Fermentation of Return Activated Sludge to Enhance Biological Phosphorus Removal

All discoveries associated with phosphorus removal were first made in plants as accidental occurrences. Once observed, they were followed by laboratory and pilot scale work to be studied and explained. While the mechanism of biological phosphorus removal has been well researched and documented to the point where it is now possible to design a plant with a very reliable phosphorus removal process using formal flow sheets, biological phosphorus removal is still observed in a number of plants that have no designated anaerobic zone, which is considered essential for phosphorus removal. It was also not possible to model all these plants with standard simulation packages such as BioWin and GPS-X. This paper will discuss some of the background, and some case histories and applications, and present a simple postulation as to the mechanism and efforts at modeling the results.

Section: Discussionmentioning

confidence: 99%

Fermentation of Mixed Liquor for Phosphorus Removal

Barnard¹,

Houweling²,

Analla³

et al. 2010

“…This could be due to the fermentation of all the RAS as opposed to only a portion. The Pho-strip process at the Truckee-Meadows plant was successfully converted to a Phoredox process (Narayanan et al, 2002) by partitioning the aeration basin to form an anaerobic zone and then fermenting only about 10% of the RAS without the need to strip the phosphorus. No nitrification took place in this process.…”

Section: Fermentation Of Mixed Liquor or Return Activated Sludgementioning

confidence: 99%

Fundamentals of Sludge Fermentation for Enhanced Biological Phosphorus Removal

Barnard¹

2014

Most enhanced biological phosphorus removal (EBPR) plants do not have sufficient influent carbon in the form of either short-chain volatile fatty acids (SCVFA) or readily biodegradable COD (rbCOD) that could be converted into VFA in the anaerobic zone. This requires an external source of rbCOD or the generation of either rbCOD or VFA on site. Fermentation of the primary sludge or some of the mixed liquor is then required to augment the available soluble carbon to ensure reliable phosphorus removal. This paper describes the background and fundamentals of fermentation for ensuring an adequate supply of VFA.

“…Less than 10% of the RAS stream was passed from the anaerobic zone to the side-stream fermenter. Narayanan et al, (2002) described the conversion of a high-rate secondary treatment process with Phostrip at the Truckee Meadows WRF in Nevada to a high rate Phoredox plant with side stream fermentation of part of the return sludge. As shown in Figure 8, when operated as Phostrip, all the RAS was passed through the stripper where fermentation took place and phosphorus was released.…”

Section: Ras Fermentationmentioning

confidence: 99%

Mixed Liquor Fermentation and Other Alternatives for Providing VFA to EBPR Processes

deBarbadillo¹

2014

Fermentation of primary sludge to generate a source of volatile fatty acids for enhanced biological phosphorus removal processes is a well-established practice that has been in use since the 1970s. At wastewater treatment plants that do not have primary clarifiers, fermentation of activated sludge solids can offer a promising alternative. This paper provides a review of mixed liquor and return activated sludge solids fermentation configurations along with options for fermenting raw wastewater solids, fermentation of external carbon sources, and utilization of sludge treatment liquors to provide the necessary readily biodegradable carbon source to support EBPR operation.