Integrated low-cost wastewater treatment for reuse in irrigation

For sustainable wastewater management in developing countries, the implementation of low-cost, simple treatment systems should be encouraged. In this study, the performance of three treatment schemes was evaluated. The first step in all schemes was upflow anaerobic sludge blanket (UASB). The post treatment was either Algal Pond (AP). Lemna Pond (LP) or Rotating Biological Contactor (RBC). The results show that the performance of the UASB was satisfactory. Mean COD and BOD removal values were 78% and 85% respectively. The combination of UASB with an AP achieved significant improvement in the microbiological quality of the effluent. The geometric mean of fecal coliform in the effluent was 1.3 x 10(3) MPN/100 ml. Residual COD was 143 mg O2/L. This relatively high value was due to the presence of algae in the AP effluent. The use of the LP as a post treatment achieved better quality effluent. As indicated by the physico-chemical characteristics. However, fecal coliform removal was less by one log as compared to the AP effluent. When the RBC was used as a second stage. COD and BOD removal rates were 47% and 66% respectively. Also complete nitrification took place. Fecal coliform density declined by 5 logs.