Pilot-scale textile dyeing wasted sludge reduction via microbial agent and aeration: Parameter optimization and mechanisms exploration

Abstract

Abstract New methods to treat textile dyeing wasted sludge (TDWS) should be developed. In this study the sludge reduction induced by microbial agent addition and aeration in pilot-scale was studied. The one-off addition mode was employed in which better sludge reduction (i.e., 58.4%) and lower moisture content (i.e., 71.6%) were achieved. 25 L/min of aeration rate was best for sludge reduction and 52.8% of sludge reduction was achieved and aeration did play an important role in the sludge reduction. 15000 mg/L was determined as the suitable initial sludge concentration. The mechanisms of TDWS reduction were explored subsequently. As the results, the sludge particle size decreased with microbial agent addition while no such reduction was observed without microbial agent. The sludge would react with hydrolase to release organic substance and produce chemical oxygen demand (SCOD) in the liquid, which could be consumed by microorganisms. Finally, the change of microbial community was explored so as to further explain the mechanism of sludge reduction. The phylum Bacteroidetes increased from 33.30% to 45.37% with microbial agent addition which indicated the important role in sludge reduction. The genus Sphingopyxis, Thermomonas and Fluviicola would be the most relevant microorganisms with sludge reduction while the moisture content was most related with Dok59.