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Role and characteristics of problematic biofilms within the removal and mobility of trace metals in a pilot-scale membrane bioreactor

Paper ID Volume ID Publish Year Pages File Format Full-Text
34609 45035 2013 10 PDF Available
Title
Role and characteristics of problematic biofilms within the removal and mobility of trace metals in a pilot-scale membrane bioreactor
Abstract

•Problematic biofilm may have an important role in toxic metals removal in submerged membrane bioreactor.•Clogging sludge from pilot-scale plant was characterised by chemical, biological and gene based analysis.•EPS and microbial speciation enhanced the biosorption of trace heavy metals.•During acid cleaning of the membrane module, metals dissolved in the acid solution up to 15%.

The characteristics of problematic biofilms (i.e., fouling and clogging layers) were studied with regards to the removal and fate of trace metals (contents well under 100 μg/L) during the long-term operation of a pilot-scale membrane bioreactor for the treatment of real wastewaters from a large industrial area.Results showed that clogging layer was more effective than suspended activated sludge in the biosorption of As > Zn > Ni > Cd > Sb > Fe > Se due to the synergic effects of extracellular polymeric compounds and metal-resistant bacteria. In fact the selective microbial speciation of the phylum of Bacteroidetes, which is highly resistant to heavy metals, was observed in the clogging sludge in spite of the very low concentration of dissolved metals in the bioreactor.Compared to the suspended activated sludge, the clogging layer enhanced the biosorption of very toxic substances such as As, Cd and Ni. In fact, the metal contents were respectively: 7.9–7.4 vs. 690–840 μgAs/kgTS; 1.5–2.2 vs. 149–219 μgCd/kgTS; 58.8–71.7 vs. 227–298 μgNi/kgTS. Then, the potential desorption of metals during the membrane acid cleanings was estimated as relevant as 10–15% of the metals associated to the clogging sludge. The combined effects of pH and the selected microbial community, and the minor effect of the redox potential, let us conclude on the major importance of bio-sorption/desorption mechanisms with respect to bio-precipitation/dissolution.

Keywords
MBR; Real industrial wastewater; Trace heavy metals; Sorption–desorption; Clogging sludge; EPS
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Role and characteristics of problematic biofilms within the removal and mobility of trace metals in a pilot-scale membrane bioreactor
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 48, Issue 11, November 2013, Pages 1757–1766
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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