Biodegradation and toxicity of melamine at high activated sludge concentrations in a membrane bioreactor

2017 ◽  
Vol 77 (4) ◽  
pp. 979-987 ◽  
Author(s):  
Shengnan Xu ◽  
Minghao Sun ◽  
Allen Thompson ◽  
Zhiqiang Hu
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Hydrolytic Enzymes ◽  
Biomass Concentration ◽  
Batch Studies ◽  
Conventional Activated Sludge ◽  
Low Mass ◽  
Removal Efficiencies ◽  
Low Mass Ratio

Abstract Melamine is recalcitrant and toxic to bacteria in conventional activated sludge systems. In this study, we investigated the degradation and toxicity of melamine in a membrane bioreactor (MBR) system operated at high activated sludge concentrations (∼8.5 g TSS/L). Melamine was dosed at 3 mg/L for about 100 days. The average melamine removal efficiency in the MBR system was 20 ± 11%. Meanwhile, batch studies showed the acclimated sludge from the MBR had higher removal efficiencies after the depletion of readily biodegradable substrate (acetate) while non-acclimated sludge did not remove any melamine. As acclimated sludge had removal efficiencies ranging from 33 ± 6% (by 1.7 g TSS/L biomass) to 41 ± 10% (by 8.5 g TSS/L biomass), microbial specialists with unique hydrolytic enzymes in the acclimated sludge were likely responsible for melamine degradation. Since bacteria prefer to use readily biodegradable substrates for growth in the MBR, the population of microbial specialists capable of degrading melamine or the capability of cometabolism appeared not to increase with an increase in biomass concentration. Nevertheless, because of high sludge concentrations and thus low mass ratio of toxic melamine to biomass in the MBR, the long-term melamine exposure did not affect MBR activated sludge performance.

Comparison of two treatments for the removal of selected organic micropollutants and bulk organic matter: conventional activated sludge followed by ultrafiltration versus membrane bioreactor

2011 ◽  
Vol 63 (4) ◽  
pp. 733-740 ◽  
Author(s):  
E. Sahar ◽  
M. Ernst ◽  
M. Godehardt ◽  
A. Hein ◽  
J. Herr ◽  
...  
Keyword(s):  
Organic Matter ◽  
Activated Sludge ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Macrolide Antibiotics ◽  
Organic Micropollutants ◽  
Removal Rates ◽  
Conventional Activated Sludge

The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8–10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin – at an MLSS of 6–9 g/L – showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.

scholarly journals Two Contact Binaries with Mass Ratios Close to the Minimum Mass Ratio

2021 ◽  
Vol 922 (2) ◽  
pp. 122
Author(s):  
Kai Li ◽  
Qi-Qi Xia ◽  
Chun-Hwey Kim ◽  
Shao-Ming Hu ◽  
Di-Fu Guo ◽  
...  
Keyword(s):  
Gyration Radius ◽  
Mass Ratio ◽  
Mass Ratios ◽  
Contact Binaries ◽  
Contact Binary ◽  
Low Mass ◽  
Ratio Limit ◽  
Low Mass Ratio ◽  
Diagram Analysis

Abstract The cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q ∼ 0.055 for J082700 and q ∼ 0.089 for J132829). J082700 is a shallow contact binary with a contact degree of ∼19%, and J132829 is a deep contact system with a fill-out factor of ∼70%. The O − C diagram analysis indicated that the two systems manifested long-term period decreases. In addition, J082700 exhibits a cyclic modulation which is more likely resulting from the Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of q ≲ 0.1 and discovered that the values of J spin/J orb of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One explanation is that some physical processes, unknown to date, are not considered when Hut presented the dynamic stability criterion. The other explanation is that the dimensionless gyration radius (k) should be smaller than the value we used (k 2 = 0.06). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.

Integration of nitrification and denitrification by combining anoxic and aerobic conditions in a membrane bioreactor

2010 ◽  
Vol 62 (11) ◽  
pp. 2590-2598 ◽  
Author(s):  
Jianfeng Li ◽  
Fenglin Yang ◽  
Dieudonné-Guy Ohandja ◽  
Fook-Sin Wong
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Membrane Bioreactor ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Biomass Concentration ◽  
Morphological Properties ◽  
Utilization Rate ◽  
Gradient Gel Electrophoresis ◽  
Microbial Characterization ◽  
Nitrification And Denitrification

A membrane bioreactor (MBR) was developed to achieve nitrogen removal by combining nitrification and denitrification conditions in one reactor. The activated sludge was alternated between aerobic and anoxic conditions using peristaltic pump. The biomass concentration and floc morphological properties were observed to be similar in anoxic and aerobic compartments. However, the homogeneous properties of the activated sludge did not lead to the failure of oxygen gradient formation in the reactor. Due to the position of the air diffuser, an anoxic compartment at the bottom and an aerobic compartment in the upper part of the reactor were formed after 40 days. The average total nitrogen (TN) removal efficiency was then observed to increase to 77%. The microbial characterization using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, as well as the specific nitrogen utilization rate measurements, indicated that the nitrogen removal in the reactor occurred via nitrification and denitrification processes.

scholarly journals LCA of a Membrane Bioreactor Compared to Activated Sludge System for Municipal Wastewater Treatment

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 421
Author(s):  
Dimitra C. Banti ◽  
Michail Tsangas ◽  
Petros Samaras ◽  
Antonis Zorpas
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Real Data ◽  
Municipal Wastewater Treatment ◽  
Conventional Activated Sludge

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution—where GWPMBR = 0.50 kg CO2-eq*FU−1 and GWPCAS = 2.67 kg CO2-eq*FU−1 without sludge removal—and the wastewater treatment plant life cycle contribution—where GWPMBR = 0.002 kg CO2-eq*FU−1 and GWPCAS = 0.14 kg CO2-eq*FU−1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found.

scholarly journals Proliferation of biomass and its impact on the operation of a submerged membrane bioreactor

2020 ◽  
Vol 145 ◽  
pp. 02076
Author(s):  
Wenzhong Liang ◽  
Zhipeng Zhuang ◽  
Yutao Lei ◽  
Zhihua Pang ◽  
Weijian Zhou
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Programmable Logic Controller ◽  
Endogenous Respiration ◽  
Programmable Logic ◽  
Submerged Membrane Bioreactor ◽  
Removal Efficiencies

The aim of this work was to investigate the biomass proliferation and its impact on the operation of a submerged membrane bioreactor (sMBR). A programmable logic controller (PLC) was used to control the process of the sMBR with no discharge of sludge. When MLSS was 9670 mg/L and the solid retention times (SRT) ranged from 20 to 40 days, the optimal removal efficiencies of COD, NH3-N, TP were 93.89%, 93.02%, 80.57%, respectively. Accompanying with the decreasing of the sludge loading, the substrate and nutrition were insufficient in the sMBR, leading to endogenous respiration of the activated sludge, which decreased the activity of sludge and resulted in the death of more microorganisms.

Feasibility of the membrane bioreactor process for water reclamation

2001 ◽  
Vol 43 (10) ◽  
pp. 203-209 ◽  
Author(s):  
S. Adham ◽  
P. Gagliardo ◽  
L. Boulos ◽  
J. Oppenheimer ◽  
R. Trussell
Keyword(s):  
Literature Review ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Cost Evaluation ◽  
Water Reclamation ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
In Series ◽  
Volumetric Loading ◽  
Conventional Activated Sludge Process

The feasibility of the membrane bioreactor (MBR) process for water reclamation was studied. Process evaluation was based on the following: literature review of MBRs, worldwide survey of MBRs, and preliminary costs estimates. The literature review and the survey have shown that the MBR process offers several benefits over the conventional activated sludge process, including: smaller space and reactor requirements, better effluent water quality, disinfection, increased volumetric loading, and less sludge production. The MBR process can exist in two different configurations, one with the low-pressure membrane modules replacing the clarifier downstream the bioreactor (in series), and the second with the membranes submerged within the bioreactor. Four major companies are currently marketing MBRs while many other companies are also in the process of developing new MBRs. The MBR process operates in a considerably different range of parameters than the conventional activated sludge process. The preliminary cost evaluation has shown that the MBR process is cost competitive with other conventional wastewater treatment processes.

scholarly journals Sludge reduction via biodegradation of the endogenous residue (XE): experimental verification and modeling

2016 ◽  
Vol 75 (3) ◽  
pp. 561-570 ◽  
Author(s):  
Cheikh Fall ◽  
Ericka L. Millan-Lagunas ◽  
Carlos Lopez-Vazquez ◽  
Christine Maria Hooijmans ◽  
Yves Comeau
Keyword(s):  
Activated Sludge ◽  
Continuous Process ◽  
Synthetic Wastewater ◽  
Yield Reduction ◽  
Actual Behavior ◽  
Sludge Reduction ◽  
Conventional Activated Sludge ◽  
Retention System ◽  
Solids Retention

The feasibility of sludge reduction via the XE biodegradation process was explored both experimentally and through modeling, where the main focus was on determining the value of the bE parameter (first order degradation of XE) from a continuous process. Two activated sludge (AS) systems (30 L) were operated in parallel with synthetic wastewater during 16 months: a conventional activated sludge (CAS) system and a modified low-sludge production activated sludge (LSP-AS) process equipped with a side-stream digester unit (DU). First, the long term data of the CAS reactor (1 year) were used to calibrate the ASM model and to estimate the heterotrophic decay constant of the cultivated sludge (bH = 0.29 d−1, death-regeneration basis). Second, pre-simulations were performed to design the LSP-AS system and to estimate the DU volume required (40 L), to avoid XE accumulation in the process. Third, the LSP-AS process was built, put in operation and monitored for more than 9 months. This allowed assessment of the actual behavior of the quasi-complete solids retention system. Once calibrated, the modified AS model estimated the value of the bE parameter to be in the range of 0.003–0.006 d−1, satisfactorily describing the overall sludge yield reduction of up to 49% observed in the experiments.

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