Securing Water, food and energy is an important and vital issue not only for India but also for the world. The effects of agricultural growth, industrialization and urbanization has affected most of the river basins in India and elsewhere and brought on moderate to severe water shortages. Current and future fresh water demand needs to be met by enhancing water use efficiency and demands waste water management. Thus, wastewater/low quality water management after essential treatment is the ‘need of the times’.
What is wastewater? Wastewater or sewage is the by-product of many uses of water. There are the household uses such as bathing, washing utensils, clothes and flushing the toilet. Industries use water for many purposes including the different processes, products and cleaning. After the water has been used it flows to the wastewater treatment plant which provides a high quality end product. Why treat wastewater? We need to remove the wastewater pollutants to protect the environment and protect public health. When water is used by our society, the water becomes contaminated with pollutants. If left untreated, these pollutants would negatively affect our water environment. For example, the depletion of oxygen in lakes, rivers, and streams due to the pollutants in them and results in dead fish and/or foul odours. Waterborne diseases can be eliminated through proper wastewater treatment as many pollutants could exhibit toxic effects on aquatic life and the public.
How do we collect the wastewater? The sewer or collection system is designed so that it flows to a centralized treatment location. The collection system is comprised of smaller sewers. As more homes and companies are connected along the system, the pipes become larger in diameter. Where gravity systems are not practical, pumping stations are often included to lift the wastewater. In many states, there are some very old collection systems - the late 1800s! Materials of construction and methods of construction have changed significantly over the years. Many systems experience problems during rainy season with inflow and infiltration. This is when water should flow into a storm water system and not into the sanitary sewer system. The “combined sewers” carry street waste as well as wastewater. Older sewer pipes may have leaking joints or cracks that allow the water to enter the system. Ignoring wastewater management leads to chemical contamination and microbial pollution. The industrial and commercial effluents are often mixed with domestic wastewater.
Wastewater contains a number of pollutants and contaminants, including: • plant nutrients (nitrogen, phosphorus, potassium); • pathogenic microorganisms (viruses, bacteria and protozoa); • heavy metals (e.g. cadmium, chromium, copper, mercury, nickel, lead and zinc); • organic pollutants (e.g. polychlorinated biphenyls, polyaromatic hydrocarbons, pesticides); and biodegradable organics (BOD, COD); and • micro-pollutants (e.g. medicines, cosmetics, cleaning agents). All of these can cause health and environmental problems and when improperly or untreated wastewater is released into the environment.