Possible cause of excess sludge reduction in an oxic-settling-anaerobic activated sludge process (OSA process)

Chen, Guanghao; An, Alicia Kyoungjin; Saby, Sébastien; Brois, Etienne; Djafer, M.

doi:10.1016/s0043-1354(03)00331-2

Cited by 143 publications

(72 citation statements)

References 22 publications

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“…The possible mechanism of sludge reduction in the OSA process is that sludge decay is accelerated effectively under a low ORP in the anaerobic tank. Such an increase in the sludge decay coefficient induced by a low ORP is able to explain a low production rate of the excess sludge in the OSA system [75]. However, the soluble COD increase in the anaerobic tank was observed in their experiments [73][74][75].…”

Section: Oxic-settling-anaerobic Processmentioning

confidence: 92%

“…Such an increase in the sludge decay coefficient induced by a low ORP is able to explain a low production rate of the excess sludge in the OSA system [75]. However, the soluble COD increase in the anaerobic tank was observed in their experiments [73][74][75]. The cryptic growth in the aeration tank of the OSA process may be induced by the soluble COD increase of the returned sludge after its exposure in the anaerobic tank, and then cause low sludge production in the OSA system.…”

Section: Oxic-settling-anaerobic Processmentioning

confidence: 99%

“…Such a cyclic change in the ATP content in the sludge thus leads to an energy uncoupling between the catabolism and the anabolism, thereby inducing sludge reduction. Through extensively studying the mechanisms of sludge reduction in an OSA process, the effects of energy uncoupling, domination of slow growers, and soluble microbial products (SMPs) on sludge reduction could not be found [74,75]. The possible mechanism of sludge reduction in the OSA process is that sludge decay is accelerated effectively under a low ORP in the anaerobic tank.…”

Section: Oxic-settling-anaerobic Processmentioning

confidence: 99%

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Minimization of excess sludge production for biological wastewater treatment

Wei

Houten²,

Borger³

et al. 2003

Water Research

618

278

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Excess sludge treatment and disposal currently represents a rising challenge for wastewater treatment plants (WWTPs) due to economic, environmental and regulation factors. There is therefore considerable impetus to explore and develop strategies and technologies for reducing excess sludge production in biological wastewater treatment processes. This paper reviews current strategies for reducing sludge production based on these mechanisms: lysis-cryptic growth, uncoupling metabolism, maintenance metabolism, and predation on bacteria. The strategies for sludge reduction should be evaluated and chosen for practical application using costs analysis and assessment of environmental impact. High costs still limit technologies of sludge ozonation-cryptic growth and membrane bioreactor from spreading application in full-scale WWTPs. Bioacclimation and harmful to environment are major bottlenecks for chemical uncoupler in practical application. Sludge reduction induced by oligochaetes may present a cost-effective way for WWTPs if unstable worm growth is solved. Employing any strategy for reducing sludge production may have an impact on microbial community in biological wastewater treatment processes. This impact may influence the sludge characteristics and the quality of effluent. r

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Section: Oxic-settling-anaerobic Processmentioning

confidence: 92%

Section: Oxic-settling-anaerobic Processmentioning

confidence: 99%

Section: Oxic-settling-anaerobic Processmentioning

confidence: 99%

See 1 more Smart Citation

Minimization of excess sludge production for biological wastewater treatment

Wei

Houten²,

Borger³

et al. 2003

Water Research

618

278

View full text Add to dashboard Cite

show abstract

“…Some methods are aimed at increasing the rate and extent of hydrolysis during anaerobic digestion by physical and/or chemical methods or enzymatic pre-treatment of the sludge [4][5][6]. Other methods are aimed at reducing excess sludge production by increasing the sludge age [7][8][9] and thus increasing cell lyses and cryptic growth mechanics [10], which in turn results in a decrease in sludge production.…”

Section: Introductionmentioning

confidence: 99%

Physical and biochemical changes in sludge uponTubifex tubifexpredation

Valk

Khadem

Foreman

et al. 2016

Environmental Technology

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Worm predation (WP) on activated sludge leads to increased sludge degradation rates, irrespective of the type of worm used or reactor conditions employed. However, the cause of the increased sludge degradation rates remains unknown. This paper presents a comparative analysis of the physical and biochemical aspects of predated sludge, providing insight into the hydrolytic mechanisms underlying WP. To this end, the sessile worm Tubifex tubifex was used as a model oligochaete and was batch cultivated in an 18-L airlift reactor. Predation on activated sludge showed an average reduction rate of 12 ± 3.8%/d versus 2 ± 1.3%/d for endogenous respirated sludge. Sludge predation resulted in an increased release of inorganic nitrogen, phosphate and soluble chemical oxygen demand (sCOD). The sCOD consisted mainly of polysaccharides; however, fluorescence excitation emission matrix spectroscopy analysis also revealed the presence of Tryptophan-protein-like substances. Results suggest that the released polysaccharides contain a protein-like element. Additionally, soluble iron increased slightly in concentration after WP. The extent of hydrolysis seemed to reach an average plateau of about 40% volatile solids (VS) reduction after 4 days, which is substantially higher than the 29% VS reduction for endogenous decay of activated sludge after 30 days. Furthermore, T. tubifex predominantly consumed the protein fraction of the extracellular polymeric substances. Results suggest that that the worms specifically target a fraction of the sludge that is predominantly biodegradable under aerobic conditions, albeit at significantly higher degradation rates when compared to the endogenous decay of waste activated sludge. ARTICLE HISTORY

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“…Although, reduced sludge production has been observed in OSA, its mechanism has not yet been elucidated. Chudoba et al (1991), , Chudoba, Morel et al (1992) and Chen et al (2003) suggested that sludge reduction in OSA might be attained by energy uncoupling, domination of slow growers, soluble microbial products effect, and sludge decay in the SHT under low oxidation-reduction potential. Others assumed that SHT play a critical role in reducing sludge production (Chen et al 2003;Chudoba et al, 1991;Chudoba, Morel et al, 1992).…”

Section: Introduction 1)mentioning

confidence: 99%

Intracellular Concentrations of NAD(P), NAD(P)H, and ATP in a Simulated Oxic-settling-anaerobic (OSA) Process

Ventura¹,

Nam²,

Yang³

et al. 2015

Journal of Korean Society on Water Environment

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In order to investigate why OSA (oxic-settling-anaerobic) process produces less sludge than CAS (conventional activated sludge) process, sequential cultivation through 1 st aerobic-anaerobic-2 nd aerobic conditions, were carried out. Then, the intracellular concentrations of adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD and NADH), and nicotinamide adenine dinucleotide phosphate (NADP and NADPH) were monitored for these three stages. Results showed that the concentrations of these energy substances rapidly decreased through time in both aerobic and anaerobic conditions but the anaerobic culture contained the lower energy level than aerobic culture. The 2 nd aerobic culture that experienced anaerobic condition showed lower concentration of these energy substances than those of the 1 st aerobic culture. Meanwhile, the anaerobic culture corresponding to the sludge holding stage of OSA was subjected to different soluble chemical oxygen demand (SCOD) levels, detention time, and temperature to evaluate the effects of these variations on the energy level difference between the 1 st and 2 nd aerobic stages. The lower the SCOD concentration, the longer detention time; and the higher temperature in the anaerobic stage tended to further reduce the intracellular level of the 2 nd aerobic culture. On the average, the intracellular energy level of the anaerobic and 2 nd aerobic stage were 57.73% and 39.12% of the 1 st aerobic culture, respectively. These indicated that the insertion of an anaerobic stage between two aerobic stages could lower the intracellular energy levels, hence the lower the sludge in OSA than CAS process. Moreover, manipulation of the operating conditions of the intervening anaerobic stage can change intracellular energy levels thereby controlling sludge production.

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Possible cause of excess sludge reduction in an oxic-settling-anaerobic activated sludge process (OSA process)

Cited by 143 publications

References 22 publications

Minimization of excess sludge production for biological wastewater treatment

Minimization of excess sludge production for biological wastewater treatment

Physical and biochemical changes in sludge uponTubifex tubifexpredation

Intracellular Concentrations of NAD(P), NAD(P)H, and ATP in a Simulated Oxic-settling-anaerobic (OSA) Process

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