Are Membrane Bioreactors Better than Conventional Activated Sludge Systems to Remove Compounds of Emerging Concern?

The potential of a membrane bioreactor (MBR) and a conventional activated sludge (CAS) system to remove polar micropollutants was evaluated using linear alkylbenzene sulfonates (LAS) as model components. Removal efficiencies over 97% were achieved in both reactor systems. The appearance of biological breakdown metabolites and the respirometric response of the sludges to LAS addition indicated that LAS removal was due to biodegradation, rather than sorption phenomena. The effect of operational variables, such as hydraulic retention time, LAS composition and hydrophobicity of the membrane used in the MBR, was negligible in the range tested. A stepwise increase in LAS influent concentration resulted in higher residual effluent concentrations but did not change the procentual removal efficiency. Because an increase in LAS and SPC effluent concentration occurred to a larger extent in the CAS than in the MBR under similar operating conditions, MBRs may turn out to be be more robust with respect to biological degradation of micropollutants than CAS.

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Sludge production in membrane bioreactors under different conditions

Water Science & Technology ◽

10.2166/wst.2000.0655 ◽

2000 ◽

Vol 41 (10-11) ◽

pp. 251-258 ◽

Cited By ~ 32

Author(s):

J. Wagner ◽

K-H. Rosenwinkel

Keyword(s):

Activated Sludge ◽

Pilot Plant ◽

Membrane Bioreactors ◽

Conventional Activated Sludge ◽

Theoretical Approaches ◽

One Year ◽

Conventional Systems ◽

The University ◽

Activated Sludge Systems ◽

Sludge Production

With membrane bioreactors, the production of surplus sludge is lower than with conventional activated sludge systems, a fact that has been confirmed in a large number of analyses. There is, however, no consensus about the dimension of the reactions and their respective causes. In order to examine these, at the University of Hanover a pilot plant with a capacity of 220 l was run for one year without any extraction of surplus sludge. The plant was started with 2 g MLSS/l; after one year, this value had risen to approximately 18 g MLSS/l. In order to be able to set the plant for different sludge loads (0.04 to 0.2 kg COD/(kg MLSS · d)), the wastewater was artificially stocked up. The emerging result was that in contrast to conventional systems the sludge growth was lower, but still continuously existing. Then, comparisons with theoretical approaches were run – among others with the ASM1-Model – which confirmed the findings. One possible reason could be the different biocoenoses, which was assumed to be the cause after several microscopic examinations had been run.

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Modeling of Wastewater Treatment Processes in Membrane Bioreactors Compared to Conventional Activated Sludge Systems

Processes ◽

10.3390/pr7050285 ◽

2019 ◽

Vol 7 (5) ◽

pp. 285 ◽

Cited By ~ 8

Author(s):

Marta Bis ◽

Agnieszka Montusiewicz ◽

Adam Piotrowicz ◽

Grzegorz Łagód

Keyword(s):

Activated Sludge ◽

Total Nitrogen ◽

Biomass Concentration ◽

Membrane Bioreactors ◽

Effluent Quality ◽

Conventional Activated Sludge ◽

Treatment Processes ◽

Significant Difference ◽

Interesting Alternative ◽

Activated Sludge Systems

Membrane techniques constitute an interesting alternative to conventional activated sludge systems (CAS). In membrane bioreactors (MBR), the biomass separated on membranes is retained independently of sludge sedimentation properties. As a consequence, a high biomass concentration as well as low food to microorganisms ratio can be obtained. Moreover, the development of a characteristic activated sludge population is stimulated by the specific conditions prevailing in MBRs. In the study, the operation and treatment efficiency of the MBR and CAS processes were examined and compared. Simulation was performed with the use of GPS-X software. The effluent quality obtained for the MBR system was either better or comparable to that of CAS. The most significant difference concerned the elimination of total suspended solids, which amounted to 99.8% in the MBR. Regarding nutrients, a low concentration of total phosphorus in the effluent from CAS and MBR was obtained (0.67 gP m−3 and 0.50 gP m−3, respectively). Greater differences were achieved in the case of total nitrogen. Although almost complete nitrification took place in both systems, a lower concentration of nitrate in the effluent from MBR in comparison to CAS, i.e., 11.2 gN m−3 and 14.1 gN m−3, respectively, allowed us to obtain a higher removal of total nitrogen (80.8% and 76.1%, respectively).

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The Research of Reduction Characteristics of Fe(III) Dissimilated by Different Activated Sludge

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.663.1011 ◽

2013 ◽

Vol 663 ◽

pp. 1011-1016

Author(s):

Jie Li ◽

Si Yuan Zhai ◽

Ya E Wang ◽

Juan Juan Feng ◽

Li Zhao

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Nutrient Solution ◽

Anaerobic Condition ◽

Reduction Rate ◽

Anoxic Condition ◽

Maximum Accumulation ◽

Conventional Activated Sludge ◽

Reduction Characteristics ◽

Better Than

The effect of reduction characteristics of microbe dissimilating of Fe(III) under different activated sludge, carbon source and anoxic/anaerobic condition was studied by activated sludge as inoculum under laboratory condition. The results showed that the maximum accumulation of Fe(Ⅱ) and the reduction rate of Fe(III) inoculated by biological iron mud were higher than that inoculated by conventional activated sludge. The reduction characteristics of Fe(III) was better in nutrient solution as carbon source than that in sewage as carbon source when inoculated biological iron mud. But the reduction characteristics of Fe(III) was better in sewage as carbon source than that in nutrient solution as carbon source when inoculated conventional activated sludge. From the whole test, the reduction characteristics of dissimilating Fe(III) microbe under anaerobic condition were better than that under anoxic condition.

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A plant-wide modelling comparison between membrane bioreactors and conventional activated sludge

Bioresource Technology ◽

10.1016/j.biortech.2019.122401 ◽

2020 ◽

Vol 297 ◽

pp. 122401 ◽

Cited By ~ 6

Author(s):

Giorgio Mannina ◽

Alida Cosenza ◽

Taise Ferreira Rebouças

Keyword(s):

Activated Sludge ◽

Membrane Bioreactors ◽

Conventional Activated Sludge

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New approaches to minimize excess sludge in activated sludge systems

Water Science & Technology ◽

10.2166/wst.2001.0621 ◽

2001 ◽

Vol 44 (10) ◽

pp. 203-208 ◽

Cited By ~ 25

Author(s):

G.-H. Chen ◽

S. Saby ◽

M. Djafer ◽

H.-K. Mo

Keyword(s):

Activated Sludge ◽

Activated Sludge Process ◽

Conventional System ◽

Excess Sludge ◽

Active Sludge ◽

New Approaches ◽

Conventional Activated Sludge ◽

Sludge Settleability ◽

Activated Sludge Systems ◽

Sludge Production

This paper presents three new approaches to reduce excess sludge production in activated sludge systems: 1) modification of conventional activated sludge process with insertion of a sludge holding tank in the sludge return line; 2) chlorination of excess sludge so as to minimize excess sludge production; and 3) utilization of a metabolic uncoupler, 3, 3′, 4′, 5-Tetrachlorosalicylanilide (TCS) to maximize futile activity of sludge microorganisms thereby leading to a reduction of sludge growth. Pilot study was carried out to evaluate this modified activated sludge process (OSA). It has been confirmed that the OSA process is effective in reducing excess sludge; particularly when the ORP level in the sludge holding tank was kept at -250 mV, more than 50% of the excess sludge was reduced. This process can maintain the effluent quality and even perform with a better sludge settleability than a conventional system. Experimental work on the second approach showed that chlorination treatment of excess sludge at a chlorine dose of 0.066 g Cl2/g MLSS reduced the excess sludge by 60%, while concentration of THMS was found below 200 ppb in the treated sludge. However, such sludge chlorination treatment sacrificed sludge settleability. Thus, it is not feasible to introduce the chlorination step to a conventional system. The third approach confirmed that addition of TCS could reduce sludge growth effectively if the TCS concentration is greater than 0.4 ppm. A 0.8-ppm concentration of TCS actually reduced excess sludge by 45%. It was also experimentally demonstrated that presence of TCS increases the portion of active sludge microorganisms over the entire microbial population.

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Oxygen transfer in activated sludge – new insights and potentials for cost saving

Water Science & Technology ◽

10.2166/wst.2011.607 ◽

2011 ◽

Vol 63 (12) ◽

pp. 3034-3038 ◽

Cited By ~ 16

Author(s):

J. Henkel ◽

P. Cornel ◽

M. Wagner

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Oxygen Transfer ◽

Transfer Rate ◽

Oxygen Transfer Rate ◽

Organic Load ◽

Current Opinion ◽

Conventional Activated Sludge ◽

Current State ◽

Activated Sludge Systems

The α-factor has the greatest impact on the calculation of the required standard oxygen transfer rate (SOTR) in activated sludge systems equipped with submerged aeration systems. Knowing the dependencies of the α-factor leads to a better design of the aeration devices and, consequently, to a more efficient use of aeration energy. Applying the current state of knowledge about oxygen transfer leads to the conclusion that, in contrast to current opinion, simultaneous aerobic stabilization requires the same SOTR as conventional activated sludge systems with advanced nutrient removal, even though a higher organic load is degraded.

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