Prospects of Using Wastewater as a Resource-Nutrient Recovery and Energy Generation

It is well understood that both untreated and partially treated wastewater comprise substantial amount of resources, which can be recovered and utilized for different purposes. Since Waste Water Treatment Plant (WWTP) is energy intensive and expensive, substantiating the WWTPs with Resource Recover Technologies (RRTs) will not only save a considerable amount of energy but also make the environment cleaner and safer. In line with this, this paper seeks to review several RRTS and to identify their limitations. Several effective nutrient recovery methods using both biota (e.g., microalgae, duckweed, aquatic macrophytes) and chemical processes (e.g., struvite precipitation and HAIX resin) are discussed in this study. The recovered nutrients can be used as fertilizer, animal feed and for production of protein rich by-products. In order to enhance the efficiency of nutrient recovery processes, several researchers suggest introducing hybrid system of nutrient recovery. On the other hand, biosolids, biogas, conserved heat, effluent flow, Microbial Fuel Cells (MFC), Microbial Electrolysis Cells (MEC) can potentially be employed to produce electricity and other forms of energy that can meet the demand of existing WWTPs. Moreover, the comparative analysis of these technologies in terms of advantages and disadvantages and their recovery potential has been discussed. The review analysis indicates that despite having limitations, several RRTs are being practiced mostly in developed world. Future research should focus on how to increase the efficiency of existing RRTs and identify innovative RRTs available in developing countries.