SOIL BIOTECHNOLOGY (SBT)

           

Untreated sewage water is a significant and widespread problem in both cities as well as in rural areas. With rising population comes a rise in consumption of water, which results in large amount of waste water. While there are solutions but they come with disadvantages that have prevented them from gaining popularity and wide acceptance. There is a clear need for new solutions that meet this need.

 Soil Biotechnology (SBT) is an indigenous waste-water treatments process that brings together different biochemical processes in nature in order to treat human sewage waste. Soil Bio-technology is a terrestrial system for waste-water treatment which is based on the principle of trickling filter. In this system, combination of physical processes like sedimentation, infiltration and biochemical processes are carried out to remove the suspended solids, organic and inorganic contents of the waste-water.

 SBT system consists of an impervious containment having soil, granular filter media, select culture of micro-organisms such as earthworms and plants. It involves a combination of physical and biological process for processing waste-water.

The combined grey and black water from all the residential facilities are collected and transported via underground sewerage network to a central collection point.

In the first stage the physical separation of waste is accomplished in a primary treatment unit consisting of a perforated screen and gravity-settling tank and an equalization tank. The perforated screen helps in separating the un-dissolved solid wastes from the waste water and allows it to pass through a settling chamber, facilitating the settling of solid particulates with higher specific gravity than the waste stream. Then the water enters the open top equalization tank that allows the dissolved pollutants to be exposed to natural sterilization by sunlight and ambient air.

In this second stage the waste-water is sprayed, by means of a pump, onto a plant bed which is part of an engineered ecosystem that constitutes two bio-reactors, one for a coarse purification and the other for further refining through recycling. This ecosystem consisting of soil, bacterial culture and earthworms, mineral additives and select plants, treats the water is a combination of physio-chemical and biological processes.

Purification takes place by adsorption, filtration and biological reaction. The entire waste is processed and converted into bio-fertilizer which is rich in organic content. The other useful by-product is the Biomass in the form of flower, fodder, fruit and fiber which are also completely utilized in house. Since the entire waste is used so there are no issues like handling the wastes after treating the water, as is common in conventional chemical based sewage treatment plants. The entire process operates in aerobic mode thus eliminating the possibility of foul odor near the plant, creating a safe and serene ambiance for the people dwelling near the plant. The processed water can be reused in gardening, agriculture and also support marine life.

Anushri Joshi

Kamala  Nehru college

University of Delhi