Anaerobic treatment of swine waste by the anaerobic sequencing batch reactor

Anaerobic sequencing batch reactor (ASBR) uses a high-rate anaerobic bioconversion process to stabilize organic wastes for odor control and generate biogas for energy use. It is well suited for treating animal wastes. This article reviews previous research on the ASBR and reported a laboratory study to evaluate the ASBR with swine waste at short hydraulic retention times (HRTs) (two, three, and six days), over a wide range of volatile solids loading rate (0.9 to 5.5 g/L/day) and at 25 degrees C. The ASBR demonstrated satisfactory performance at all three HRTs. The three-day HRT reactor showed the best overall performance in terms of biomass settleability, biogas production rate, and reductions of volatile solids and biochemical oxygen demand in the manure after the treatment. In the intermediate range of VS loading rate (1.6-4.5 g/L/day), the VS reduction was 55 to 61%, BOD5 reduction was 81 to 86% and biogas production rate was 0.9 to 1.8 L/L/day. it was found that ammonia did not adversely affect the performance of the ASBR at a concentration as high as 2470 mg/L in a pH range of 6.8 to 7.4. The ASBR can be easily integrated into a waste management system on a swine farm. The conceptual designs for the configurations and operational schemes of the ASBR system for working with swine confinement operations using flushing, scraping, or gravity draining (pull-plug) systems are presented.