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Food waste anaerobic digestate (FWAD) containing high concentrations of contaminants must be purified or recycled. Bio-conditioning dewatering followed by activated sludge process (BDAS) has emerged as a promising technology for treating FWAD. However, the bio-conditioning dewatering as a pivotal step of BDAS is often negatively affected by low ambient temperatures often occurred in winter. This study investigated the role of heating FWAD in improving the bio-conditioning dewatering performance of FWAD. Batch experiments demonstrated that the bio-conditioning dewatering efficiency increased with temperature rise. Notably, due to the low energy consumption, 50°C was considered to be the most appropriate heating treatment temperature, realizing a drastic reduction of specific resistance to filtration (SRF) of bio-conditioned FWAD from initial 1.24 × 1012 m/kg in the control at a ambient temperature of 10°C to 5.42 × 1011 m/kg and a saving of 25% in bio-conditioning reagents cost. The results of the pilot-scale and large-scale experiments revealed that heating treatment made the bio-conditioning dewatering more stable regardless of the fluctuation of ambient temperature in practical engineering. The decrease in the viscosity of bio-conditioned FWAD and the enhancement in microbial fermentation liquor flocculation capacity through heating treatment played pivotal roles in improving the bio-conditioning dewatering performance of FWAD. This work provides a cost-effective strategy to achieve efficient bio-conditioning dewatering at a relatively low ambient temperature, which was helpful in the engineering application of the novel BDAS process in wastewater treatment. [ABSTRACT FROM AUTHOR]

The multi-soil-layering (MSL) systems is an emerging solution for environmentally-friendly and cost-effective treatment of decentralized rural domestic wastewater. However, the role of the seemingly simple permeable layer has been overlooked, potentially holding the breakthroughs or directions to addressing suboptimal nitrogen removal performance in MSL systems. In this paper, the mechanism among diverse substrates (zeolite, green zeolite and biological ceramsite) coupled microorganisms in different systems (activated bacterial powder and activated sludge) for rural domestic wastewater purification was investigated. The removal efficiencies performed by zeolite coupled with microorganisms within 3 days were 93.8% for COD, 97.1% for TP, and 98.8% for NH 4 +-N. Notably, activated sludge showed better nitrification and comprehensive performance than specialized nitrifying bacteria powder. Zeolite attained an impressive 89.4% NH 4 +-N desorption efficiency, with a substantive fraction of NH 4 +-N manifesting as exchanged ammonium. High-throughput 16S rRNA gene sequencing revealed that aerobic and parthenogenetic anaerobic bacteria dominated the reactor, with anaerobic bacteria conspicuously absent. And the heterotrophic nitrification-aerobic denitrification (HN-AD) process was significant, with the presence of denitrifying phosphorus-accumulating organisms (DPAOs) for simultaneous nitrogen and phosphorus removal. This study not only raises awareness about the importance of the permeable layer and enhances comprehension of the HN-AD mechanism in MSL systems, but also provides valuable insights for optimizing MSL system construction, operation, and rural domestic wastewater treatment. [ABSTRACT FROM AUTHOR]

Micron-size ceramic waste powder (< 75 μm and 75–150 μm) was used as the carrier in a high-concentration powder carrier bio-fluidized bed (HPB) to treat simulated overflow sewage (CSOs). The sludge extracellular polymers (EPS), electron transfer capacity of EPS, nitrogen removal pathways, and microbiological characteristics were analyzed to gain insights into the nitrogen removal pathways and mechanisms. The results showed that only the effluent from the HPB (< 75 μm) could meet the stringent pollutant discharge standards in China of 50 mg/L for CODCr and 15 mg/L for total nitrogen from beginning to end. Meanwhile, the electrochemical performance tests indicated that the electron accepting and donating capacities of the sludge EPS in the HPB (< 75 μm) were 42.75% and 32.73% higher than those in the conventional activated sludge, meaning that ceramic powder carriers can increase the extracellular electron transfer capacity of the sludge and accelerate the denitrification process. Also, metagenomics analysis results showed that the relative abundances of the denitrification-related Nor genes were 28–39% higher in the HPB (< 75 μm) and HPB (75–150 μm) than in the conventional activated sludge (CAS). These results show that ceramic waste powders have the potential to be used as carriers in HPB systems to treat CSOs. [ABSTRACT FROM AUTHOR]

This study investigates the performance of sludge-added pervious concrete (SPC) at different curing temperatures by replacing some of the cement with activated sludge (AS). The results reveal that the incorporation of AS into pervious concrete had a favorable impact. At a curing temperature of 30 °C, the 28-day compressive strength and specific surface area reached 20.8 MPa and 9.14 m2/g, respectively, representing a 60% and 98.7% increase, in comparison to conventional concrete. Furthermore, the addition of AS to the concrete results in a notable reduction in the concentration of chemical oxygen demand (COD) in surface runoff water. The maximum rate of COD removal observed was 55.6%. A mechanism study revealed that the strength of concrete increased due to the reaction between reactive SiO2 in AS and CaO in the aggregate. At a temperature of 30 °C, the microorganisms in the activated sludge fermentation process exhibit a higher production rate of fermentation gas, resulting in a greater escape of gas and an increase in the number of micropores in the permeable concrete. This leads to an enhanced specific surface area, which in turn exhibits a superior adsorption effect on COD. [ABSTRACT FROM AUTHOR]

Anaerobic ammonia oxidation (Anammox) is an economical and sustainable wastewater nitrogen removal technology, and its application in the mainstream process is the inevitable trend of the development of Anammox. However, how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications. In this study, the rapid and efficient enrichment of Anammox bacteria was achieved by raising the reflux ratio and nitrogen loading rate (NLR) using conventional activated sludge as the inoculant. In the screening phase (days 1–90), the reflux ratio was increased to discharge partial floc sludge, resulting in the relative abundance of Candidatus Brocadiaceae increased from 0.04% to 22.54%, which effectively reduced the matrix and spatial competition between other microorganisms and Anammox bacteria. On day 90, the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26, indicating that the Anammox reaction was the primary nitrogen removal process in the system. In the enrichment phase (days 91–238), the NLR increased from 0.43 to 1.20 kgN/(m3·d) and removal efficiency was 71.89%, resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27% on day 180. The reactor operated steadily from days 444 to 498, maintaining the nitrogen removal rate (NRR) of 3.00 kgN/(m3·d) and achieving successful sludge granulation with the particle size of 392.4 µm. In short, this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge, supporting to start an Anammox process efficiently. [Display omitted] [ABSTRACT FROM AUTHOR]

The organic compound composition of wastewater, serves as a crucial indicator for the operational performance of activated sludge processes and has a major influence on the development of filamentous bulking in activated sludge. This study focused on the impact of typical soluble and slowly-biodegradable organic compounds, investigating the pathways through which these substrates affect the occurrence of filamentous bulking in systems operated under both high- and low-oxygen conditions. Results showed that slowly-biodegradable organic compounds lead to a concentrated distribution of microorganisms within flocs, with inward growth of filamentous bacteria. Both Tween-80 and granular starch treated systems exhibited a significant increase in protein content. The glucose system, utilizing soluble substrates, exhibited a markedly higher total polysaccharide content. Microbial communities in the Tween-80 and granular starch treated systems were characterized by a higher abundance of bacteria known to enhance sludge flocculation and settling, such as Competibacter, Xanthomonadaceae and Zoogloea. These findings are of high significance for controlling the operational performance and stability of activated sludge systems, deepening our understanding and providing a novel perspective for the improvement of wastewater treatment processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are biodegradable plastics with great performance and development prospects. However, their traditional anaerobic/aerobic enrichment process requires a high concentration of dissolved oxygen (DO), resulting in high energy consumption. In this study, an anaerobic/oxygen-limited with secondary feeding enrichment mode was used to enhance the synthesis of PHAs while reducing energy consumption. The enrichment process of PHAs-synthesizing bacteria lasted up to 100 days, and the experiment was conducted to investigate the change of the PHAs synthesizing ability of the system in this mode by detecting the PHAs content and community distribution of the activated sludge under different stages. Under these conditions, the system enriched two major genera of PHAs-synthesizing bacteria, Thauera (30.21%) and Thiothrix (21.30%). The content of PHAs in the sludge increased from 4.51% to 30.87% and was able to achieve a concomitant increase in poly(3-hydroxyvalerate) (PHV) monomer content. After nitrogen limitation (C/N = 150) treatment, the content of PHAs reached 63.05%. The results showed that the enrichment mode of anaerobic/oxygen-limited with secondary feeding could enrich more PHAs-synthesizing bacteria and significantly increase the synthesis amount of PHAs, which revealed the great potential of this mode in solid waste value-added and reduce the production cost of PHAs and could provide a theoretical basis for the production of PHAs from activated sludge. [ABSTRACT FROM AUTHOR]

The article contains the procedure of image acquisition, including sampling of analyzed material as well as technical solutions of hardware and preprocessing used in research. A dataset of digital images containing identified objects were obtained with help of automated mechanical system for controlling the microscope table and used to train the YOLO models. The performance of YOLOv4 as well as YOLOv8 deep learning networks was compared on the basis of automatic image analysis. YOLO constitutes a one-stage object detection model, aiming to examine the analyzed image only once. By utilizing a single neural network, the image is divided into a grid of cells, and predictions are made for bounding boxes, as well as object class probabilities for each box. This approach allows real-time detection with minimal accuracy loss. The study involved ciliated protozoa Vorticella as a test object. These organisms are found both in natural water bodies and in treatment plants that employ the activated sludge method. As a result of its distinct appearance, high abundance and sedentary lifestyle, Vorticella are good subjects for detection tasks. To ensure that the training dataset is accurate, the images were manually labeled. The performance of the models was evaluated using such metrics as accuracy, precision, and recall. The final results show the differences in metrics characterizing the obtained outputs and progress in the software over subsequent versions of the YOLO algorithm. [ABSTRACT FROM AUTHOR]

A water resource recovery facility sited in a region at a high elevation has experienced the effects of over‐designing its blowers. In this case study, we used off‐gas analysis and site‐specific power tariffs to quantify actual process loading and air requirements, and we quantitatively evaluated various options for blower replacement or upgrade. Off‐gas analysis mapped the oxygen uptake rate at the surface of the tank, suggesting that the tanks were not evenly loaded across their sections. The local cost of energy directly affects the return on the investment calculation and limits the available solutions. The payback of partial or complete blower replacement may not be justified even in the event of excessive aeration, and the sequencing of aeration system improvements including diffuser replacement, process controls, and blower modifications should be evaluated contemporaneously. Practitioner Points: Off‐gas analysis can be used to evaluate process loading imbalances by mapping the oxygen uptake rate.Alpha factors from off‐gas testing are used in process models to evaluate air requirements and blower air demand.Comparative evaluation of blowers must be done considering the net present value of the status quo, upgrades, or replacement. [ABSTRACT FROM AUTHOR]

The mutual combination of permeable membrane aeration for oxygen supply and biofilm process has formed an innovative wastewater treatment technology, i・ e・, membrane aeration biofilm reactor (MABR), which has received extensive attention and research in recent years・ Based on the introduction of membrane materials, membrane components and mass transfer mechanism of MABR, we focused on the review of the influence of oxygen transfer rate, hydraulic retention time (HRT), carbon/nitrogen ratio (C/N), biofilm thickness, and pH on the process system of MABR in the process of practical application. Finally, MABR as an energy-saving and carbon-reducing water treatment process has become a breakthrough for improving quality and reducing consumption of traditional sewage plants in China. [ABSTRACT FROM AUTHOR]

The performance of anaerobic digestion of mixed sludge (MS) with upstream thermal hydrolysis of waste activated sludge (WAS) was evaluated and compared to conventional anaerobic digestion. In contrast to previous studies, this work focuses on the evaluation of the impact of the activated sludge process, which was assessed using a temperature-normalized solids retention time (SRTASP,T). For this purpose, data from a full-scale wastewater treatment plant related to SRTASP,T, primary sludge (PS) and WAS production were combined with experimental data from laboratory-scale anaerobic digestion of PS, WAS, thermally hydrolyzed WAS, and MS. The parameter SRTASP,T was used as a key link between the full-scale and experimental data. For WAS, SRTASP,T essentially influenced the efficacy of thermal hydrolysis on the performance of anaerobic digestion. The increase in methane yield was higher with increasing SRTASP,T. When considering MS, however, the increase was significantly lower and leveled out over the investigated range of SRTASP,T, mainly due to corresponding WAS/MS ratios. This study demonstrates that the knowledge of SRTASP,T, sludge production, and anaerobic degradability enables the assessment of the potential of thermal hydrolysis and its effect on anaerobic digestion. [ABSTRACT FROM AUTHOR]

In order to investigate the enhancement mechanism of modified three-dimensional elastic filler (MTEF) on the nitrogen removal performance of the integrated fixed-film activated sludge (IFAS) process, and to clarify the interactions between competition and synergy between activated sludge and biofilm in the IFAS system, an IFAS reactor (T2) filled with MTEF was employed for the study, while a sequencing batch reactor activated sludge process (SBR) reactor (T1) was utilized for comparison. IFAS and SBR reactors were operated over an extended period at ambient temperature to assess the enhancement of pollutant removal performance with the addition of the filler to investigate the competitive dynamics between activated sludge and biofilm under varying influent water qualities (C/N, N/P, and organic loading), and to analyze the synergistic relationship between activated sludge and biofilm at the microbial level using high-throughput sequencing technology. The results demonstrate that throughout the entire operational phase, reactor T2 exhibited superior pollutant removal efficiency. Compared to reactor T1, reactor T2 achieved an average increase in the removal rates of COD, ammonia nitrogen, and total nitrogen by 13.07%, 12.26%, and 28.96%, respectively. The findings on the competitive dynamics between activated sludge and biofilm indicate that the nitrification volumetric load of the IFAS system is significantly higher than that of a pure activated sludge system, suggesting that the IFAS system possesses enhanced nitrification capabilities. Furthermore, when dealing with wastewater characterized by low C/N ratios and high phosphorus pollution, or under substantial organic loads, the biofilm holds a competitive edge and the IFAS system exhibits improved stability. High-throughput sequencing data reveal that the microbial community structures in activated sludge and biofilm can influence each other, thereby enabling the IFAS system to effectively enrich denitrification-related functional microbial populations. Additionally, the biofilm has a certain enhancing effect on the expression levels of nitrogen metabolism-related functional genes in the activated sludge phase microorganisms, indicating that, in addition to competitive interactions, there is also a synergistic effect between the biofilm and activated sludge. [ABSTRACT FROM AUTHOR]

This study evaluates the influence of micropollutant chemical characteristics on the removal of pharmaceutical substances through three different treatments: membrane bioreactor, full wastewater treatment with final filtration (WWTP), and secondary treatment through a conventional activated sludges system, operated in parallel at realistic sludge retention time (SRT) over three years and four sampling campaigns. Treated wastewater from the WWTP enters the local canal with a low dilution ratio. Therefore, the monitoring of water contamination is of particular interest for a reliable assessment of environmental risk. A total of 39 pharmaceutical substances were screened. While differences among the three types of treatments were found statistically not significant, data analysis performed through a generalized linear model showed that both the influent concentration and the physicochemical characteristics are strong predictors for the removal of micropollutant. SRT had no significance for the three types of treatment of this study. Finally, pharmaceuticals were divided into three major classes based on their influent concentration and removal. A canonical discriminant analysis was used to predict the removals and showed that the pharmaceuticals removal rates are strongly influenced by their hydrophobicity/hydrophilicity and enabled to predict their removal categories with high accuracy (i.e., 65% of correct predictions). [ABSTRACT FROM AUTHOR]

Addressing the global antimicrobial resistance (AMR) crisis requires a multifaceted innovative approach to mitigate impacts on public health, healthcare and economic systems. In the complex evolution of AMR, biofilms and the acquisition of antimicrobial resistance genes (ARGs) play a pivotal role. Aeromonas is a major AMR player that often forms biofilm, harbors ARGs and is frequently detected in wastewater. Existing wastewater treatment plants (WWTPs) do not have the capacity to totally eliminate antimicrobial-resistant bacteria favoring the evolution of ARGs in wastewater. Besides facilitating the emergence of AMR, biofilms contribute significantly to biofouling process within the activated sludge of WWTP bioreactors. This paper presents the inhibition of biofilm formation, the expression of biofilm-linked genes and ARGs by phytochemicals andrographolide, docosanol, lanosterol, quercetin, rutin and thymohydroquinone. Aeromonas species were isolated and purified from activated sludge samples. The ARGs were detected in the isolated Aeromonas species through PCR. Aeromonas biofilms were quantified following the application of biocompounds through the microtiter plate assay. qPCR analyses of related genes were done for confirmation. Findings showed that the natural compounds inhibited the formation of biofilms and reduced the expression of genes linked to biofilm production as well as ARGs in wastewater Aeromonas. This indicates the efficacy of these compounds in targeting and controlling both ARGs and biofilm formation, highlighting their potential as innovative solutions for combating antimicrobial resistance and biofouling. [ABSTRACT FROM AUTHOR]

Vermicelli production generates wastewater that is rich in organic and nutrient pollutants, which poses significant environmental challenges. Conventional biological treatments, either alone or in combination with other methods, often fail to achieve high efficiency and operational stability. This study explored the potential of the Fenton process, followed by aerobic activated sludge treatment, to enhance the biodegradability and mineralization of organic substances in vermicelli wastewater. Orientation experiments were performed to examine the effects of operating variables such as pH, reaction time, settling time, and ratio H2O2/Fe2+ on COD removal in order to select the optimal conditions for operating the model in a batch of 20 L, that is, pH = 3, reaction time of 90 min, settling time of 90 min, and ratio of H2O2/Fe2+ used 3 : 1 (4.5 : 1.5 g/L). The removal efficiencies of COD, BOD5, TN, TP, and SS reached 75.83%, 67.26%, 28.24%, 26.63%, and 91.9%, respectively. The BOD5/COD increased from 0.52 to 0.63, facilitating aerobic activated sludge, which had batch conditions of 15 L with pH of 6.5–8.5, DO ≥3 mg/L, additional nutrients with a dose of 12 mg/L, retention time of 14 h, and settling time of 2 h. As a result, the removal rate of those parameters climbed quite notably, except in SS (95.6%, 96.0%, 84.6%, 84.1%, and 83.6%), and their concentration parameters remained within the allowance levels of the National Technical Regulation in Vietnam before being discharged into the environment. However, the efficiency of treatment in the aerobic activated sludge stage for removing COD and BOD5 was not as high as anticipated (83% and 87.33%, respectively) owing to the influence of the high TDS concentration. Thus, additional research is required to address this challenge. The integrated treatment system combining the Fenton process with aerobic activated sludge demonstrated significant potential for the effective reduction of organic and nutrient pollutants in vermicelli wastewater, thereby achieving compliance with regulatory standards. However, the observed limitations in COD and BOD5 removal efficiency, likely due to elevated TDS levels, indicate the need for further investigation and optimization to enhance the overall treatment performance. [ABSTRACT FROM AUTHOR]

Paracetamol is one of the most commonly used painkillers. Its significant production and consumption result in its presence in the environment. For that reason, paracetamol has a negative impact on the organisms living in ecosystems. Therefore, it is necessary to develop effective methods to remove paracetamol from sewage. One of the methods is the bioaugmentation of activated sludge with organisms with increased degradation potential in relation to paracetamol. This study determined the effectiveness of paracetamol degradation by activated sludge augmented with a free or immobilised Pseudomonas moorei KB4. To immobilise the strain, innovative capsules made of cellulose acetate were used, the structure of which provides an optimal environment for the development of bacteria. Augmentation with both a free and immobilised strain significantly improves the efficiency of paracetamol biodegradation by activated sludge. Over a period of 30 days, examined systems allowed ten doses of paracetamol decomposition, while the unaugmented system degraded only four. At the same time, using the immobilised strain does not significantly affect the functioning of the activated sludge, which was reflected in the stability of processes such as nitrification. Due to the high stability of the preparation, it can become a valuable tool in wastewater treatment processes. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of different seasons (where the temperature would be different) on the performance (phosphorous, nitrogen, and organic matter removal) of sequencing batch reactor (SBR) based wastewater treatment plants. The modified activated sludge model 2D (ASM2d) module, including the microbial kinetics is used to simulate the enhanced biological phosphorus removal (EBPR) SBR process and the temperature is chosen between 10 and 33°C. Influent data from two distinct wastewater treatment plants located in India and Europe are considered. The investigation of the kinetic variables is performed over a wide temperature range, and significant increases are seen as the temperature rises. The effluent parameters are within the government regulations. It is clear that an increase in temperature results in better effluent quality with reduced values of chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium nitrogen and ammonium ions (NH4), and total nitrogen (TN) and a slight increase in total phosphorus (TP) and total suspended solids (TSS). According to the current findings, as the temperature changes from low to high levels, the values of COD, BOD, TN, and NH4 decreased by 2.50, 14.92, 5.80, and 9.90% respectively, for Indian data. There is a slight increase of 1.07% in the TSS profile. In conclusion, this study highlights the importance of considering the effect of different climatic conditions on the performance of SBR-based wastewater treatment plants. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of tracking the output of an activated sludge process using fuzzy integral control. First, the dynamics of the nonlinear process are modeled with a dynamic state space fuzzy model integrating the effect of external disturbances, and then an additional integral state of the output tracking error is introduced to obtain an augmented Takagi-Sugeno (TS) fuzzy model. The TS fuzzy model is able to describe the dynamics of complex nonlinear systems with an excellent degree of accuracy. It is formulated by fuzzy if-then rules which can give local linear representation of the overall nonlinear system. Second, the design of the fuzzy integral control is performed, in which the state feedback gains are obtained by solving linear matrix inequalities (LMI). The objective is to ensure trajectory tracking of an activated sludge process (ASP) by controlling two key variables: the substrate concentration and the level of dissolved oxygen. To assess the performance of the proposed control strategy, a comparative analysis is carried out with a gain scheduling PI (GS-PI) controller. Simulation results are provided to illustrate the effectiveness of the proposed approach. Where, the fuzzy integral control reduces the high energy consumption in water treatment plants. [ABSTRACT FROM AUTHOR]

This study investigated the decolorization and detoxification of a dye originating from a feather-dyeing house using the laccase enzyme. Efficient decolorization was achieved under a wide range of environmental conditions, including pH, temperature, enzyme loading, and dye concentration. The decolorization rate reached up to 98% within 10 min when the mediator acetosyringone was present. Decolorization was attributed to the degradation of the dye by laccase, as analyzed using liquid chromatography-mass spectrometry (LC–MS). At least three dominant intermediates (m/z 167.993, 194.475, 118.040) were identified, deriving from the original dye (m/z 521.044). Compared to the non-decolorized dye solution, the decolorized dye ones at various concentrations exhibited lower toxicity towards aerobic activated sludge (AS). This was evident from the significantly higher respiratory intensity of AS, with an O₂ uptake of 35 mg for the decolorized solution versus 11 mg for the non-decolorized solution after 12 h at a 100 mg/L dye concentration. The results suggest that laccase-catalyzed decolorization could serve as an effective pretreatment method for traditional activated sludge (AS)-based processes, thereby enhancing the overall treatment performance of dye wastewater. [ABSTRACT FROM AUTHOR]

Wastewater treatment using the activated sludge method requires a large amount of electricity for aeration. Therefore, wastewater treatment using co-culture systems of microalgae and heterotrophic microorganisms, which do not require aeration, has attracted attention as an energy-saving alternative to the method. In this study, we investigated different combinations of microalgae and heterotrophic microorganisms to improve the efficiency of wastewater treatment. Three types of microalgae and five heterotrophic microorganisms were used in combination for wastewater treatment. The combination of Chlamydomonas reinhardtii NIES-2238 and Saccharomyces cerevisiae SH-4 showed the highest wastewater treatment efficiency. Using this combination for artificial wastewater treatment, the removal rates of total organic carbon, PO43−, and NH4+ reached 80%, 93%, and 63%, respectively, after 18 h of treatment. To the best of our knowledge, this is the first study to show that a combination of green algae and yeast improves the efficiency of wastewater treatment. Transcriptome analysis revealed that the combined wastewater treatment altered the expression of 1371 and 692 genes in C. reinhardtii and S. cerevisiae, respectively. One of the main reasons for the improved wastewater treatment performance of the combination of green algae and yeast was the increased expression of genes related to the uptake of phosphate and ammonium ions in the green algae. As both the green algae C. reinhardtii and the yeast S. cerevisiae are highly safe microorganisms, the establishment of their effective combination for wastewater treatment is highly significant. Key points: • Combination of various microalgae and heterotrophic microorganisms was tested • Combination of green algae and yeast showed the highest efficiency • This is the first report that this combination is effective for wastewater treatment [ABSTRACT FROM AUTHOR]

Achieving carbon neutrality in wastewater treatment plants relies heavily on mainstream anaerobic ammonia oxidation. However, the stability of this process is often compromised, largely due to the significant influence of microbial morphology. This study analyzed 208 microbial samples using bioinformatics and machine learning (ML) across four different morphologies: Suspended Sludge (SS), Biofilm, Granular Sludge (GS) and the Integrated Fixed-film Activated Sludge process (IFAS). The results revealed IFAS's notably complex and stable community structure, along with the identification of endemic genera and common genera among the four microbial morphologies. Through cooccurrence network analysis, the interaction between microorganisms of various genera was displayed. Utilizing the Extreme Gradient Boosting (XGBoost) model, a ML modeling framework based on microbiome data was developed. The MLbased feature importance analysis identified LD-RB-34 as a key organism in SS and BSV26 was an important bacterium in IFAS. Additionally, functional bacteria KF-JG30-C25 occupied a higher proportion in GS, and Unclassified Brocadiaceae occupied a higher proportion in Biofilm. Furthermore, dissolved oxygen, temperature and pH were identified as the primary factors determining microbial communities and influencing anammox activity. Overall, this study deepens our understanding of bacterial communities to enhance the mainstream anammox nitrogen removal. [ABSTRACT FROM AUTHOR]

Intensified cavitation‐assisted biogas production from sustainable feedstock has been discussed describing the working principles and governing mechanisms for intensification. Various methods of biogas production discussed in the work include activated sludge processes, membrane bioreactor (MBR), and processes involving methanogenic and sulfate‐reducing microorganisms. Design aspects of cavitational reactors (sonochemical and hydrodynamic cavitation) have been presented with detailed understanding into effect of several operational parameters, such as the biomass‐to‐water ratio, operating pressure, treatment duration, operating temperature, power dissipation, and so on. Selection of optimum parameters is crucial to improve the performance and observed intensification from such processes. The possible benefits in terms of applicability to various types of biomass, efficiency, higher yields, and energy‐saving as compared to the conventional production processes have been demonstrated. Overall, cavitation‐assisted techniques are very effective in increasing biogas production and have significant potential for commercial applications, which would result in significant cost savings. [ABSTRACT FROM AUTHOR]

To prioritise which faults should be detected in a biological wastewater treatment process, and with what level of urgency, it is necessary to understand the effect that they have on the process. Using the Benchmark Simulation Model No. 1 and 2. (BSM1 and BSM2), several process and sensor faults were considered and their impacts on various cost, quality, and controller performance evaluation metrics analysed. Both the cost of treating the wastewater and the quality of the effluent were impacted in varying degrees of severity by the faults tested. The most influential faults in both models were decreases to autotrophic and heterotrophic growth rates, decreases to the heterotrophic death rate, and the inhabitation fault. It was shown that only larger fault sizes were significant, and the required speed of detection is dependent on the fault profile. Prioritising detection of the most influential faults was shown to have significant effects on monitoring requirements for fault detection and the subsequent complexity required of a fault detection system. A valuable takeaway was the similarity of results from BSM1 and BSM2; the consistency of the influential process faults suggests that systems that can be described by these models are likely affected by the same faults. HIGHLIGHTS Critical faults can be effectively highlighted through a simulation-based analysis of their effects.; Consistency of influential process faults across BSM1 and BSM2 provides transferrable knowledge.; Complexity of diagnostic algorithms can be reduced by knowing which faults should be prioritised.; Physical monitoring requirements and costs can be reduced if the monitoring focus is narrowed.;

In wastewater treatment by the activated sludge (AS) process, settleability and dewaterability of AS are key issues that are directly related to the treated water quality and sludge treatment costs. Several studies investigated the relationship between the shape of AS flocs and their settling/dewatering property. To quantify the floc morphology, it is imperative to attach a camera to a microscope or move the stage manually. Hence, labour and equipment costs may increase. In this study, by combining a digital microscope and an automatic stage, more than 100 magnified floc images were rapidly obtained from one AS sample dropped on a slide glass, and shape parameters were collectively calculated using an analysis software. During 1-year monitoring of four wastewater treatment plants in Sapporo City (Hokkaido, Japan), the morphological parameters and extracellular polymeric substances (EPS) quantity/quality of AS were analyzed on the basis of their correlation to the time to filtration (TTF) and sludge volume index (SVI), which are indicators for describing the dewatering and settling properties of AS, respectively. In one plant, larger, denser, and smoother flocs tended to contain less EPS and exhibited better sludge dewaterability. In another plant, larger, denser, and smoother flocs were considered to contribute to better settlement. Especially, an equivalent high-density floc diameter and the ratio of mixed liquor suspended solids (MLSS) concentration to the total floc area were commonly suggested to explain AS dewaterability and settleability. [ABSTRACT FROM AUTHOR]

It is well accepted that the high performance of wastewater treatment plants (WWTPs) relies on the microbial community in activated sludge (AS). Hence, it is crucial to illuminate the geographic distributions and influencing factors of the ecological strategies employed by the AS microbial community. Here, we investigated how the ecological strategies of AS microbial communities influenced their ecological characteristics in 60 WWTPs across 15 cities in China. Our study showed that the average rrn copy number of the whole AS microbial community across China was 2.25 ± 0.12. The highest average rrn copy number of the core community indicated that core members tend to be r-strategists with an advantage in rapid pollutant removal and recovery of the community after environmental disturbances. High nutrient availability promoted microorganisms with higher average rrn copy numbers, while long sludge retention time (SRT) was preferred to the microorganisms with lower average rrn copy numbers. Homogenous selection and dispersal limitation were the predominant assembling processes at the city level, with a shift from deterministic to stochastic processes with increasing average rrn copy numbers. Furthermore, more r-strategists participated in chemoheterotrophic functions, while more K-strategists were related to the nitrification processes. Overall, our findings enrich the knowledge of AS microbial ecology and lay the theoretical foundation for the precise regulation of WWTPs. [ABSTRACT FROM AUTHOR]

Conventional wastewater treatment plants (WWTPs) are not designed for the abatement of antibiotics, and their effluents are one of the main entry ways of these emerging contaminants to the aquatic environment, causing major concern due to their toxicity, persistence, and bioaccumulation. When wastewater containing antibiotics enters the bioreactor, they can impact microbial communities of the activated sludge, affecting biodegradation processes of organic matter and nutrients. There is scarce information about the effect of activated carbon on the activated sludge within the bioreactor in presence of antibiotics. In light of this, the effect of representative antibiotics, ciprofloxacin (CIP), nalidixic acid (NAL), and erythromycin (ERY), on the performance of a conventional activated sludge of a WWTP was analyzed by respirometry with and without activated carbon. NAL and ERY negatively affected the net heterotrophic biomass growth rate (r′x,H), with reduction percentages of 26%–90% and 31%–81%, respectively. The addition of activated carbon mitigated this effect, especially for ERY, with increments of even 8% in the r′x,H for the hybrid process when working with 5 ppm of ERY and 80 ppm of activated carbon compared with the value in the absence of antibiotic and activated carbon. This effect was attributed to the enhanced retention of ERY, in comparison to NAL, on the surface of the activated carbon, probably due to its higher molecular size and affinity towards the activated carbon (log Kow = 3.06). This effect was more marked at low sludge retention times (below 8 days). Practitioner points: Ciprofloxacin (CIP), nalidixic acid (NAL), and erythromycin (ERY) were studied.NAL and ERY exerted negative impact on heterotrophic growth rate.Effect of antibiotics on microorganisms in the presence of activated carbon was studied.Activated carbon was mainly relevant for ERY due to its adsorption retention.Enhancement by activated carbon was more significant at low sludge retention times. [ABSTRACT FROM AUTHOR]

Partial denitrification granular sludge (PDGS) can provide long-term stable nitrite for anaerobic ammonia oxidation (anammox). The cultivation of ordinary activated sludge from wastewater treatment plants into PDGS can further promote the application of PD in practical engineering. In this study, the feasibility of fast start-up of PDGS was explored by inoculating waste sludge in up-flow anaerobic sludge blanket (UASB) reactor with synergistic control of nitrogen load rate (NLR, 0.05–0.65 kg N/m3/d) and electron donor starvation (EDS) (240–168 mg L−1), and system performance, particle characteristics and microbial structure were studied. The results showed that PD-UASB started successfully within 48 days, the average nitrite accumulation rate (NTR) and nitrate removal ratio (NRR) reached 79.6% and 82.5% after successful initiation, accompanied by high abundance of PD bacteria (Thauera, Pseudomonas, unclassflied commamonadaceae and Limnobacter) (25.3%). The increase of PD activity, and the difference between nitrate reductase (NAR) and nitrite reductase (NIR) contributed to nitrite production. Besides, the sludge shifted from flocculated (≤0.5 mm, 95.37%) to granulated state (0.5–2 mm, 64.74%), which could be due to the increase of extracellular polymers (EPS) (especially T-EPS) and metabolism of specific microorganisms (Bacteroidota and Chloroflexi, 19.92%). Good sludge granulation promoted the settleability of PD (the SVI5 was 47.248 mL/ g. ss after successful start-up). In summary, good PD sludge granulation process could be achieved in a short time by synergistically controlling NLR and EDS. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) shows promise in treating piggery wastewater compared to conventional activated sludge methods. However, current AGS research primarily remains confined to the laboratory, with limited practical applications in actual piggery wastewater treatment. Besides, AGS faces challenges such as unstable structure and susceptibility to sludge bulking in practical settings. This study aimed to assess AGS's efficacy in treating actual piggery wastewater and successfully resolved the non-filamentous bulking issue through various measures. AGS formation occurred by the 13th day of operation, demonstrating high pollutant removal rates, with ammonia nitrogen (NH4+-N), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP) removal rates reaching 99%, 99%, 90%, and 96%, respectively. However, Zoogloea overgrowth led to increased polysaccharide secretion and subsequent non-filamentous bulking on the 32nd day, which adversely impacted TN, COD, and TP removal efficiency. To address the bulking issue, the influent COD concentration was initially adjusted from 500 ± 50 mg/L to 2000 ± 50 mg/L and then decreased to 700 ± 50 mg/L. Additional measures included lowering water temperature, enhancing hydraulic shear force and selective pressure, and conducting manual screening, resulting in a notable decrease in sludge bulking by the 60th day. Throughout the granulation process, there was a reduction in species diversity and microbial biomass in the sludge, especially noticeable before and after addressing the sludge bulking issue. Initially, Zoogloea dominated the AGS, but following the resolution of the non-filamentous bulking issue, there was a shift to Thauera as the dominant bacterium. [ABSTRACT FROM AUTHOR]

This paper presents a concept of architecture and ontology layouts for the development of multiagent model-based predictive control systems. The presented architecture provides guidelines to simplify the development of agent-based systems and improve their maintainability. The proposed multiagent system (MAS) layout is split into multiple subsystems that include agents dedicated to performing assigned tasks. MAS implementation was prepared which can use provided algorithms and actuators and can react to changes in its environment to reach the best available control quality. An example of MAS based on the proposed architecture is shown in the application of dissolved oxygen (DO) concentration control in a laboratory-activated sludge setup with a biological reactor. For that application, MAS incorporates agent-based controllers from the boundary-based predictive controllers (BBPC) family. Presented experiments prove the flexibility, resilience, and online reconfiguration ability of the proposed multiagent system. [ABSTRACT FROM AUTHOR]

The direct equalizing ray method was employed to design three groups of mixtures of oxytetracycline(OTC) and norfloxacin(NOR) with varying proportions(Group R1 had a higher proportion of OTC, while R2 had similar concentrations of both antibiotics, and R3 had a higher proportion of NOR).The effects of these mixtures on the content and properties of extracellular polymeric substances (EPS) in the biological denitrification process were investigated using an sequencing batch reactor activated sludge reactor (SBR). The results revealed that the removal rates of ammonia nitrogen(NH 3 -N) decreased in all three groups with the addition of antibiotics. As the antibiotic concentration increased, the EPS content decreased by 68.46%, 55.53%, and 65.03% in R1, R2, and R3, respectively. To understand the interaction mechanism of mixed antibiotics on EPS in activated sludge, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques were employed. The findings demonstrated significant effects of mixed antibiotics on functional groups such as C-O, C O, and C-O-C. Specifically, hydrogen bonding was found to be the primary influencing factor in the R1 ratio, while Π-Π conjugation played a major role in the R3 ratio. [Display omitted] • High-concentration mixture of OTC and NOR inhibitory nitrogen removal performance of SBR. • High-concentration mixture of OTC and NOR reduced the production of extracellular polymeric substances. • High proportion of OTC, the EPS characteristics are mainly affected by hydrogen bonding interactions. • High proportion of NOR, the EPS characteristics are mainly affected by hydrogen bonding interactions and π-π conjugation. [ABSTRACT FROM AUTHOR]

Biological treatment with a stable activated sludge process, followed by chemical treatment is one of the potential and accepted cyanide remediation processes for coke plant wastewater treatment. Biologically treated coke plant wastewater contains free cyanide above permissible limit. Presently, chemical treatment with NaOCl is being used to attenuate free cyanide below permissible limit in biologically treated water. This process increases the TDS and colour content in discharge water. Ca(OCl)2 can be used as an alternative to NaOCl for cyanide remediation in biologically treated coke plant wastewater without increasing TDS. In the present work, cyanide removal efficiency of NaOCl and Ca(OCl)2 for real coke plant wastewater after biological treatment has been studied. Optimisation of chemical dosage, treatment time and pH study has been done for Ca(OCl)2 and NaOCl treatment. It was found that up to 90% of free cyanide removal could be achieved through Ca(OCl)2 treatment without increasing the TDS value. In addition, more than 50% colour of the wastewater was removed. pH elevation step required in NaOCl treatment can be eliminated in Ca(OCl)2 treatment, thereby reducing caustic consumption. The study indicated that the use of Ca(OCl)2 is economically more viable than that of NaOCl in cyanide treatment. [ABSTRACT FROM AUTHOR]

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This research examines advancements in the development of process-based models of constructed wetlands (CWs) tailored for simulating conventional water quality parameters (CWQPs). Despite the promising potential of CWs for emerging organic contaminant (EOC) removal, the available CW models do not yet integrate EOC removal processes. This study explores the need and possibility of integrating EOCs into existing CW models. Nevertheless, a few researchers have developed process-based models of other wastewater treatment systems (e.g., activated sludge systems) to simulate certain EOCs. The EOC removal processes observed in other wastewater treatment systems are analogous to those in CWs. Therefore, the corresponding equations governing these processes can be tailored and integrated into existing CW models, similarly to what was done successfully in the past for CWQPs. This study proposed the next generation of CW models, which outlines 12 areas for future work: integrating EOC removal processes; ensuring data availability for model calibration and validation; considering quantitative and sensitive parameters; quantifying microorganisms in CWs; modifying biofilm dynamics models; including pH, aeration, and redox potential; integrating clogging and plant sub-models; modifying hydraulic sub-model; advancing computer technology and programming; and maintaining a balance between simplicity and complexity. These suggestions provide valuable insights for enhancing the design and operational features of current process-based models of CWs, facilitating improved simulation of CWQPs, and integration of EOCs into the modelling framework. [ABSTRACT FROM AUTHOR]

The activated sludge process plays a crucial role in modern wastewater treatment plants. During the treatment of daily sewage, a large amount of residual sludge is generated, which, if improperly managed, can pose burdens on the environment and human health. Additionally, the highly hydrated colloidal structure of biopolymers limits the rate and degree of dewatering, making mechanical dewatering challenging. This study investigates the impact and mechanism of microwave irradiation (MW) in conjunction with peracetic acid (PAA) on the dewatering efficiency of sludge. Sludge dewatering effectiveness was assessed through capillary suction time (CST) and specific resistance to filtration (SRF). Examination of the impact of MW-PAA treatment on sludge dewatering performance involved assessing the levels of extracellular polymeric substances (EPS), employing three-dimensional excitation-emission matrix (3D-EEM), Fourier transform–infrared spectroscopy (FT-IR), and scanning electron microscopy. Findings reveal that optimal dewatering performance, with respective reductions of 91.22% for SRF and 84.22% for CST, was attained under the following conditions: microwave power of 600 W, reaction time of 120 s, and PAA dosage of 0.25 g/g MLSS. Additionally, alterations in both sludge EPS composition and floc morphology pre- and post-MW-PAA treatment underwent examination. The findings demonstrate that microwaves additionally boost the breakdown of PAA into •OH radicals, suggesting a synergistic effect upon combining MW-PAA treatment. These pertinent research findings offer insights into employing MW-PAA technology for residual sludge treatment. [ABSTRACT FROM AUTHOR]

More‐than‐human, multispecies and animal geographic accounts of the city have tended to focus on large, charismatic and wild organisms, to the detriment of spatially invisible other‐than‐humans that are central to urban reproduction. At the same time, urban microbial geographies have foregrounded embodied interactions between humans and microorganisms, whether they are symbiotic or pathogenic, often marginalising the material contributions of extracorporeal microbiomes to the urban fabric. Building from these two blindspots, this article focuses on microbial ecologies that live constitutively outside of (other‐than‐)human bodies and which are intimately caught up in the metabolic intensities and infrastructural environments of the urban realm. There are two key aims: (1) to explore different forms of urban microbial ecologies and (2) to examine their relationships with urban infrastructures and reproduction. My disciplinary lenses are animal geography, microbe studies and urban ecology and my case studies are focused on urban water metabolism. Thus, based on empirical fieldwork on the urban River Lea in East London and supplemented by scientific literature and technical documents, I analyse three urban microbial ecologies that correspond to the urban realms' 'extended microbiomes': those involved in slow sand filtration for the treatment of drinkable water, those involved in sewage treatment via the activated sludge process and those emerging and evolving in disused urban canal infrastructure. These processes spatially manage microbial growth and modulate the distribution of different forms of microbial agency with important effects for the smooth functioning of urban water metabolism. I suggest these ecologies correspond to the 'spaces' of microbes in the city, and characterise a mundane system of repetition and regulation. However, microbes continue to assert their agency within the spaces of urban water metabolism, create their own places and worlds and highlight a more‐than‐human contingency and indeterminacy at the heart of urban reproduction. [ABSTRACT FROM AUTHOR]

Tanneries generate copious amounts of potentially toxic sludge and effluent from the processing of skins and hides to leather. The effluent requires remediation before discharge to protect the receiving environment. A range of physicochemical methods are used for pre- and post-treatment, but biological secondary remediation remains the most popular choice for the reduction of the organic and macronutrient fraction of tannery effluent. This review provides an update and critical discussion of biological systems used to remediate tannery effluent. While the conventional activated sludge process and similar technologies are widely used by tanneries, they have inherent problems related to poor sludge settling, low removal efficiencies, and high energy requirements. Treatment wetlands are recommended for the passive polishing step of beamhouse effluent. Hybrid systems that incorporate anoxic and/or anaerobic zones with sludge and/or effluent recycling have been shown to be effective for the removal of organics and nitrogenous species at laboratory scale, and some have been piloted. Novel systems have also been proposed for the removal and recovery of elemental sulfur and/or energy and/or process water in support of a circular economy. Full-scale studies showing successful long-term operation of such systems are now required to convince tanneries to modernize and invest in new infrastructure. [ABSTRACT FROM AUTHOR]

Aeration is crucial for the biological decomposition of organic compounds in wastewater treatment. However, it is a highly energy-intensive process in traditional activated sludge systems, accounting for 50% to 75% of a plant's electricity consumption and making it a major cost driver for wastewater treatment plants. Nanobubbles (NBs), characterized by their tiny size with diameters less than 200 nm, have emerged as a potential alternative to the low efficiency of aeration and high sludge production in aeration systems. NBs proved effective in removing COD and other pollutants from wastewater. For example, when applied in flotation, aeration, and advanced oxidation, NBs achieved up to 95%, 85%, and 92.5% COD removal, respectively. Considering the recent advancements in wastewater treatment, a compelling need arises for a thorough investigation of the effectiveness and mechanisms of nanobubbles in this field. This systematic review summarizes recent advancements in understanding nanobubbles (NBs) and their unique properties that enhance physical, chemical, and biological water and wastewater treatment processes. Moreover, this study reviews various methods for generating NBs and provides an in-depth review of their applications in wastewater treatment, with a particular focus on poultry slaughterhouse wastewater (PSW) treatment. [ABSTRACT FROM AUTHOR]

Introduction: Simultaneous chemical phosphorus removal process using iron salts (Fe(III)) has been widely utilized in wastewater treatment to meet increasingly stringent discharge standards. However, the inhibitory effect of Fe(III) on the biological phosphorus removal system remains a topic of debate, with its precise mechanism yet to be fully understood. Methods: Batch and long-term exposure experiments were conducted in six sequencing batch reactors (SBRs) operating for 155  days. Synthetic wastewater containing various Fe/P ratios (i.e., Fe/P  =  1, 1.2, 1.5, 1.8, and 2) was slowly poured into the SBRs during the experimental period to assess the effects of acute and chronic Fe(III) exposure on polyphosphate-accumulating organism (PAO) growth and phosphorus metabolism. Results: Experimental results revealed that prolonged Fe(III) exposure induced a transition in the dominant phosphorus removal mechanism within activated sludge, resulting in a diminished availability of phosphorus for bio-metabolism. In Fe(III)-treated groups, intracellular phosphorus storage ranged from 3.11 to 7.67  mg/g VSS, representing only 26.01 to 64.13% of the control. Although the abundance of widely reported PAOs (Candidatus Accumulibacter) was 30.15% in the experimental group, phosphorus release and uptake were strongly inhibited by high dosage of Fe(III). Furthermore, the abundance of functional genes associated with key enzymes in the glycogen metabolism pathway increased while those related to the polyphosphate metabolism pathway decreased under chronic Fe(III) stress. Discussion: These findings collectively suggest that the energy generated from polyhydroxyalkanoates oxidation in PAOs primarily facilitated glycogen metabolism rather than promoting phosphorus uptake. Consequently, the dominant metabolic pathway of communities shifted from polyphosphateaccumulating metabolism to glycogen-accumulating metabolism as the major contributor to the decreased biological phosphorus removal performance. [ABSTRACT FROM AUTHOR]

Direct ammonia oxidation (Dirammox) might be of great significance to advance the innovation of biological nitrogen removal process in wastewater treatment systems. However, it remains unknown whether Dirammox bacteria can be selectively enriched in activated sludge. In this study, a lab-scale bioreactor was established and operated for 2 months to treat synthetic wastewater with hydroxylamine as a selection pressure. Three Dirammox strains (Alcaligenes aquatilis SDU_AA1, Alcaligenes aquatilis SDU_AA2, and Alcaligenes sp. SDU_A2) were isolated from the activated sludge, and their capability to perform Dirammox process was confirmed. Although these three Dirammox bacteria were undetectable in the seed sludge (0%), their relative abundances rapidly increased after a month of operation, reaching 12.65%, 0.69%, and 0.69% for SDU_A2, SDU_AA1, and SDU_AA2, respectively. Among them, the most dominant Dirammox (SDU_A2) exhibited higher nitrogen removal rate (32.35%) than the other two strains (13.57% of SDU_AA1 and 14.52% of SDU_AA2). Comparative genomic analysis demonstrated that the most dominant Dirammox bacterium (SDU_A2) possesses fewer complete metabolic modules compared to the other two less abundant Alcaligenes strains. Our findings expanded the understanding of the application of Dirammox bacteria as key functional microorganisms in a novel biological nitrogen and carbon removal process if they could be well stabilized. Key points: • Dirammox-dominated microbial community was enriched in activated sludge bioreactor. • The addition of hydroxylamine played a role in Dirammox enrichment. • Three Dirammox bacterial strains, including one novel species, were isolated. [ABSTRACT FROM AUTHOR]

In recent years, microplastics (MPs) have attracted worldwide attention as emerging pollutants, and wastewater treatment plants are among the environment's most important sources of MPs. This study aimed to summarize MPs effects on various aspects of sludge systems. The results showed that MPs inhibited substance transformation in sludge systems, with greater inhibition observed at higher concentrations and smaller MP particle sizes. Moreover, low concentrations of MPs promote extracellular polymeric substance (EPS) secretion, whereas high concentrations suppress EPS secretion, destroying the sludge structure. Granular sludge systems exhibit higher resistance to MPs than activated sludge systems owing to their layered structures. Micrometer-sized MPs primarily inhibit the dewatering performance of activated sludge through physical crushing, while nano-sized MPs primarily affect sludge dewatering through biological effects. However, for granular sludge system, micrometer-sized MPs were unable to penetrate the granular sludge interior, their affinity and aggregation capabilities enabled them to accumulate on the sludge surface. In contrast, nano-sized MPs can enter the interior of granular sludge and impair mass-transfer pathways, ultimately resulting in toxic effects. Furthermore, MPs induce various toxic effects in sludge systems (single and combined toxic effects). These toxic effects affect the expression of key enzymes and functional genes, leading to changes in microbial communities. Because of the layered structure of granular sludge systems, MPs may initially affect the microbial community structure outside the granules, with less impact on the internal microorganisms. However, the specific mechanism still needs to be explored. Finally, this study presents research questions and directions that require further investigation. [ABSTRACT FROM AUTHOR]

Wastewater Treatment Plants (WWTPs) play a crucial role in maintaining ecological balance, a cornerstone of environmental health for thriving biodiversity and undisturbed natural processes. This balance is crucial for the sustainability of ecosystems, directly influencing human health, biodiversity, and the overall quality of our natural environment. WWTPs contribute to this equilibrium by efficiently removing pollutants and harmful substances from wastewater, thus averting the degradation of water bodies that are essential for numerous ecological processes. WWTPs encompass multiple stages of wastewater and sludge treatment and are significant energy consumers globally, especially in secondary treatment, particularly the activated sludge method which is the most common method. With an upcoming directive from the European Union aiming to reduce energy consumption in WWTPs, this paper focuses on a literature review examining global practices implemented across all stages of WWTP treatment processes. It summarizes the key points of each study, focusing primarily on the outcomes of each application. This document concludes with an in-depth review of each study and provides general conclusions for each group of studies. The objective is to identify methods that have effectively reduced energy consumption and enhanced the overall energy efficiency of WWTPs. The main conclusions indicate that the studies encompass a wide range of applications that achieve significant reductions in energy consumption. However, additional testing of these applications in more diverse operating environments through trials could further enhance their reliability and increase acceptance among WWTP operators. [ABSTRACT FROM AUTHOR]

This research presents an innovative data fusion model that utilizes Monte Carlo simulations (MC) and the Gray Analytic Hierarchy Process (G-AHP) to address the complexity and uncertainty in decision-making processes, particularly in selecting sustainable wastewater treatment systems. The study critiques and extends the Dempster–Shafer and Yager's theories by incorporating a novel MC algorithm that mitigates the computational challenges of large numbers of experts and sensors. The model demonstrates superior performance in synthesizing diverse expert opinions and evidence, ensuring comprehensive and probabilistically informed decision-making under uncertainty. The results show that the combined MC algorithm produces satisfactory results, and thus, offers wide applicability in decision-making contexts. To determine its effectiveness, an extensive empirical study was conducted to identify an appropriate wastewater treatment system for the busy city of Tehran, incorporating the insights and perspectives of respected experts in the field. The selection was based on three technical, economic, and environmental–social criteria. Due to the large dimensions of each of the defined criteria, sub-criteria were also defined to achieve better results for each of the criteria. The in-depth analysis conducted revealed that enhanced aeration activated sludge (EAAS) emerged as the best choice for Tehran's most urgent needs among various competitors, with a remarkable priority rating of 34.48%. Next, the Gray Analytic Hierarchy Process (G-AHP) was used to determine the most important sub-criterion, based on which resistance to hydraulic shock is most important in the enhanced aeration activated sludge system. Due to its versatility in different fields and industries, this method is a powerful tool for managers to optimize system efficiency and identify defects and risks and eventually to minimize costs. [ABSTRACT FROM AUTHOR]

Development of environment-friendly and efficient aquaculture effluent treatment system is crucial for sustainable intensification of aquaculture, in the face of the rapidly increasing environmental pressure in the mariculture industry. In this study, mariculture wastewater was treated by the anoxic-anaerobic-oxic biochemical treatment system (A2O system) with traditional activated sludge replaced by nitrifying bacteria, denitrification bacteria and phosphorus accumulating bacteria absorbed on PBS carrier biofilms suitable for saline/brackish water. The results showed that biofilm-enhanced A2O system can effectively remove pollutants from aquaculture wastewater. The removal efficiencies of CODMn, NH4 +-N, TN and TP in A2O system were approximately 86.3%-90.8%, 97.7%-99.5%, 94.6%-95.2% and 97.0%-98.1%. The results further showed that CODMn, NH4 +-N, and TN were mainly removed in anaerobic tank and anoxic tank, while TP was mainly removed in the anoxic tank and oxic tank. The biofilm-enhanced A2O system by adding nitrifying bacteria and phosphorus accumulating bacteria biofilms using PBS as carriers instead of conventional activated sludge could be applied to the treatment of circulating aquaculture wastewater. This study provides a feasible scheme for enhancing the efficiency of A2O system in the treatment of aquaculture tail water, and provides a reference for the immobilization of microorganisms. [ABSTRACT FROM AUTHOR]

This study presents a novel method for seepage control in calcareous sand using microbially induced Ca-Alginate polymeric sealant, which was achieved by the reaction between supplied alginate and microbially induced Ca2+ ions directly derived from calcareous sand. This approach includes two steps: (i) microbially induced soluble Ca2+ generated inside the pores of calcareous sand through a bio-acidification process using activated sludge and (ii) reacting with supplied alginate to form Ca-alginate polymeric sealant via the in situ gelation. With the effect of Ca-alginate polymeric sealant, the seepage rate of the calcareous sand was intensely decreased to the level of 10–9 m/s from an initial 10–4 m/s when 5 g/L of alginate was applied. In this way, a low seepage rate of calcareous sand was achieved which was able to remove heavy metal ions and suspended solids from the wastewater sludge. A model test was also carried out to assess the erosion resistance of Ca-alginate treated calcareous sand dam subjected to wave attack. Built on the current research, the proposed polymeric sealant is a promising method for the reduction of seepage, formation barriers for coastal construction on the island, and remediation of specific contaminants. [ABSTRACT FROM AUTHOR]