The present study evaluated the performance of a static granular bed reactor (SGBR) and an upflow anaerobic sludge blanket (UASB) reactor at mesophilic conditions under various hydraulic retention times (HRTs) for the treatment of paper mill wastewater. Wastewater was provided by Grand Rapids Wastewater Treatment Facility (WWTF) in Minnesota, USA. Anaerobic seed granules were obtained from a UASB reactor at the Cedar Rapids Water Pollution Control Facility in Iowa, which treats waste water from the Cedar River Paper Company. A range of HRTs were used following a 29-day start-up period. Initial HRT conditions were 24 h prior to being decreased to 4 h. The overall chemical oxygen demand (COD) removal efficiency was higher for the SGBR than the UASB. At the 4 hour HRT, the COD removal was greater than 70% for the SGBR and 60% for the UASB. Otherwise, solids removal was higher for the UASB especially at the 9 and 6 h HRTs. Effluent volatile fatty acids (VFA) concentrations were lower for the SGBR at every HRT condition.
Anaerobic, pulp and paper, SGBR, UASB, HRT, specific COD removal