Sequencing Batch Membrane Bioreactor Research Articles

Impact of feeding regimes on the performance of anaerobic sequencing batch membrane bioreactor treating wastewater from an urban drain

ABSTRACT This work evaluated an anaerobic sequencing batch membrane bioreactor (AnSBR-MBR) equipped with waste-based ceramic membranes for treating low-strength real drain wastewater. Two feeding regimes, viz. settled feed (Phase 1) and mixed feed (Phase 2) were compared. The biological performance (chemical oxygen demand (COD) and phosphate (PO43-) removal) and filtration performance (total suspended solids (TSS) removal and membrane fouling) were investigated. The reactor characteristics in terms of solids content, sludge settling behaviour, and extracellular polymeric substances (EPS) were also assessed. In Phase 1, the settled feed (with the absence of particulate organic matter) resulted in low volatile suspended solids (VSS; 0.23 ± 0.15 g/L), causing low COD removal (28.38 ± 8.14%). In the mixed feed regime in Phase 2, VSS increased (1.82 ± 0.60 g/L) due to the organic content in the particulate matter, which gave microorganisms additional food, resulting in increased COD removal (47.42 ± 2.81%); this phase was also characterised by lower membrane fouling because of the lower EPS content. Marginally higher TSS removal was obtained as well in Phase 2 (96.72 ± 3.26%) than in Phase 1 (90.48 ± 8.14%). This work demonstrates that AnSBR-MBR performance is superior with mixed drain wastewater containing suspended solids and thus pre-settling is not recommended.

Combined recovery of polyhydroxyalkanoates and reclaimed water in the mainstream of a WWTP for agro-food industrial wastewater valorisation by membrane bioreactor technology

The present study investigated the combined production of reclaimed water for reuse purposes and polyhydroxyalkanoates (PHA) from an agro-food industrial wastewater. A pilot plant implementing a two-stage process for PHA production was studied. It consisted of a mainstream sequencing batch membrane bioreactor (SBMBR) in which selection of PHA-accumulating organisms and wastewater treatment were carried out in, and a side-stream fed-batch reactor (FBR) where the excess sludge from the SBMBR was used for PHA accumulation. The performance of the SBMBR was compared with that of a conventional sequencing batch reactor (SBR) treating the same wastewater under different food to microorganisms’ ratios (F/M) ranging between 0.125 and 0.650 kgCOD kgTSS−3 d−1. The SBMBR enabled to obtain very high-quality effluent in compliance with the relevant national (Italy) and European regulations (Italian DM 185/03 and EU, 2020/741) in the field of wastewater reclamation, whereas the performances in the SBR collapsed at F/M higher than 0.50 kgCOD kgTSS−1d−1.A maximum intracellular storage of 45% (w/w) and a production yield of 0.63 gPHA L−1h−1 were achieved when the SBMBR system was operated with a F/M ratio close to 0.50 kgCOD kgTSS−1d−1. This resulted approximately 35% higher than those observed in the SBR, since the ultrafiltration membrane avoided the washout of dispersed and filamentous bacteria capable of storing PHA.Furthermore, while maximizing PHA productivity in conventional SBR systems led to process dysfunctions, in the SBMBR system it helped mitigate these issues by reducing membrane fouling behaviour. The results of this study supported the possibility to achieve combined recovery of reclaimed water and high-value added bioproducts using membrane technology, leading the way for agro-food industrial wastewater valorization in the frame of a circular economy model.

Effect of external carbon addition and enrofloxacin on the denitrification and microbial community of sequencing batch membrane reactor treating synthetic mariculture wastewater

The effect of sequencing batch membrane bioreactor (SMBR) on external carbon addition and enrofloxacin was investigated to treat synthetic mariculture wastewater. Anoxic/anaerobic and low COD/TN can improve the ammonia oxidation of the system, and the NH4+-N removal efficiency above 99%. External carbon was added and an anoxic environment was set to provide a suitable environment for denitrifying bacteria. When the external carbon source was 50–207 mg/L, the TN removal efficiency (31.82%–37.73%) and the COD of the effluent (28.85–36.58 mg/L) had little change. The partition resistance model showed that cake deposition resistance (RC,irr) and irreversible resistance (RPB) were the main components. And with the increase in cleaning times, the fouling rate of membrane components accelerated. Enrofloxacin can promote the TN removal efficiency (45.66%–93.74%) and had a significant effect on TM7a, Cohaesibacter, Vibrio and Phaeobacter.

Fouling mechanisms in anoxic-aerobic sequencing batch membrane bioreactor based on adapted Hermia models and main foulant characteristics

Various derivatives of Hermia models (complete pore blocking, intermediate pore blocking, cake layer formation, and standard pore blocking) and different assessments of foulant characteristics have long been used to determine the membrane fouling mechanisms. Accordingly, this study aims to adapt Hermia models and their combination according to the operating conditions of an anoxic-aerobic sequencing batch membrane bioreactor (A/O-SBMBR). In addition, fouling mechanisms of the A/O-SBMBR were assessed using these models along with the main foulant characteristics. Models fitting with the transmembrane pressure (TMP) data indicated that the intermediate-standard model was accounting for the increased fouling during the whole regular operating period, with the residual sum of squares (RSS) of 58.3. A more detailed study on the distinct stages of TMP curve showed that the intermediate-standard model had the best fit in stages of 2 and 3, with the RSS equal to 2.6 and 2.8, respectively. Also, the complete-standard model provided the best description of the fouling mechanism in stage 4, with the RSS of 12.5. Different analyzes revealed how the main foulant characteristics affect the occurrence of intermediate, complete and standard fouling mechanisms in the A/O-SBMBR, which is consistent with the fitting results of the adapted Hermia models. The modeling and experimental methods used in the presented study provided a valuable basis to prevent and control membrane fouling in membrane bioreactors.

Assessment of nanoclay-sludge ratios in sequencing batch membrane bioreactors: Azo dye removal and fouling alleviation

This study characterized the Sequencing Batch Membrane Bioreactors (SB-MBR) system containing nanoclay in the treatment of Acid Red 18 (AR 18) azo dye in two steps. The first step compared SB-MBRs operations containing six different concentrations of Cloisite® 20A as nanoclay. A Hydraulic Retention Time (HRT) of 24 h was considered to remove a high initial concentration of 500 mg/L of dye at a sludge retention time of 45 d. In the first step, the Transmembrane Pressure (TMP) changes was reduced 74 % by 10 g/L cumulative nanoclay Cloisite® 20A concentration (0.22 g/L.d), but no improvement in dye removal was observed. The TMP rate reduction was due to Extracellular Polymeric Substances (EPS) decreasing from 370 mg/L to 330 mg/L for SB-MBR1 to SB-MBR6. Change in the morphology via reduced particle sizes and floc stability was another main factor of fouling alleviation following the addition of nanoclay. Floc stability reduction can also be confirmed by changing Tightly Bound EPS (TB-EPS) (≈330−160 mg/L) to Loosely Bound EPS (LB-EPS) (≈40−170 mg/L) in SB-MBR1 to SB-MBR6, respectively. In the second step, some parameters were changed to obtain the optimum values and improve obtained ≈30 % dye removal efficiency in the first step for all the reactors. The HRT and fresh daily nanoclay were increased to 48 h and 1.5−4 g/L.d, respectively. Consequently, dye removal improved to about 80 %.

Comparison of an integrated short-cut biological nitrogen removal process with magnetic coagulation treating swine wastewater and food waste digestate

An integration of two processes, magnetic coagulation (MC) and short-cut biological nitrogen removal (SBNR), coupled with a sequencing batch membrane bioreactor (SMBR) controlled by an automatic real-time control strategy (RTC), was developed to treat different characteristics of high strength wastewater. The treatment efficiency and microbial community-diversity of the proposed method was evaluated and investigated using swine wastewater and food waste (FW) digestate. The MC showed high removal of TSS (89.1 ± 1.5%, 92.21 ± 1.8%), turbidity (90.58 ± 2.1%, 95.1 ± 2.1%), TP (88.5 ± 1.9%, 92.1 ± 1.5%), phosphate (87.76 ± 1.6%, 91.22 ± 1.5%), and SMBR achieved stable and excellent removal of COD (96.05 ± 0.2%, 97.39 ± 0.2%), TN (97.30 ± 0.3%, 97.44 ± 0.3%) andNH4+-N (99.07 ± 0.2%, 98.54 ± 0.2%) for swine wastewater and FW digestate, respectively. The effluent COD andNH4+-N concentrations were found to meet their discharge standards. The microbial community comparison showed similar diversity and richness, and genus Diaphorobacter and Thaurea were dominant in denitritation, and Nitrosomonas was dominant in nitritation treating both swine wastewater and FW digestate.

An experimental study on the use of a sequencing-batch membrane bioreactor (SBMBR) for the treatment of mixed municipal wastewater.

Several water treatment techniques have been combined using the sequencing batch reactor with the membrane bioreactor for addressing water pollution. However, cleaning of the membrane is dependent on the approach involved as well as the operating conditions. In the present study, the sequencing-batch membrane bioreactor was used to treat real mixed municipal wastewater. The pollutant removal and membrane filtration performances were examined. The results show that the average removal rates of chemical oxygen demand (COD), total nitrogen, NH3-N, total phosphorus, and turbidity were 90.75, 63.52, 92.85, 87.58, and 99.48%, respectively, when the system was in continuous operation for 95 days. The membrane had a significant effect on COD and turbidity removal and provided stable performances for nitrogen and phosphorus removal. By observing the appearance of the membrane modules before and after the cleaning operation, it was concluded that the deposited sludge and granular sediment on the membrane surface can be effectively removed by hydraulic cleaning. In addition, recovery of membrane filtration performance to 60% of that of a new membrane can be achieved. Furthermore, we found that different sequences and duration of cleaning have different effects on the recovery of membrane filtration performance.

Effect Analysis of Sequential Batch Membrane Bioreactor on Mixed Municipal Sewage Treatment

The removal efficiency of pollutants and the development of membrane fouling were investigated by using sequencing batch membrane bioreactor (SBMBR) to treat mixed municipal wastewater without membrane cleaning. The results showed that under the condition of DO 1.0 ∼ 2.0 mg/L and operating cycle 6h, the system operated continuously for 89d, and the pollutant removal effect was good. The average removal rates of COD, TN, NH3-N, TP and turbidity were 89.4%, 70.6%, 89.9%, 91.1% and 99.4%, respectively. In addition, the enhanced removal of COD and turbidity was significant, and the removal of nitrogen and phosphorus was stable. Moreover, the membrane filtration pressure difference rose slowly, and the membrane filtration performance was relatively stable during the continuous operation of the system.

Membrane fouling suppression using intermittent electric current with low exposure time in a sequencing batch membrane bioreactor

Abstract This study assessed for the first time the use of intermittent electric current with low exposure time in a sequential batch membrane bioreactor (SB-MBR) aiming at reducing the membrane fouling and improving the treatment performance. The SB-MBR was initially operated without electric current application (control period) and, subsequently, using the electric current density of 10 A m−2 and intermittent exposure mode of 6 min ON/30 min OFF (1.2 h d−1). Compared to the control period, the mixed liquor filterability improved substantially when the electrocoagulation was applied, resulting in a membrane fouling rate 65% lower. This better filterability condition was attributed to the improvement of the floc formation process, which resulted in larger floc size and lower sludge volume index. The biomass growth was positively impacted by the electrochemical process, resulting in a higher sludge yield coefficient. The reactor performance regarding COD and NH4+-N removal was not influenced by the electric current application, exhibiting efficiencies above 99% in both experimental periods. On the other hand, the phosphorus concentration in the reactor effluent decreased as the electrocoagulation was applied, increasing its average removal efficiency from 62% (control period) to 89%. The anodic dissolution rate was estimated at 1.28 g d−1, considerably lower than the values reported in other studies regarding EBRM running in continuous mode. Thus, it can be inferred that the integration of the electrochemical process with SB-MBR using low exposure mode is an interesting alterative to reduce the membrane fouling, extend the anode lifespan and improve the reactor performance.

Performance and microbial community of the CANON process in a sequencing batch membrane bioreactor with elevated COD/N ratios.

In this study, the effects of elevated chemical oxygen demand/nitrogen (COD/N) ratios on nitrogen removal, production and composition of the extracellular polymer substances (EPS) and microbial community of a completely autotrophic nitrogen removal via nitrite (CANON) process were studied in a sequencing batch membrane bioreactor (SBMBR). The whole experiment was divided into two stages: the CANON stage (without organic matter in influent) and the simultaneous partial nitrification, anaerobic ammonia oxidation and denitrification (SNAD) stage (with organic matter in influent). When the inflow ammonia nitrogen was 420 mg/L and the COD/N ratio was no higher than 0.8, the addition of COD was helpful to the CANON process; the total nitrogen removal efficiency (TNE) was improved from approximately 65% to more than 75%, and the nitrogen removal rate (NRR) was improved from approximately 0.255 kgN/(m3·d) to approximately 0.278 kgN/(m3•d), while the TNE decreased to 60%, and the NRR decreased to 0.236 kgN/(m3•d) when the COD/N ratio was elevated to 1.0. For the EPS, the amounts of soluble EPS (SEPS) and loosely bound EPS (LB-EPS) were both higher in the CANON stage than in the SNAD stage, while the amount of tightly bound EPS (TB-EPS) in the SNAD stage was significantly higher due to the proliferation of heterotrophic bacteria. The metagenome sequencing technique was used to analyse the microbial community in the SBMBR. The results showed that the addition of COD altered the structure of the bacterial community in the SBMBR. The amounts of Candidatus 'Anammoxoglobus' of anaerobic ammonia oxidation bacteria (AAOB) and Nitrosomonas of ammonia oxidizing bacteria (AOB) both decreased significantly, and Nitrospira of nitrite oxidizing bacteria (NOB) was always in the reactor, although the amount changed slightly. A proliferation of denitrifiers related to the genera of Thauera, Dokdonella and Azospira was found in the SBMBR.

Removal of antibiotics by sequencing-batch membrane bioreactor for swine wastewater treatment

This study investigated the removal of antibiotics by sequencing-batch membrane bioreactor (SMBR) for swine wastewater treatment. Nine compounds categorized into three groups of commonly used veterinary antibiotics, namely sulfonamides, tetracyclines and fluoroquinolones, were evaluated. Results showed that both sulfonamides and tetracyclines were efficiently removed by SMBR (>90%) while a lower removal was observed for fluoroquinolones (<70%). Mass balance analysis evidenced that biodegradation/biotransformation was the main mechanism for the removal of antibiotics in SMBR operation. Moreover, sludge adsorption and membrane retention also slightly contributed to antibiotic removal. Of the three groups of antibiotics, tetracyclines and fluoroquinolones were more prone to accumulate in biosolids. It is noteworthy that antibiotics temporarily affected SMBR performance by inhibiting sludge growth and activity as well as increasing the concentrations of extracellular polymeric substances and soluble microbial products in the mixed liquor. Nevertheless, >60% of organic matter and nutrients in swine wastewater could be removed over SMBR operation.

Evaluation of Enhanced Ozone-Biologically Active Filtration Treatment for the Removal of 1,4-Dioxane and Disinfection Byproduct Precursors from Wastewater Effluent.

Ozonation followed by biologically active filtration (BAF) (O3-BAF) treatment has become an alternative to reverse osmosis in potable wastewater reuse applications because of the ability to produce a high-quality effluent while reducing brine production and disposal. In this study, effluent from a sequencing batch membrane bioreactor (SBMBR) was treated by O3-BAF at three specific ozone doses (0.5, 0.7, and 1.0 mg O3/mg DOC) and different empty bed contact times (EBCTs; 15-45 min). The reaction of O3 with granular activated carbon (GAC) (O3/GAC) to promote the formation of hydroxyl radicals (·OH) was evaluated at 1.0 mg O3/mg DOC followed by BAF at 15-45 min EBCT. The efficacy of these techniques was compared for the removal of O3 refractory 1,4-dioxane and the reduction in the formation of bromate, 35 regulated and unregulated halogenated disinfection byproducts (DBPs), and 8 N-nitrosamines after chloramination. Conventional ozonation (without the presence of GAC during ozonation) removed 6-11% of 1,4-dioxane, while BAF increased the removal to ∼25%. O3/GAC improved the removal of 1,4-dioxane to ∼40%, while BAF increased the removal to ∼50%. No bromate was detected during conventional ozonation. Although O3/GAC formed 12.5 μg/L bromate, this concentration was reduced during BAF treatment to <6.8 μg/L. Even though conventional ozonation was more effective than O3/GAC for the reduction in chloramine-reactive N-nitrosodimethylamine (NDMA) precursors, BAF treatment after either conventional or enhanced ozonation reduced NDMA formation during chloramination to <10 ng/L. O3/GAC was more effective at reducing halogenated DBP formation during postchloramination. Regardless, the reduction in halogenated DBP formation during postchloramination achieved by BAF treatment was ∼90% relative to the formation in the SBMBR effluent after either conventional or enhanced ozonation. The reduction of haloacetic acid (HAA) formation improved moderately with increasing BAF EBCT. Both O3-BAF and (O3/GAC)-BAF met regulatory levels for trihalomethanes, HAAs, NDMA, and bromate.

Pilot Scale Biological Treatment as Pre-Treatment for Reverse Osmosis

Treatment of pharmaceutical wastewaters is a challenging task owing to their complexity and pollution load, variability in strength of waste streams accompanied with shock loads. Since no single treatment system is a viable option, integration of existing systems with advanced physical/chemical processes has been gaining attention for treatment of pharmaceutical wastewater. In the present study, two biological treatment methods were evaluated for their efficiency as pre-treatment system for RO which are sequencing batch reactor and membrane bioreactor. Efficiency of biological treatments tested SBR and MBR was pre-sented in terms of percentage removal of physico-chemical parameters. Total dissolved solids removal by SBR was 31.82% while MBR showed 29.25% reduction. Chemical oxygen demand removal by SBR was 69.54% while MBR showed 30.35% removal. Efficiency of combined treatments SBR-RO and MBR-RO was presented in terms of removal of total dissolved solids, COD and ammonia. TDS removal was the highest in the combination of SBR-RO with 95.94% removal, while MBR-RO combination resulted in 87.29% removal. Chemical oxygen demand was achieved maximum with the combination of MBR-RO 92.33% while competitive results were achieved with the combination SBR-RO also with 88.62% removal. Removal of ammonia was maximum with the combination SBR-RO 87.5%, while competitive results were obtained with MBR-RO 85.51%. From the results, it can be understood that SBR was efficient in removing ammonia, total dissolved solids and was equally competent in removing chemical oxygen demand. This study concludes that combined treatment of SBR-RO proves to be promising in treating pharmaceutical wastewaters.

Comparative study on treatment performance, membrane fouling, and microbial community profile between conventional and hybrid sequencing batch membrane bioreactors for municipal wastewater treatment.

A sequencing batch conventional membrane bioreactor (SB-CMBR) and sequencing batch hybrid membrane bioreactor (SB-HMBR) were operated in parallel under two different hydraulic retention times (HRTs) (namely 12h and 6h), and their chemical oxygen demand (COD) and nutrient removal performance, membrane fouling behavior, and microbial community characteristics were compared. Both systems exhibited high organic matter (> 95%) and ammonium (> 98%) removal performance regardless of the HRT applied. As the HRT was reduced from 12 to 6h, total nitrogen removal slightly increased in both reactors, being higher in the carrier-based MBR, where anoxic zones may have been established within the biofilm. Conversely, total phosphorus removal improved only in the SB-CMBR at the shorter HRT. Moreover, activity batch assays have shown a faster P uptake rate in the SB-CMBR than in the SB-HMBR, a result likely associated with the lower relative abundance of phosphate-accumulating organisms in both adhered and suspended biomass fractions in the hybrid MBR. The results also revealed that more pronounced increases in the transmembrane pressure and, consequently, in the membrane fouling rate at higher COD loading rates were observed in the SB-CMBR, where the soluble microbial products (proteins, polysaccharides, and especially, transparent exopolymer particles), supernatant turbidity, and filamentous bacteria were more significant. Overall, as compared to the conventional MBR, the plastic media-based SB-HMBR showed a lower fouling propensity at all hydraulic conditions tested.

Membrane Bioreactors for wastewater reuse: Respirometric assessment of biomass activity during a two year survey

Stricter effluent limits, water shortage conditions, land availability requires today even more the needs of advanced wastewater treatments. Attractive solutions come from membrane bioreactors (MBR), Integrated Fixed Film Activated Sludge (IFAS) or combinations (i.e., IFAS-MBRs). One crucial aspect for the applicability of this overall new technology, compared to the conventional activated sludge systems, is the lack of knowledge for design and manage (e.g., kinetic constants, optimal operative conditions etc.). In view of the above frame, the aim of the present study was to assess the kinetic and stoichiometric parameters of bacterial species in MBRs by means of respirometric techniques. Plant configurations, operational conditions and wastewater features (domestic/industrial) were analysed. Four different MBR plants were investigated: i) sequencing batch MBR subjected to a gradual salinity increase; ii) pre-denitrification MBR treating saline wastewater contaminated by hydrocarbons; iii) University of Cape Town (UCT) MBR treating domestic wastewater subjected to a carbon-to-nitrogen (C/N) ratio variation; iiii) UCT- IFAS -MBR treating domestic wastewater. Results show a significant influence on biomass respiratory activity from both plant configurations and operational conditions. The salinity increase severely affected the activity of autotrophic species, while heterotrophic community was mainly influenced by the C/N variation. Moreover, it was observed a specialization in the IFAS-MBR configuration, with the suspended biomass more affine to organic matter, whilst biofilm in the nitrification process. The respirometric analysis confirmed to be an effective tool for the evaluation of the biomass kinetic and stoichiometric parameters. The results of this study can be useful for the application of mathematical models in the design phase and for the monitoring of biomass viability during plant operations.

Does the biological treatment or membrane separation reduce the antibiotic resistance genes from swine wastewater through a sequencing-batch membrane bioreactor treatment process

Swine wastes are the reservoir of antibiotic resistance genes (ARGs), which can potentially spread from swine farms to the environment. This study establishes a sequencing-batch membrane bioreactor (SMBR) for ARG removal from swine wastewater, and analyzes the effect of biological treatment and membrane separation on the ARG removal at different solid retention times (SRTs). The SMBR removed 2.91 logs (copy number) of ARGs at a short SRT (12 days). Raising the SRT reduced the removal rates of the detected genes by the biological treatment. Under the relative long SRT (30 days), ARGs and mobile genetic elements (MGEs) were maximized within the reactor and were well removed by membrane separation, with the average genes removal rate of 2.95 (copy number) and 1.18 logs (abundance). At the relatively low SRT, the biological treatment showed the dominant ARG removal effect, while the membrane separation took the advantages of ARG removal especially at the relatively long SRT. The ARG profile was related to the shift of the microbial community structure. The ARGs coexisted with the functional bacteria (ammonia oxidizing bacteria, nitrite oxidizing bacteria and denitrifiers), suggesting they are hosted by the functional bacteria.

Study on the Performance Characteristics of Sequencing Batch Membrane Bioreactor for Distributed Treatment of Domestic Wastewater

A large amount of domestic wastewater is produced in our daily life. To sustainably use the urban domestic wastewater in the residential area and develop the equipment for distributed domestic wastewater treatment, the present work carried out a pilot study on the treatment of domestic wastewater by sequencing batch membrane bioreactor (SBMBR). Under the conditions of 20 L/h·m2 of average water flux, and 2 h/3 h of anaerobic/aerobic period, the SBMBR process showed a good treatment effect with a good quality of effluent (&lt;50 mg/L of chemical oxygen demand (COD), &lt;5 mg/L of ammonia nitrogen (NH3-N), &lt;15 mg/L of total nitrogen (TN), &lt;2.6 NTU of turbidity, 96.9% of color removal and 99.9% of bacteria removal). The aeration quantity had a certain degree of impact on the removal of COD and the optimum aeration rate was 13.9 m3/m3·h considering both the effectiveness and cost. When the SBMBR was continuously operated for 40 days, the transmembrane pressure reached 50 kPa and the membrane needed to clean. The hydrochloric acid (pH ≈ 2) was a suitable cleaning agent and the membrane was almost completely restored after cleaning.

Assessing the performance and microbial community of hybrid moving bed and conventional membrane bioreactors treating municipal wastewater

ABSTRACTA conventional (SB-CMBR) and a hybrid moving-bed (SB-HMBR) sequencing batch membrane bioreactor treating municipal wastewater were compared during their start-up in terms of organic matter and nutrient removal, membrane fouling characteristics and microbial community. Both systems exhibited similar COD, ammonium, total nitrogen (TN) and phosphorus removal efficiency, amounting up to 96%, 99%, 70% and 85%, respectively. Results from cycle tests revealed that the contribution of attached biomass to the overall ammonium removal in the hybrid reactor was marginal. Moreover, higher despite the similar phosphorus removal efficiency attained in both reactors, nitrate-dosing activity batch assays specifically revealed that the anoxic phosphate uptake rate (PUR) in the SB-HMBR was 1.71 times higher than in the SB-CMBR. Moreover, a higher frequency of Candidatus Accumulibacter-related polyphosphate-accumulating organisms was observed in the biofilm carriers of the hybrid reactor. These findings may explain why the overall PUR was almost 50% higher in the SB-HMBR. By operating the reactors in sequencing batch mode, adhesion of particles on the membrane surface was reduced while fouling was mitigated as compared to continuous MBR systems. Better filterability conditions with lower fouling rate were found in the SB-HMBR, important features of the hybrid reactor for reducing membrane cleaning-related energy demand.

Activated Sludge and other Aerobic Suspended Culture Processes.

This is a literature review for the year 2016 regarding to activated sludge in upflow anaerobic sludge blanket, sequencing batch reactor and membrane bioreactor. This article reviews process modeling and kinetic, population dynamic, pollution control, and system design and operation. Compared to past reviews, several topics show increasing concerns in 2016, like anammox process. It refers to the adsorption and biodegradation of nutrition by granular sludge, also including the emerging micropollutant like pharmaceuticals. Activated sludge codigestion with microalgal, municipal solid waste, food waste and agricultural waste to produce biomass energy was also mentioned.

Investigation of HRT effects on membrane fouling in sequencing batch membrane bioreactor with respect to batch filtration mode

Membrane fouling in sequencing batch membrane bioreactor (SBMBR) was studied with respect to batch filtration mode at the two hydraulic retention times (HRT) of 16 h (SBMBR1) and 48 h (SBMBR2). Investigating the characteristics of batch filtration phases illustrated different TMP (Transmembrane Pressure) changing trends at the two HRTs. In SBMBR1, TMP rising rates per cycle were remarkably high and represented an increasing trend versus the filtration number, while in SBMBR2, TMP rising rates per cycle were comparatively low and did not change much with increase of the number of filtration. Larger particle sizes of the bulk sludge resulted in formation of a reversible cake layer on the membrane surface in SBMBR1. In the contrary, smaller particle sizes of the bulk sludge in SBMBR2 induced an internal pore blocking of the membrane, which was less reversible. In addition to cake layer formation, higher SMP content of the bulk sludge along with the accelerating effect of the higher filtration frequency resulted in the higher values of TMP rising rate per cycle in SBMBR1. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1785–1793, 2017