How additives affect microbial populations and overall breakdown of municipal waste in anaerobic digesters

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Title: How additives affect microbial populations and overall breakdown of municipal waste in anaerobic digesters
Author: Bush, Randy Lee
Abstract: A bench scale analysis of twelve 4 -Liter anaerobic digesters with a 3 -Liter working volume were operated to examine the effects of five commercial additives on the degradation of primary municipal sludge . The reactors were loaded with 150 ml per day of 3 % volatile -solid content waste collected from the Lubbock Municipal Treatment Plant . Ten of the reactors were loaded with one of five commercial additives , in duplicate , with two reactors serving as the control . The objective of the experiments was to determine the efiects that the additives would have on the performance of the digestion of the waste and the microbial populations . It was found that during steady state operation , the total volatile solids content of reactors with the Biocope additive were significantly lower (16 .5 % ) than the control (p <0 .05 ) , for an overall increase in volatile solids degradation of 8 .2 % . A preliminary levelone economic feasibility test showed that $193 ,257 could be saved over an assumed 20 years of operation , by constructing an 8 .2 % down -sized treatment plant with the inclusion of Biocope^^ , based on an average flow rate of 1 million gallons per day of wastewater into the treatment plant . During the last two and one -half months of operation , pH , and anaerobic bacteria levels were substantially lower (p <0 .05 ) in reactors loaded with the MPC additive than the control reactors . The total volatile solids destruction and chemical oxygen demand removal , and biomass readout from the HMBrV device were also was significantly lower (p <0 .05 ) in these reactors than in the control . The HMB -IV device used to measure aerobic activity of a sample , was shown to be effective in determining unsteady mixing in the anaerobic digesters , and early detection of a drop in pH below the threshold value of 6 .5 . HMB -IV readings significantly dropped 1 -2 weeks before a pH drop would be detected that would inhibit the digestion process . It was concluded that the HMB -IV device could be excellent for early detection of process failure thereby providing an early response to corrective action .
URI: http : / /hdl .handle .net /2346 /9232
Date: 1998-05

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Bush, Randy Lee How additives affect microbial populations and overall breakdown of municipal waste in anaerobic digesters. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /9232 .

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