Modeling the impact of food wastes disposers on biological wastewater treatment intensification technologies

The impact of food wastes (FW) on suspended growth systems like the activated sludge process and in large plants with anerobic digestion has been widely studied. However, information on impact on hybrid systems and biofilm processes used for intensification, as well as with aerobic biosolids digestion, is scant. This modeling study investigated the performance, operational costs, and greenhouse gas (GHG) emissions of multiple wastewater treatment technologies-membrane bioreactor (MBR), moving bed biofilm reactor (MBBR), integrated fixed film activated sludge (IFAS), membrane aerated biofilm reactor (MABR), and oxidation ditch at the 1 and 10 MGD scales. FW addition achieved effluent total nitrogen reductions of 30%-35% for the MBR, MBBR, and IFAS, up to 85% for the MABR, and up to 70% for the oxidation ditch systems. Aeration demand increased by up to 16%-34% while biosolids production and methane production rose by <13%, and 29%-38%, respectively. Food COD conversion efficiency to methane was 35%-48%. At 100% FW addition, despite a 30% increase in organic loading, the GHG emissions increased by 3.7%-11.2% for the MBR, MBBR, and IFAS, and decreased by 5.2%-11.2% for the MABR. Anaerobic digestion mitigated GHG emissions from food wastes compared to aerobic digestion, with COD-based carbon footprints 50%-90% lower than wastewater.