This work investigated the application of Focused Pulsed pretreatment on the subsequent anaerobic digestion of a mixture of primary and waste activated sludge. We present results from laboratory, pilot, and full-scale applications of the technology. In all cases, Focused Pulsed treatment resulted in significant solubilization of COD and other components from the sludge; treatment was effective on a continuous basis at pilot and full scale. Focused Pulsed treatment achieved two major benefits: 1) Increased utilization of the treated material in downstream processes, resulting in a significant reduction in waste biosolids requiring disposal; and 2) Improved conversion of treated material to methane, increasing the potential net energy capture from the biosolids. On-going work is focused on quantifying these operating and economic benefits, as well as verifying an additional benefit from the significant reduction of fecal coliform counts following treatment.
The Gippsland Water Factory (GWF) is being implemented to reclaim domestic and industrial (pulp and paper) wastewater to provide a reliable and sustainable industrial water supply, replacing the high quality raw water currently provided by Gippsland Water. A grassroots facility, the GWF will process domestic wastewater by preliminary treatment, primary sedimentation, membrane bioreactor (MBR) nutrient removal activated sludge, and reverse osmosis (RO). Domestic primary and waste activated sludge and industrial wastewater is treated in anaerobic reactors (ARs) (lagoons) prior to biological treatment via MBR. Significant H 2 S is produced in the ARs and is oxidized to elemental sulfur in the aerobic MBR by controlled oxidation. In Stage 2 of the GWF the industrial wastewater will be reclaimed using nanofiltration and RO. Extensive pilot testing supported design of the ARs and industrial MBR. Development of the GWF was based on multi-criteria analysis to create an innovative and sustainable solution. Innovative features in addition to those already mentioned include biological sulfur removal from the AR biogas and odor control which includes treatment of off-gases in the biological reactor followed by two-stage biological treatment.Glen T. Daigger (corresponding author) CH2M HILL,
The emission of volatile sulfur compounds (VSCs) was evaluated for stored anaerobically digested biosolids cakes. This evaluation was conducted on the headspace of anaerobically stored cakes obtained from two municipal wastewater treatment plants. The objective of this investigation was to determine the impact of high-shear solids processing on VSC production from digested biosolids. Experiments were conducted on biosolids obtained from full-scale lowand high-solids centrifuges, and from screw conveyors. The results of this study indicate that storage of biosolids obtained from high-solids centrifuges (high shear equipment) can produce 3 orders of magnitude more VSCs than biosolids obtained from low-solids centrifuge (low-shear equipment). Similarly, biosolids subject to a combination of centrifugation and screw conveyance (high-shear conveyance) produced as much as 3 orders of magnitude more VSCs than biosolids that were subject to centrifugation alone. These results verify the impact of biosolids shear on VSC production. Preliminary laboratory-scale experiments were also conducted to study the impact of biosolids shear and protein amendment on VSC production. These experiments demonstrated that storage of laboratory-sheared or protein amended biosolids resulted in greater VSC (specifically methyl mercaptan) production than the unaltered control. A model was developed that relates increase in biosolids shear during solids processing to increase labile protein. The subsequent hydrolysis of labile protein results in the formation of VSCs.
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