Key influential factors for sludge pre-fermentation process design--a case study.
Sewage sludge pre-fermentation process produces readily biodegradable carbon, which is essential for reliable biological phosphorus removal and efficient denitrification. This bench scale study was to develop site-specific design parameters for a sludge fermentation process, and to look into the effects of various influential factors. The key factors investigated induded solids retention time (4-8 days), temperature (9-19 degrees C) and sludge concentrations (0.5%-4% DS). The optimum Volatile Fatty Adds yield was found at a sludge concentration of 1%-1.5% DS. A solid retention time of 4 days at 15-20 degrees C was found to be most cost effective. The fermentation reaction was temperature sensitive, which was found to be inefficient at temperature below 12-15 degrees C. Under the optimum conditions, 80-100 mgVFA g(-1) VSS can be generated from fermentation process, which will result in an increase of 20-24 mg l(-1) in the settled sewage based on average flow. A significant pathogen reduction level was also demonstrated over the fermentation period. Liquid sludge from the small rural wastewater treatment plants is often imported to a regional sludge treatment centre for more advanced treatment to comply with the Regulations. The suitability of this imported sludge for pre-fermentation process was also investigated in this study.
Chen
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Anglian Water Services Ltd., Thorpe Wood House, Peterborough, PE3 6WT, UK.
Steen
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FM
Green
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PG
D001673:Biodegradation, Environmental; D005285:Fermentation; D006801:Humans; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
D012722:Sewage