Clean water is essential to life in general, as the saying goes, "water is life." Every single life form in the universe, from the most complex multicellular creatures to the simplest single celled organisms requires water for survival. About 70 % of the earth's surface is water, but only a tiny percentage of about 1% is readily available for consumption or use by man. Therefore water conservation, recycling and efficient waste water management and treatment is vital for survival.
Contamination of our natural water systems like the rivers, lakes, and oceans is on the rise every day due to industrialization and modernization of the society. Most of industrial, household and even agricultural waste water sometimes referred to as sewage, ends up in the natural water sources in one way or the other. Once in the wastewater recycling system, they pose a threat to the balance of the ecosystem and human life. Thus it is vital to treat waste water before releasing it into the natural water systems.
Industrial waste water treatment systems allow the waste water to pass through various phases of treatment before release into the environment. The processes
involved are chemical, biological or mechanical.
The mechanical treatment process includes sieving of the waste water at the inlet of the treatment plant to remove large particles like tree logs, plastics, and plant residues by placing metal or mesh barriers at the inlet. Clarification and filtration of the waste water also fall under this category. For clarification, the water is let into a clarifier at a very slow speed to ensure settling of particles which make up the waste. Filtration requires the waste water to be passed via a medium, for example, sand, to trap other particles or organisms that sometimes are not visible with naked eyes.
The chemical process involves flocculation where a chemical is added to the waste water to ensure the formation of flocs that later settle at the bottom of the flocculation chambers. Sometimes flocs can float, but if the speed of the water is slow and a flocculant/coagulant is optimum, all the formed flocks easily settle at the bottom of the chambers. For more details about water purification, visit https://en.wikipedia.org/wiki/Portable_water_purification.
The organic phase includes oxidation of the water to allow biodegradation of the organic wastes. Both aerobic and anaerobic bacteria break down the waste and utilize it for energy. The latter mainly contributes to treating the waste water by enhancing biodegradation. Sometimes, anaerobic bacteria release oxygen causing bubbles to appear on the surface. The bubbles may contain flocs sometimes. Flushing air into the clarifier can solve this problem. Sometimes an artificial oxidant like hydrogen peroxide can be added into the drinking water treatment systems to enhance biodegradation.
After all the phases are complete, the water is now clear and can be released into the water systems without causing pollution. The water can also be conveyed into a drinking water treatment plant for further treatment. The solid waste from the process should be buried in landfills to avoid land pollution