Hybrid UASB approach to winery wastewater treatment

A synthetic winery wastewater was used to study the startup, and performance of anaerobic hybrid reactors which incorporate a combination of an upflow anaerobic sludge blanket reactor (UASB) and ea packed bed reactor (PBR). Monitored parameters included pH, COD, alkalinity, suspended solids, gas production and methane content of the gas. Three hybrid reactors were started separately at 35°C and initial influent COD concentrations between 5kg/m³ and 6kg/m³. Startup of the hybrid reactors required a gradual increase of organic loading rate (OLR) from a low of 0.66 kgCOD/m³d up to 3.5 kgCOD/m³d over a 50 day period following startup. Throughout the startup and at quasi - steady – state conditions, COD removal efficiency was maintained well above 80% and peak methane yield was 0.24 m³/kg.d. Biogas production was highly sensitive to organic loading rate and pH fluctuations. High substrate removal efficiencies indicate that the reactors operated under substrate limiting conditions until the organic loading rate was increased to 3.5 kgCOD/m³d. pH in the reactors was controlled with alkalinity addition and influent pH had minimum effect on the pH of the reactor effluent. The hybrid reactor did not achieve effluent COD goals of less than 50 mg/L required for the treated effluent wastewater to be reclaimed for drip and spray irrigation. Therefore an aerobic reactor would be required for further polishing of the effluent wastewater from the anaerobic reactors.