Application of DHS Reactor to Sewage Treatment in a Developing Country: Performance during Start-Up Period and under High Organic Load Condition

Abstract

A full-scale UASB (Up-flow Anaerobic Sludge Blanket) -DHS (Down-flow Hanging Sponge) system, which is a sewage treatment technology for developing countries, was applied in India, and its performance was evaluated. In the initial phase of start-up (up to the 3rd month) , the DHS system showed a 60% COD_Cr removal efficiency. Up to the 9th month, the operation of the DHS reactor was affected by various unforeseeable situations, e.g. inappropriate volume of DHS influent. However, from the 9th month onwards, a stable flow was received by the DHS reactor. From the 9th to the 12th month, the average COD_Cr in the DHS effluent was 92 (±20) mg L^-1. During this period, organic load fluctuated from 2.59 to 12.59 kg-COD_Cr m^-3 day^-1, and was high. However, the organic load and removal of the DHS reactor were directly proportional to each other. As a result, it was clarified that this system can maintain its organic matter treatment performance even under high organic load. Also start-up of the DHS reactor was achieved without maintenance, despite some common problem that can be seen in developing countries. It was shown that the DHS reactor is an appropriate sewage treatment technology for developing countries.