Sequencing Batch Reactor Process Research Articles

Releasing characteristics and influencing factors analysis of nitrogen-containing gaseous pollutants in wastewater treatment plants with sequencing batch reactor process

The discharge of nitrogen-containing gaseous pollutants from wastewater treatment plants (WWTP) has caused a certain threat to the surrounding environment and human health, which has attracted wide attention in recent years. This study investigated the release characteristics of nitrogen-containing pollutants at different treatment stages in WWTP with sequencing batch reactor (SBR) process, including nitrogen-containing odorous gases (NH3 and dimethylamine) and nitrogen-containing greenhouse gases (N2O), all of which achieved the highest release in the aeration stage, with emissions of 35.2, 12.5mg/(m2·d) and 229.7mg/L, respectively. Besides, the emission factors of NH3 and dimethylamine were calculated for 0.0091 and 0.0026g/m3, and the carbon emission of N2O was estimated for 158.4kg of CO2 per day. Furthermore, the pilot experiment of SBR showed that the odorous gas decreased first and then increased with the increase of aeration intensity and sludge concentration, and increased with the increase of influent chemical oxygen demand (COD) concentration. This study provides theoretical and data support for the emission reduction of nitrogen-containing pollutants in SBR process WWTP.

Innovative Strategies for Tannery Wastewater Remediation with Sequential batch reactor and phycoremediation

<p style="line-height:150%;text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;" lang="EN-IN">This research assessed the performance of combining Sequential Batch Reactor (SBR) and phycoremediation method used for tanning effluent. The SBR system obtained high removal efficiencies with Chemical Oxygen Demand (COD)  is reduced by  85%, Biological Oxygen Demand (BOD) is reduced  by 80% as well as ammonia by more than 75%. Chromium and lead were dropped by 65% and 60% correspondingly after treatment. Following SBR process, inclusion of Chlorella vulgaris in the phycoremediation stage further improves the removal of pollutants achieving 95% COD and 92% BOD reductions. Heavy metal removal was enhanced with chromium and lead by reducing 85% each. Kinetic analysis indicated that ammonia and COD removal followed first-order kinetics with high model fit (R2=0.93 for COD; R2=0.91 for ammonia). Heavy metal removal using Chlorella vulgaris also conformed to first-order kinetics. A temporary increase in ammonia levels was observed due to nitrification inhibition during periods of high organic loads in the wastewater discharged from tanneries into rivers or lakes without treatment facilities such as oxidation ditches or stabilization ponds used in some cases. Finally, it can be concluded that an integrated SBR phycoremediation process shows very good potentialities with respect to good performances in treating wastewater efficiently.</span></p>

Comparative analysis and application of soft sensor models in domestic wastewater treatment for advancing sustainability

ABSTRACT This study focuses on the development and evaluation of soft sensor models for predicting NH3-N values in a wastewater treatment process. The study compares the performance of linear regression (LR), neural networks (NN) and random forest regression (RFR) models. The proposed methodology involves optimizing the sequencing batch reactor process using artificial intelligence and an automatic control system. Real-time NH3-N values are obtained by inputting data from electronic conductivity and temperature sensors into the prediction models. Once the predicted NH3-N value falls below the effluent standard, the cycle ends, improving energy efficiency and sustainability by cutting down the agitator and aerator. The research results demonstrate that the RNN-based NH3-N soft sensor built in this study exhibits the best performance, which is promising for wastewater treatment process optimization and evaluation. The results show that sensor model NNR[0.5Y]H exhibits exceptional performance, utilizing recurrent neural network with 5-step input delays. Sensor NNR[0.5Y]H exhibits an R2 of 0.921, an RMSE of 6.110, and an MAE of 4.558. Based on the findings, recurrent neural network (RNN) variants emerge as the most effective modeling technique due to their ability to capture temporal dependencies and handle variable-length sequences. This study provides satisfied performance results for the NNR[0.5Y]H soft sensor model in NH3-N monitoring and process optimization in wastewater treatment, highlighting the effectiveness of recurrent neural networks and their contribution to improving interpretability, accuracy, and adaptability of soft sensor models.

XRL-FlexSBR: Multi-agent reinforcement learning-driven flexible SBR control with explainable performance guarantee under diverse influent conditions

The sequencing batch reactor (SBR) process stands out for its small footprint and operational flexibility. However, the SBR process is highly nonlinear and subject to influent disturbances. In this study, we suggested an explainable multi-agent reinforcement learning (XRL) approach coupled with multi-agent reinforcement learning (MARL) and explainable AI (XAI); then, an XRL-driven flexible SBR control (XRL-FlexSBR) system was developed to conduct multivariate control the SBR process autonomously. Influent big datasets including biochemical oxygen demand (BOD) and total nitrogen (TN) were collected from the wastewater treatment plants (WWTPs) of South Korea. Then, the Gaussian mixture model was utilized to cluster the diverse influent conditions and the SBR mechanistic model was developed. A game abstraction method based on a two-stage attention network (G2ANET), one of MARL algorithms, was employed to manipulate dissolved oxygen (DO) and extra carbon injection (EC) controllers in the SBR process; furthermore, layer-wise relevance propagation (LRP) of explainable AI (XAI) technique was utilized to evaluate a control performance guarantee by G2ANET. The results verified that XRL-FlexSBR can control the DO and EC controllers in the SBR process while reducing the energy consumption by 4.93 % on average and maintaining effluent quality criteria across the diverse influent conditions. Furthermore, XAI explained that the improved control performance of XRL-FlexSBR agents is attributed to their understanding of the mechanism underlying SBR operations without human intervention. Hence the proposed XRL-FlexSBR can flexibly control the SBR to improve sustainability and profitability under varying influent conditions.

N2O Emission Factors from Wastewater Treatment Plants Based on Literature Statistics and Model Fitting

The emission of nitrous oxide （N2O） during wastewater treatment cannot be ignored. The analysis of statistical data from literature based on 126 empirical studies revealed that the geographical factors of wastewater treatment plants （WWTPs） had a significant impact on N2O emission factors. However, the N2O emission factors of WWTPs in all regions of the world were generally lower than the Intergovernmental Panel on Climate Change （IPCC） recommended values. In China, the N2O emission factors （in N2O-N/Ninfluent） of WWTPs were approximately 0.000 35-0.065 20 kg·kg-1. Meanwhile, the N2O emission factors of different wastewater treatment processes were also significantly different, especially since the sequencing batch reactor （SBR） process had higher emissions. The use of uniform default emission factors for accounting was prone to overestimate N2O emissions, and it is recommended that countries conduct actual monitoring or modeling studies to develop categorical emission factors suitable for local conditions. In addition, the N2O emission factor based on total nitrogen （TN） removal was weakly negatively correlated with TN removal in 126 empirical data, which was more in line with bioprocessing stoichiometry and could provide an accurate accounting method for N2O. To this end, a digital twin model was developed to dynamically simulate a case anaerobic-anoxic-aerobic （AAO） WWTP to comprehensively quantify the dynamic emission behavior of N2O, which demonstrated that N2O emissions had significant seasonal and daily variability and were only equivalent to 11% of the calculated value of the emission factor based on the IPCC recommendation. Comparing the scatter linear fitting and categorical mean exponential fitting methods, it was found that the latter could more accurately reflect the negative correlation between the N2O emission factors and the TN removal rate, and an exponential regression equation between the average N2O emission factor based on the amount of TN removed and the TN removal rate was further developed to predict the N2O emission. The dynamic simulation and categorical index fitting methods provided in this study are important references for the accurate accounting of N2O emissions in similar WWTPs and provide help for understanding and responding to the N2O emission problems.

Parachlorometaxylenol stress caused multidrug-type antibiotic resistance genes proliferation via simultaneously reshaping microbial community and interfering metabolic traits during wastewater treatment process

Despite biological wastewater treatment processes (e.g., sequencing batch reactors (SBR)) being able to reduce the dissemination of antibiotic resistance genes (ARGs), the variation of ARGs under exogenous pollutant stress is an open question. This work investigated the impacts of para-chloro-meta-xylenol (PCMX, typical antibacterial contaminants) on ARGs spread in long-term SBR operation. Although the SBR process inherently decreased ARGs abundance, the presence of PCMX substantially amplified both the prevalence (mainly multidrug) and abundance of total ARGs (1.17-fold of the control). Further analysis demonstrated that PCMX disintegrated sludge structures as well as increased membrane permeability, facilitating the release of mobile genetic elements and subsequent horizontal transfer of ARGs. In addition, PCMX selectively enriched potential ARG hosts, notably Nitrospira and Candidatus Accumulibacter, which predominantly served as multidrug ARG hosts. Concurrently, the self-adaptive functions of ARGs hosts in the PCMX-exposed SBR system were activated via quorum sensing, two-component regulatory system, ATP-binding cassette transporters, and bacterial secretion system. The upregulation of these metabolic pathways also contributed to the dissemination of ARGs.

Aerobic granular sludge sequencing batch reactor for high strength domestic wastewater treatment: Assessing kinetic models and microbial community dynamics

The study aims to treat high strength domestic wastewater (HSDW) and cultivate microbial granular sludge in a sequencing batch reactor (SBR). A bench-scale bioreactor was used for startup. Response surface methodology (RSM) was used to determine the ideal parameters for removing organic materials from HSDW. Organic loading rate (OLR) and cycle time were the independent variables taken into consideration, while the response variable was COD removal. Results from RSM revealed that the optimal conditions for achieving > 98 % COD and TP (>80) removal were a cycle length of 6 h and an OLR of 1.5 kgCOD/m3d. The Modified-Kincannon and the Grau second-order kinetic models were compared to the COD removal rate for the SBR system. The saturation rate constant (Ni) and maximal substrate removal rate (Vc) were proposed to be 6.8 g L−1 d−1 and 0.83 g L−1 d−1, respectively, based on the modified Stover-Kincannon model. The modified Stover-Kincannon (R2 = 0.93673) and Grau second order (R2 = 0.99219) models high correlation coefficient values show that the experimental results and the prediction for the microbial aerobic granular based SBR system accord well. It was discovered that the modified Stover-Kincannon model was less suitable than the Grau second order model. The system microbial community changed because of the granulation process, as the reactor design operation had a big impact on the community structure. Decreased filamentous bacteria favoured several taxa that have been found to exist in granular biomass that is appropriate for treating wastewater. This study sheds important light on the complex interactions that occur between microbial populations and operational variables all through the granulation process in SBR.

Advanced leachate treatment at Mascara landfill (Algeria): A hybrid pilot approach with activated sludge and ferric chloride

This study investigates a hybrid treatment approach, that combines a Sequencing Batch Reactor (SBR) with a coagulation-flocculation process, to reduce the contaminants in Landfill Leachate (LL), targeting Chemical Oxygen Demand (COD), Turbidity, and Total Suspended Solids (TSS). The experimental set-up incorporated a batch reactor at room temperature and a pH between 7.7 and 8.7, with an Arduino monitoring system for heightened precision. The SBR was operated continuously over a 24-hour cycle, with a Hydraulic Retention Time (HRT) set at 5 days and variable sludge retention times (SRT) of 5, 10, and 15 days. The Aluminum sulfate (Al2 (SO4)3), Ferric Chloride (FeCl3), and Lime (CaO) were assessed for the coagulation-flocculation process. The results indicate a promising removal efficiency of 40 % for COD, 31 % for turbidity, and 47 % for TSS using the SBR process. FeCl3 showed higher findings, achieving removal yields of 87 % for COD and 86 % for turbidity, at an optimized dose of 10 g/L and pH 5.5. Furthermore, adding 0.25 g/L of CaO significantly improved the removal efficiency to 94.14 % for COD, 98.22 % for turbidity and 99.78 % of the TSS. Therefore, this study's results underline the effectiveness of combining SBR with coagulation-flocculation, particularly using FeCl3 and CaO, in treating landfill leachate.

Phosphate recovery from urban sewage by the biofilm sequencing batch reactor process: Key factors in biofilm formation and related mechanisms

The biofilm sequencing batch reactor (BSBR) technique has been deployed in the laboratory to enrich phosphorus from simulated wastewater, but it is still not clear what its performance will be when real world sewage is used. In this work, the effluent from the multi-stage anoxic-oxic (AO) activated sludge process at a sewage plant was used as the feed water for a BSBR pilot system, which had three reactors operating at different levels of dissolved oxygen (DO). The phosphorus adsorption and release, the biofilm growth, and the extracellular polymeric substances (EPS) components and contents were examined. The microbial communities and the signaling molecules N-acyl-l-homoserine lactones (AHLs) were also analyzed. Gratifyingly, the BSBR process successfully processed the treated sewage, and the biofilm developed phosphorus accumulation capability within 40 days. After entering stable operation, the system concentrated phosphate from 2.59 ± 0.77 mg/L in the influent to as much as 81.64 mg/L in the recovery liquid. Sludge discharge had profound impacts on all aspects of BSBR, and it was carried out successfully when the phosphorus absorption capacity of the biofilm alone was comparable to that of the reactor containing the activated sludge. Shortly after the sludge discharge, the phosphate concentration of the recovery liquid surged from 50 to 140 mg/L, the biofilm thickness grew from 20.56 to 67.32 μm, and the diversity of the microbial population plunged. Sludge discharge stimulated Candidatus competibacter to produce a large amount of AHLs, which was key in culturing the biofilm. Among the AHLs, both C10-HSL and 3OC12-HSL were significantly positively correlated with EPS and the abundance of Candidatus competibacter. The current results demonstrated BSBR as a viable option to enrich phosphorus from real world sewage with low phosphorus content and fluctuating chemistry. The mechanistic explorations also provided theoretical guidance for cultivating phosphorus-accumulating biofilms.

Cultivation of phosphate-accumulating biofilm: Study of the effects of acyl-homoserine lactones (AHLs) and cyclic dimeric guanosine monophosphate (c-di-GMP) on the formation of biofilm and the enhancement of phosphate metabolism capacity

This study investigated the mechanisms of microbial growth and metabolism during biofilm cultivation in the biofilm sequencing batch reactor (BSBR) process for phosphate (P) enrichment. The results showed that the sludge discharge was key to biofilm growth, as it terminated the competition for carbon (C) source between the nascent biofilm and the activated sludge. For the tested reactor, after the sludge discharge on 18 d, P metabolism and C source utilization improved significantly, and the biofilm grew rapidly. The P concentration of the recovery liquid reached up to 157.08 mg/L, which was sufficient for further P recovery via mineralization. Meta-omics methods were used to analyze metabolic pathways and functional genes in microbial growth during biofilm cultivation. It appeared that the sludge discharge activated the key genes of P metabolism and inhibited the key genes of C metabolism, which strengthened the polyphosphate-accumulating metabolism (PAM) as a result. The sludge discharge not only changed the types of polyphosphate-accumulating organisms (PAOs) but also promoted the growth of dominant PAOs. Before the sludge discharge, the necessary metabolic abilities that were spread among different microorganisms gradually concentrated into a small number of PAOs, and after the sludge discharge, they further concentrated into Candidatus_Contendobacter (P3) and Candidatus_Accumulibacter (P17). The messenger molecule C-di-GMP, produced mostly by P3 and P17, facilitated P enrichment by regulating cellular P and C metabolism. The glycogen-accumulating organism (GAO) Candidatus_Competibacter secreted N-Acyl homoserine lactones (AHLs), which stimulated the secretion of protein in extracellular polymeric substances (EPS), thus promoting the adhesion of microorganisms to biofilm and improving P metabolism via EPS-based P adsorption. Under the combined action of the dominant GAOs and PAOs, AHLs and C-di-GMP mediated QS to promote biofilm development and P enrichment. The research provides theoretical support for the cultivation of biofilm and its wider application.

Characterization of simultaneous ammonium and nitrate removal and microbial communities in airlift reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier

As a novel trend, solid carbon sources are applied to act as electron donors and biofilm carrier in biological denitrification process. In this study, simultaneous nitrate and ammonium removal process in an airlift sequencing batch reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier under intermittent aeration conditions was established to treat effluent of synthetic marine recirculating aquaculture system. The results showed that maximum nitrate and ammonia nitrogen removal rates of 0.45 and 0.09 kg m−3 d−1 were achieved. No significant nitrite accumulation was found during 200-day operation, while effluent dissolved organic carbon accumulation and particle size reduction significantly increased. Microbial community analysis and batch tests illuminate that the generated sludge and attached biofilm played important roles in nitrogen removal. This study demonstrates the potential mechanism for the nitrogen removal process mediated by 3-hydroxybutyrate-co-3-hydroxyvalerate and provide a new idea for the alternative solutions of solid carbon sources.

Exploring nutrient removal mechanisms in column-type SBR with simultaneous nitrification and denitrification

A comprehensive investigation utilized a column-type sequencing batch reactor (SBR) to efficiently remove nutrients throughout various phases of its operational cycle by forming granules. This study assessed the influence and mechanisms of a simultaneous nitrification and denitrification (SND) system employing a column-type sequential batch reactor (SBR). The primary focus was on elucidating the functional groups involved in nitrogen transformation and removal within the extracellular polymeric substances (EPS). The research findings demonstrate the superior performance of the SBR process compared to the control group. It achieved an impressive SND efficiency of 69%, resulting in a remarkable 66% total nitrogen removal. Furthermore, a detailed analysis unveiled that the SBR process had a beneficial impact on the composition and properties of EPS. This impact was observed through increased EPS content and enhanced capacity to transport, convert, and retain nitrogen effectively. Additionally, after initial acclimatization, the SBR process showed its effectiveness in removing nutrients (88–98%) and COD (93%) from the generated wastewater within a hydraulic retention time (HRT) of 6 h. A statistically significant difference between the treatments for the investigated mixing ratios was found by univariate analysis of variance (ANOVA). Machine learning (CatBoost model) was employed to understand each parameter’s relationship and predict the outcomes in measurable quantity. The findings of the SBR trials showed that the concentration of generated wastewater and the HRT impacted the treatment efficiency. However, the effluent may still need other physicochemical processes, such as membrane filtering, coagulation, electrocoagulation, etc., as post-treatment options, even though COD, nutrients, and turbidity have been entirely or significantly effectively removed. Overall, this work offers insightful information on the critical function of the SBR bacterial community in promoting SND.

Occurrence, removal, and risk assessment of emerging contaminants in aquatic products processing sewage treatment plants.

Emerging contaminants (ECs) in aquatic environments have attracted attention due to their wide distribution and potential ecotoxicities. Sewage treatment plants (STPs) are proven to be the major source of ECs in the aquatic environment, while there remains insufficient understanding of the removal and risk assessment of ECs in STPs. Here, we clarified the degradation and risk impact of 13 ECs in two aquatic product processing sewage treatment plants (APPSTPs) along the southeast coast of China. The concentrations of ECs followed the order: endocrine-disrupting chemicals (1877.85-15,398.02ng/L in influent, 3.37-44.47ng/L in effluent) > > sulfonamide antibiotics (SAs, 75.14-906.19ng/L in influent, 1.14-15.33ng/L in effluent) > pharmaceutical and personal care products (PPCPs, 44.47-589.93ng/L in influent, 2.54-34.16ng/L in effluent) ≈ fluoroquinolone antibiotic (54.76-434.83ng/L in influent, 10.75-32.82ng/L in effluent) > other antibiotics (16.21-51.96ng/L in influent, 0.68-6.17ng/L in effluent). Moreover, the concentrations of PPCPs (decreased by 55.33-87.65% in peak fishing season) and antibiotics (increased by 44.99% in peak fishing season) were affected by fishing activities. In particular, the sequencing batch reactor (SBR) process had a better removal effect than the anaerobic-anoxic-oxic (A2/O) process on the treatment of some contaminants (e.g., norfloxacin and nonylphenol). Risk evaluations of ECs demonstrated that nonylphenol and SAs were at high- and low-risk states, respectively. Overall, our results provide important information for the degradation treatment of ECs, which is essential for pollutant management policy formulation.

Metagenomics, metatranscriptomics, and proteomics reveal the metabolic mechanism of biofilm sequencing batch reactor with higher phosphate enrichment capacity under low phosphorus load

The biofilm sequencing batch reactor (BSBR) process has higher phosphate recovery efficiency and enrichment multiple when the phosphorus load is lower, but the mechanism of phosphate enrichment at low phosphorus load remains unclear. In this study, we operated two BSBR operating under low and high phosphorus load (0.012 and 0.032 kg/(m3·d)) respectively, and used metagenomic, metatranscriptomic, and proteomics methods to analyze the community structure of the phosphorus accumulating organisms (PAOs) in the biofilm, the transcription and protein expression of key functional genes and enzymes, and the metabolism of intracellular polymers. Compared with at high phosphorus load, the BSBR at low phosphorus load have different PAOs and fewer types of PAOs, but in both cases the PAOs must have the PHA, PPX, Pst, and acs genes to become dominant. Some key differences in the metabolism of PAOs from the BSBR with different phosphorus load can be identified as follows. When the phosphorus load is low, the adenosine triphosphoric acid (ATP) and NAD(P)H in the anaerobic stage come from the TCA cycle and the second half of the EMP pathway. The key genes that are upregulated include GAPDH, PGK, ENO, ppdk in the EMP pathway, actP in acetate metabolism, phnB in polyhydroxybutyrate (PHB) synthesis, and aceA, mdh, sdhA, and IDH1 in the TCA cycle. In the meantime, the ccr gene in the PHV pathway is inhibited. As a result, the metabolism of the PAOs features low glycogen with high PHB, Pupt, Prel, and low PHV. That is, more ATP and NAD(P)H flow to phosphorus enrichment metabolism, thus allowing the highly efficient enrichment of phosphorus from low concentration phosphate thanks to the higher abundance of PAOs. The current results provide theoretical support and a new technical option for the enrichment and recovery of low concentrations of phosphate from wastewater by the BSBR process.

Waste Activated Sludge-High Rate (WASHR) Treatment Process: A Novel, Economically Viable, and Environmentally Sustainable Method to Co-Treat High-Strength Wastewaters at Municipal Wastewater Treatment Plants.

High-strength wastewaters from a variety of sources, including the food industry, domestic septage, and landfill leachate, are often hauled to municipal wastewater treatment plants (WWTPs) for co-treatment. Due to their high organic loadings, these wastewaters can cause process upsets in both a WWTP's liquid and solids treatment trains and consume organic treatment capacity, leaving less capacity available to service customers in the catchment area. A novel pre-treatment method, the Waste Activated Sludge-High Rate (WASHR) process, is proposed to optimize the co-treatment of high-strength wastewaters. The WASHR process combines the contact stabilization and sequencing batch reactor processes. It utilizes waste activated sludge from a municipal WWTP as its biomass source, allowing for a rapid start-up. Bench-scale treatment trials of winery wastewater confirm the WASHR process can reduce loadings on the downstream WWTP's liquid and solids treatment trains. A case study approach is used to confirm the economic viability and environmental sustainability of the WASHR process compared to direct co-treatment, using life-cycle cost analyses and greenhouse gas emissions estimates.

Performance evaluation and optimization of simultaneous phosphorus and nitrogen removal from anaerobically digested liquid-dairy-manure using an intermittently-aerated-extended-idle sequencing batch reactor

Wastewater from confined dairy operations requires efficient treatment to reduce its potential to pollute the surrounding environments. In this study, a novel intermittently-aerated-extended-idle sequencing batch reactor (IA-EI SBR) process was developed, evaluated, and optimized for simultaneously removing phosphorus (P) and nitrogen (N) from anaerobically digested liquid-dairy-manure (ADLDM) with lower carbon-to-nutrient-ratios. Four influential operating parameters including cycle-time of 5–9 h, intermittent-aeration strategy of 10–50 min/h, two feed-phases of 6–30 min, and idle-phase of 40–120 min were statistically analyzed using central-composite design coupled with response-surface methodology for optimal removal efficiencies of ortho-phosphorus (%OPremoval), total-phosphorus (%TPremoval), ammonia-nitrogen (%NH3-Nremoval), total-nitrogen (%TNremoval), and chemical oxygen demand (%CODremoval). Results showed that the interactions of cycle time-idle phase, and aeration strategy-feed phases were significant in affecting %TPremoval (p-value ≤ 0.005). The synergistic effect of aeration strategy-idle phase was significant for %TNremoval and %CODremoval (p-value ≤ 0.006), while the cycle time-feed phases interaction had significant effect on %NH3-Nremoval. The maximum simultaneous nitrification-denitrification (SND) efficiency of 85.7% was recorded under influent COD and TN loading of 3,999.2 and 785.7 mg L−1 at 30 min/h aeration time in 7 h. The quadratic regression models based on statistical analysis of the experimental results adequately described the IA-EI SBR performance and showed that the applied levels of operating parameters were highly correlated with all five responses (p-value ≤ 0.030). Operating conditions for optimal IA-EI SBR process efficiency determined by desirability analysis were cycle-time of 8 h, intermittent-aeration strategy of 36 min/h, feed-phases of 24 min, and idle-phase of 100 min. Under these optimal conditions, the corresponding removal efficiencies for OP, TP, NH3-N, TN, and COD of 82.64, 95.82, 92.92, 73.84, and 90.94%, respectively, were achieved in validation experiments.

Performance of short-cut denitrifying phosphorus removal and microbial community structure in the A2SBR process

ABSTRACT Acclimatization of short-cut denitrifying polyphosphate accumulating organisms (SDPAOs), metabolic mechanism, and operating parameters were analyzed to investigate the performance of the anaerobic/anoxic sequencing batch reactor (A2SBR) process. The high-throughput sequencing technology was employed to explore the microbial community structures of activated sludge systems. The experimental results illustrated that SDPAOs were successfully enriched with three-phase inoculation for 36 days. The removal rates of TP and NO2 −-N were 93.22% and 91.36%, respectively, under the optimal parameters of a pH of 7.5, an SRT of 26 days, a temperature of 24 ℃ and a COD of 200.00 mg·L−1 using acetate as the carbon source. In the anaerobic stage, 82.20% external carbon source was converted into 88.78 mg·g−1 PHB, and the removal rate of NO2 −-N in the anoxic stage was characterized by ΔNO2 −-N/ΔPHB, anoxic ΔP/ΔPHBeffective was 0.289, which was higher than anaerobic ΔP/ΔCODeffective of 0.203. Ignavibacterium and Povalibacter with significant phosphorus removal ability were the dominant bacterial genera. The nitrogen and phosphorus removal could be realized simultaneously in an anaerobic/anoxic sequencing batch reactor. Therefore, this study provided an important understanding of the removal of nitrogen and phosphorus from low-carbon nitrogen wastewater.

Development and application of random forest regression soft sensor model for treating domestic wastewater in a sequencing batch reactor

Small-scale distributed water treatment equipment such as sequencing batch reactor (SBR) is widely used in the field of rural domestic sewage treatment because of its advantages of rapid installation and construction, low operation cost and strong adaptability. However, due to the characteristics of non-linearity and hysteresis in SBR process, it is difficult to construct the simulation model of wastewater treatment. In this study, a methodology was developed using artificial intelligence and automatic control system that can save energy corresponding to reduce carbon emissions. The methodology leverages random forest model to determine a suitable soft sensor for the prediction of COD trends. This study uses pH and temperature sensors as premises for COD sensors. In the proposed method, data were pre-processed into 12 input variables and top 7 variables were selected as the variables of the optimized model. Cycle ended by the artificial intelligence and automatic control system instead of by fixed time control that was an uncontrolled scenario. In 12 test cases, percentage of COD removal is about 91. 075% while 24. 25% time or energy was saved from an average perspective. This proposed soft sensor selection methodology can be applied in field of rural domestic sewage treatment with advantages of time and energy saving. Time-saving results in increasing treatment capacity and energy-saving represents low carbon technology. The proposed methodology provides a framework for investigating ways to reduce costs associated with data collection by replacing costly and unreliable sensors with affordable and reliable alternatives. By adopting this approach, energy conservation can be maintained while meeting emission standards.

A comprehensive approach to SBR modelling for monitoring and control system design

The aim of this research is to provide a comprehensive description of the Sequencing Batch Reactor (SBR) modelling for monitoring, control, and plant operational optimisation validation. The paper provides a detailed modelling of the SBR, its components and constituent processes. For this purpose, the mass balance principle and continuity equations were provided with a reactive term implemented using Activated Sludge Model (ASM). The spatially discretised models (along the vertical axis) are then used in numerical experiments. Simulations performed enable comparison of the impact of different models of activated sludge settling velocity, as well as two different approaches to modelling reactions in the SBR. The latter was achieved by using the ASM2d and ASM3-BioP extended with an enzyme group modelling the lag phase observed in microorganisms during a rapid change in environmental conditions. The presented results have been obtained using the model of the SBR at Swarzewo in the North of Poland.

Integrated sonophotocatalytic oxidation and SBR processes for the effective treatment of antibiotics with an emphasis on process optimization and microbial diversity

The presence of antibiotics in water and wastewater is a serious environmental concern of emerging interest globally. Their effective removal with a single treatment process is, however, challenging because of their widely varying characteristics, and requires innovative integration of treatment processes. In this study, sonophotocatalytic oxidation process was integrated with an aerobic sequencing batch reactor (SBR) for the comprehensive removal of a mixture of antibiotics. Initially, a Central Composite Design using Response Surface Methodology was used to optimise the operational parameters, viz. ultrasound (US) frequency, pH, and catalyst dosage, for the removal of Ciprofloxacin (CPX), Amoxicillin (AMX), and Tetracycline (TTC) in simulated wastewater. An optimised condition of 20 kHz US frequency, 6.59 initial pH, and 0.94 g L−1 catalyst dosage was observed for the maximum pollutant removal. These experimental conditions were subsequently used for combined sonophotocatalysis-aerobic SBR treatment. Three SBR systems representing a control system, pre-treated system, and untreated system, were used for the study. All three systems were able to achieve an average COD and NH4+-N removal of 85 % and 98 %, respectively. Results from the biological systems concluded that an enhanced CPX and TTC removal was observed in the pre-treated system, whereas maximum AMX removal was observed in the untreated SBR system. The metagenomic analysis confirmed the significant difference of microbial species with the addition of pretreated and untreated wastewater into the biological reactor, and pretreated system having higher number of species and greater biodiversity in comparison to untreated system.