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Wastewater Treatment Anaerobic Digester Foaming Prevention and Control Methods - Literature Review and Survey - Full-Scale Studies (WERF Report INFR1SG10)
Citation:
Pagilla, K. AND B. Subramanian. Wastewater Treatment Anaerobic Digester Foaming Prevention and Control Methods - Literature Review and Survey - Full-Scale Studies (WERF Report INFR1SG10) . Water Environment Research Foundation, Alexandria, VA, 2014.
Impact/Purpose:
This project and report highlights research needs and gaps to better understand the issue of anaerobic digester (AD) foaming in water resource recovery facilities. The literature review helped to identify gaps in knowledge of AD foaming including causes, measurement methods, effects, and prevention and control in WRRFs. Plant survey shows current status of full-scale AD foaming. Full-scale studies show that primary cause and supplementary factors are necessary for foam formation, which is valuable for foaming control and mitigation. The study highlights that mixing is a certain factor exacerbating AD foaming when a primary cause of foaming such as filaments exists. Mixing can be reduced without adversely affecting digester performance while helping control the foam episodes. The report forms the basis for a guidance document on AD foaming prevention and control methods.
Description:
This project addresses the issue of anaerobic digester (AD) foaming in different water resource recovery facilities (WRRFs). This two-volume report is a compilation of an AD foaming literature review, a plant survey, and findings from full-scale studies. The literature review helped to identify gaps in knowledge of AD foaming including causes, measurement methods, effects, and prevention and control in WRRFs. Survey responses from full-scale plants were used to reconcile the knowledge gaps found in the literature. The survey also helped to identify plants for full-scale study as well as the parameters to be varied in each plant studied. The key gaps in the knowledge were investigated at full-scale in selected WRRFs. The literature review and survey results are presented in one volume, and the full-scale studies in the other. Full-scale studies included review of historical operational data, plant information from various publications such as technical memoranda and engineering reports, extensive discussion with plant personnel, and full-scale modification of key parameters to determine foaming causes and control. These findings were used to develop case studies including critical parameters to be varied and control strategies to be implemented to prevent and control AD foaming at each plant. Various gaps in existing knowledge on AD foaming were identified – in causes, control, prevention, and impacts of AD foaming. Filamentous bacteria were found to be the most common cause of foaming in the survey respondents. Most of the causes and control strategies reported from the survey respondents were in accordance with published literature. Full-scale studies confirmed the existence of filaments M. parvicella and G. amarae (which are linked to AD foaming) in most of the plants. Prevention and control options include minimizing foam-causing materials (including filamentous bacteria) in the feed sludge, reduced mixing in most cases, and AD process control to operate in steady state mode. A case study report of AD foaming causes, methods of foam detection, control, and mitigation methods was developed for each full-scale plant studied. [NOTE: The link below connects to a WERF site where the Final Report can be downloaded for free, after registering at the WERF site. To view the WERF registration link, which is on the WERF home page (www.werf.org), it may be necessary to move the page so the top right corner is visible. For some projects the Executive Summary is available and can be downloaded for free without registering on the WERF site.]
URLs/Downloads:
https://www.werf.org/a/ka/Search/ResearchProfile.aspx?ReportId=INFR1SG10
www.werf.org