Effects of Anaerobic Selector Hydraulic Retention Time on Biological Foam Control and Enhanced Biological Phosphorus Removal in a Pure‐Oxygen Activated Sludge System

Abstract

Increased anaerobic selector hydraulic retention times (HRTs) in a high-purity oxygen activated sludge process resulted in an increase in soluble orthophosphate release and biodegradable chemical oxygen demand removal, confirming that enhanced biological phosphorus removal occurs at aeration solids retention times (SRTs) below 1.7 days. Under operating conditions that included biological foam trapping and recycling, an anaerobic selector with HRTs higher than 55 minutes resulted in a decrease in filament counts and effective foam control. Effective norcardioform control is achieved through the combination of metabolic selective pressure and increased soluble organic substrate removal in the anaerobic selector and low aeration SRT. Water Environ. Res., 79, 472 (2007).

Foaming Scum Index (FSI) – A new tool for the assessment and characterisation of biological mediated activated sludge foams

“…Kerley and Forster (1995) Kim and Pagilla (2000) foam potential) which simulate aeration conditions within a plant and provides an indication of the propensity of sludge samples to foam. Microscopic analysis of the biomass is often carried out alongside such foam potential tests (Ho and Jenkins, 1991;Oerther and De Los Reyes, 2001;de los Reyes and Raskin, 2002;Jolis et al, 2007). The combination of these analytical techniques has led to the concept of threshold numbers being assigned to known foam causing filaments above which foaming is most likely to occur (Davenport et al, 2000;de los Reyes and Raskin, 2002).…”

Integrated Treatment of Per- and Polyfluoroalkyl Substances in Existing Wastewater Treatment Plants─Scoping the Potential of Foam Partitioning

“…Foam control strategies are common at wastewater treatment plants, particularly chemical methods, such as dosing of anti-foaming agents or disinfectants. , Additionally, design decisions may be made to minimize foam formation, e.g., lowering the sludge retention time in activated sludge, operating at lower aeration rates, or implementing anoxic, anaerobic, or aerobic selector systems . Such selector systems aim to provide unfavorable conditions for the growth of foam-causing filamentous microorganisms . If tanks are mechanically stirred, this may also lead to foam collapse instead of buildup.…”

“… 26 Such selector systems aim to provide unfavorable conditions for the growth of foam-causing filamentous microorganisms. 39 If tanks are mechanically stirred, this may also lead to foam collapse instead of buildup. When foam formation is to be exploited as a PFAS removal technology, foam removal devices that skim foam from the water surface should be installed instead.…”

Evaluating the Measurement of Activated Sludge Foam Potential

“…Despite the range of methods which have already been used to evaluate foaming characteristics, to date there is no standard method for assessing the foam potential or stability of activated sludge [2] ( Table 1). Due to its simplicity and ease of operation, the Alka-Seltzer test remains the most popular method for both researchers and operators [40,[49][50][51][52]. Some significant relationships have been identified using this test.…”