Deforestation and pollution have contributed to the build-up of ‘green house’ gases that have triggered profound changes in global climate. However, besides this central challenge, one problem which has remained untackled and caused considerable concern to environmentalists is the generation and accumulation of solid and liquid waste in the developing countries, which emanate from the discarded materials from industrial, commercial and agricultural operations or domestic activities. At the same time, waste management is inadequate and thus air pollution and environmentally-induced diseases have increased.
The rapidly expanding population of Pakistan has generated an ever-increasing volume of municipal solid/liquid waste (MS/LW) which has caused many serious environmental problems from its ultimate disposal. This, in turn, has raised questions as to how this waste should be managed and possibly recycled for the benefit of the society. More than 95 per cent of the total MS/LW produced is disposed off by land reclamation/landfills and less than 5 per cent is incinerated. The ultimate disposal of solid/liquid waste has caused severe problems of pollution of surface and ground water while the incineration has adversely affected the air quality. Consequently, there is a need to explore other alternatives that would allow solid/liquid wastes to be recycled. Pakistan and particularly its arid and semi-arid regions such as Sindh, faced with the shortage of water, can benefit immensely from adopting properly controlled waste water treatment technologies so that the treated water could be re-used to irrigate plants/crops in the rural areas and maintenance of large playgrounds, parks, nurseries and greenbelts in the urban areas.
Significance of waste recycling: Since the nutrient status and inferior quality of water bring major constraints in the development of agriculture, harvesting the nutrient energy of biological/organic and industrial waste water is of prime importance for maximizing the food, feed, fodder and fuel production in the country. The pollution of stream and rivers receiving this waste water can be minimized to a large extent, as compared to their direct disposal in water resources.
Biological waste materials are sewage sludge, waste water, fishpond effluent, city refuse and some wastes of food processing industry. Organic resources such as the farmyard manure (FYM), sugarcane filter cake (SFC), composts and crop residues are also dealt with. The domestic and industrial waste water amenable for crop production can help increase the irrigated area. Prevention of environmental pollution through recycling of waste is difficult to quantify but it will be several times valuable. The degradable solid waste generated all over the country to the tune of million tons per day, can be recycled into high quality bio-fertilizer, thus can be highly helpful in reducing the input bill for chemical fertilizers, pollution and above all enhancing the productivity/quality of soil.
Domestic effluent at present seems to be an awful waste creating a lot of problems, in safe disposal, may become an alternate water resource for irrigation of agriculture crops. Waste water irrigation may solve various associated problems of its disposal and may give a new life to the rivers, natural streams and other water bodies. Problems related with environmental degradation with waste water disposal into the natural streams and other water bodies can be minimized and in relation vast area could be brought under cultivation with least expenses on developing additional water resources. Pathogens and health hazards: the sewage water, city refuse, industrial effluents, etc, are some of the identified sources carrying environmental pollution on our ecosystem. A wide variety of bacteria, viruses and protozoa are present in the waste which can cause a large number of diseases. The presence of pathogenic bacteria viruses, ascaris and protozoan in sewage sludge/city garbage, need special consideration when these wastes are used in agriculture. These waters are most hazardous for human health. If the waste water is not properly treated it may contain heavy metals and chemicals that may accumulate in the soil and contaminate it over a longer period of application and can act as slow poison to human and animal health. Similarly, the plants may take certain chemicals and heavy metals or transmit diseases if consumed raw. Skin rashes, eye irritations and gastrointestinal disorders can develop among gardeners and agricultural workers if proper treatment control measures are not maintained. In a country like Pakistan, where the level of genetic diseases is very high, the waste water should be expected to contain high levels of pathogens and chemicals. Certain chemicals can induce cancer, birth deformities and epidemiological problems.
Future approach: Today it is necessary to emphasize that the ‘wastes are a resource’ and therefore their management and utilization is also required. For these wastes, a utilization approach rather then mere disposal needs to be adopted for the conservation of resources. In case of domestic and industrial wastewater, it is necessary to update the collection, treatment and minimization of the contamination with pollutants, particularly in case of industrial wastes. This will improve the waste water quality for crop irrigation. Re-use of waste is an issue which should receive proper attention and a country like Pakistan should pursue this policy and adopt the relevant technologies as soon as possible. However, it is of extreme importance that the implementation of such technologies should be left to those who have the necessary technological background and possess the required skills in order to ensure safe and trouble- free use of the waste re-use option. Suggestions:We must
1. Protect, rehabilitate and develop our natural resources for better environment.
2. Extend cooperation to local efforts for garbage management.
3. Optimize organic manuring for improvement of soil productivity without creating environmental problems.
4. Set up garbage recycling units in every city, where peoples should come and ask the information and learn how wastes are recycled
5. Ccoordinate between the scientists working in agriculture, waste disposal and recycling.