Resource Recovery and Municipal Wastewater Treatment: A New Approach Combining Biological and Physical-Chemical Processes

There is growing belief that in the future the objective should be to treat wastewater not as a waste but as a resource for water, energy and nutrients while reducing the impact of wastewater treatment on greenhouse gas (GHG) emissions. With this objective in mind, a municipal wastewater treatment flowsheet concept has been developed which achieves the goals of energy sustainability and water and nutrient recovery, while minimizing residual solids production and the release of GHGs. The new flowsheet embodiment detailed here integrates established biological and physical-chemical process systems in a unique fashion which allows for conversion of the organic carbon in the wastewater to methane, the removal and recovery of phosphorus and nitrogen from the wastewater, and the production of water suitable for reuse. Computer modeling results provide confidence in the validity of many of the claimed advantages of the new flowsheet, implying 80 percent of the wastewater COD can be shunted to the anaerobic digestion step of the flowsheet and the flowsheet can reduce residual solids production by 45 percent in comparison to conventional methods. The new flowsheet has a significant advantage over conventional treatment with respect to capital costs and the treatment plant energy balance