Enhancing the hydrolysis of saline waste sludge with thermophilic bacteria pretreatment: New insights through the evolution of extracellular polymeric substances and dissolved organic matters transformation

• Published in: The Science of the total environment Vol. 670; pp. 31 - 40
• Main Authors: Gao, Pengtao, Guo, Liang, Sun, Jian, Wang, Yi, She, Zonglian, Gao, Mengchun, Zhao, Yangguo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.06.2019
• Subjects: Salinity; Sludge hydrolysis; Sludge reduction; Thermophilic bacteria (TB); Sludge hydrolysis; Sludge reduction; Thermophilic bacteria (TB); Salinity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.03.158

Recently, the treatment and utilization of saline waste sludge has drawn growing attention because large amounts of saline waste sludge were generated with the increase of saline wastewater discharge. In this study, thermophilic bacteria (TB) pretreatment was applied to accelerate the hydrolysis of saline waste sludge and the efficiency of hydrolysis at different salinities was evaluated. Compared with the group without salinity, the releasing of carbohydrate (up to a 67.0% decrease) in extracellular polymeric substances (EPS) was inhibited at the salinity ranging from 1.0% to 2.5%, and the releasing of protein (up to a 17.6% decrease) was inhibited under salinity conditions. Excess salinity (4.0%) caused the cell lysis, and the content of soluble chemical oxygen demand (SCOD), soluble carbohydrate and protein in dissolved organic matter (DOM) increased by 44.9%, 38.8% and 20.8% than that obtained without salinity, respectively. According to the excitation-emission matrix (EEM) fluorescence spectroscopy, the biodegradability of sludge was improved at 2.0% salinity. At 2.0% salinity, the maximum fluorescence intensity of soluble microbial byproduct substances (76,358.9 (au)) and the minimum fluorescence intensity of humic acid-like substances (173,424 (au)) were obtained. The increased salinity was beneficial for the sludge stabilization and was disadvantageous for the sludge reduction. [Display omitted] •The sludge hydrolysis with TB was not inhibited at the salinity below 2.0%.•High salinity (2.5%–3.5%) had a negative effect on the releasing of EPS.•The biodegradability of sludge was enhanced at the salinity of 2.0%.•The increased salinity was beneficial for the sludge stabilization.