ANAEROBIC TREATMENT OF SWINE WASTE WITH AND WITHOUT BIOAUGMENTATION

Kim, Hyungjin; Cheunbarn, Tapana; Pagilla, Krishna R.

Environmental Engineering Research 1999;4(4): 269-276.

Hyungjin Kim¹, Tapana Cheunbarn², and Krishna R. Pagilla¹^†

¹Department of Chemical and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA
²Faculty of Science, Maejo University, Chiang-Mai, Thailand 50290

Corresponding Author: Krishna R. Pagilla ,

Received: May 15, 1999; Accepted: October 14, 1999.

ABSTRACT

Treatment of swine waste slurry by high rate anaerobic digestion and batch anaerobic storage reactors was investigated in the laboratory. Two lab-scale completely mixed anaerobic digesters using swine waste slurry as the feed were operated at a 10-day sludge retention time and 37℃. One digester was supplemented with 62 g/kg total solids (TS) of an enzyme/microbial additive (EMA), while the other digester was used as the control. In addition, five batch anaerobic storage reactors were operated to investigate the influence of mixing, and EMA dose and its frequency on the treatment of swine waste slurry. Both control and EMA added digesters were able to treat the swine waste satisfactorily, and the process was stable. The volatile solids (VS) reduction (52%), soluble chemical oxygen demand (SCOD) reduction (62%), sludge gas production rate (0.90 m³/kg VS destroyed), and CH₄ content in sludge gas (60%) with EMA control were better by 11, 15, 13, and 3%, respectively than those obtained with the control digester. H₂S content in the sludge gas from EMA added digester (433 ppm v/v) was significantly lower than that from the control (656 ppm v/v). Batch anaerobic storage reactors dosed with 31 to 124 g EMA/kg TS once every 10 days were able to reduce the VS of the swine waste by 43 — 52%, soluble COD by 36—47%, and fecal coliform density to 1.3— 9.5X 10⁶ MPN (most probable number)/g TS compared to 37—41% VS reduction, 34% soluble COD reduction, and fecal coliform density of 1.7-8.1 x 10⁷ MPN/g TS in the two control reactors over a 35-day period. Mixing and EMA dose increase generally improved the performance of the storage reactors. However, no significant improvement was observed in the performance with increase in frequency of EMA addition from once in every 10 days to once in every 5 days. The results from this research suggest that both high rate anaerobic digestion and batch anaerobic storage reactors are capable and stable in swine waste treatment, and that addition of enzyme/microbial additives for bioaugmentation can improve the treatment of swine waste in these two processes.

Keywords: swine waste | anaerobic digestion | bioaugmentation