Full‐Scale Class A Biosolids Production by Two‐Stage Continuous‐Batch Thermophilic Anaerobic Digestion at the Hyperion Treatment Plant, Los Angeles, California

Iranpour, R.; Cox, Huub H. J.; Fan, S.; Abkian, Varouj; Minamide, Traci; Kearney, Ray; Haug, Roger T.

doi:10.2175/106143006x143939

Cited by 8 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The continuous-batch process in Phase IV was the only process that met the time-temperature relationship of Alternative 1 (Iranpour et al, 2006b). As expected, fecal coliforms and pathogens were completely eliminated in the digesters and fecal coliform recurrence in post-digestion did not occur.…”

Section: Discussionsupporting

confidence: 54%

Evaluation of thermophilic anaerobic digestion processes for full‐scale Class A biosolids disinfection at hyperion treatment plant

Iranpour

Cox

2006

Biotech & Bioengineering

View full text Add to dashboard Cite

This paper describes 5 phases of full-scale testing at the City of Los Angeles Hyperion Treatment Plant (HTP) for producing Class A biosolids (U.S. EPA Part 503 Biosolids Rule) by thermophilic anaerobic digestion. Phases I and II were tests with a two-stage continuous-batch process in a thermophilic battery of six digesters and a designated post-digestion train that was isolated from mesophilic operations. These tests demonstrated that digester outflow biosolids met the Class A limits for fecal coliforms and Salmonella sp. However, fecal coliform densities sharply increased during post-digestion. The recurrence was possibly related to a combination of a large drop of the biosolids temperature after the dewatering centrifuges and contamination of thermophilically digested biosolids from mesophilic operations. Phase III was conducted after insulation and electrical heat-tracing of the post-digestion train to maintain a biosolids temperature throughout post-digestion at about the same level as in the digester outflow. Biosolids monitoring at the last points of plant control (silos at Truck Loading Facility and farm for land application) indicated that fecal coliform recurrence was prevented. After completing the conversion of HTP to thermophilic operation, certification tests of Phases IV and V demonstrated Class A compliance of a two-stage continuous-batch process under Alternatives 1 and 3 of the Part 503 Biosolids Rule, respectively. HTP received the permit for Class A (indeed exceptional quality) biosolids land application in Kern County, California, in December 2002 under Alternative 3. Since 2003, HTP has consistently complied with the federal and local standards for Class A biosolids, indicating that Class A limits can be met under conditions less stringent than defined by the Alternative 1 time-temperature requirement for batch treatment.

show abstract

Section: Discussionsupporting

confidence: 54%

Evaluation of thermophilic anaerobic digestion processes for full‐scale Class A biosolids disinfection at hyperion treatment plant

Iranpour

Cox

2006

Biotech & Bioengineering

View full text Add to dashboard Cite

show abstract

“…It is expected that fecal regrowth or contamination observed in phases I and II will be resolved: (a) once full conversion to thermophilic digestion has been completed and mesophilic biosolids are no longer produced; and (b) all biosolids transfer lines and the storage silos have been insulated and heat‐traced to prevent temperatures in the postdigestion train from dropping to values that could allow the regrowth of fecal coliforms. Results of phases III, IV, and V testing have been submitted for publication ( Iranpour and Cox, 2005 ; Iranpour et al, 2005c ).…”

Section: Future Directionsmentioning

confidence: 99%

“…These studies were similar to a wide variety of others during this period (e.g., Andrews and Pearson, 1965 ; Fair and Moore, 1934 ; McCarty, 1964 ; Pohland and Bloodgood, 1963 ), in being motivated, to a large degree, by the hope that the more rapid metabolism of thermophilic organisms would translate into advantages in digestion speed or operational efficiency, if process stability could be maintained. Recent interest in thermophilic‐anaerobic digestion at the HTP is driven by stricter regulations for removal of pathogens from wastes being digested for final use as a soil amendment ( Ahring et al, 2001 ; Ghosh, 1998 ; Iranpour and Cox, 2005 ; Iranpour et al, 2002 , 2004 , 2005a , b , and c ).…”

Section: Introductionmentioning

confidence: 99%

Thermophilic‐Anaerobic Digestion to Produce Class A Biosolids: Initial Full‐Scale Studies at Hyperion Treatment Plant

Iranpour¹,

Cox²,

Oh³

et al. 2006

Water Environment Research

View full text Add to dashboard Cite

The highest quality of biosolids is called exceptional quality. To qualify for this classification, biosolids must comply with three criteria: (1) metal concentrations, (2) vector‐attraction reduction, and (3) the Class A pathogen‐density requirements. The City of Los Angeles Bureau of Sanitation Hyperion Treatment Plant (HTP) (Playa del Rey, California) meets the first two requirements. Thus, the objective of this study was to ensure that HTP's biosolids production would meet the Class A pathogen‐reduction requirements following the time–temperature regimen for batch processing (U.S. EPA, 1993; Subsection 32, Alternative 1). Because regulations require the pathogen limits to be met at the last point of plant control, biosolids sampling was not limited to immediately after the digesters, i.e., the digester outflows. The sampling extended to several locations in HTP's postdigestion train, in particular, the last points of plant control, i.e., the truck loading facility and the farm for land application.     A two‐stage, thermophilic‐continuous‐batch process, consisting of a battery of six egg‐shaped digesters, was established in late 2001 for phase I of this study and modified in early 2002 for phase II. As the biosolids were discharged from the second‐stage digesters, the Salmonella sp. (pathogen) and fecal‐coliform (indicator) densities were well below the limits for Class A biosolids, even though the second‐stage‐digester temperatures were a few degrees below the temperature required by Alternative 1. Salmonella sp. densities remained below the Class A limit at all postdigestion sampling locations. Fecal‐coliform densities were also below the Class A limit at postdigestion‐sampling locations, except the truck‐loading facility (phases I and II) and the farm for final use of the biosolids (phase II). Although federal regulations require one of the limits for either fecal coliforms or Salmonella sp. to be met, local regulations in Kern County, California, where the biosolids are land‐applied, require compliance with both bacterial limits. Additional work identified dewatering, cooling of biosolids after the dewatering centrifuges, and contamination as possible factors in the rise in density of fecal coliforms. These results provided the basis for the full conversion of HTP to the Los Angeles continuous‐batch, thermophilic‐anaerobic‐digestion process. During later phases of testing, this process was demonstrated to produce fully disinfected biosolids at the farm for land application.

show abstract

“…As discussed by Iranpour et al (2003b;2005b), full-scale testing indeed confirmed that fecal coliform recurrence did not occur after these modifications were implemented. Figure 3.…”

Section: Discussionmentioning

confidence: 75%

Lab and Pilot-Scale Tests with Post-Digestion Biosolids to Prevent Indicator and Pathogen Regrowth

Palacios¹,

Cox²,

Fan³

et al. 2005

proc water environ fed

View full text Add to dashboard Cite

Several experiments were conducted to investigate the cause of fecal coliform recurrence in biosolids after thermophilic anaerobic digestion. Fecal coliform recurrence has been observed at the City of Los Angeles Hyperion Treatment Plant (HTP) during pilot-scale experiments with a designated thermophilic battery of six digesters, while other digesters were still at a mesophilic temperature. The main results of the present investigation were:-QA/QC plant inspections indicated that the designated thermophilic battery and its post-digestion train likely were isolated from mesophilic operations, but contamination by mesophilically digested biosolids could not entirely be excluded. -High-pressure effluent and Mannich polymer did not contain fecal coliforms, hence, their additions to the post-digestion train could be ruled out as contamination sources. -Laboratory simulations could not confirm the suspected role of dewatering centrifuges in the recurrence of fecal coliforms observed at HTP. -Regrowth tests in the laboratory and the field demonstrated that the minimum temperature for preventing fecal coliform recurrence was about 50 0 C.Based on these results, it was postulated the fecal coliform recurrence observed during the pilot-scale tests could probably be attributed to a combination of contamination by mesophilically digested biosolids and a large drop of the biosolids temperature during post-digestion processing.

show abstract

Full‐Scale Class A Biosolids Production by Two‐Stage Continuous‐Batch Thermophilic Anaerobic Digestion at the Hyperion Treatment Plant, Los Angeles, California

Cited by 8 publications

References 20 publications

Evaluation of thermophilic anaerobic digestion processes for full‐scale Class A biosolids disinfection at hyperion treatment plant

Evaluation of thermophilic anaerobic digestion processes for full‐scale Class A biosolids disinfection at hyperion treatment plant

Thermophilic‐Anaerobic Digestion to Produce Class A Biosolids: Initial Full‐Scale Studies at Hyperion Treatment Plant

Lab and Pilot-Scale Tests with Post-Digestion Biosolids to Prevent Indicator and Pathogen Regrowth

Contact Info

Product

Resources

About