Fecal coliform recurrence has been observed at the City of Los Angeles Hyperion Treatment Plant during pilot-scale experiments with a designated thermophilic battery of six anaerobic digesters, while other digesters were still at a mesophilic temperature. Several lab and full-scale experiments indicated the following possible causes of the growth/reactivation of fecal coliforms in post-digestion: a) contamination of thermophilically digested biosolids with mesophilically digested biosolids; b) a large drop in the biosolids temperature between the centrifuges and silos, which could have allowed the reactivation and/or growth of fecal coliforms. These were resolved by the full plant conversion to thermophilic anaerobic digestion and design modifications of the post-digestion train.
Solving fecal coliform growth/reactivation in biosolids during full-scale post-digestion processes
R. Iranpour, R. Palacios, H.H.J. Cox, V. Abkian; Solving fecal coliform growth/reactivation in biosolids during full-scale post-digestion processes. Water Sci Technol 1 July 2005; 52 (1-2): 283–288. doi: https://doi.org/10.2166/wst.2005.0529
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