Management and kinetics of methane production from anaerobic batch reactors treating PET bottle washing wastewater

Abstract

The study evaluated the methanogenic potential of anaerobic sludge in Wastewater from the Washing of PET (Polyethylene terephthalate) bottles sent for Recycling (WWPR). The bioreactors were inoculated with sludge from an upflow anaerobic sludge blanket reactor treating poultry waste. The operation occurred under anaerobic conditions at 35 °C and 150 rpm for three bioreactors in triplicate with the initial COD concentration of 2000 mg L−1 (C1), 5000 mg L−1 (C2), and 10,000 mg L−1 (C3). The inhibition in the anaerobic biological treatment caused by high surfactant concentration impaired the wastewater biodegradation. COD removals were 67.8 ± 0.4% (C1), 67.6 ± 2.7% (C2), and 59.1 ± 2.9% (C3), indicating a process inhibition in the latter condition. The modified Gompertz model indicated a cumulative methane production of 290 mL for condition C1 with an adjustment coefficient of 99.11%. The methane potential for the production of electricity revealed a maximum annual production of 188,292 MWh. Annual thermal energy from condition C1 could produce 1.01 × 108 PET bottles. Therefore, the anaerobic treatment of WWPR is an alternative to wastewater management, avoiding greenhouse gases emission and potentiating the generation of electrical and thermal energy.