Performance of anaerobic sequencing batch reactors in series followed by polishing ponds on the treatment of swine wastewater. Part II: removal of nutrients and coliforms

On this study the performance of two anaerobic sequencing batch reactors (ASBR) installed in series was evaluated, on a pilot-scale testing (volumes of 280 L and 140 L, respectively) for the treatment of swine wastewater with total suspended solids concentrations (TSS) around 10,000 mg L-1. For the post-treatment of the effluents from ASBR, two polishing ponds in series were used (1,000 L of volume each). The organic loading rates (OLR) applied on the first ASBR varied from 4.43 to 12.75 g totalCOD (L d)-1. The mean removal efficiencies for total Kjeldahl nitrogen (TKN) and total-P varied of 30 to 82% and 42 to 100%, respectively, on the anaerobic treatment system compounded by the ASBR followed by polishing ponds. The use of polishing ponds in series has allowed the maintenance of mean removal efficiencies above 80% for Fe, Mn and Zn and 76% for Cu. A number of fecal coliforms above 8 x 10³ NMP/100/mL were observed on the effluents.

anaerobic digestion; metals removal; organic loading rate; post-treatment; two-stages