Improving the effluent of small wastewater treatment plants by bacteria reduction and nutrient removal with an algal biofilm

Abstract

In wastewater ponds, bacteria numbers decrease considerably in the case of raised algae concentrations in the effluent. This shows that algae have a high potential for bacteria reduction in wastewater. Simultaneously, algae remove nutrients from the water for the formation of biomass. However, suspended algae also cause a high secondary pollution in the effluent of wastewater treatment plants. By using attached algae, as they are frequently observed as an algal biofilm in the effluent of wastewater treatment plants, the problem of separation of algae and water can be avoided. Furthermore, the algae can be removed simply from the water. In this study the possibilities for bacteria reduction and nutrient removal were examined with the aid of an algal biofilm. The results show that an algal biofilm process can be used for cases where small amounts of wastewater should be treated and a high quality of the effluent should be attained.