Impact of new sanitation technologies upon conventional wastewater infrastructures

Abstract

Separation of wastewater split streams and utilization of the resources contained therein are an important prerequisite for a sustainable wastewater treatment. In areas with existing infrastructures, this leads to transition states during which current systems must continue to operate. A simple mass-flow based method was developed to assess the impacts of an incremental transition (co-digestion of blackwater and sewage sludge) upon plant operation. The results proved that blackwater co-digestion could be easily integrated into existing wastewater infrastructures; however, beyond 8% transition thickening was required due to hydraulic limitations in the digester. Additionally, nitrogen recovery was necessary beyond 35% transition to avoid unfavorable C:N ratios. The investigated concept also led to a power gain of 11 kWh/(PE∙a) due to enhanced biogas production and aeration savings. The developed Excel-based method was considered suitable for evaluating the benefits and probable tipping points for plant operation during transition to source-separated sanitation systems.