Combined MBR Research Articles

Reverse Osmosis Performance in MBR-RO Process with Recirculation of RO Concentrate to MBR for Water Reclamation

An integrated membrane system, membrane bioreactor-reverse osmosis (MBR-RO), has become highly efficient in producing high-quality water for municipal wastewater reclamation. However, disposal of a highly concentrated waste stream (RO concentrate or RO retentate) generated in this combination is an important issue. This work investigated RO behaviour in an integrated pilot scale MBR-RO system for municipal wastewater reuse with the continuous recycling of RO retentate to the MBR influent. RO membrane retention and the fouling propensity were studied. RO concentrate, produced by the RO process at a fixed concentration factor (CF) of 3, was recycled continuously to the MBR, leading to water recovery of the entire process around 92%. Osmotic pressure model, saturation index method, high performance liquid chromatography equipped with size exclusion column (HPLC-SEC) and specific filtration test were used to analyse the fouling potential of the RO membrane. The results obtained showed that even though RO concentrate recycling changed remarkably, the compositions of both MBR permeate and RO concentrate, the quality of RO permeate remained almost constant in terms of organic matters, conductivity, and ionic salts. However, these high concentrations of organic or inorganic substances in RO concentrate were major factors leading to the RO membrane fouling. Before RO concentrate recycling, a decline of approximately 30% of the initial RO permeate flux was observed in the period when the CF was increasing to 3, mainly due to the osmotic pressure effect of retained ions and the deposits of organic matters at the RO membrane surface. After RO concentrate addition to the MBR, due to the continuous accumulation of ionic salts on the RO membrane surface, a gradual reduction in RO permeate flux (additional 19%) was also mainly attributed to the osmotic pressure effect of the retained ions. These observations showed that the continuous addition of RO concentrate to the MBR was successful in a combined MBR and RO process in terms of the excellent quality of RO permeate.

Assessment of a combined UASB and MBR process for treating wastewater from a seafood factory at different temperatures

Assessment of a combined UASB and MBR process for treating wastewater from a seafood factory at different temperatures

SBR 및 MBR 복합공정을 적용한 Bench-scale Shipboard STP에서의 미생물 우점종에 관한 연구

SBR 및 MBR 복합공정을 적용한 Bench-scale Shipboard STP에서의 미생물 우점종에 관한 연구

Eliminación/Degradación de Triazinas Mediante Biorreactor de Membrana con Post-Tratamiento de Ozonización

The aim of the research was to evaluate the removal of micropollutants in a combined system MBR + ozonation. The research was carried out in a MBR scale laboratory plant which was fed with synthetic wastewater, doped with simazine (SIM), atrazine (ATZ) and terbutilazine (TBZ). The MBR operational conditions were: hydraulic retention time (HRT) of 20 h, organic loading rate (OLR) of 0.23 KgCOD/KgSSV·day, sludge retention time (SRT) of 30 d, and flux of 5.5 LMH. Two ozone doses were tested: low dose (16 mg O3/L) and high dose (45 mg O3/L). The removal eficiency of organic matter was 96%. For the studied triazines, low biodegradation effiencies were reached by biological treatment (MBR): 57%, 53% and 63% for SIM, ATZ and TBZ, respectively. The complementary treatment of ozonation improved the quality of the effluents. At low ozonation dose the overall removal efficiencies increased to 95%, 92% and 96% for SIM, ATZ and TBZ, respectively. At high ozonization dose the overall removal efficiencies were 98%, 97% and 97 % for SIM, ATZ and TBZ, respectively, percentages slightly higher than those obtained at low dose. The results showed the combination of MBR + O3 is effective to remove micropollutants from wastewater, contributing to the preservation of a good ecological state of water bodies.Keywords: Bioreactor, Membrane, Ozone, Triazines, Herbicides.

A novel membrane bioreactor inoculated with symbiotic sludge bacteria and algae: Performance and microbial community analysis

This study combined sludge MBR technology with algae to establish an effective wastewater treatment and low membrane fouling system (ASB-MBR). Compared with control-MBR (C-MBR), the amelioration of microbial activity and the improvement of sludge properties and system environment were achieved after introducing algae resulting in high nutrients removal in the combined system. Further statistical analysis revealed that the symbiosis of algae and sludge displayed more remarkable impacts on nutrients removal than either of them. Additionally, membrane permeability was improved in ASB-MBR with respect to the decreased concentration, the changed of characteristics and the broken particular functional groups of extracellular polymeric substances (EPSs). Moreover, the algae inoculation reduced sludge diversity and shifted sludge community structure. Meantime, the stimulated bacteria selectively excite algal members that would benefit for the formation of algal-bacterial consortia. Consequently, the stimulated or inhibited of some species might be responsible for the performance of ASB-MBR.

Advanced treatment of semiconductor wastewater by combined MBR–RO technology

The combination of membrane bioreactor and reverse osmosis (MBR–RO) is becoming an attractive technology for wastewater reclamation and reuse. In this work, the combined MBR–RO technology was applied to treat the semiconductor wastewater through a two-phase (I, II) operation. To demonstrate the feasibility of this technology, the operational performances of MBR and RO were investigated in Phase I. The good operational stability, high contaminant removal efficiency of the combined system, as well as qualified treated water for reuse were observed. To understand the possible fouling characteristics of RO membrane in a long-term operation, the antiscalant addition and chemical cleaning in RO process were abolished in Phase II. The membrane autopsy analysis showed that the dominant foulants on the RO membrane surface were loose inorganic deposits with plate-like morphology, while the biological and organic fouling were ignorable. The major component of the foulants was BaSO4, with small amounts of SrSO4 and deposits involving Ca, Si, Al, Mg, Fe and Zn. The foulants could be effectively removed by chemical cleaning of HCl–NaOH/EDTA. After the cleaning, the RO membrane permeability was recovered to the fresh one. This work provides a deep understanding of treating the semiconductor wastewater by MBR–RO technology for industrial application.

Contribution of extracellular polymeric substances (EPS) and their subfractions to the sludge aggregation in membrane bioreactor coupled with worm reactor

This study focused on the effect of predated sludge recycle on the contribution of extracellular polymeric substances (EPSs) and their subfractions to sludge aggregation in combined MBR system. It was observed that aggregation abilities of sludge samples were decreased by worm predation. Furthermore, worm predation enhanced the energy barriers and weakened the secondary energy minimum in the interaction energy profiles of slime, loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). Further investigations demonstrated that the content decrease and structural change of different EPS fractions induced by worm predation may be the reason for the decreased aggregation of sludge. Concomitantly, the adsorption tests and atomic force microscopy observation confirmed that the worm predation decreased the adsorption of slime, LB-EPS and TB-EPS on membrane. This would indicate the worm predation could keep an optimum EPS level for which floc structure was maintained and the fouling propensity of mixed liquid was reduced.

Feasibility of combined UASB and MBR system in dairy wastewater treatment at ambient temperatures

The aim of this study was to investigate the feasibility of a combined UASB and MBR system for the treatment of dairy wastewater at ambient temperatures. The system consisted of a methanogenic UASB stage and a two-compartment post-treatment aerobic MBR stage, with a membrane ultrafiltration module. The objectives of the system were to decrease the COD of dairy wastewater whilst producing biogas rich in methane, diminish overall sludge production, and to obtain a high quality effluent due to the implementation of membrane filtration. The system presented a high tolerance to loading changes (up to 4.85kgCODm−3d−1) and temperature fluctuations (17–25°C). The average total and soluble COD removals were above 95%, reaching 99% during stable operation periods. The observed overall biomass yield was low, from 0.13 to 0.07gMLVSSgCOD−1. Biogas production yield reached 150Lkg−1 of t-COD, with an average methane content of 73%. With respect to membrane performance, permeability values between 140 and 225Lm−2h−1bar−1 were obtained, similar to those reported for aerobic MBR systems. The average flux obtained was 13Lm−2h−1, reaching 19Lm−2h−1 during stable operation periods depending on conditions. These values were lower than those observed in aerobic MBR systems, but much higher than those found in methanogenic AnMBRs.

Study on Activated Sludge Properties of A/A/O Combined Membrane Bioreactor during Startup Period

To improve treatment performance and alleviate membrane fouling, the physical and biological properties of sludge in combined MBR which divided into anoxic, anaerobic and aerobic zone were studied. During initial startup period, the sludge in A/A/O combined MBR was suspended growth, after textile carrier package, the sludge was suspended and fixed growth. The biomass analysis showed that with the increase of operation time, MLVSS/MLSS decreased from 0.93 to 0.72 which certified that high MLSS concentration caused biomass growth slow gradually, while packing textile carrier could supply attached biomass which maximum value was 0.18g/cm(3777.8mg/L). Meanwhile, high MLSS concentration also resluted in high sludge viscosity which could reach to 35.42mPa•s and decreased sludge activity. Particle size anaylisis showed that shear stress of aeration made the sludge flocs smaller than conventional activated sludge process. All the sludge properties which had been analysis in this study showed A/A/O combined MBR had great difference from conventional MBR process, and some parameters could be used for membrane fouling control in A/A/O combined MBR for wastewater treatment project.

Characteristics of membrane fouling of dye wastewater treatment by combined MBR

Characteristics of membrane fouling of dye wastewater treatment by combined MBR

A novel membrane bioreactor based on membrane distillation

This paper describes a novel wastewater treatment process known as the membrane distillation bioreactor (MDBR). The MDBR process integrates a wastewater bioreactor, such as activated sludge, with membrane distillation (MD). The ability of MD to transfer only volatiles means that very high quality treated water is obtainable, with TOC levels below 1 ppm and negligible salts. A unique feature is that the MDBR allows for the organic retention times to be much greater than the hydraulic retention time. The MDBR uses thermophilic bacteria at about 50°C to treat wastewater. Stable fluxes in the range 2–5 L/m 2 h have been sustained over extended periods. A typical experiment is described using a submerged membrane module. The MDBR has the potential to achieve in one step the reclamation obtained by the combined MBR + RO process. For viable operation it would be necessary to use low grade (waste) heat and water cooling. The potential benefits and applications of the MDBR are discussed.