Journal of Chemical Engineering & Process Technology
Open Access

Abstract

Effect of pH Control Strategy on Anaerobic Fermentation of Oxytetracycline Excess Sludge

Yunxia Wang, Hong Liu, Zhiqiang Tang, Qi Wang, Li Zhang and Yongzhi Chen*

The high cost of treating Oxytetracycline (OTC) sludge poses a significant risk of secondary pollution, emphasizing the need efficient, eco-friendly, and safe methods. In this study, OTC-containing excess sludge was subjected to continuous pH adjustments to levels of 5, 8, 10, and 12, as well as intermittent regulation to pH 10 and 12 at a temperature of 35 ± 3°C. Notably, intermittent pH regulation was found to be more effective in producing Short-Chain Fatty Acids (SCFAs) compared to continuous regulation at pH 10. The maximum production of SCFAs reached was 1590.5 mg Chemical Oxygen Demand (COD)/g Volatile Suspended Solids (VSS), with acetic acid comprising 82% of the total SCFAs. Additionally, a sludge reduction of 33.1% was achieved. The concentration of the emitted OTC was 22.58 mg/L under intermittent pH regulation was comparable with 18.5 mg/L under continuous pH regulation, while the removal rate of OTC was 62.5% in OTC-containing excess sludge anaerobic fermentation. The qualitative analysis by mass spectrometry revealed that the main metabolites such as 4-Epi-Oxytetracycline (EOTC) and alpha-apo-Oxytetracycline (α-apo-OTC) were formed. The intermittent regulation of pH proved more conducive to the enrichment of hydrolytic acidifying bacteria (Bacillus (29.94%), Hydrotalea (4.32%) and Thauera (13.67%)). Moreover, Pseudomonas (1.56%) demonstrated remarkable efficiency in degrading OTC.

Published Date: 2024-12-23; Received Date: 2024-11-19