The objective of this study was to evaluate the effects of bioaugmenting anaerobic biosolids digestion with a commercial product containing selected strains of bacteria from genera Bacillus, Pseudomonas, and Actinomycetes, along with ancillary organic compounds containing various micronutrients. Specifically, the effects of the bioaugment in terms of volatile solids destruction and generation and fate of odor-causing compounds during anaerobic digestion and during storage of the digested biosolids were studied. Two bench-scale anaerobic digesters receiving primary and secondary clarifier biosolids from various full-scale biological wastewater treatment plants were operated. One of the digesters received the bioaugment developed by Organica Biotech, while the other was operated as control. The bioaugmented digester generated 29% more net CH(4) during the 8 weeks of operation. In addition, the average residual propionic acid concentration in the bioaugmented digester was 54% of that in the control. The monitoring of two organic sulfide compounds, methyl mercaptan (CH(3)SH) and dimethyl sulfide (CH(3)SCH(3)), clearly demonstrated the beneficial effects of the bioaugmentation in terms of odor control. The biosolids digested in the bioaugmented digester generated a negligible amount of CH(3)SH during 10 days of post-digestion storage, while CH(3)SH concentration in the control reached nearly 300 ppm(v) during the same period. Similarly, peak CH(3)SCH(3) generated by stored biosolids from the bioaugmented digester was only 37% of that from the control.

The effects of bioaugmenting anaerobic biosolids digestion with a commercial product that contained selected strains of bacteria from genera Bacillus, Pseudomonas, and Actinomycetes, along with ancillary organic compounds containing various micronutrients were evaluated. The main objective of the study was to investigate the effects of bioaugmentation specifically on the performance of methanogenesis during anaerobic digestion, as well as on the generation and fate of odor-causing compounds during the storage of the digested biosolids. The bench-scale digester with 5 g/L bioaugment generated 29% more net CH4 than a control during the eight weeks of operation. In addition, the average residual propionic acid concentration in the bioaugmented digester was 46% lower than that in the control. The biosolids digested in the bioaugmented digester generated a negligible amount of methyl mercaptan (CH3SH) during 10 days of post-digestion storage, while CH3SH concentration in the control reached nearly 300 ppmv during the same period. Similarly peak dimethyl sulfide (CH3SCH3) generated by stored biosolids from the bioaugmented digester was only 37% of that from the control. Similar results were obtained in a subsequent short term study designed to confirm the repeatability of the findings.

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The objective of this work was to study the anaerobic digestion of an industrial waste with 84% total and 57% volatile solids content. The waste was also characterized by high total COD content, 42% by weight. The anaerobic digestion of the waste alone and its co-digestion with the waste activated sludge (WAS) that is generated at the industrial facility were investigated. Particularly, kinetics of digesting the waste alone and co-digesting it with the WAS were determined. The substrate utilization rates under varying initial substrate concentrations were determined in batch reactors by measuring the methane generation rates. Then the substrate utilization rates were modeled according to the Monod kinetics. The solution to nonlinear regression resulted in the maximum specific substrate utilization rates (k) of 0.138 and 0.165 g COD g VSS(-1).day(-1) for the waste alone and the waste co-digested with the WAS, respectively. The half velocity constants (K s) were 4.390 and 4.860 g COD 1(-1) for the same conditions. It is important to note that since the methane generation data were used to determine the substrate utilization rates, these kinetic constants are likely to represent the methanogenic Archaea rather than the entire anaerobic consortium. It is concluded that the anaerobic co-digestion of this industrial waste with the WAS is beneficial from the digestion kinetics point of view since the k increased approximately 20% with the addition of the WAS. Moreover, there will be cost savings associated with digesting the WAS anaerobically rather than aerobically, the currently used method of WAS management, if anaerobic digestion is adopted in the future.