(655c) Performance of a-Stage Process Treating Wastewater Containing Domestic Food Waste from Disposers: An Alternative for Community-Based Sewage Treatment

Authors: 
Zamalloa, C., University of Minnesota
Hu, B., University of Minnesota
About one third of the food supply is wasted in the US. Food waste is the second highest component of landfills and is therefore heavily contributing to the production of greenhouse gas emissions. Although nationwide initiatives have been implemented to collect food waste for biological treatment, most household food waste is currently processed with food waste disposers (FWDs) and ends up in the sewage system together with the municipal wastewater. The A-stage of the adsorption/bio-oxidation (A/B) process, is a technology that has recently regained popularity for the primary treatment of domestic wastewater at a decentralized level due to its high efficiency removing pollutants, low energy consumption, small footprint and producing a sludge with high energy content. To our knowledge, there has not been any research undertaken on the potential effects of food waste on the A-stage process. In this study, the impact of food waste on the performance of the A-stage process was studied. In addition, biochemical methane potential (BMP) tests were conducted to evaluate the potential energy generation from the A-sludge with food waste. One lab-scale A-stage reactor was operated with a hydraulic retention time (HRT) of about 60 minutes with a dissolved oxygen (DO) concentration of about 0.7 mg/L and a mixed liquor suspended solids (MLSS) concentration of 2000 mg/L. Overall, the chemical oxygen demand (COD) removal efficiency of the A-stage was about 48% when operated without food waste and 46% with the addition of food waste. BMP tests showed that the biodegradability of the A-sludge treating wastewater with food waste was 20% higher. The implementation of A-stage technology for treating domestic wastewater combined with food waste using FWDs could be an opportunity to increase the energy production from domestic wastewater and decreasing potential GHG’s emissions.