Anaerobic treatment of sugar industry wastewater by Upflow anaerobic sludge blanket reactor at ambient temperature

Sugar industry wastewater was treated in a UASB reactor seeded with nongranular anaerobicallly digested sewage sludge. The ambient room temperature during the study period was between 2937°C. Successful reactor startup with granulation was achieved within 95 days of operation. The reactor was started with an OLR of 0.5 g COD/L. d. and was loaded up to 16 g COD/L. d. During startup the HRT was reduced from 488 h. The optimum HRT was found as 6 h. After the startup the loading was increased at constant HRT of 6 h by increasing the COD concentration of the feed. A maximum COD removal efficiency of 89.4% was achieved. The COD removal rate linearly increased with increase in OLR. The ratio of VFA to alkalinity was varied between 0.190.33 during the treatment. Maximum volumetric biogas production was 4.66 L/L. d. at OLR of 16 g COD/L. d. The methane content in the biogas was found to be between 73 and 82% at steady state conditions. After reaching an OLR of 16 g COD/l. d. the loading was increased by reducing HRT to 4 h. Reactor performance deteriorated when loading increased to 24 g COD/L. d. It was concluded that sugar industry wastewater can be treated at maximum loading of 16 g COD/L. d. at low HRT of 6 at ambient temperature.