Laboratory Studies on a Sequencing-Batch Temperature-Phased Anaerobic Digestion (Tpad) System

Santha, Hari; Sandino, Julián; Shimp, Gary F.; Sung, Shihwu; Isik, Ferit

doi:10.2175/193864703784292205

Cited by 3 publications

(3 citation statements)

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“…Moen et al (2001) reported that, in two years of bench-scale studies of TPAD for King County (Seattle), foaming was routinely observed in the mesophilic "control" reactor whereas in the thermophilic stage of the TPAD reactor system it was not. Santha et al (2003) noted similar observations from bench-scale studies at Iowa State University. In lab-scale experimentation in Sweden, Westlund et al (1998) concluded that the heating WAS to 70 o C (pre-pasteurization temperature) changes the foaming potential of activated sludge with high content of Microthrix parvicella and could be used as a solution to prevent foaming.…”

Section: Reducing the Potential For Foaming Via Process Changessupporting

confidence: 67%

Coping with Digester Foaming in an Age of Increasing Incidence

Shimp¹,

Kobylinski²,

Rowan³

et al. 2009

proc water environ fed

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Digester foaming is poorly understood. An increasing number of wastewater utilities are experiencing significant disruption of both liquid stream treatment and solids processing operations as a result of foaming episodes and, in some cases, costly structural damage to their digesters. A review of the literature indicates that we should anticipate increased foaming problems in the future as the use of biological nutrient removal (BNR) and membrane (MBR) processes become more prevalent, and as utilities operate at lower DO concentrations to contain operating costs and reduce their carbon footprint. This paper reviews research findings and actual operating experience related to digester foaming and describes foam formation and its behavior inside the digester. Measures to reduce the impacts of digester foaming such as changes in digester operational practices and facility and equipment modifications that can make a digestion complex more "foam tolerant" are reviewed, along with the prospects for their success based on observations at operating plants. Merely optimizing operational practices may not be sufficient in all cases, and some wastewater utilities have opted to make major process changes in an effort to reduce digester foaming. Early operating experience with two phase digestion, in particular, has shown considerable promise at several treatment plants with long histories of foaming in conventional digestion systems. Short of undertaking major capital improvements to effect process changes, there are more modest steps that can be taken to reduce the potential for facility damage and disruption from digester foaming.

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Section: Reducing the Potential For Foaming Via Process Changessupporting

confidence: 67%

Coping with Digester Foaming in an Age of Increasing Incidence

Shimp¹,

Kobylinski²,

Rowan³

et al. 2009

proc water environ fed

Self Cite

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“…One possible option to reduce odor emissions is to use a process in which the thermophilic stage is followed by a mesophilic stage, such as temperature phased anaerobic digestion (TPAD) ( Schafer et al, 2003 ). Although volatile solids and pathogen destruction by TPAD has been well‐documented in laboratory‐ and pilot‐scale tests (e.g., Bucher et al, 2001 ; Reusser and Zelinka, 2001 ; Sandino et al, 2002 ; Santha et al, 2003 ), and several plants have implemented TPAD on a full scale ( Arant et al, 2003 ; Schafer et al, 2003 ; Wilson and Dichtl, 1998 ), the effect of polishing by a mesophilic stage on reducing odor emissions has not been well‐established. We opted for reducing the digester temperature in Phase V to the lower end of the thermophilic range, to maintain disinfecting conditions, while reducing odor emissions.…”

Section: Discussionmentioning

confidence: 99%

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

Iranpour

Cox²,

Fan³

et al. 2006

Water Environment Research

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The City of Los Angeles Hyperion Treatment Plant (HTP) (California) converted its anaerobic digesters to thermophilic operation to produce Class A biosolids. Phase IV tests demonstrated compliance of a two‐stage, continuous‐batch process with Alternative 1 of U.S. Environmental Protection Agency 40 CFR Part 503 (U.S. EPA, 1993), which defines the time–temperature requirement for batch treatment (T ≥ 56.3°C at 16‐h holding). Fecal coliforms, Salmonella sp., viable helminth ova, and enteric viruses were not detected in biosolids in the postdigestion train, including the truck‐loading facility and the farm for land application as the last points of plant control where compliance is to be demonstrated. The same results were achieved during Phase V tests, after lowering the second‐stage holding temperature to 52.6°C to reduce the elevated methyl mercaptan production that was observed during Phase IV. Hence, the Phase V process complied with Alternative 3 of 40 CFR Part 503. Currently, HTP operates its digesters under the same conditions as tested in Phase V. In 2003, monthly monitoring of the biosolids at the truck‐loading facility and the farm for land application demonstrated consistent compliance with Alternative 3.

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“…They propose that the model can be employed to evaluate the performance of alternate digester operating conditions. The performance and stability of the temperature phased anaerobic digestion (TPAD) process when operated in sequential batch mode was investigated at bench scale (Santha et al, 2003). Operating with a mixture of primary and thickened waste activated sludges, the TPAD process was observed to operate stably at a residence time as low as 12 days.…”

Section: Sludge Treatment Technologiesmentioning

confidence: 99%