Sequencing Batch Reactor Reactor Research Articles

Wastewater Treatment through Sequencing Batch Reactor: Adaptation of a Hydro-cyclone Decanter to Enhance Particle Segregation

Objectives:This study investigates the integration of a hydro-cyclone decanter into Sequencing Batch Reactor (SBR) systems to enhance particle segregation during the decanting phase, aiming to improve removal efficiencies of suspended particles in SBR. Methods:A hydro-cyclone separator was designed for the SBR reactor, optimizing particles separation using centrifugal forces without extensive process modifications. Experiments were conducted to evaluate the performance with synthetic and actual wastewater at different concentrations and flow rates.Results and Discussion:The hydro-cyclone decanter achieved removal efficiencies of up to 32.3% for synthetic wastewater and approximately 73.2% for actual wastewater, demonstrating significant particle segregation capabilities. However, its impact on dissolved pollutants like total nitrogen (T-N) and total phosphorus (T-P) was limited.Conclusion:Integrating a hydro-cyclone decanter in SBR systems significantly enhances particle segregation, particularly for larger particles, while moderately improving COD removal, suggesting its effective use in wastewater treatment processes.

Promoting mechanism of nitrogen removal by Fe3O4 magnetic particles during the start-up phase in sequencing batch reactor.

In this paper, a magnetic sequencing batch reactor (SBR) was constructed, and the influence rule of magnetic particle dosing performance of denitrification was investigated. The diversity, structure, and potential functions of the microbial community were comprehensively explored. The results showed that the particle size and the dosage of Fe3O4 magnetic particles were the main parameters affecting the sedimentation performance of activated sludge. The start-up phase of the SBR reactor with Fe3O4 magnetic particles was 5days less than the control. Moreover, total nitrogen removal efficiency during the start-up phase was improved, with the maximum value reaching 91.93%, surpassing the control by 9.7% with the Fe3O4 dosage of 1.2g L-1. In addition, the activated sludge concentration and dehydrogenase activity were improved, compared to the control. High-throughput sequencing showed that the denitrifying bacterium Saccharimonadales dominated the reactor and was enriched by magnetic particles. According to predicted functions, the abundance of genes for denitrification increased with the addition of magnetic particles, suggesting the capacity of nitrogen removal was enhanced in the microbial community. Overall, the Fe3O4 magnetic particles provide great potential for enhanced wastewater nitrogen removal.

Aerobic granular sludge with filamentous bacteria immobilized by string carriers to treat simulated municipal wastewater in a continuous flow reactor

Aerobic granular sludge with filamentous bacteria (FAGS) has displayed many desirable properties. However, the selective pressure based on settling speed cannot effectively separate FAGS from water in sequencing batch reactor (SBR), which limits FAGS development. In this study, a new selection pressure was created by adding string carriers. Strings were used as crystal nuclei to form immobilized FAGS to achieve rapid separation from water. The immobilization of FAGS was achieved in both SBR and continuous flow reactor (CFR). The immobilization and long-term operation of FAGS in CFR were explored. NH4+ and COD removal efficiency remained above 90 % and 85 %, respectively. Sphaerotilus, denitrifying microorganisms and EPS-secreting microorganisms were the main microorganisms in the immobilized FAGS. The selection pressure provided by the strings, the operating characteristics of the CFR, and the properties of Sphaerotilus may play key role in the immobilization of FAGS.

Full-scale demonstration of a floating seal for enhanced biological nutrient removal in a sequencing batch reactor establishing chemical-free environment in wastewater treatment at low carbon source availability

ABSTRACT Due to the cyclical nature and changing water levels in the sequencing batch reactor (SBR), oxygen diffusion and utilization can be difficult to control particularly in light of the need to conserve the limited quantity of carbon source required to optimize biological nutrient removal. During the fill period, oxygen penetration may be undesirable since heterotrophic and autotrophic organisms cause a reduction in the readily biodegradable carbon source (rbCOD). This carbon source is essential and often limited in the anaerobic and anoxic periods. As a consequence, unwanted oxygen penetration can hinder efficient biological phosphorus and nitrogen removal. The purpose of the present research was to verify the advantage of a floating seal on the continuously moving surface of an SBR reactor to minimize undesirable oxygen penetration. In the floating seal-covered SBR both nitrification and denitrification efficiency proved to be higher due to insulation, and even during wintertime biological phosphorus removal met target removals without chemical dosing. The SVI values in the two SBR trains proved to be close to each other, despite the high difference in chemical dosing. Having experienced the higher efficiency of the seal-covered train, microbiome compositions of the two differently operated systems were investigated to determine potential differences via 16S rRNA gene amplicon sequencing experiments. In the samples taken from the seal-covered system, higher ratios of fermentative bacteria and phosphate accumulating organisms (PAOs) as well as glycogen accumulating organisms (GAOs) could be observed as compared to the samples deriving from the uncovered system. Highlights Seal-covering the periodically decreasing open water surface increased SBR efficiency Seal-covering the open water surface increased nitrification efficiency by insulation No chemical dosing was necessary for phosphorous removal in the Test system Metagenome investigations provided almost doubled amount of fermentative bacteria Production of GAOs indicated nutrient deficiency due to phosphorous removal.

Physical characterization of oxygenic photogranules

This study investigated hydrodynamic properties of oxygenic photogranules (OPGs) generated in a sequencing batch reactor (SBR) treating wastewater without aeration and OPGs cultivated under hydrostatic conditions and used to seed an SBR reactor. Using isopycnic centrifugation the average density of OPGs was found to be 1037 kg/m3 and 1050 kg/m3 for the reactor OPGs and hydrostatic OPGs, respectively. The reactor OPGs had measured settling velocities in the range of 0.001–0.021 m/s while the hydrostatic OPGs had higher velocities, up to 0.07 m/s. The estimated porosity of reactor granules was 86 % while that of hydrostatic granules was 81 %. The porosity and settling velocities of reactor OPGs showed a general decrease with increasing granular size. In contrast, the porosity of the hydrostatic OPGs showed low correlations with granular size while their settling velocities decreased with increasing diameter (0.6–1.4 mm). These physical parameters reflect OPGs amenability to rapid solids separation during wastewater treatment. Moreover, the high porosity and low permeability reflect the microbial mobility with increasing size to optimize functionality especially related to motile filamentous cyanobacteria. Strategies utilizing size based bioreactor operations for different treatment objectives and optimized agitation minimizing energy use towards environmental stewardship in treatment can also be achieved.

A COMPARATIVE STUDY ON TREATMENT OF CETP WASTEWATER USING SBR AND SBR-IFAS PROCESS

The wastewater generated from industries needs to be treated before discharge but ETPs are not affordable and hence the common effluent treatment plant was provided for collectively treating wastewater from various industries. The existing treatment methods used for such wastewater are costly and hence the present study focusses on using biological method for treating pre-treated mixed industrial wastewater from CETP using a sequencing batch reactor (SBR) with suspended biomass and an SBR-IFAS, a combined suspended and attached growth process at an HRT of 10 hours. After treatment with SBR technology, the maximum COD removal efficiency obtained was 68.69% at an MLSS concentration of 2756 mg/L. Similarly, for the SBR-IFAS reactor, the COD removal efficiency reached 75.51% at an MLSS concentration of 2846 mg/L. MLVSS obtained was 1395.00 mg/L in SBR and 1433.00 mg/L in SBR-IFAS. Chromium removal reached 62.85% and 66.67% in SBR and SBR-IFAS reactors, respectively. The study revealed that the attached growth media and suspended growth media combinedly resulted in a higher reduction in industrial wastewater treatment and can ultimately help reduce the volume of the secondary treatment at CETP by increasing the footprint of the treatment plant.

Effective removal of heavy metals from industrial effluent wastewater by a multi metal and drug resistant Pseudomonas aeruginosa strain RA-14 using integrated sequencing batch reactor

Sequencing batch reactor (SBR) is useful in removal of both non-biodegradable and biodegradable contaminants from wastewater. The main aim of the present investigation was to evaluate the potential of biocatalyst strain RA-14 on heavy metal removal under SBR. The selected strain was screened from the soil sediment contaminated with heavy metals. It was able to survive at different (Hg2+, Pb2+, Zn2+, Cu2+, Cd2+ and Ni2+) heavy metals (>500 ppm). The bacterial strain RA-14 showed maximum bioaccumulation potential than other strains. Heavy metal resistance patterns of Pb2+ > Cu2 > Cd2+ > Hg2+, Ni2+ and Zn2 was observed. Strain RA-14 was resistant to penicillin–G, nalidixic acid, ceftazidime, cefotaxime, kanamycin and ampicillin. The results revealed that bioaccumulation activities were improved at pH 7.0 (83.2 ± 1.8%), 40 °C (89.34 ± 3%) and affected at higher pH values and temperature. The results showed that contact time and initial Lead concentration was also affected Lead accumulation. The heavy metal tolerant strain RA-14 was further investigated towards heavy metal removal in SBR. Heavy metal was removed in SBR within 10 h of hydraulic retention time. Heavy metal removal was high at 2 mg/L (0.33 mg/L Cu2+, 0.33 mg/L Hg2+, 0.33 mg/L Pb2+, 0.33 mg/L Zn2+, 0.33 mg/L Cd2+ and 0.33 mg/L Ni2+) heavy metals. Total nitrogen, biological oxygen demand (BOD) and chemical oxygen demand (COD) of treated water in SBR was removed and the removal efficacy was 91.3 ± 2.1%, 97.6 ± 3.3%, and 94.3 ± 4.4%, respectively in 10 h hydraulic retention time. However, the efficiency of BOD, COD and total nitrogen content removal was decreased, due to the reduced metabolic process of bacteria after 10 h. The SBR reactor proved to be an efficient method for the treatment of various heavy metals from the wastewater.

The Impact of an Ultrasonic Field on the Efficiency of Coke Wastewater Treatment in a Sequencing Batch Reactor

The growing production of coke and, consequently, coke wastewater is a significant problem for the environment. Coke wastewater, because it contains high amounts of toxic substances, is classified as an extremely hazardous industrial wastewater. The treatment of such wastewater requires a combination of advanced physicochemical and biological methods. The aim of the research was to investigate the effectiveness of the application of the ultrasonic disintegration of coke wastewater in a sequencing batch reactor (SBR). The tests were conducted in two stages, wherein the first stage involved determining the most favorable sonication conditions, that is, time and amplitude. The authors used the following amplitudes: 31 µm; 61.5 µm; 92 µm; 123 µm and times: 120 s; 240 s; 480 s; 960 s. The second stage focused on treating coke wastewater in SBRs (Reactor A—a proportion of coke wastewater in the mixture: 5%, 10%, and 20%; reactor B—sonicated coke wastewater, proportion in mixture: 5%, 10%, 20%). The efficiency of the treatment process was determined based on the rate of removal of selected parameters: chemical oxygen demand (COD), total organic carbon (TOC), inorganic carbon (IC), ammoniacal nitrogen (N-NH4), total nitrogen (TN), the course of pH changes. The study revealed that sonication of coke wastewater increased biodegradability and reduced its toxicity. The use of the preliminary sonication of coke wastewater before biological treatment improved the degree of removal of the tested parameters by approximately 10%. The volumetric ratio of coke wastewater in the mixture had the greatest impact on the obtained results. The use of an ultrasound field allows the treatment process to be executed with a coke wastewater addition exceeding 10%. In addition, it was found that in order to increase the coke wastewater treatment efficiency, one should optimize individual phases in the SBR and the pollution load.

Shell outlines transformation plan for Singapore refining, chemicals businesses.

The present study evaluates the sequential integration of two advanced biological treatment methods viz., sequencing batch reactor (SBR) and bioelectrochemical treatment systems (BET) for the treatment of real-field petrochemical wastewater (PCW). Initially two SBR reactors were operated in aerobic (SBRAe) and anoxic (SBRAx) microenvironments with an organic loading rate (OLR) of 9.68 kg COD/m3-day. Relatively, SBRAx showed higher substrate degradation (3.34 kg COD/m3-day) compared to SBRAe (2.9 kg COD/m3-day). To further improve treatment efficiency, the effluents from SBR process were fed to BET reactors. BETAx depicted higher SDR (1.92 kg COD/m3-day) with simultaneous power generation (17.12 mW/m2) followed by BETAe (1.80 kg COD/m3-day; 14.25 mW/m2). Integrating both the processes documented significant improvement in COD removal efficiency due to the flexibility of combining multiple microenvironments sequentially. Results were supported with GC–MS and FTIR, which confirmed the increment in biodegradability of wastewater.

The performance and bacterial community shifts in an anaerobic-aerobic process treating purified terephthalic acid wastewater under influent composition variations and ambient temperatures

Anaerobic-aerobic process is an efficient way to treat purified terephthalic acid (PTA) wastewater. In this study, the effect of changing feed composition on the performance of a combined upflow anaerobic fluidized bed (UAFB) and sequencing batch reactor (SBR) was investigated under ambient conditions (15–25 °C). The 187 days’ operation was divided into 4 stages by consecutively elevating the loading rate of terephthalic acid (TA), p-toluic acid, benzoic acid and acetic acid. Results revealed that almost all iso-phthalic acid, benzoic acid and acetic acid could be completely removed in the UAFB reactor, while only about 35% p-toluic acid was degraded in the UAFB reactor. Nevertheless, over 97.0% average COD removal efficiency could be achieved after the consecutive aerobic treatment. Furthermore, the load elevation of easily biodegradable organics might enhance the operational stability together with a less diverse bacterial community in anaerobic system. The microbial analysis elucidated a large amount of versatile aromatic degraders including Syntrophorhabdus, Syntrophus and Syntrophobacteraceae were observed in UAFB reactor, but they did not show clear correlation with any specific pollutant. Meanwhile, the growth of Thauera and Rhodobacteraceae in SBR reactor were stimulated by p-toluic acid load elevation, and both of them showed strong positive correlation with p-toluic acid degradation. Overall, this study provides a comprehensive insight into the organics degradation characteristics and bacterial profiles of UAFB-SBR process treating complex industrial wastewater at ambient temperatures.

The effect of Np-magnetite on the granulation process of an SBR reactor used for domestic wastewater treatment.

This study investigated the effect of magnetite nanoparticles (Np-magnetite) added to a pilot-scale sequencing batch reactor (SBR) treating domestic wastewater, to improve aerobic granular sludge (AGS) formation and the effects of granule disintegration. Np-magnetite additions (75mg L-1) were made during the start-up of the reactor and repeated after 100 and 170days, when granule disintegration was observed. From the first Np-magnetite addition, SVI5 was reduced from 1315 to 85mLg-1. The granular biomass was observed on the 56th day, when 57% of the granules presented diameters bigger than 212µm. The 100-day disintegration episode disturbed the granular biomass, reducing the volatile suspended solids by 51%, increasing the SVI values to above 200mLg-1. Np-magnetite addition recovered all the granular biomass parameters to the values observed before disintegration. The treatment efficiency was stable during operation of the reactor for nutrients (52.8 ± 23.4% NH4+-N; 54.5 ± 12.2% PO43--P) and carbonaceous organic matter (71.7 ± 12.7% BOD5; 77.5 ± 10.0% CODt). Np-magnetite addition changed the microbial community of the granular sludge, analysed via high-throughput 16S RNA sequencing, and recovered the treatment efficiency previously disturbed by the disintegration processes. These results indicate the potential of Np-magnetite as an agent for sludge aggregation in an aerobic granular reactor.

Evaluating the performance of a sequencing batch reactor for sanitary wastewater treatment using artificial neural network

AbstractIn this work, the performance of a sequencing batch reactor (SBR) was studied for treating sanitary wastewater of Yazd power plant, Iran. For this purpose, at the first, a pilot system was designed, installed, and started up. Then the effects of retention time, pH, temperature, influent chemical oxygen demand (COD) concentration, and air flow rate were investigated on the effluent concentration of COD. In SBR reactor used in the Yazd power plant, the microalga was not used for the wastewater treatment. In this case, the COD effluent output was, at the best conditions, approximately 92 mg/L. In the studied SBR system, we used the Chlorella vulgaris microalgae and microorganisms, simultaneously. In this case, the COD level reached 34 mg/L. An artificial neural network (ANN) was developed by applying Levenberg‐Marquardt training algorithm to predict the effluent concentration of COD. The optimum conditions were obtained at pH = 8, temperature of 30°C, influent COD concentration of 600 mg/L, and air flow rate of 50 L/min. ANN predicted results were in good agreement with the experimental data with a validation coefficient of determination (R2) and validation mean square error of 0.962 and 0.0015, respectively.

Characteristics of MEG Removal from Industrial Wastewater by Sequencing Batch Reactor (SBR)

Background: MEG is extensively applied in the sour gas industry as a hydrate inhibitor. It is toxic in oral drinking and serious injury or death may result from swallowing of pure ethylene glycol and poses a potential hazard to the environment through impact soil. Glycols are harmful to aquatic life. There is little information about the digestion of MEG in the aerobic reactor. Therefore, the feasibility of MEG removal in the aerobic reactor was investigated. Materials and method: Biodegradation of MEG was done in an aerobic SBR reactor with the capacity of 2000 cc and sanitary wastewater as primarily required microorganisms. The experiments were done in the three stages. In stages 1 and 2, 500cc of reactor content was drawn-off and solutions contain 500 cc of 0.073 (wt %) of MEG (for the first stage) and 0.201 (wt %) of MEG (for the second stage) were added to the reactor. In stage 3, 500 cc of wastewater of MEG removal unit in the 2nd refinery of South Pars Gas Company, Iran with a concentration of 4.021 (wt %) of MEG was added to 1500 cc of reactor content. The feed of stage 1 was pure MEG that was diluted in demineralized water but Feed of stage 2 was a dilution of industrial feed of stage 3. Results: In stage 1, after four days, the removal efficiency of more than 80% was obtained. In stage 2 after six days, the efficiency of 20% was obtained. In stage 3, after seven days, more than 70 percent of MEG removal was obtained. Conclusion: by increasing residence time, the removal efficiency of the reactor could be increased acceptably. Therefore, the MEG solution of more than 4 (wt %) of MEG can be treated biologically.

Experimental investigation and mathematical modeling of the competition among the fast-growing “r-strategists” and the slow-growing “K-strategists” ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in nitrification

Based on their differences in the kinetic values, the nitrifiers could be classified into the fast-growing “r-strategists” and the slow-growing “K-strategists” bacteria. However, the difference in the kinetic values originated not only from the intrinsic differences among the nitrifier species, but also from other factors, i.e. sludge floc morphology, and the environment in which the nitrifiers were cultivated. It is not clear how these factors interact and affect the measured kinetic parameters and the competition among the “r-strategists” and the “K-strategists” bacteria. In this study, the kinetic parameters of nitrifiers cultivated in the SBR (sequencing batch reactor) under different substrate concentrations were monitored, together with the identification of nitrifier species and sludge floc morphology characterization. The results showed that the r-AOB and r-NOB (“r-strategists” ammonium-oxidizing bacteria and nitrite-oxidizing bacteria, i.e., Nitrosomonas and Nitrospira) were the dominant nitrifiers in the SBR reactor. A mathematical model describing the competition between r/K AOB and NOB showed that r-AOB and r-NOB could be enriched in the SBR. The experimental investigation supported the model simulation results. The model simulation also revealed that the different r/K AOB and NOB species could be enriched in different DO concentrations and SRT conditions, which could be manipulated to promote the growth of r-AOB and NO2− accumulation for the autotrophic nitrogen removal using ANAMMX.

Mixed Integer nonlinear optimization of biological processes in wastewater sequencing batch reactor

Wastewater treatment plays a key role for humanity. The waste entering lakes, rivers, and seas deteriorates daily quality of life. Therefore, it is very important to improve the efficiency of wastewater treatment. From a control point of view, a biological wastewater treatment plant is a complex, non-linear, multidimensional, hybrid control system. The paper presents the design of the optimizing hierarchical control system applied to a Sequencing Batch Reactor (SBR) in a biological Wastewater Treatment Plant (WWTP). Based on real data records, the ASM2d model of biological processes and the aeration system model are applied. The two-layer hierarchical control structure described in previous works has been extended by an additional optimization layer, used to determine the optimal operating parameters of the SBR reactor (sequence and durations of individual phases), the optimal desired trajectory of dissolved oxygen, and the optimal parameters of the adaptive controller operating in the upper control layer. A large number of different deterministic and non-deterministic optimization algorithms were tested. Finally, the Artificial Bee Colony (ABC) algorithm and the Direct Search Algorithm (DSA) were applied. In the proposed control structure, the lower control layer is the Internal Model Control (IMC) based airflow controller. Results of simulation tests for the wastewater treatment plant case study are presented. As an optimization result, the process operations have become more efficient and the electrical energy consumption has been reduced.

Adding an anaerobic step can rapidly inhibit sludge bulking in SBR reactor

Activated sludge from wastewater treatment plants was seeded into a sequencing batch reactor (SBR) in which synthetic wastewater was used as the influent. The sludge was bulked by decreasing the concentration of dissolved oxygen (DO). By adding a 30 min step of anaerobic stirring after the water inflow, the sludge bulking was rapidly inhibited after 10 running cycles, and the sludge volume index (SVI) decreased from 222 to 74 mL·g−1. The results of high-throughput sequencing showed that the relative abundance of bacteria Thiothrix, bacteria norank_o_Sphingobacteriales and fungi Trichosporon was increased by 6.3, 4.3 and 81.2%, after initial SBR stages, but these bacteria were inhibited by the addition of an anaerobic step, as their relative abundances decreased by 0.7, 0.8 and 14.7%, respectively. The proliferation of Thiothrix, norank_o_Sphingobacteriales and Trichosporon was the primary reason for the observed sludge bulking in the reactor. After the anaerobic step was added, the sludge extracellular polymeric substances (EPS) concentration was increased from 84.4 to 104.0 mg·(gMLSS)−1 (grams of mixed liquor suspended solids). Thus, the addition of an anaerobic step can inhibit the growth of filamentous bacteria, increasing the sludge EPS concentration and promoting the precipitation of activated sludge.

Start-up performance of anaerobic/aerobic/anoxic-sequencing batch reactor (SBR) augmented with denitrifying polyphosphate-accumulating organism (DPAO) and their gene analysis.

This paper was aimed at investigating the bio-augmentation performance of anaerobic/aerobic/anoxic-type sequencing batch reactor (SBR) during its start-up period by introducing a strain of denitrifying polyphosphate-accumulating organism (DPAO). Two SBR reactors were inoculated to study the start-up performance, with one for DPAO introduction and the other as the control specimen. A comparison, of microbial community diversity based on the reactor which obtained a better performance, was made between polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analyses encoded by 16S rRNA and functional genes (nirS, nirK). The results indicated that the introduction of DPAO had a positive effect on the biological system, including a reduction of the start-up period, the improvement of sludge characteristics and the removal efficiency of nutrients, especially for phosphorus. By comparing the phylogenetic relationship of 16S rRNA and functional genes (nirS, nirK) of the reactor augmented with DPAO, it could be found that the phylogenetic relationship of these genes were remarkably inconsistent with each other. Therefore, 16SrRNA should not be used to determine the microbial community diversity of functional bacteria which could accomplish denitrification, and gene nirK should not be neglected when determining functional bacteria.

Filamentous Sludge Microbial Community of a SBR Reactor Based on High-throughput Sequencing

Samples were collected from a sequencing batch reactor (SBR) to characterize the similarities and differences in microbial community composition in samples using Illumina high-throughput sequencing. The main objective of this study was to characterize changes in microbial community composition during filamentous sludge bulking and control processes. The SBR working volume was 11 L, and the reactors were operated for 399 days in total. High-throughput sequencing results indicated that rich diversity existed in the microbial communities of the seeding sludge. Generally, during sludge bulking, microbial composition decreased, and after the sludge was remediated, the diversity gradually increased. The dominant bacteria in the seeding sludge were Saprospiraceae_norank, Comamonadaceae_unclassified, and Tetrasphaera, comprising 13.37%, 10.54%, and 8.59% of the community, respectively. After culturing using sodium acetate as the sole carbon source, Thiothrix and Trichosporon increased significantly from the seeding to the bulking sludge, with ranges from 0.1% to 60.14% and from 19.60% to 94.82%, respectively. After the sludge bulking was controlled, the relative abundances of Thiothrix and Trichosporon were 0.1% and 2.32%, respectively. Therefore, we postulate that increases in filamentous Thiothrix and Trichosporon were the main cause for the sludge bulking.

Treatment Efficiency and Microbial Community Diversity in a Magnetic Field Enhanced Sequencing Batch Reactor (SBR)

The application of SBR reactors is becoming more common and in order to further improve the efficiency of their treatment it has been proposed to add a magnetic field to SBR systems. The effects of different magnetic fields on the degradation efficiency of conventional pollutants in an SBR was studied. MiSeq high-throughput sequencing techniques were used to analyze the diversity of microbial communities in activated sludge under magnetic field conditions. These results show that the addition of a magnetic field improves the performance of a SBR system to an extent and magnetic induction effects are most obvious at 7×10-2 T. This is identified through a significant effect on the removal efficiency of total nitrogen and an increase in the denitrification rate from 65.69% to 85.98%. It also significantly improves the activity of sludge dehydrogenase and has a positive effect on the removal of various pollutants. The diversity of microbial communities in activated sludge under different magnetic field intensities shows a greater microbial abundance and diversity in the active sludge. The bacterial domain in the experimental SBR includes 14 phyla, which are mainly Proteobacteria (25.3%-61.5%), Bacteroidetes (18.6%-46.2%), Actonobacteria (5.3%-47.2%), and Acidobacteria (0.4%-4.0%). Important denitrification bacteria such as Rhodoblastus, Paracoccus of α-Proteobacteria, Alicycliphilus, Comamonas, Xenophilus, Acidovorax, Dechloromonas, Thauera of β-Proteobacteria, Desulfovibrio of δ-Proteobacteria and Planctomycetes, etc. at a moderate magnetic induction of 7×10-2 T have a high abundance and there is an internal relationship between this and an increase in denitrification efficiency. Polyphosphate-accumulating organisms (PAOs) such as Acinetobacter, Pseudomonas, Propionicimonas, etc., are present at higher levels under these conditions and follow the same trends as for the phosphorus removal rates. There is a correlation between bacterial community structure changes and sewage treatment efficiency in activated sludge. Applied magnetic fields have a positive effect on sewage treatment by changing the microbial community structure.

Organic loading rate effect on the acidogenesis of cheese whey: a comparison between UASB and SBR reactors

ABSTRACTVolatile fatty acids (VFA) production and degree of acidification (DA) were investigated in the anaerobic treatment of cheese whey by comparison of two processes: a continuous process using a laboratory upflow anaerobic sludge blanket (UASB) reactor and a discontinuous process using a sequencing batch reactor (SBR). The main purpose of this work was to study the organic loading rate (OLR) effect on the yield of VFA in two kinds of reactors. The predominant products in the acidogenic process in both reactors were: acetate, propionate, butyrate and valerate. The maximum DA obtained was 98% in an SBR at OLR of 2.7 g COD L−1 d−1, and 97% in the UASB at OLR at 15.1 g COD L−1 d−1. The results revealed that the UASB reactor was more efficient at a medium OLR with a higher VFA yield, while with the SBR reactor, the maximum acidification was obtained at a lower OLR with changes in the VFA profile at different OLRs applied.