Enhancement of Kelowna’s Biosolids to Energy Conversion with Thermal Pretreatments

Description:The potential of using biogas as energy source is broadly recognized and anaerobic digestion has become a major part of modern wastewater treatment plants (WWTPs). This study evaluates advanced anaerobic digestion incorporating thermal pretreatments (microwave at 2.45 GHz and conventional heating) as an alternative disposal method for the biosolids generated by Kelowna WWTP. The laboratory studies started with acclimation of anaerobic inocula to thermally pretreated (at 175oC) Kelowna biosolids at 18% total solids (TS) concentration. For acclimation, thermophilic inoculum was taken from the effluent line of the sludge digesters at Annacis Island WWTP (BC) and mesophilic inoculum was taken from Penticton WWTP (BC). Four semi-continuous flow digesters (2, 2.0 L of mesophilic and 2, 2.0 L of thermophilic) were run for more than 7 months at a sludge retention time (SRT) of 20 days. Organic loading rates (OLR) of the acclimation digesters was started from 1.58 ± 0.27 g chemical oxygen demand (COD)/L/d and gradually doubled during 7 months under feed concentrations ranged from 1.71 ± 0.15% to 3.65 ± 0.30 % TS by weight. All four digesters were able to acclimatize thermally pretreated sludge without any indication of acute or chronic toxicity. Daily biogas productions were 0.26 ± 0.02 and 0.29 ± 0.01 ml biogas/mg CODfed for thermophilic and mesophilic digesters. The methane percentage in the acclimation reactors ranged from 60-65%. The total number of ten lab-scale digesters set-up with acclimatize inocula is currently underway to optimize energy (methane) output, and SRT requirements of untreated and thermally pretreated digesters.

Authors: Mehdizadeh, Neda; Galvagno, Piero; Eskicioglu, Cigdem

Subjects: Wastewater, Residuals and Biosolids, Energy and Climate Change

Tags:sludge,digestion,biogas,anaerobic digestion,WWTP,ac2012

Citation:2012 BCWWA Annual Conference, Session 8, Penticton

Publication Date:Aug 7th, 2012 Upload Date:Aug 7th, 2012

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