Sequencing Batch Reactor System Research Articles

Genera complying denitrifying phosphorus removal community contribute excellent SND-PR in a pilot cyclic SBR: Effect of DO, settling and recirculation rate on process performance.

This work investigated the role of operational conditions and typical functional microbes to maximize the nutrient removal efficiency of a pilot-scale sequencing batch reactor (SBR) system (100 m3/d) that treated municipal wastewater. The pilot system was operated in five phases, including start-up and four runs at variable cycle times (2.0, 1.5, 1.7, 2.0, and 3.0h) with an average readily biodegradable chemical oxygen demand (rbCOD) to chemical oxygen demand (COD) ratio of ∼15.3%. The best TN removal 'ηmax' of 75.6 ± 5.6% (TNinfluent= 27.5 ± 6.5 mg/L, TNeffluent ≤5.9 mg/L) and TP removal 'pmax' 77.9 ± 6.3% (TPinfluent= 3.8 ± 1.3 mg/L, TPeffluent ≤1.0 mg/L) along with the COD, biochemical oxygen demand (BOD), and total suspended solids (TSS) removal efficiencies of 87.3 ± 4.5%, 92.7 ± 2.8%, 92.0 ± 3.5%, respectively, were observed during run 3 (2h cycle) at settling/ total cycle times ratio (S/T) of 0.33 and recirculation/ total cycle times ratio (R/T) of 0.017 (6.4%), and operating DO of 0.5-2.5 mg/L. The denitrifying polyphosphate accumulating organisms 'DPAOs' of Burkholderia (17.0%), Rhodocyclales (6.1%), and Flavobacterium (8.7%) classes, and Nitrifiers of Nitrospira (5.4%) and Nitrosomonas (5.4%) classes were dominant in accomplishing simultaneous nitrification, denitrification, and phosphorus removal (SND-PR) in the pilot system.

Evaluation of hydraulic retention time on hydrogen production from corn industry wastewater by dark fermentation

ABSTRACT Dark fermentation has the potential to produce biohydrogen using raw material waste, such as wastewater from the corn industry (cornWW), which is characteristically alkaline and improperly discharged. This study aimed to assess the impact of different hydraulic retention times (HRT) on hydrogen production in a sequencing batch reactor system using raw cornWW as feedstock. Different HRTs were evaluated (4, 2, and 1 day(s)). Higher biohydrogen productivity was observed in HRT value of 1 day (893.6 ± 10.1 NmL H2/Lreactor/day), indicating its favorable metabolic pathways leading to the generation of hydrogen, carbon dioxide, acetate, butyrate, and caproate. Microbial analysis revealed that the Atopobium and Clostridium (genera) played key roles in hydrogen and organic acid production. Additionally, during the fermentation of cornWW, lactic acid in the feedstock facilitated the production of caproic and propionic acids, further enriching the range of valuable byproducts obtained through this process.

Removal of Ampicillin with Nitrifying Cultures in a SBR Reactor.

The presence of antibiotics in wastewater discharges significantly affects the environment, mainly due to the generation of bacterial populations with multiple antibiotic resistances. The cometabolic capacity of nitrifying sludge to simultaneously remove ammonium (NH4+) and emerging organic contaminants (EOCs), including antibiotics, has been reported. In the present study, the removal capacity of 50mg ampicillin (AMP)/L by nitrifying cultures associated with biosorption and biotransformation processes was evaluated in a sequencing batch reactor (SBR) system. The contribution of nitrifying enzymes (ammonium monooxygenase (AMO) and nitrite oxidoreductase (NOR)) and β-lactamases in AMP biodegradation was evaluated using specific inhibitors in batch cultures. AMP was 100% eliminated after 5h since the first cycle of operation. The sludge maintained its ammonium oxidizing capacity with the total consumption of 102.0 ± 2.5mg NH4+-N/L in 9h, however, the addition of AMP altered the nitrite-oxidizing process of nitrification, recovering 30 cycles later at both physiological and kinetic level. The kinetic activity of the nitrifying sludge improved along the operating cycles for both AMP removal and nitrification processes. The elimination of 24% AMP was attributed to the biosorption process and 76% to biotransformation, wherein the AMO enzyme contributed 95% to its biodegradation. Finally, the repeated exposure of the sludge to AMP for 72 operating cycles (36days) was not sufficient to detect β-lactamase activity. The cometabolic ability of ammonium-oxidizing bacteria for biodegrading AMP could be employed for bioremediation of wastewater.

The Effectiveness of an Anoxic-Oxic-Anoxic-Oxic Sequencing Batch Reactor System (A2/O2-SBR) to Treat Electroplating Wastewater and the Bacterial Community within the System

This study presents an examination of the effectiveness of an anoxic-oxic-anoxic-oxic sequencing batch reactor (A2/O2-SBR) for treating electroplating wastewater (EPWW). The A2/O2-SBR was monitored for 60 days and the bacterial composition in the treatment system was determined. The system consisted of four reactors, which had the following anoxic/oxic ratios: reactor-I, 0:9 h; reactor-II, 2:7 h; reactor-III, 4.5:4.5 h; and reactor-IV, 7:2 h. The combined cycle time of the reactors was 12 h, the hydraulic retention time (HRT) was five days, and the total volume of mixed liquor suspended solids (MLSS) was 2,000 mg/L. The results demonstrate the importance of an anoxic period for the treatment of heavy metals. Most of the ammonium nitrogen (NH4+-N), Total Kjeldahl nitrogen (TKN), and total nitrogen (TN) were removed during the oxic period. However, as the anoxic period increased, the amounts of TKN, nitrite nitrogen (NO2--N), nitrate nitrogen (NO3--N), and TN declined. Reactor-IV showed a high removal efficiency for heavy metals (Zn2+, 89.74%; Cd2+, 81.37%), TKN (89.20%), and TN (84.25%), and also effectively treated NH4+-N (78.84%), biochemical oxygen demand (BOD5; 93.5%), and chemical oxygen demand (COD; 84.9%). Reactor-IV showed an appropriate difference in the dissolved oxygen (DO) concentration between the anoxic period and oxic period (2.12-2.00 mg/L). The main bacterial phyla in the treatment system were Proteobacteria, Actinobacteria, and Firmicutes, while Pseudomonas vancouverensis and Cryobacterium arcticum were the most common species. The anoxic period and bacterial community have significantly demonstrated the ability to remove Zn2+ and Cd2+ for effective treatment of EPWW.

Improvement of biofilm activities in sequencing batch reactor via polyvinyl alcohol (PVA) granules addition

Polyvinyl alcohol (PVA) (C2H4O)n is a synthetic polymer material commercially available on an industrial scale. In this study, two formulas were tested for preparing biofilm carriers in spherical shape from PVA/H3BO3 (formula 1) and PVA/NaNO3 (formula 2) crosslink bonds without activated sludge entrapment. Formula 2 gave better results with white, round, gel-textured, flexible, and firm carriers. The PVA/NaNO3 granules continued to be used as moving-bed biofilm carriers at a ratio of 10% of the working volume to evaluate the wastewater treatment capacity in the sequencing batch reactor (SBR). After five weeks of operation, the results showed that the PVA/NaNO3 granules turned light yellow due to the presence and development of aerobic biomass. The surface of PVA/NaNO3 granules was plump, elastic, not cracked, and settled well. The amount of biomass attached to the PVA/NaNO3 granules was 0.4 gTSS/g granules. The hydraulic settling velocity of the PVA/NaNO3 granules was 56 mm/s. The wastewater treatment efficiency of the SBR system using moving-bed biofilm activity developed on the PVA/NaNO3 granular carriers was evaluated according to the TSS, COD, and NH4+– N parameters at 88%, 90%, and 92%, respectively. The experimental results have demonstrated the potential of developing a new type of biofilm carriers from PVA polymer materials that offer good settling ability and resistance to hydraulic shear force during aeration. Therefore, PVA granules can be easily applied in the column SBR configuration.

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>

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.

Enhanced tetracycline removal in sequencing batch reactors by bioaugmentation using tetX-carrying strains: Efficiency and mechanisms

Tetracyclines antibiotics (TCs) pose notable environmental challenges due to their persistence in the effluent of wastewater treatment systems. Bioaugmentation offers a promising strategy for their removal, yet information is still very limited. This study aimed to assess the efficacy of bioaugmentation using wild-type (Sphingobacterium sp. WM1) and engineered tetX-carrying (PUC-tetX) strains for enhancing tetracycline (TC) removal in sequencing batch reactors (SBRs). Bioaugmentation mitigated TC's inhibitory effects on denitrification and phosphorus removal processes within SBR systems. Specifically, strain WM1 outperformed strain PUC-tetX in removing TC from sludge and maintained a longer viability. TC addition (500 μg/L, at an environmentally relevant concentration) and bioaugmentation did not significantly impact overall microbial community diversity. Notably, the introduction of these exogenous bacteria markedly increased the abundance of the tetX gene, correlating with the increase in TC degradation. Interestingly, MAGs associated with the Chloroflexi phylum in bioaugmented reactors showed the transfer of the tetX gene to autochthonous bacterial species, promoting TC removal capability. These findings underscored the potential of bioaugmentation to enhance antibiotic removal and provided insights into the dynamics of ARGs and tetX gene within activated sludge systems.

Exploring the regulation mechanism of signaling molecules on algal-bacterial granular sludge through different N-acyl-homoserine lactones

As a recently emerging wastewater treatment technology, Algal-bacterial granular sludge (ABGS) process shows significant advantages. However, current research on the ABGS system is a lack of a clear and complete understanding of the potential mechanism of signal molecules on the growth of ABGS. This study comprehensively explores the variations in the ABGS under different N-acyl-homoserine lactone (AHL)conditions by constructing three sequencing batch reactor (SBR) systems. The results indicate that N-hexanoyl-L-homoserine lactone (C6-HSL) accelerates the granulation process in the early stages by promoting the loosely bound extracellular polymeric substances (LB-EPS) secretion and filamentous bacteria growth, thereby shortening required time for initial granule formation. On the other hand, N-(3-oxodecanoyl)-L-homoserine lactone (3-oxo-C12-HSL) expedites the granulation process by promoting the tightly bound extracellular polymeric substances (TB-EPS) and aromatic protein secretion, benefiting structural stability and nitrogen and phosphorus removal efficiency of mature ABGS.

Select of the most suitable simulation for design and management of the wastewater treatment system for the SaVan-XeNo industrial park

Now, water environment in industrial zones increasingly contaminated by wastewater. Therefore, the production facilities must build preliminary processing system before discharging into the collective wastewater treatment system. The study aims to provide an optimal scenario for installation design and operate the wastewater treatment system to effectively nutrients remove. In the case study, the scenarios are simulated by the ASM2d model (Activated Sludge Model No. 2d) based on the AAO (Anaerobic, Anoxic, Aerobic/Oxic) and SBR (Sequencing Batch Reactor) system to select scenarios that have met NH4+ ≤3 mg/l, TN ≤ 5 mg/L, TP ≤ 1 mg/L associated with American and Lao standards. The results showed 269/855 scenarios were satisfactory, 16 scenarios optimized in AAO system. and 27/180 scenarios of the SBR system have been achieved, 4 scenarios achieved optimization. In the study, the optimal simulation scenario of the AAO system was more suitable than the SBR system with a total volume of 2,056 m3 and oxygen consumed 509,364 kg/day.

Winery wastewater treatment by microalgae Chlorella sorokiniana and characterization of the produced biomass for value-added products.

The microalgae Chlorella sorokiniana was used for the treatment of winery wastewater (WWW). Batch experiments were initially conducted to investigate how biomass acclimatization in different media, dilution of wastewater, and addition of ammonium nitrogen (NH4-N) affect the growth of microalgae and the removal of major pollutants. Afterwards, two sequencing batch reactor (SBR) systems were tested applying different configurations and hydraulic retention times. The biomass collected at the end of the experiments was characterized for proteins, lipids, carbohydrates, amino acid profile, and the existence of lutein, β-carotene, chlorophyll a, and tocopherols. Batch experiments showed that Chlorella sorokiniana acclimatization to urban wastewater enhanced the removal of NH4-N and total phosphorus (TP). The operation of a two-stage SBR system achieved COD and NH4-N removal equal to 85 ± 9% and 91 ± 20%, respectively, while the use of a single-stage system feeding with anaerobically pretreated WWW resulted to COD and NH4-N removal of 78 ± 9% and 95 ± 9%, respectively. Analyses of biomass showed higher protein content (up to 58.8%) in batch experiments with NH4-N addition as well as in SBR experiments. The cultivation of microalgae under SBR conditions enhanced the production of pigments and tocopherols. The maximum concentrations of 1075mgkg-1, 45.5mgkg-1, and 131.2mgkg-1 were achieved for lutein, β-carotene, and tocopherols, respectively, in the one-stage system. Our findings suggested that Chlorella sorokiniana cultivation in WWW not only removed nutrients from WWW but also could potentially serve for the production of value-added ingredients used in food industry, cosmetics, and animal feedstock.

Design and Life Cycle Assessment (LCA)-based Sustainability Evaluation of a Novel Microbial Fuel Cell (MFC)-Integrated Sequencing Batch Reactor (SBR) System

Although sewage treatment plants form one of the major environmental interventions for eco-friendly and sustainable management of domestic sanitary wastes, yet their own overall sustainability enhancement, rather than process performance assessment are seldom addressed. The sustainability study of a standard sewage treatment plant, namely Sequencing Batch Reactor (SBR) is addressed in the present research work through Life Cycle Assessment (LCA) tools using SimaPro. Following this, an attempt was made herewith to integrate a potential, yet much lesser commercially explored, wastewater management strategy, namely Microbial Fuel Cell (MFC) unto the SBR chamber, with suitable design-modification. The sustainability parameters of the resultant MFC-augment SBR system were also analysed using LCA to compare the effect of this intervention unto the said parameters. The study shows similar normalized trends of overall damage unto sewage as well as sludge, with global warming being the dominant damage cause. Human health was found to be most vulnerable category for both types of SBR’s (namely, with and without MFC), with relatively lower effect in case of MFC-augmented SBR, particularly with regard to infrastructural and short-term domains, in addition to improved water quality and lower water-footprint.

Effects of aeration control strategies on nitrous oxide emissions in alternating anoxic–oxic sequencing batch reactor systems

Reducing N2O emissions is key to controlling greenhouse gases (GHG) in wastewater treatment plants (WWTPs). Although studies have examined the effects of dissolved oxygen (DO) on N2O emissions during nitrogen removal, the precise effects of aeration rate remain unclear. This study aimed to fill this research gap by investigating the influence of dynamic aeration rates on N2O emissions in an alternating anoxic–oxic sequencing batch reactor system. The emergence of DO breakthrough points indicated that the conversion of ammonia nitrogen to nitrite and the release of N2O were nearly complete. Approximately 91.73 ± 3.35% of N2O was released between the start of aeration and the DO breakthrough point. Compared to a fixed aeration rate, dynamically adjusting the aeration rates could reduce N2O production by up to 48.6%. Structural equation modeling revealed that aeration rate and total nitrogen directly or indirectly had significant effects on the N2O production. A novel regression model was developed to estimate N2O production based on energy consumption (aeration flux), water quality (total nitrogen), and GHG emissions (N2O). This study emphasizes the potential of optimizing aeration strategies in WWTPs to significantly reduce GHG and improve environmental sustainability.

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.

Hybrid peroxymonosulfate/activated carbon fiber-sequencing batch reactor system for efficient treatment of coking wastewater: Establishment and influential factors

Coking wastewater contains high concentrations of toxic and low biodegradable organics, causing long hydraulic retention times for its biological treatment process. This study developed a pretreatment method for coking wastewater by using activated carbon fiber (ACF) activated peroxymonosulfate (PMS) to improve the treatment performance of subsequent biological post-treatment process, sequencing batch reactor (SBR). The results showed that, after optimization of treatment processes, the removal efficiency of chemical oxygen demand (COD), phenol, and chroma in coking wastewater reached to 76, 98, and 98%, respectively, with a significantly improved biodegradability. Compared with the sole SBR system without any pretreatment that could remove 73% of COD, the ACF/PMS+SBR system removed over 97% of COD in coking wastewater. Moreover, this pretreatment method facilitated the growth of functional bacteria for organics biodegradation, indicating its high potential as a highly efficacious pretreatment strategy to improve the overall treatment efficiency of coking wastewater.

Advanced nitrogen and phosphorus removal in pilot-scale anaerobic/aerobic/anoxic system for municipal wastewater in Northern China

Removing nitrogen and phosphorus from low ratio of chemical oxygen demand to total nitrogen and temperature municipal wastewater stays a challenge. In this study, a pilot-scale anaerobic/aerobic/anoxic sequencing batch reactor (A/O/A-SBR) system first treated 15 m3/d actual municipal wastewater at 8.1–26.4 °C for 224 days. At the temperature of 15.7 °C, total nitrogen in influent and effluent were 45.5 and 10.9 mg/L, and phosphorus in influent and effluent were 3.9 and 0.1 mg/L. 16 s RNA sequencing results showed the relative abundance of Competibacter and Tetrasphaera raised to 1.25 % and 1.52 %. The strategy of excessive, no and normal sludge discharge enriched and balanced the functional bacteria, achieving an endogenous denitrification ratio more than 43.3 %. Sludge reduction and short aerobic time were beneficial to energy saving contrast with a Beijing municipal wastewater treatment. This study has significant implications for the practical application of the AOA-SBR process.

Copper oxide nanoparticles influence on the performance of sequencing batch reactor and the transfer of antibiotic resistance genes by regulating bacterial quorum sensing system

The environmental pollution caused by copper oxide nanoparticles (CuO NPs) has attracted widespread attention. In this study, microbial community, key metabolic pathways and quorum sensing (QS) were investigated to reveal the impact of copper oxide nanoparticles (CuO NPs) on the performance of sequencing batch reactor (SBR) and the transfer of antibiotic resistance genes (ARGs). Results showed that under CuO NPs impact, the removal efficiency of COD, ammonium nitrogen (NH4+-N) and total nitrogen (TN) was stable at around 90%, 96% and 60%, respectively. However, removal efficiency of total phosphorus (TP) was reduced to below 60% under 0.1 mg/L and 1 mg/L CuO NPs exposure. Microbial community analysis showed CuO NPs was advantageous to the growth of key functional bacterial phyla Bacteroidetes, Proteobacteria and Patescibacteria. The relative abundance of Candidatus Accumulibacter genus and ppX gene were decreased, which then lower the TP removal efficiency. Besides, CuO NPs might trigger QS system, affecting Candidatus Accumulibacter, Aeromonas genus and ppX gene, and then regulated the removal of TP in the SBR system. The co-occurrence network analysis revealed a correlation among core ARGs, signaling molecule, QS-related microbial community and ARGs’ hosts, suggesting that the spread of ARGs might be driven by QS system under selective pressure of CuO NP. These findings could reveal the effect of CuO NPs on the performance of activated sludge system and provides new ideas for ARGs control through regulating the QS system.

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.

Advanced steam-explosion pretreatment mediated anaerobic digestion of municipal sludge: Effects on methane yield, emerging contaminants removal, and microbial community

Advanced steam explosion pretreatment, i.e., the Thermal hydrolysis process (THP) is applied mainly to improve the sludge solubilization and subsequent methane yield in the downstream anaerobic digestion (AD) process. However, the potential of THP in pretreating the high solids retention time (SRT) sludges, mitigating the risk of emerging organic micropollutants and effects on anaerobic microbiome in digester remains unclear. In this study, sludge from a sequencing batch reactor (SBR) system operating at a SRT of 40 days was subjected to THP using a 5 L pilot plant at the temperature ranges of 120–180 °C for 30–120 min. The effect of THP on organics solubilization, methane yield, organic micropollutant removal, and microbial community dynamics was studied. The highest methane yield of 507 mL CH4/g VSadded and volatile solids (VS) removal of 54% were observed at 160°C- 30min THP condition, i.e., 4.1 and 2.6 times higher than the control (123 mL CH4/gVSadded, 20.7%), respectively. The experimental values of hydrolysis coefficient and methane yield have been predicted using Modified Gompertz, First order, and Logistics models. The observed values fitted well with all three models showing an R2 value between 0.96 and 1.0. THP pretreated sludges showed >80% removal of Trimethoprim, Enrofloxacin, Ciprofloxacin, and Bezafibrate. However, Carbamazepine, 17α-ethinylestradiol, and Progesterone showed recalcitrant behavior, resulting in less than 50% removal. Microbial diversity analysis showed the dominance of Proteobacteria, Firmicutes, Chloroflexi, and Bacteroidetes, collectively accounting for >70–80% of bacterial reads. They are mainly responsible for the fermentation of complex biomolecules like polysaccharides, proteins, and lipids. The THP-mediated anaerobic digestion of sludge shows better performance than the control digestion, improved methane yield, higher VS and micropollutants removal, and a diverse microbiome in the digester.