A novel aquatic worm (Limnodrilus hoffmeisteri) conditioning method for enhancing sludge dewaterability by decreasing filamentous bacteria

Wanqing Ding; Xu Zhou; Wenbiao Jin; Zhicheng Zhao; Shuhong Gao; Yidi Chen; Wei Han; Huan Liu; Qilin Wang

doi:10.1016/j.scitotenv.2022.157949

A novel aquatic worm (Limnodrilus hoffmeisteri) conditioning method for enhancing sludge dewaterability by decreasing filamentous bacteria

Sci Total Environ. 2022 Nov 25:849:157949. doi: 10.1016/j.scitotenv.2022.157949. Epub 2022 Aug 9.

Authors

Wanqing Ding¹, Xu Zhou², Wenbiao Jin¹, Zhicheng Zhao¹, Shuhong Gao³, Yidi Chen¹, Wei Han¹, Huan Liu⁴, Qilin Wang⁴

Affiliations

¹ State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
² State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China. Electronic address: zhouxu@hit.edu.cn.
³ State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China; Shenzhen Engineering Laboratory of Microalgal Bioenergy, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China. Electronic address: gaoshuhong@hit.edu.cn.
⁴ Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.

PMID: 35961391
DOI: 10.1016/j.scitotenv.2022.157949

Abstract

In this study, a novel aquatic worm conditioning method was proposed to enhance sludge dewaterability by reducing filamentous bacteria. The optimal treatment time was 4 days and the optimal sludge concentration was 5000 mg/L. Under these conditions, the sludge dewaterability was improved with CST of 16.69 s, reduction in sludge SRF of 48.95 %, and reduction in LfA of 58.23 %. After bio-conditioning, sludge flocs broke up by the aquatic worm predation. The absolute zeta potential decreased to -8.27 mV, and the particle size increased from 36.64 μm to 48.05 μm. Proteins, polysaccharides and other organic substances in sludge EPS and microbial cells were released, with the viscosity reduced to 1.16 mPa·s and the bound water converted into free water. Besides, the number and abundance of representative filamentous Chloroflexi decreased, resulting in the enhancement of sludge dewatering performance. Overall, the aquatic worm conditioning process can be divided into two steps: Sludge destruction by the aquatic worm predation and sludge re-coagulation by filamentous bacteria as a skeleton.

Keywords: Aquatic worm; Chloroflexi; Filamentous bacteria; Sludge conditioning; Sludge dewaterability.

MeSH terms

Animals
Bacteria
Oligochaeta*
Particle Size
Polysaccharides
Sewage* / microbiology
Waste Disposal, Fluid / methods
Water

Substances

Polysaccharides
Sewage
Water