Aerobic and Anaerobic Biodegradability of Organophosphates in Activated Sludge Derived From Kitchen Garbage Biomass and Agricultural Residues

Xingfeng Yang; Deling Fan; Wen Gu; Jining Liu; Lili Shi; Zhi Zhang; Linjun Zhou; Guixiang Ji

doi:10.3389/fbioe.2021.649049

Aerobic and Anaerobic Biodegradability of Organophosphates in Activated Sludge Derived From Kitchen Garbage Biomass and Agricultural Residues

Front Bioeng Biotechnol. 2021 Feb 17:9:649049. doi: 10.3389/fbioe.2021.649049. eCollection 2021.

Authors

Xingfeng Yang^{1

2}, Deling Fan², Wen Gu², Jining Liu², Lili Shi², Zhi Zhang¹, Linjun Zhou², Guixiang Ji²

Affiliations

¹ College of Modern Agriculture and Ecological Environment, Heilongjiang University, Harbin, China.
² Nanjing Institute of Environmental Science, Ministry of Ecology and Environment, Nanjing, China.

Abstract

Organophosphates (also known as organophosphate esters, OPEs) have in recent years been found to be significant pollutants in both aerobic and anaerobic activated sludge. Food waste, such as kitchen garbage and agricultural residues, can be used as co-substrates to treat the active sludge in sewage treatment plants (STPs). We investigated the biodegradability of nine OPEs derived from kitchen garbage biomass and agricultural residues under different conditions. Under anaerobic conditions, the rate of removal of triphenyl ester OPEs was significantly higher than that of chloride and alkyl OPEs. The addition of FeCl₃ and Fe powder increased the rate of degradation of triphenyl ester OPEs, with a DT₅₀ for triphenyl ester OPEs of 1.7-3.8 d for FeCl₃ and 1.3-4.7 d for Fe powder, compared to a DT₅₀ of 4.3-6.9 d for the blank control. Addition of an electron donor and a rhamnolipid increased the rate of removal of chlorinated OPEs, with DT₅₀ values for tris(2-carboxyethyl)phosphine) (TCEP) and tris(1,3-dichloroisopropyl)phosphate (TDCPP) of 18.4 and 10.0 d, respectively, following addition of the electron donor, and 13.7 and 3.0 d, respectively, following addition of the rhamnolipid. However, addition of an electron donor, electron acceptor, surfactant, and Fe powder did not always increase the degradation of different kinds of OPEs, which was closely related to the structure of the OPEs. No treatment increased the removal of alkyl OPEs due to their low anaerobic degradability. Tween 80, a non-ionic surfactant, inhibited anaerobic degradation to some degree for all OPEs. Under aerobic conditions, alkyl OPEs were more easily degraded, chlorinated OPEs needed a long adaptation period to degrade and finally attain a 90% removal rate, while the rates of degradation of triphenyl ester OPEs were significantly affected by the concentration of sludge. Higher sludge concentrations help microorganisms to adapt and remove OPEs. This study provides new insights into methods for eliminating emerging pollutants using activated sludge cultured with kitchen garbage biomass and agricultural residues.

Keywords: active sludge; aerobic; anaerobic; biodegradation; biomass; kitchen garbage; organophosphates.