STUDIES ON FULL SCALE UASB-DHS SYSTEM FOR THE TREATMENT OF MUNICIPAL WASTEWATER

Abstract

Rapid population growth, industrialization, urbanization and increasing energy demand leads to the problem of water pollution. India’s current population growth rate is 1.19% and its fast economic development is putting high pressure on the existing natural water resources such as river and lake. In India, the main source of river pollution is the discharge of untreated wastewater directly into river bodies. Wastewater treatment is the most appropriate solution to overcome the problems of water crisis in developing countries like India. Among various wastewater treatment technology, the up flow anaerobic sludge blanket (UASB) reactor is a sustainable alternative for the treatment of municipal wastewater in developing countries. However, UASB reactor alone was considered inefficient for the treatment of municipal wastewater. Among many aerobic post treatment options for UASB reactor, down flow hanging sponge (DHS) systems gained remarkable attention as a post-treatment option for the UASB reactor especially for developing countries. DHS system has been successfully implemented at lab and pilot scale from last 20 years. However, very limited application of full scale DHS using G3.4 sponge media was available for municipal wastewater treatment. Therefore, in this study a full scale DHS reactor was installed at sewage treatment plant at Agra, India. The purpose of this study was to investigate the removal efficiency in terms of organic, ammonia and solids along the vertical as well as horizontal axis of the reactor. When organic concentration reduces to half in the upper half of the reactor then nitrification process starts mainly in the lower half of the reactor. The sewage treatment performance was investigated especially along the horizontal direction, due to difference in oxygen concentration in the reactor. Also, flow distribution in the horizontal direction increases from centre of the reactor to outside. Therefore, there is possibility of change in organic load and also treatment performance. The results of this study will not only helps to improve the designs of the DHS system but also to demonstrate the applicability of the full scale DHS reactor in the developing countries having low capital budget, less land area available and less energy requirement.