Performance of on-site pilot static granular bed reactor (SGBR) for treating dairy processing wastewater and chemical oxygen demand balance modeling under different operational conditions

The performance and operational stability of a pilot-scale static granular bed reactor (SGBR) for the treatment of dairy processing wastewater were investigated under a wide range of organic and hydraulic loading rates and temperature conditions. The SGBR achieved average chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS)-removal efficiencies higher than 90 % even at high loading rates up to 7.3 kg COD/m3/day, with an hydraulic retention time (HRT) of 9 h, and at low temperatures of 11 °C. The average methane yield of 0.26 L CH4/g CODremoved was possibly affected by a high fraction of particulate COD and operation at low temperatures. The COD mass balance indicated that soluble COD was responsible for most of the methane production. The reactor showed the capacity of the methanogens to maintain their activity and withstand organic and hydraulic shock loads.