Anaerobic–Aerobic Treatment of Fruit and Vegetable Wastes and Municipal Wastewater

Abstract

Waste management in large urban centers is one of the main challenges for public administration. Two of the most abundant wastes in cities are waste solid and municipal wastewater (MWW). Their management can be optimized if they are treated together. This work analyzed an anaerobic–aerobic system for the treatment of fruit and vegetable wastes (FVWs) and MWW. Firstly, FVWs were collected and characterized; once in the laboratory, they were placed in a tank with the MWW, aiming at transferring to the water those solids with a particle size below 105 µm; then, they were separated by sieving. The mixture of MWW and FVWs with a particle size below 105 µm was fed into an up-flow anaerobic sludge reactor (UASB); in the latter, dissolved and suspended organic matter was transformed into methane and carbon dioxide. The water that left the UASB was sent to be post-treated in an activated sludge reactor (ASR). The chemical oxygen demand (COD) was used as an evaluation parameter of the anaerobic–aerobic system; a removal efficiency higher than 80% was achieved, whereas it was 60% in the ASR. Another evaluation parameter was methane (CH4) productivity, with an average of 3.0 LCH4 L−1 d−1. VWF leaching achieved an average COD extraction of 7.68 kg∙m−3. The UASB efficiency was on average 70% for the assayed loads (2–8 kg COD·L−1·d−1). The energy potential calculated for the anaerobic–aerobic system was 510.2 kW∙h∙d−1