Feasibility study and process optimization of citric acid wastewater treatment and biomass production by photosynthetic bacteria

摘要

Using photosynthetic bacteria (PSB) in wastewater treatment could not only eliminate environmental pollutants, but also recycle bacteria biomass. This paper studied the feasibility of using PSB in citric acid wastewater treatment. Some important factors which influence the pollutants removal efficiency and biomass were also examined to determine the optimal conditions. The results showed that PSB could effectively remove pollutants, and biomass production was also achieved. The optimal conditions were initial pH at 7.0, ratio of carbonitrogen at 10, initial chemical oxygen demand (COD) of 2,400mg/L, natural light-micro aerobic condition, and hydraulic retention time of 40h. Under these conditions, the removal rate of COD and the biomass could reach 89.4% and 2,250mg/L, respectively, and the biomass yield was 0.76mg(-biomass)/mg(-COD-removal). By process evaluation, compared with anaerobic wastewater treatments, this process had better effluent quality and simpler process, compared with aerobic wastewater treatment, this process had the advantage of biomass recovery.