Effect of organic loading rate on anaerobic digestion: Case study on recycled paper mill effluent using Modified Anaerobic Hybrid Baffled (MAHB) reactor

摘要

Organic Loading Rate (OLR) effect on the performance of Modified Anaerobic Hybrid Baffled (MAHB) bioreactor treating recycled paper mill effluent (RPME) was investigated in this present study. The MAHB reactor is operated with a range of OLR of 0.14-4.00 gm COD/lit/day by varying the influent Chemical Oxygen Demand (COD) concentration of 1000, 2000, 3000 and 4000 mg/lit and Hydraulic Retention Time (HRT) of 1, 3, 5 and 7 days. From the experiment, it was found that the reactor performance decrease when OLRs increase. Highest specific methane yield is 8.47 lit CH4/day with OLR of 1.33 gm COD/lit/day. The highest methane content achieved is 91.63 % from total of 6.43 lit biogas/day at a range pH of 6.6-7.5. Effluent Volatile Fatty Acid (VFA) was below 35 mg/lit HOAC throughout the experiment while alkalinity where fluctuated at low OLR and slightly stable as the OLR increases. Higher OLRs of 2.0 to 3.0 gm COD/lit/day results in addition of inorganics in the reactor causing destabilization of the reactor and process failure, and thereby significantly affect the reactor performance in terms of organic removal. The OLR of 1.33 gm COD/lit/day was found to be optimum for MAHB reactor for the effective treatment of RPME both in terms of specific methane yield and COD removals.