irrigation methods which can have low levels of risks. Using micro irrigation techniques to
irrigate vegetables, which can greatly reduce the risk of pathogenic contamination compared to
flood or furrow irrigation. The use of sewage in urban and peri-urban agriculture can also
improve water use efficiency in cities with limited water resources. Properly treated sewage
effluent can be used for ground water recharge, aquaculture and irrigation of lawns and urban
recreational parks and other non-potable uses. The best approach will need to balance both
farmers livelihood needs, and public health concerns. In future, water shortage and waste water
handling would be a major challenge in Pakistan. The result of increased attention to this issue
is expected to improve the health, economic and agricultural factors of developing community
in relation to waste water treatment and its re-use in agriculture sector.