Treatment Of Sugar Industry Wastewater By Upflow Anaerobic Sludge Blanket Reactor

Abstract

Rapid urbanization and industrialization in the developing countries like India are facing severe problems in collection, treatment and disposal of effluents. Unmanaged organic waste fractions from industries, municipalitiesand agricultural sector decompose in the environment resulting in large scale contaminationof land, water and air. This is leading to serious public health problems and environmental degradation.Unfortunately, due to the lack of knowledge, financial support and sometimes unwillingness to spend on treatment of wastewater, most of sugar industries in developing countries discharge their wastewater withoutadequate treatment. This not only creates problem but also wastes the water resource. For treating the biodegradable impurities, the natural choice is biological treatment,which could either be aerobic or anaerobic. But anaerobic digestion is an attractive waste treatment practice in which both pollution control and energy recovery can be achieved. Many industrial wastes are ideal candidates for anaerobic digestion3,4,11,14. In the recent years energy considerations and environmental concerns have increased the popularity of anaerobic process. Sugar industry wastewater was treated in a UASB reactor seeded with non-granular mixed septic tank sludge. The study was carried out at ambient (26-39oC) conditions, in a laboratory scale reactor of effective volume of 8.4 ltrs. The reactor was operated in two phases. In the I phase, OLR was gradually increased from 1g COD/l.d to 6 g COD/l.d and HRT was reduced from 48 to 12 hrs respectively. The granule formation was observed on the 42nd day. When HRT was reduced to 12 hrs, the granules disintegrated. In the II phase (from 61st day) restabilisation process was restarted with an increased HRT of 24 hrs and decreased OLR of 2g COD/l.d. Further a gradual increase of OLR to 4.67 g COD/l.d and reduction in HRT to18 hrs was done. Granules were once again seen within a very short period of 14 days. The COD removal efficiency obtained ranged from 80 to 96 %. The COD removal rate linearly increased with increase in OLR.The ratio of VFA to alkalinity was varied between 0.14 to 0.3 during the treatment. Maximum volumetric biogas production was 13.72 L/ d. at OLR of 6 g COD/L. d. Themethane content in the biogas was found to be 71% at steady state conditions. A successful start-up with non-granular mixed septic tank sludge was achieved within 100 days of operation.