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PCB and AOX removal in mesophilic and thermophilic sewage sludge digestion

Paper ID Volume ID Publish Year Pages File Format Full-Text
4591 233 2007 7 PDF Available
Title
PCB and AOX removal in mesophilic and thermophilic sewage sludge digestion
Abstract

In this study, a comparison of the biodegradation of adsorbed organic halogen compounds (AOX) and polychlorinated biphenyls (PCB) in thermophilic and mesophilic anaerobic digestion (seeded with waste activated sludge) at different hydraulic retention times (HRT 18, 22 and 26 days in the mesophilic digester and 8, 12, 18, 22 and 26 days in the thermophilic digester) was performed. Results obtained in this work showed an enhancement of both PCB and AOX biodegradation under thermophilic conditions. The total PCB removal efficiency was in the range of 59.4–83.5% under thermophilic conditions and 33.0–58.0% under mesophilic conditions. HRT played an important role in the digester performance since high working HRTs implied more reduction of the total PCB amount in the sludge. The total PCB content in the treated sludge under thermophilic conditions lied below the cut-off limit proposed in the 3rd draft of Directive presented to the European Commission [CEC, Working Document on Sludge (3rd Draft), Commission of the European Communities Directorate-General Environment, ENV.E.3/LM, Brussels, 27 April 2000]. Besides, a bioaccumulation of lightly chlorinated PCBs was detected in the mesophilic digester, which is in concordance with the theory that the PCBs are anaerobically biodegraded by means of a reductive dechlorination mechanism. On the other hand, the AOX removal efficiency was in the range of 40.4–50.3% for thermophilic conditions and 30.2–43.2% for mesophilic conditions. The AOX content in the treated sludge of both thermophilic and mesophilic digesters did not exceed the cut-off limit proposed in the 3rd draft [CEC, Working Document on Sludge (3rd Draft), Commission of the European Communities Directorate-General Environment, ENV.E.3/LM, Brussels, 27 April 2000]. Moreover, high HRTs promoted an improvement of the AOX removal capacity of the anaerobic digestion.

Keywords
Anaerobic digestion; AOX; Mesophilic; PCB; Sewage sludge; Thermophilic
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PCB and AOX removal in mesophilic and thermophilic sewage sludge digestion
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biochemical Engineering Journal - Volume 36, Issue 3, 1 October 2007, Pages 281–287
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