Waste water agriculture Threats, challenges and remedies

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


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.

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