The remediation of urban freshwater sediment by humic-reducing activated sludge

Meng Li; Jingmei Sun; Chang Liu; Yinqi Tang; Jianjun Huang

doi:10.1016/j.envpol.2020.115038

The remediation of urban freshwater sediment by humic-reducing activated sludge

Environ Pollut. 2020 Oct;265(Pt B):115038. doi: 10.1016/j.envpol.2020.115038. Epub 2020 Jun 20.

Authors

Meng Li¹, Jingmei Sun¹, Chang Liu², Yinqi Tang², Jianjun Huang³

Affiliations

¹ School of Environment Science and Engineering, Tianjin University, Tianjin, 300350, PR China; State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin, University, Tianjin, 300350, PR China.
² School of Environment Science and Engineering, Tianjin University, Tianjin, 300350, PR China.
³ School of Environment Science and Engineering, Tianjin University, Tianjin, 300350, PR China. Electronic address: hjj@tju.edu.cn.

PMID: 32599325
DOI: 10.1016/j.envpol.2020.115038

Abstract

Organic pollution of urban rivers caused by stormwater discharge is a global problem. Traditional bioremediation of organic matters (OM) by aerobes could be restrained in anaerobic environments, which usually occurr in polluted river sediments. In this study, an anaerobic remediation technology has been developed to enhance the in-situ removal of organic matters in river sediments, humic-reducing sludge (HRS) was adapted from traditional activated sludge; it exhibited a strong humic-reducing ability. Nitrate and biostimulants were used to stimulate HRS. The change of microbial community between AQDS-adapted and non-AQDS-adapted was analyzed, and the effect of HRS augmentation and Nitrate/biostimulant addition on TOM removal were discussed from the perspective of light and heavy fraction organic matters (LFOM and HFOM). The results have indicated that, after adaptation, HRS had increased the bacterial population of Anaerolineales and Desulfuromonadales, which was related to the carbon metabolism and electron-transfer ability. On the other hand, the adaptation decreased the population of bacteria related to the sulfur/sulfate circulation. This characteristic of the HRS was potentially benificial to reducing the occurrence of black-odor phenomenon. Also, the removal efficiency of TOM in sediment was significantly improved by using HRS because HRS could facilitate the removal of HFOM. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated that the advantage of decomposing HFOM using HRS resulted from the fact that the HFOM contained redox mediators to facilitate humic-reducing respiration. In addition, nitrate appeared to be crucial for the enhancement of HRS in sediments. These findings have allowed for the development of a technology for in-situ anaerobic remediation of urban river sediments. They could also help to understand humic-reducing mechanism in the sediment during anaerobic bioremediation.

Keywords: Biostimulant; FTIR; Microbial community; Nitrate; Organic matters.

MeSH terms

Biodegradation, Environmental
Fresh Water / analysis
Geologic Sediments*
Rivers
Sewage*

Substances

Sewage