Advanced organic recovery from municipal wastewater with an enhanced magnetic separation (EMS) system: Pilot-scale...

The up-concentration process has been demonstrated as an attractive approach to carbon-neutral wastewater treatment. Innovation in the separation processes can help eliminate the current heavy dependence on gravity, and credible pilot-scale verification is crucial for application promotion. We hereby proposed a pilot-scale enhanced magnetic separation (EMS) system as an up-concentration step to maximize energy recovery from municipal wastewater. The design of EMS was based on the hypothesis that magnetic-driven separation could be a breakthrough in separation speed, and adsorption could further enhance the separation efficiency by capturing soluble substances. Jar tests confirmed the feasibility of activated carbon adsorption, which could also roughen the surface of aggregates. Further, over one-year operation of a 300 m³/d EMS equipment provided optimum operation strategies and evidence of system effectiveness. More than 80% of particulate organics and 60% of soluble organics were removed within 10 min at an energy consumption of only 0.036 kWh/m³. The characteristics of sludge were clarified in terms of organic concentration, extracellular polymeric substances composition, and micro-community analysis. The anaerobic experiments further demonstrated the potential value of the concentrated products. Surprisingly, the developed EMS system exhibited significant advantages in time consumption and space occupation, with competitive operating cost and energy consumption. Overall, the results of this study posed the EMS process for up-concentration as a potential approach to organics recovery from municipal wastewater.