Operational strategy and mechanism analysis of an iron–carbon micro-electric technology coupled with the activated sludge process for copper-containing dyeing wastewater treatment

Abstract

The escalating volume of copper-containing dyeing wastewater and the unparalleled challenges it presents to the traditional activated sludge (TAS) process are incontrovertible. Prior investigations had seldom considered the impact of dosing methodology and key ecological factors on the pollutant removal performance of iron–carbon micro-electric technology coupled with the activated sludge process (the CAS + IM system), and exhaustive exploration into the impact mechanism of iron–carbon (Fe/C) compounds on activated sludge remained scant. In this study, the dosing methodology (i.e., ratios and dosages) of Fe/C compounds and affecting factors (i.e., aerobic time to anaerobic time and ratio of food to microbe) were evaluated individually via batch tests and reactor operation tests. SEM images indicated that the morphological structure of sludge in the CAS + IM system was more compact and stable than that in the TAS process. Microbial community analysis showed that the CAS + IM system was rich in heterotrophic microorganisms (unclassified_o_Saccharimonadales), phosphorus-accumulating bacteria (e.g., Tetrasphaera, Candidatus Accumulibacter and Dechloromonas), and denitrifying phosphorus-accumulating bacteria including Pseudomonas, Thauera and Paracoccus. Two distinct kinetic models were developed to simulate the CAS + IM system, and the kinetic parameter υ_MAX,COD of carbon degradation kinetics in the system was approximately 2.1-fold higher than that in the TAS process. This finding verifies that the CAS + IM system is eminently suitable for the treatment of copper-containing dyeing wastewater.