FULL-SCALE THERMOPHILIC ANAEROBIC DIGESTION AT THE HYPERION TREATMENT PLANT: Experiments for The Production of EQ Biosolids

Iranpour, R.; Cox, Huub H. J.; Oh, Sangjun; Soung, T.; Alatriste, F.; Ardent, T.; Chang, Soon-Woong; Moghaddam, O.; Fan, S.; Mundine, J. E.; Kearney, Ray

doi:10.2175/193864702784247693

Cited by 3 publications

(3 citation statements)

References 10 publications

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“…Since 2000, several tests were conducted to convert HTP to thermophilic anaerobic digestion. During Phase I (late 2001) and Phase II (early 2002), a two-stage continuous-batch process was investigated in a designated battery of six thermophilic digesters and a designated thermophilic postdigestion train that was isolated from mesophilic plant operations to prevent contamination of the thermophilically digested biosolids (Iranpour et al, 2002b(Iranpour et al, , 2004 (Figure 1a). It was originally intended that Phase III at HTP (mid 2002) would be a test of a plant-wide thermophilic process that was guaranteed to meet the batch time/temperature requirement of Alternative 1 of 40 CFR 503.…”

Section: Plant Descriptions and Process Operationsmentioning

confidence: 99%

“…The indicator/pathogen density requirements for Class A biosolids usually need to be met at the last point of control by the plant, which usually is at the truck loading facility or the farm for land application. In response to local bans and ordinances on biosolids land application and growing public concern on the safety of biosolids, an increasing number of plants are implementing thermophilic anaerobic digestion to produce a higher quality of biosolids with indicator/pathogen densities below the limits for Class A qualification (Drury et al, 2002;Iranpour et al, 2002bIranpour et al, , 2004Mittsdörffer et al, 1990;Wilson and Dichtl, 1998). Recent investigations have indicated the recurrence of fecal coliforms in post-digestion biosolids at some wastewater treatment plants that produce Class A biosolids by thermophilic anaerobic digestion (Iranpour et al, 2002a).…”

Section: Introductionmentioning

confidence: 99%

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DISINFECTION OF FECAL COLIFORMS AND SALMONELLA IN THERMOPHILICALLY DIGESTED BIOSOLIDS

Iranpour¹,

Cox²,

Starr³

et al. 2004

proc water environ fed

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Several wastewater treatment plants that were investigated in this study produce biosolids that meet the Class A pathogen reduction requirements for both fecal coliforms (indicator) and Salmonella sp. (pathogen). The U.S. EPA Part 503 Biosolids Rule specifies that the Class A limits for these bacteria shall be met at the last point of plant control, which is usually interpreted as the truck loading facility when the biosolids are prepared for transport or at the farm for land application. However, a recurrence of fecal coliforms was observed in post-digestion biosolids from the City of Los Angeles Hyperion and Terminal Island Treatment Plants and in the biosolids at the farm for land application. Biosolids sampled from dewatering centrifuges, silos and the farm sometimes contained fecal densities in densities up to 10 7 MPN/g dry wt, causing exceedance of the Class A limit for fecal coliforms. In contrast, recurrence of Salmonella sp. was never observed, which indicates that fecal coliforms are a poor indicator of the pathogen content in biosolids after digestion. Regrowth tests with fecal coliforms in biosolids from several locations in the post-digestion train indicated the presence of a self-disinfecting effect that caused killing of fecal coliforms spiked to biosolids from the digester. Such an effect was not present in centrifuge and silo biosolids. Hence, the dewatering centrifuge was identified as the most likely location where the recurrence of fecal coliforms originated. Laboratory simulations of centrifuge dewatering achieving only 10% total solids could not confirm the field observations and the possible role of centrifuge dewatering in the recurrence of fecal coliforms remained unknown. Comparison of observations at three wastewater treatment plants indicated that the recurrence of fecal coliforms can possibly be related to the following combination of factors: i) contamination of Class A biosolids with fecal coliforms from external sources; ii) a large drop of the post-digestion biosolids temperature to below the maximum for fecal coliform growth; iii) the loss of a self-disinfecting effect that causes killing of fecal coliforms in digested sludge. Recurrence of fecal coliforms in biosolids during postdigestion and at the farm was prevented by insulation of the post-digestion train of the Hyperion Treatment Plant, which maintained a biosolids temperature above the maximum for growth of fecal coliforms. When silo and farm biosolids were subsequently stored at 21 0 C, no recurrence of fecal coliforms was observed for at least 6 days. KEYWORDSBiosolids regulations, Class A, last point of plant control, indicator and pathogenic bacteria, anaerobic digestion, regrowth and inactivation, laboratory simulations, selfdisinfecting

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Section: Plant Descriptions and Process Operationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

DISINFECTION OF FECAL COLIFORMS AND SALMONELLA IN THERMOPHILICALLY DIGESTED BIOSOLIDS

Iranpour¹,

Cox²,

Starr³

et al. 2004

proc water environ fed

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“…The Holbaek plant was operated at a temperature range of 50-55°C and an HRT of 12 days. Iranpour et al (2002) described the start up and operation of a full-scale thermophilic digester at 55°C at the Terminal Island Treatment Plant, Los Angeles, USA.…”

Section: Watanabementioning

confidence: 99%

Producing enhanced quality biosolids through anaerobic digester optimization

Salsali¹

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Regrowth of Fecal Coliforms in Class A Biosolids

Jolis¹

2006

Water Environment Research

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Eight types of Class A biosolids were tested for fecal coliform (FC) reactivation and/or regrowth at 20, 35, and 50°C for 21 days. Growth of FC did not occur at 20 or 50°C, but it was observed in two samples incubated at 35°C after a lag period of 48 hours. In undigested biosolids, final FC concentration exceeded 10 4 MPN/g, whereas in thermophilically digested biosolids, the final FC concentration remained below 10 3 MPN/g, as FC regrowth may have been affected by the presence of the anaerobic bacterial consortium responsible for the digestion process. Fecal‐coliform reactivation and regrowth within treatment plant operations seem unlikely but can occur in land application of biosolids.

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FULL-SCALE THERMOPHILIC ANAEROBIC DIGESTION AT THE HYPERION TREATMENT PLANT: Experiments for The Production of EQ Biosolids

Cited by 3 publications

References 10 publications

DISINFECTION OF FECAL COLIFORMS AND SALMONELLA IN THERMOPHILICALLY DIGESTED BIOSOLIDS

DISINFECTION OF FECAL COLIFORMS AND SALMONELLA IN THERMOPHILICALLY DIGESTED BIOSOLIDS

Producing enhanced quality biosolids through anaerobic digester optimization

Regrowth of Fecal Coliforms in Class A Biosolids

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