Comparison of Mechanical Pretreatment Methods for the Enhancement of Anaerobic Digestion of Pulp and Paper Waste Activated Sludge

The conventional anaerobic digestion process, requiring long solids retention times (SRTs) to digest solids, is currently viewed as impractical for the pulp and paper industry because of high capital costs associated with the construction of new digesters. Recent developments in sludge solubilizatio...

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Bibliographic Details
Published in:	Water environment research 2012-06, Vol.84 (6), p.497-505
Main Authors:	Elliott, Allan, Mahmood, Talat
Format:	Article
Language:	eng
Subjects:	Activated sludge Alternative energy sources Anaerobic digestion Anaerobiosis Applied sciences Bacteria Biogas Biological and medical sciences Bioreactors Biotechnology Capital costs Carbon dioxide Chemical oxygen demand Cost control Digestion Exact sciences and technology Fundamental and applied biological sciences. Psychology General purification processes General treatment and storage processes Homogenization Industrial Waste - analysis Methane Methods Methods. Procedures. Technologies Operating costs Other industrial wastes. Sewage sludge Others Pollution Pretreatment pretreatments Pulp & paper industry pulp and paper Pulp and paper industry Sewage - chemistry Sludge Sludge digestion Various methods and equipments Waste Disposal, Fluid - methods Wastes Wastewaters Water Pollutants, Chemical - chemistry Water Pollutants, Chemical - metabolism Water treatment and pollution
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Summary:	The conventional anaerobic digestion process, requiring long solids retention times (SRTs) to digest solids, is currently viewed as impractical for the pulp and paper industry because of high capital costs associated with the construction of new digesters. Recent developments in sludge solubilization technology could be promising in reducing digester size, which also allows for the potential use of decommissioned tanks, both of which can reduce the capital cost. Three pretreatment technologies for use with anaerobic digestion were tested on laboratoryscale to investigate their feasibility. The SRTs in all three digesters systematically decreased from 20 to 3 days. The reference digester was fed waste activated sludge (WAS) to serve as the control at the same SRTs. The other digesters were fed WAS that had been preconditioned using mechanical shearing, sonication, or high-pressure homogenization technology. Anaerobic digestion with high-pressure homogenization produced as much methane at 3-day mean SRT as that from the reference digester operated at 20-day SRT. Therefore, a new digester can theoretically be 85% smaller than a conventional digester. An added benefit of WAS to methane conversion is the recovery of nutrients nitrogen and phosphorus.
ISSN:	1061-4303 1554-7531