Pathogen inactivation in biosolids with lime and fly ash addition

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Liu, Chunhe
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A laboratory study was conducted adding alkali to inactivate pathogens in anaerobically digested, dewatered biosolids from North End Wastewater Pollution Control Center (NEWPCC). Fecal coliform bacteria were used as indicator microorganism in this study. The indigenous fecal coliform density in the samples ranged from 6.6 * 106 to 21 * 107 Colony Forming Unit (CFU)/g total solid (TS). The results of bench scale work showed that lime addition followed by storing the biosolids samples in airtight containers at room temperature (20-23C) was very effective in inactivation of fecal coliform bacteria. The effect of fly ash addition on fecal coliform inactivation was also studied. Fly ash dose required for inactivating fecal coliforms depends on the alkaline component of the fly ash. The laboratory work also showed that expressing the alkali dose, for example, as 20g/kg TS or 5% on a wet-weight basis, was inconvenient since alkali dose requirement for pathogen inactivation varies with biosolids composition (mainly, total solid or moisture content). As a control, a storage test on biosolids without lime addition was also conducted. (Abstract shortened by UMI.)