The Effects of MCRT and Temperature on Enhanced Biological Phosphorus Removal

Mamais, Daniel; Jenkins, David

doi:10.2166/wst.1992.0537

Cited by 71 publications

(46 citation statements)

References 14 publications

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“…For both of these biological processes a reduction in sludge age increases the N and P removal per mass organic load (Wentzel et al, 1990;WRC, 1984), respectively, provided the sludge age remains longer than some lower limit to prevent "washout" of the P-removal and denitrifying organisms (both OHOs and PAOs) (Mamais and Jenkins, 1992). There are indications that, if nitrification and sludge age are uncoupled, then the sludge age can be reduced to less than half, from about 20 to 25 days to about 8 to 10 days.…”

Section: Long Sludge Age Requirement For Nitrificationmentioning

confidence: 99%

Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system

Sötemann

Moodley

et al. 2003

Biotech & Bioengineering

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A systematic lab-scale experimental investigation is reported for the external nitrification (EN) biological nutrient removal (BNR) activated sludge (ENBNRAS) system, which is a combined fixed and suspended medium system. The ENBNRAS system was proposed to intensify the treatment capacity of BNR-activated sludge (BNRAS) systems by addressing two difficulties often encountered in practice: (a) the long sludge age for nitrification requirement; and (b) sludge bulking. In the ENBNRAS system, nitrification is transferred from the aerobic reactor in the suspended medium activated sludge system to a fixed medium nitrification system. Thus, the sludge age of the suspended medium activated sludge system can be reduced from 20 to 25 days to 8 to 10 days, resulting in a decrease in reactor volume per ML wastewater treated of about 30%. Furthermore, the aerobic mass fraction can also be reduced from 50% to 60% to <30% and concommitantly the anoxic mass fraction can be increased from 25% to 35% to >55% (if the anaerobic mass fraction is 15%), and thus complete denitrification in the anoxic reactors becomes possible. Research indicates that both the short sludge age and complete denitrification could ameliorate anoxic aerobic (AA) or low food/microorganism (F/M) ratio filamentous bulking, and hence reduce the surface area of secondary settling tanks or increase the treatment capacity of existing systems. The lab-scale experimental investigations indicate that the ENBNRAS system can obtain: (i) very good chemical oxygen demand (COD) removal, even with an aerobic mass fraction as low as 20%; (ii) high nitrogen removal, even for a wastewater with a high total kjeldahl nitrogen (TKN)/COD ratio, up to 0.14; (iii) adequate settling sludge (diluted sludge volume index [DSVI] <100 mL/g); and (iv) a significant reduction in oxygen demand.

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Section: Long Sludge Age Requirement For Nitrificationmentioning

confidence: 99%

Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system

Sötemann

Moodley

et al. 2003

Biotech & Bioengineering

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“…There are several models which have been used to describe the overall kinetics of biological reactors. Two models assume a steady-state relationship of the form (Mamais and Jenkins, 1992).…”

Section: Phosphorus Removal Kineticsmentioning

confidence: 99%

“…However, few of these studies have included enhanced biological phosphorus removal (EBPR), even when anaerobic zones were included in the systems, apparently because of the very low suspended biomass MCRTs and used temperature combinations. It is known that EBPR will wash out of activated sludge systems before heterotrophic functions (McClintock et al, 1991;Mamais and Jenkins, 1992) and that EBPR processes require that the biomass experiences sequen-cing anaerobic and aerobic conditions. Therefore, EBPR by attached biomass would not be possible in most continuous-flow BNR systems because the biomass is fixed in one location and typically can not be subjected to alternating environmental conditions (Liu, 1996).…”

Section: Introductionmentioning

confidence: 99%

Kinetic analysis of enhanced biological phosphorus removal in a hybrid integrated fixed film activated sludge process

Hooshyari

Azimi

Mehrdadi

2008

Int. J. Environ. Sci. Technol.

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Hybrid integrated fixed film activated sludge is a promising process for the enhancement of nitrification, denitrification and phosphorus removal in conventional activated sludge systems that can be used for upgrading biological nutrient removal, particularly when they have space limitations or need modifications that will require large monetary expenses. In this research, successful implementation of hybrid integrated fixed film activated sludge process at temperate zone wastewater treatment facilities has been studied by the placement of fixed film media into aerobic, anaerobic and anoxic zones. The primary objective of this study was to investigate the incorporation of enhanced biological phosphorus removal into hybrid integrated fixed film activated sludge systems and study the interactions between the fixed biomass and the mixed liquor suspended solids with respect to substrate competition and nutrient removal efficiencies. A pilot-scale anaerobic-anoxic-oxic configuration system was used. The system was operated at different mean cell residence times and influent chemical oxygen demand/total phosphorus ratios and with split influent flows. The experimental results confirmed that enhanced biological phosphorus removal could be incorporated successfully into hybrid integrated fixed film activated sludge system, but the redistribution of biomass resulting from the integration of fixed film media and the competition of organic substrate between enhanced biological phosphorus removal and denitrification would affect performances. Also, kinetic analysis of the reactor with regarding to phosphorus removal has been studied with different kinetic models and consequently the modified Stover-Kincannon kinetic model has been chosen for modeling studies and experimental data analysis of the hybrid integrated fixed film activated sludge reactor.

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“…Therefore, there is a strong need to evaluate the impact of temperature variation on the EBPR process. Many studies on the effects of temperature on the efficiency of the EBPR process have been conducted; [11][12][13][14][15][16][17] however, the results are inconsistent, possibly due to differences in thermal-stress scenario. This study concentrates on the impact of temperature shock, which is likely to happen in field practice, on EBPR performance.…”

Section: Scienceasia Scienceasia Scienceasiamentioning

confidence: 99%

Untitled

Panswad¹,

Doungchai²,

Anotai³

2003

ScienceAsia

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An enhanced biological phosphorus removal (EBPR) process is currently one of the most economical and practical ways to reduce high phosphorus content in wastewaters. Under sequential conditions of anaerobic and aerobic environments, the phosphateaccumulating organisms (PAOs), which are able to accumulate intracellular phosphorus in a much higher quantity than other microorganisms, become predominant. In anaerobic stage, the PAOs absorb readily biodegradable substrate by destroying their storage polyphosphate to form adenosine triphosphate (ATP) and adenosine diphosphate (ADP), sequentially, and releasing free phosphate to the bulk solution. The substrate taken up is metabolized in the following aerobic stage to produce energy some of which replenishes the polyphosphate storage pool by absorbing phosphate from the bulk solution. The amount taken up aerobically is more than that released anaerobically; hence the phosphorus in the liquid phase is reduced. Although many researchers have recently attempted to investigate the ecology and microbiology of the EBPR processes using either culture-dependent or -independent approaches, the results are still inconclusive.1 In parallel to microbiologial approach, several investigators have tried to solve this problem through biochemical models which are developed based on mechanistic considerations of the mixed cultures in activated sludge under control conditions. These models, e.g., Comeau model, 2 Mino model, 3 metabolic model, [4][5][6] and enhanced culture kinetic model, 7-9 involve stoichiometry and process kinetic rate equations. Many EBPR systems have been designed and constructed by using the simplified versions of these models. Although most of them perform reliably as expected, some behave unpredictably. One possible explanation of most interest to the researchers is that, under certain operating conditions, other microorganisms are more selectively favored than the PAOs, hence diminishing the EBPR performance. The microbial group believed to be a major competitor of the PAOs are the glycogenaccumulating organisms (GAOs), which also assimilate substrates under anaerobic conditions. 10 As named, this microbial group aerobically synthesizes and stores glycogen as its primary energy source. Since polyphosphate is not involved in substrate assimilation, ABSTRACT: Four anaerobic-aerobic sequencing batch reactors with 9-day of sludge age were operated under a 12-hour cycle of 5, 290, 360, 60, and 5 minutes for the filling, anaerobic, aerobic, settling, and withdrawal periods, respectively. The results indicated that increasing temperature from the phosphate-accumulating organisms (PAOs) preferred temperature of 20°C by either pulse (5°C after every 5 days) or step (1°C per day) manner had negative impacts on the PAOs' activities, particularly on the aerobic phosphorus uptake. However, the pulse-increase scenario, especially from 30 to 35°C, caused more severe impacts than the stepincrease scenario. On the contrary, the shock in a decreasing manner regardless of experimen...

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The Effects of MCRT and Temperature on Enhanced Biological Phosphorus Removal

Cited by 71 publications

References 14 publications

Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system

Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system

Kinetic analysis of enhanced biological phosphorus removal in a hybrid integrated fixed film activated sludge process

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