Pollution Research Paper

C.TECH PROCESS IN MUNICIPAL SEWAGE TREATMENT PLANT – A CASE STUDY

R.RAJAMANICKAM AND S. NAGAN

Abstract

Pollution caused by sewage discharged from cities and towns is the primary cause for degradation of our water resources. It is the obligatory responsibility of every local body to collect, transport, treat and dispose wastewater produced in their respective jurisdictions. Cyclic activated sludge process technology (C. Tech) is an advanced technology of sequential batch reactor (SBR) for treatment of sewage. It operates in a cycle of batches. Each cycle is of 3 – 5 hrs duration, during which all treatment steps take place. Two or more modules are provided to ensure continuous treatment of wastewater. The complete process including removal of organics, N and P reduction takes place in a single reactor, within which all biological treatment steps take place sequentially. One cycle/sequence of operation consists of 3 steps - filling & aeration, settling and decantation. The settled sludge from the basin shows sludge volume index (SVI) < 120 and excellent settling characteristics. The excess sludge wasted from the basin is fully digested and can be used as manure directly after dewatering. No additional settling unit, secondary clarifier is required. In Tamil Nadu, Madurai Corporation has constructed two STPs of C-Tech type with capacity of 125 MLD STP at Avaniapuram and 45.7MLD at Sakkimangalam under JuNURM Scheme. These plants were commissioned in 2011. The report of analysis of treated sewage sample reveals that BOD is < 9 mg/L, COD < 25mg/L and TSS is < 8 mg/L. The treated sewage is used for farming. By considering the performance of the existing plants in operation in India, it is concluded that cyclic activated sludge process is one of the best technologies which can be adopted by the local bodies.