LOW COST TREATMENT OF SEWAGE USING ROOT ZONE TECHNOLOGY

Abstract

Large quantity of sewage is generated in urban and semi urban areas. Due to the lack of cost effective treatment methods, the world is facing problem of sewage treatment and disposal. Much advancement has taken place in the treatment technology both in aerobic and anaerobic methods. However, huge capital investment is required for providing treatment facilities, also disposal of the treated effluents is a major problem. The operation and maintenance cost in case of conventional sewage treatment plant is estimated to about Rs 12 per 1000 litres. As treatment cost is high, sewage is directly discharged into the rivers or nearby water bodies and polluting the major sources of water available to the society. The conventional methods are not feasible for small cities and towns. Hence there is a need of cost effective method for sewage treatment. Waste water treatment by Root Zone Technology (RZT) is emerging as the alternative low cost method which involves use of plants species for treatment of sewage.Studies were conducted to assess the feasibility of Root Zone Technology for sewage treatment. The study is conducted with pilot scale reactors on different types of plant species. The reactor of size 1.3m x 0.65m x 0.40 m made in PVC material was used for the study. Plants species were planted in the reactor and were irrigated initially with tap water. After stabilizing the reactor, different doses of sewage was applied at regular interval of 3 days and growth of plants was observed. After steady state is reached, hydraulic loading was determined to get zero discharge. The quality of treated waste water was assessed when the reactor was loaded with excess hydraulic loading. The reactor was found be very effective for sewage treatment.COD reduction of 88.18%, BOD reduction of 88% and solids reduction of 69.23% was observed during the study. The cost economics of Root Zone Technology was assessed to Rs 4.13 per 1000 Litters. This reveals the economical and efficient method for sewage treatment and disposal which will be useful to the small towns and isolated institute.