An integrated investigation on anaerobic membrane-based thickening of fecal sludge and the role of extracellular polymeric substances (EPS) in solid-liquid separation

Muhammad Arslan Shahid; Nida Maqbool; Sher Jamal Khan

doi:10.1016/j.jenvman.2021.114350

An integrated investigation on anaerobic membrane-based thickening of fecal sludge and the role of extracellular polymeric substances (EPS) in solid-liquid separation

J Environ Manage. 2022 Mar 1:305:114350. doi: 10.1016/j.jenvman.2021.114350. Epub 2021 Dec 31.

Authors

Muhammad Arslan Shahid¹, Nida Maqbool¹, Sher Jamal Khan²

Affiliations

¹ Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), Sector H-12, Islamabad, Pakistan.
² Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), Sector H-12, Islamabad, Pakistan. Electronic address: s.jamal@iese.nust.edu.pk.

PMID: 34974220
DOI: 10.1016/j.jenvman.2021.114350

Abstract

Pre-thickening or primary treatment of fecal sludge (FS) is a major bottleneck in designing fecal sludge treatment plants. This research demonstrates a practical analysis to improve the thickening efficiency of FS using woven fiber microfiltration membrane. A laboratory-scale anaerobic membrane-based thickening tank (MBTT) was investigated. Firstly, the system was operated with unconditioned FS at a flux range of 1-3 L/m²h. Secondly, the system was operated at an optimized flux of 2 L/m²h with conditioners, chitosan, and charcoal dust, at their optimized dosages reported in previous studies. It was observed that the solids accumulation in MBTT was linear and was specific to net solids accumulation. Feed FS was thickened to around 15% of total solids (TS) in 9-14 days. The overall solids accumulation rate was higher with conditioned FS. The less EPS accumulation and higher dewaterability in conditioned FS reduced the brushing frequency of the membrane and consequently, the average filtration duration per cycle was increased. Strong correlations of dewatering time with floc size, EPS, and electrical conductivity, indicated that higher EPS in FS tends to form flocs which can increase the dewatering rate in unstabilized FS. In permeate, the average TS and COD_t removal observed were 72-78% and 87-91%, respectively.

Keywords: Fecal sludge stabilization; Fecal sludge treatment; Onsite sanitation; Woven fiber microfiltration.

MeSH terms

Anaerobiosis
Extracellular Polymeric Substance Matrix*
Filtration
Sewage*
Waste Disposal, Fluid
Water

Substances

Sewage
Water