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Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

Paper ID Volume ID Publish Year Pages File Format Full-Text
35921 45114 2008 10 PDF Available
Title
Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)
Abstract

A three litre submerged anaerobic membrane bioreactor (SAMBR) was used to examine the effect of powdered activated carbon (PAC) on COD removal and flux. 98% COD removal efficiency was achieved at a high loading rate (16 gCOD l−1 d−1) and a low hydraulic retention time (HRT) of 6 h in the presence of 3.4 g l−1 of PAC. PAC addition improved start-up and performance during a hydraulic shock by buffering the volatile fatty acids (VFAs), however, a large amount of biomass was important in accommodating the higher loading rate in the SAMBR. Batch assays showed that PAC addition improved methane potential both in terms of amount and inoculation time. COD retention inside the SAMBR for three experiments was proportional to the soluble microbial products (SMPs) contribution to COD, as (VFAs) passed through the membrane at high sparging rates (5 litres per minute—LPM). Size exclusion chromatography showed that the membrane acted as an ultra-filter (<30 kDa) as the cake or gel layer significantly reduced the amount of organics passing through the membrane. PAC adsorbed slowly biodegradable low and high MW residual COD from the bulk liquid, and hence improved COD removal and flux. Particle size distributions demonstrated that PAC also adsorbs fine colloids, and flux data showed that only a thin biofilm was formed due to the high backtransport velocity of PAC. The combined effects of adsorption of fine colloids and dissolved organics, and the formation of a thin cake layer resulted in significant flux improvement from 2 to 9 litres per square metre per hour (LMH) in the presence of 1.67 g l−1 PAC. However, addition of 3.4 g l−1 PAC reduced the flux to 5 LMH by the combined effect of viscosity and its inability to completely adsorb the dissolved organics and fine colloids that resulted in high internal fouling. Under the given operating conditions, addition of 1.67 g l−1 PAC appears to be the optimum quantity in terms of cost, flux and soluble COD removal.

Keywords
Soluble microbial products (SMPs); Colloids; Extracellular polymers (ECPs); Critical flux; Effluent; Anaerobic digestion; Membrane bioreactor; Powdered activated carbon (PAC)
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Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 43, Issue 1, January 2008, Pages 93–102
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
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us