Proliferation of glycogen accumulating organisms induced by Fe(III) dosing in a domestic wastewater treatment plant

Abstract

To meet the effluent requirements given for the sensitive receiving body, the Southpest Wastewater Treatment Plant of Budapest, Hungary uses a combined activated sludge-biofilter system with chemical precipitation for P removal. Causes of the proliferation of glycogen accumulating organisms (GAOs) observed in the unaerated/oxic activated sludge unit of this system were investigated both in full-scale and in lab-scale experiments combined with a detailed analysis of the microbial communities. Concentration profile measurements throughout the 8-stage activated sludge unit indicated anaerobic conditions in the first two unaerated reactors and low orthophosphate level (< 1 mg l(-1)) in all of the stages that could not be attributed to the influent quality, but to Fe (III)-dosing to the returned activated sludge. Microbiological analysis revealed the presence of GAOs from the GB group in the Gammaproteobacteria and occasionally tetrad-forming organisms from Actinobacteria, and the absence of Rhodocyclus-related polyphosphate accumulating organisms (PAOs) in the activated sludge samples. Comparative lab-scale studies carried out in two identically arranged UCT-systems with staged anoxic reactors also confirmed that Fe (III)-dosing may result in phosphorus deficiency of the microbial niche, leading to the suppression of growth and EBPR activity of PAOs and to the proliferation of GAOs.

Decoupling and Optimization of Both P and N Removal in an Advanced IFAS-EBPR-MBR System

“…The FISH micrographs show that Accumulibacter type PAOs are present in both mixed liquor and in media. 35-40% of the total population (>70% of total PAOs) in both of the aerobic zones in the mixed liquor is Accumulibacter type; this is comparable to the ranges of Accumulibacter abundance reported in studies with lab scale acetate fed EBPR systems (Jobbagy et al 2006;Oehmen et al 2006;Saito et al 2004). Only the loosely attached portion of biomass in the media contained Accumulibacter type PAOs (10-15% of total cells and 50% of total PAOs) as shown in the figure.…”

Research Advances and Challenges in the Microbiology of Enhanced Biological Phosphorus Removal—A Critical Review

“…Although the nature of competition between PAO and GAO and its role in EBPR deterioration have not been elucidated fully as of yet, a number of factors have been reported to control competition between PAOs and GAOs. These factors include influent phosphorus concentration (Liu et al, 1997), presence of ferric iron (Jobbagy et al, 2006), dissolved oxygen level (Dai et al, 2007;Griffiths et al, 2002), and sludge age (Whang and Park, 2006). However, three of the most pertinent factors are temperature, pH, and carbon, and these are discussed in detail below.…”

Full‐Scale Use of Glycogen‐Accumulating Organisms for Excess Biological Carbon Removal

“…The GAOs are well-known to be repressed, because their undesired growth may severely decrease the efficiency of enhanced biological phosphorus removal systems (Erdal et al, 2002;Filipe et al, 2001a). The explanation is offered by their metabolic characteristics, which are similar to polyphosphateaccumulating organisms (PAOs) (Jobbágy et al, 2006;Liu et al, 1996;Seviour et al, 2000). Both types of bacteria are capable of taking up volatile fatty acids (VFAs), especially acetate, and other readily biodegradable organics (e.g., glucose) in the anaerobic stage of an anaerobic/aerobic system through hydrolyzing a polymer of high-energy content, which is glycogen in the case of GAOs and polyphosphate in the case of PAOs.…”