Enhanced treatment of flush-dairy manure in anaerobic sequencing batch reactors using a cationic polymer

摘要

Anaerobic sequencing batch reactors (ASBR) are preferred for treating dilute wastewaters but the retention of adequate active biomass, in successive-cycles, is always a challenge. This research investigated the efficacy of using a cationic polyacrylamide (PAM) flocculant for enhanced sludge retention in an ASBR treating flushed dairy manure, operated under psychrophilic conditions. Three PAM doses (10, 25, and 50 mg [PAM] l(-1)) were tested in duplicate reactors. At 6 d hydraulic retention time (HRT) and dosing of the feed-manure, steady state specific biogas yield for the 50 mg [PAM] 1 -1 treatment was 491 +/- 7 ml g(-1 )[TCOD] (56% greater than control). At 4 d HRT the 50 mg [PAM] l(-1) dose resulted in 465 +/- 8 ml g(-1) [TCOD] (20% higher than the control) at steady state conditions. The ratio of total volatile fatty acid to alkalinity was 0.29 +/- 0.08 during the 6 d HRT and 0.14 +/- 0.02 during the 4 d HRT, which were both below the trigger point for digester souring. This study shows that the use of PAM for high sludge retention in ASBR is a viable approach for, not only enhancing biogas yield, but also for improved and high-rate treatment of flushed dairy manure under psychrophilic conditions. (C) 2019 IAgrE. Published by Elsevier Ltd. All rights reserved.