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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]

Aerobic granular sludge (AGS) and conventional activated sludge (CAS) are two different biological wastewater treatment processes. AGS consists of self-immobilised microorganisms that are transformed into spherical biofilms, whereas CAS has floccular sludge of lower density. In this study, we investigated the treatment performance and microbiome dynamics of two full-scale AGS reactors and a parallel CAS system at a municipal WWTP in Sweden. Both systems produced low effluent concentrations, with some fluctuations in phosphate and nitrate mainly due to variations in organic substrate availability. The microbial diversity was slightly higher in the AGS, with different dynamics in the microbiome over time. Seasonal periodicity was observed in both sludge types, with a larger shift in the CAS microbiome compared to the AGS. Groups important for reactor function, such as ammonia-oxidising bacteria (AOB), nitrite-oxidising bacteria (NOB), polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs), followed similar trends in both systems, with higher relative abundances of PAOs and GAOs in the AGS. However, microbial composition and dynamics differed between the two systems at the genus level. For instance, among PAOs, Tetrasphaera was more prevalent in the AGS, while Dechloromonas was more common in the CAS. Among NOB, Ca. Nitrotoga had a higher relative abundance in the AGS, while Nitrospira was the main nitrifier in the CAS. Furthermore, network analysis revealed the clustering of the various genera within the guilds to modules with different temporal patterns, suggesting functional redundancy in both AGS and CAS. Key points: • Microbial community succession in parallel full-scale aerobic granular sludge (AGS) and conventional activated sludge (CAS) processes. • Higher periodicity in microbial community structure in CAS compared to in AGS. • Similar functional groups between AGS and CAS but different composition and dynamics at genus level. [ABSTRACT FROM AUTHOR]

Biofilm formation can help to mitigate the stress placed on organisms during biological treatment of high-salinity wastewaters, such as "produced water" resulting from oil and gas extraction. This study investigated the implementation of two different biofilm-based biological reactors, activated carbon as an adsorptive biofilm surface (Bio-GAC) and aerobic granular sludge (AGS), and a conventional activated sludge (CAS) reactor for the treatment of synthetic produced water (PW) under hypersaline conditions (85,000 mg/L NaCl). A mixture of benzyl alcohol, o-cresol, and phenol were used as a carbon source with concentrations of 100, 100, and 250 mg/L, respectively. The performance of Bio-GAC was higher than AGS, with overall removal efficiencies for aromatic compounds of 100% and 93%. The presence of catechol in all three reactors during the reaction cycle confirmed that biodegradation was occurring. The performance of CAS was significantly lower in terms of removal efficiency for aromatic compounds (73%) and resilience to high salinity. Scanning electron microscopy showed that biofilm-based biosystems establish stronger biofilm texture. Microbial community analysis showed that carbon source and biosystem type played a crucial role in selecting for microbiome structure. These findings show that biofilm reactors can be used to successfully biodegrade toxic organic contaminants in a high-salinity environment, and that the hybrid Bio-GAC process is particularly promising for treating PW. [ABSTRACT FROM AUTHOR]

In hospitals, antibiotics are utilized to treat human infectious illnesses, where extra antibiotics are frequently discharged and left in hospital wastewater. However, investigating antibiotic residues using conventional activated sludge wastewater treatment plants in hospitals has still been very limited, especially in Thailand. This research studied the contamination of antibiotics in the conventional activated sludge wastewater treatment plants from three hospitals: a first-level hospital (H1), a middle-level hospital (H2), and an advanced-level hospital (H3). The antibiotics were focused on 3 groups: bata-lactams, quinolones, and tetracyclines, which included 7 types of antibiotics (amoxicillin, ampicillin, ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, and doxycycline). Antibiotics were extracted by solid-phase extraction and analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). The results showed that amoxicillin had the highest concentrations of H2, H1, and H3 in the influent (18,434 ± 99, 11,541 ± 42 and 10,994 ± 56 ng/L, respectively). Furthermore, with 7,990 ± 53, 5,879 ± 52 and 4,892 ± 63 ng/L of H2, H3, and H1, respectively, amoxicillin appeared to have the highest concentrations in the effluent. The removal efficiency was the highest for norfloxacin (94.78%) in H1, followed by doxycycline (93.99%) in H2. However, ampicillin had the lowest removal efficiency (19.02%) in H2. This finding from the research on antibiotic contamination in hospital wastewater reveal that the conventional activated sludge treatment system could not completely remove all antibiotics in the wastewater. Therefore, the advanced treatment technology should be investigated to increase the antibiotics removal efficiency. [ABSTRACT FROM AUTHOR]

• AnMBR for hydroponic CEA was evaluated against CAS for soil-based agriculture, with a semi-quantitative comparison. • Both decentralized wastewater reclamation and food production hold promise for a sustainable and circular economy. • Perspectives and challenges of integrating AnMBR with hydroponic CEA are discussed. • Addressing regulatory gaps is essential for promoting wastewater reuse in hydroponic CEA. • We underscore key areas for future research exploration. Advancements in anaerobic membrane bioreactor (AnMBR) technology have opened up exciting possibilities for sustaining precise water quality control in wastewater treatment and reuse. This approach not only presents an opportunity for energy generation and recovery but also produces an effluent that can serve as a valuable nutrient source for crop cultivation in hydroponic controlled environment agriculture (CEA). In this perspective article, we undertake a comparative analysis of two approaches to municipal wastewater utilization in agriculture. The conventional method, rooted in established practices of conventional activated sludge (CAS) wastewater treatment for soil/land-based agriculture, is contrasted with a new paradigm that integrates AnMBR technology with hydroponic (soilless) CEA. This work encompasses various facets, including wastewater treatment efficiency, effluent quality, resource recovery, and sustainability metrics. By juxtaposing the established methodologies with this emerging synergistic model, this work aims to shed light on the transformative potential of the integration of AnMBR and hydroponic-CEA for enhanced agricultural sustainability and resource utilization. [Display omitted] [ABSTRACT FROM AUTHOR]

With continuous innovations in wastewater treatment technology, the use of excess sludge has become a research focus. Purified-hydrocolloids obtained from aerobic granular sludge (AGS) and conventional activated sludge (CAS) have many practical applications, including waterproofing, adsorption, flame retardance, slow-release properties, and seed coating. In this study, purified-hydrocolloids extracted from CAS was used as a new seed coating, which was uniformly sprayed onto the surface of wheat seeds. Purified-hydrocolloids was most effective in resisting salt stress in wheat seedlings at a NaCl concentration of 125 mmol/L (soil salinity 2.74 g/Kg). The germination percentage, plant height, K+/Na+ ratio, soluble sugar and soluble protein contents of purified-hydrocolloids-coated seeds increased by 13.33 %, 46.32 %, 37.25 %, 8.89 %, and 36.22 %, respectively, compared with wheat seeds without purified-hydrocolloids coating. Inhibition of O 2 − production activity and malondialdehyde content was reduced by 38.62 % and 48.00 %, respectively. Therefore, the purified-hydrocolloids coating had a mitigating effect on wheat seed germination and seedling growth in salt-stressed environments, and this application would be beneficial to the use of saline soil resources and the improvement of ecosystems in coastal areas. [Display omitted] [ABSTRACT FROM AUTHOR]

Conventional activated sludge system is confidently widely used for biological treatment plants of municipal wastewater but suffering from operation problems that affect their efficiencies and effluent qualities, especially when treating low-strength wastewater with increasing incoming flow. The objective of this study is to evaluate and compare the novel methods used in upgrading conventional activated sludge treatment systems receiving low-strength wastewater to generate good effluent quality. GPS-X Simulator V 8.0 was used for model calibration and plant performance prediction. The calibrated GPS-X model proved that eliminating primary settling from the treatment process does not affect BOD5 and COD removal, while TSS removal is decreased, and NH4-N removal is increased. Increasing the return activated sludge flow from 50 to 150% of influent flow does not affect conventional activated sludge process, while the change of waste activated flow had a vital effect on process performance. The presence of an anoxic zone in conventional activated sludge processes treating low-strength wastewater has no significant impact on plant performance. Also, the model outputs proved that adding filling media to the aeration tank was able to handle an increase of influent flow and a stable performance of BOD5, and NH4-N removal was observed. [ABSTRACT FROM AUTHOR]

Wastewater volumes are increasing globally as a result of increased population and industrial growth. This, together with increasingly stringent discharge limits, has resulted in a consequent rise in energy demand for wastewater treatment. Activated sludge process has been successfully used for more than a century with various configurations for the removal of organic carbon and nutrients. Compared to conventional activated sludge plants, membrane bioreactors (MBRs) offer a higher treatment efficiency, however, they are energy-intensive. The aim of this study is to investigate the operational and energy flexibility of MBRs by mathematical modeling. Based on a variable electricity price tariff, an appropriate optimization strategy can save 9%--41% of the energy cost without violating exiting discharge standards. The results of dynamic simulation revealed that, under variable energy price structures, hybrid MBRs can provide significant flexibility for reducing energy costs while maintaining satisfactory effluent quality. [ABSTRACT FROM AUTHOR]

The performance of a membrane bioreactor (MBR) was compared to a conventional activated sludge (CAS) process and it was aimed to identify the best technological option for a municipal sewage treatment plant (STP). The MBR system was fed by the diluted sewage coming from the main municipal sewer network, which contained an averagely lower concentration of organics, inorganics and biological pollutants. While the CAS system was fed by a concentrated sewage coming from household septic tanks, contained averagely high concentration of organics, inorganics and biological pollutants. CAS showed a higher removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), volatile suspended solids (VSS), Fat-Oil-Grease (FOG), nitrogen, phosphorous, helminths ova (HO), and pathogenic bacteria compared to the MBR. Nevertheless, the removal efficiencies of nitrogen, HO and pathogenic bacteria in the case of CAS were lower than MBR due to the high concentration of those parameters in the influent fed to CAS. However, both the efficiency and the amount of removal for phosphorous in the case of CAS was quite higher than that of MBR due to extended aeration in CAS. The pathogenic bacteria and HO were removed almost 99.97% by the MBR, whereas the CAS removed 91±5% of the pathogenic bacteria and HO. Therefore, the effluent of the CAS system required additional disinfection for the reduction of pathogens and HO. In terms of biological efficiency and influent flexibility, both the systems can satisfy the national standards. Overall, the data suggested that CAS possessed a higher capacity of treating concentrated sewage for removing all pollutants to satisfactory limits except complete removal of pathogenic bacteria and HO. It was obvious that MBR possessed a membrane barrier to retain the pathogens and HO; therefore, they could be removed up to very low levels. However, further investigation is necessary to verify the MBR performance using the same concentrated sewage as CAS. [ABSTRACT FROM AUTHOR]

• KMS is a Matlab application aimed for modeling and simulation a variety of reaction systems. • Friendly-user interfacial computing environment that avoids complex programming knowledge. • KCAS simulator enhances the learning skills of students in activated sludge reactors. • KCAS simulator reinforces the acquisition of competences in Environmental Engineering. Computer-based activities to study chemical kinetic principles have been widely used in engineering education for the last 60 years. These academic tools must be user-friendly for teachers and students and easy to adapt to practical cases. The Chemical and Environmental Engineering Group (GIQA) at University Rey Juan Carlos (URJC) has developed a Kinetic, Modeling and Simulation (KMS) platform for chemical and biochemical processes. The KMS platform provides different simulation applications programmed in Matlab® with a friendly interface design environment for users. In this work, we will focus on the Kinetics in Conventional Activated Sludge (KCAS) application, as part of the KMS platform. The design of kinetic models and the dynamic simulation of wastewater treatment plants are typically implemented by a variety of dedicated software, mostly developed for research and development purposes at universities, institutes or consulting companies. These programming tools have inherent weaknesses as simulators in virtual laboratories for academics, needing steep learning curves and lacking flexibility to evaluate complex problems, particularly in bachelor degrees programs that are not completely devoted to the mathematical modeling of processes. The simplicity and versatility of KCAS simulator make it very useful for students as starting educational tool to define kinetic models and to make the dynamic simulation of a conventional activated sludge reactor followed by a secondary decanter using different inlet streams or operation conditions. The students interact with the program through a friendly Graphical User Interface (GUI), and the results can be easily exported to a conventional spreadsheet in EXCEL© format files. With KCAS , the students can formulate kinetic models (potential models, diffusional models, Monod equations, etc.) to simulate the evolution from simple reaction systems, to complex biochemical models such as ASM (Activated Sludge Models) from the International Water Association (IWA). The KCAS simulator allows the students to enhance the understanding of complex interactions among the physical, chemical, and biological processes, reinforcing the acquisition of competences and learning skills in Environmental Engineering. The KCAS application was implemented as laboratory demonstration practice in subjects of different Engineering Degrees at URJC. [ABSTRACT FROM AUTHOR]

Abstract In practice, established operation of activated sludge treatment system with high biomass concentration is restricted because of difficulty in settling the sludge in clarifiers. Membrane bioreactor is a modified form of activated sludge, and despite the superior advantages, its widespread application is restricted by the membrane fouling. Therefore, in this research, to improve the sludge sedimentation at high biomass concentration in the activated sludge system, high-frequency ultrasound (1.7 MHz) was exerted in clarifier of activated sludge system and its performance was compared with a bioreactor followed by an antifouling ultrafiltration membrane. The antifouling ability of NH2-functionalized multiwall carbon nanotubes (NH2-MWCNTs)-modified nanocomposite UF membrane during filtration of mixed liquor-activated sludge was investigated. Hydraulic retention time (HRT) (8–44 h) and mixed liquor suspended solids (MLSS) (6000–14,000 mg/L) were chosen as the operating variables to analyze the process. The biological process showed high COD removal efficiency throughout the experiments (> 96%). The membrane and high-frequency ultrasound had no effect on the system performance in terms of COD, TKN, TN, TP removal. However, the HRT and MLSS indicated an increasing impact on flux. The effect of ultrasound on the sludge properties, i.e., sludge volume index, sludge settling velocity and height of sludge at high MLSS concentration (14,000 mg/L), was not considerable. It was concluded at MLSS of below 10,000 mg/L, about 40% water recovery was obtained. As a result, activated sludge equipped with ultrasound showed a promising performance; however, its industrial development needs further examinations to attain the design criteria. Graphical Abstract

[Display omitted] • EdPD was rapidly achieved by washing out PAOs, with NTR of 82.8%. • PRE got back to 88.6% and NTR remained 67.7%, good balance of PAOs and GAOs in AOA. • Competbacter was the prime EdPD-fullfilling bacteria, rising to 28.9% from 0.5%. • Accumulibacter was abundantly enriched to 7.3% after good balance of GAOs and PAOs. • Great balance of PAOs and GAOs contributed to advanced nitrogen removal by anammox. In anaerobic/aerobic/anoxic (A/O/A) process, endogenous denitrification (ED) is critically important, and achieving steady endogenous partial denitrification (EdPD) is crucial to carbon saving and anammox application. In this study, EdPD was rapidly realized from conventional activated sludge by expelling phosphorus accumulating organisms (PAOs) in anaerobic/anoxic (A/A) mode during 40 days, with nitrite transformation rate (NTR) surging to 82.8 % from 29.4 %. Competibacter was the prime EdPD-fulfilling bacterium, soaring to 28.9 % from 0.5 % in phase II. Afterwards, balance of high NTR and phosphorus removal efficiency (PRE) were attained by well regulating competition and cooperation between PAOs and glycogen accumulating organisms (GAOs) in A/O/A mode, when the Competibacter (21.7 %) and Accumulibacter (7.3 %, mainly Acc_IIC and Acc_IIF) were in dominant position with balance. The PRE recovered to 88.6 % and NTR remained 67.7 %. Great balance of GAOs and PAOs contributed to advanced nitrogen removal by anammox. [ABSTRACT FROM AUTHOR]

This study investigates the impact of pre-treatment options on the performances of soil columns simulating soil aquifer treatment (SAT). For this purpose a conventional activated sludge (CAS) process, a membrane bioreactor (MBR) and vertical flow reed beds were used as single units or in combination before SAT. The influent and effluent from each treatment train were monitored over three successive 6-month periods, corresponding to changes in the operational conditions of the MBR and CAS units from 6 days' sludge retention time (SRT) to 12 and 20 days. All the columns acted as efficient polishing steps for solids and bacteria. The column receiving effluent from the CAS system running at 6 days' SRT also presented high total nitrogen and total phosphorus removals, but this column was also associated with the lowest infiltration rates over that period. While the quality of the effluent from the column following the CAS process increased over 18 months of operation, the effluent quality of the columns receiving MBR effluent degraded. No correlations were found between variations in SRT of the MBR and CAS processes and the columns' performances. Overall, all columns, except the one receiving CAS effluent, underwent a reduction in infiltration rate over 18 months.

Purification of water containing pesticide namely Malathion in membrane bioreator has been carried out. To understand the complex fouling mechanisms and fouling propensities occurring in a Membrane Bioreactor (MBR), in the current work, comparison of malathion degradation by single species, Pseudomonas Stutzeri, and microbial consortium has been carried out. Extracellular Polymeric Substances (EPSs) and Soluble Microbial Proteins (SMPs) are considered to increase the fouling. Experimental results revealed 85-90% reduction in the COD of the malathion containing synthetic wastewater and degradation kinetics has been reported. Complete reduction of malathion observed within 24 h in both the cases. A key parameter, critical flux is found to be 10 LMH for both the membrane bioreactor systems. Cake and Membrane resistances are calculated thus giving an insight regarding the working of Membrane Bioreactor based on single species and activated sludge. [ABSTRACT FROM AUTHOR]

Abstract Despite the number of studies that have investigated the fate of endocrine disrupting compounds (EDCs), to date results are still contradictory and more research is required to evaluate the contribution of the microbial communities present in different engineered treatment systems. Thus, autotrophic and heterotrophic types of biomass were here compared in terms of efficiency in the removal of estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynilestradiol (EE2) and bisphenol A (BPA). Experiments were performed with enriched nitrifying activated sludge (NAS) and enriched ammonia oxidizing bacteria (AOB) sludge cultivated at lab-scale, as well as with conventional activated sludge (CAS) from a full-scale wastewater treatment plant. Both enriched NAS and AOB demonstrated a negligible degrading capacity. In both cases, the studied EDCs exhibited low removals (<14%) and showed no correlation with the increasing nitrification rates contradicting some of the hypothesis present in literature. Contrariwise, the biodegradation capabilities of the heterotrophic fraction of CAS were highlighted. E2 and E3 were removed by up to 100% and 78%, respectively. E1 was found to be the main transformation product of E2 (almost quantitative oxidation) and it was also highly eliminated. Finally, EE2 and BPA were more persistent biologically with removals ranging from 10% to 39%. For these two compounds similar removals were obtained during experiments with heat-inactivated biomass suggesting that sorption could be a relevant route of elimination. Graphical abstract Image 1 Highlights • Nitrifiers showed poor degrading capacity in the removal of E1, E2, E3, EE2 and BPA. • No correlation between nitrification and E1, E2, E3, EE2 and BPA removal was detected. • E2 and E3 were highly removed by heterotrophs, up to 100% and 78% respectively. • High removal can also be stated for E1, being the main transformation product of E2. • Sorption was evaluated resulting potentially significant for EE2 and BPA. [ABSTRACT FROM AUTHOR]

Total Suspended Solids (TSS) was an important parameter used to control biomass in an aeration tank during the activated sludge process also known as Mixed Liquor Suspended Solids (MLSS). The weighed standard glass-fiber filter and the residue retained on the filter are dried to a constant weight at 103 to 105°C. There were major steps in a standard method, which take time to analyze. Therefore, microwave method was an attractive technique because rapid determination of total suspended solids. This comparative study was made on the analysis of total suspended solids between the use of microwave and standard method of American Public Health Association, American Water Works Association, and Water Environment Federation (APHA, AWWA & WEF). It was conducted to examine the appropriate condition of microwave power 800-watt at two levels including medium-high and high levels at 10, 15 and 20 minutes. Synthetic wastewater was prepared by Cellulose power of thin layer chromatography at concentrations 100 mg/l. The result show on that the optimum condition was using high level at 10 minutes. Mean of total suspended solids was at 97.39 mg/L. The sample of wastewater was collected from Conventional Activated Sludge, CAS of Sakon Nakhon Hospital. After comparison, it was found that total suspended solids with microwave and standard method had an average concentration at 156.2 and 150.4 mg/L, respectively. There was no significant difference of total suspended solids from the two methods at a 95% confidence level. [ABSTRACT FROM AUTHOR]

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution—where GWPMBR = 0.50 kg CO2-eq*FU−1 and GWPCAS = 2.67 kg CO2-eq*FU−1 without sludge removal—and the wastewater treatment plant life cycle contribution—where GWPMBR = 0.002 kg CO2-eq*FU−1 and GWPCAS = 0.14 kg CO2-eq*FU−1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found.

In this study, a lab scale different activated sludge configurations methods were used to treat a municipal wastewater from effluent of; primary sedimentation tank of Al-Rustamiya wastewater treatment plant located near Baghdad city to remove organic load, nitrogen and phosphorus from the period of 15 July 2012 to 22 May 2013.Biological treatment systems were conventional activated sludge (CAS) , extended aeration , anaerobic-anoxic-aerobic( A2O) , anoxic-aerobic (MLE) and anaerobic –oxic(A/O). During the operation periods, the average removal efficiency of BOD5, COD and TSS is 81.9, 77.7 and 85.8 respectively regardless of the fluctuation in influent quality. In addition the results show removal efficiency of ammonia, nitrate, nitrite and phosphorus with ranges (61-85.8), (34-81.7) , (35-81.4) (32.3-85.54) % respectively. The biological treatment systems produced high quality effluent which can achieve the Iraqi limitations of rivers maintenance for all measured parameters.

Emerging global threats, such as climate change, urbanization and water depletion, are driving forces for finding a feasible substitute for low cost-effective conventional activated sludge (AS) technology. On the other hand, given their low cost and easy operation, nature-based systems such as constructed wetlands (CWs) and waste stabilization ponds (WSPs) appear to be viable options. To examine these systems, a 210-day experiment with 31 days of peak load scenario was performed. Particularly, we conducted a deliberate strategy of experimentation, which includes applying a preliminary study, preliminary models, hypothetical tests and power analysis to compare their removal efficiencies and resilience capacities. In contrast to comparable high removal efficiencies of organic matter--around 90%--both natural systems showed moderate nutrient removal efficiencies, which inferred the necessity for further treatment to ensure their compliance with environmental standards. During the peak period, the pond treatment systems appeared to be the most robust as they indicated a higher strength to withstanding the organic matter and nitrogen shock load and were able to recover within a short period. However, high demand of land--2.5 times larger than that of AS--is a major concern of the applicability of WSPs despite their lower operation and maintenance (O&M) costs. It is also worth noting that initial efforts on systematic experimentation appeared to have an essential impact on ensuring statistically and practically meaningful results in this comparison study. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol A [2,4'-isopropylidenebis(2,6-dibromophenol)] has been identified in wastewater samples collected from the Guelph municipal wastewater treatment plant (GWWTP). In order to assess the kinetics and metabolic mechanisms of the dissolved TBBPA, bench scale experiments were completed with batch bioreactors. The biodegradation test was conducted by taking aerobic sludge from the conventional activated sludge reactor (CAS) and membrane bioreactor (MBR), and bioaugmenting both reactors with soil based strains of Bacillus brevis and Bacillus pumilus. This novel biodegradation process showed that the CAS bioreactor had a biodegradation rate of 0.127 d-1, while the sludge from the MBR had a biodegradation rate of 0.171 d-1. This is the first reported aerobic biodegradation of TBBPA by heterotrophic and nitrifying bacteria in an activated sludge bioreactor system. A tentative biotransformation metabolic scheme for TBBPA biodegradation and metabolite formation has been proposed as well. [ABSTRACT FROM AUTHOR]

Wastewater-originated nitrogen (N) is considered a primary N source in urban waters. In order to mitigate eutrophication in such waters, decreasing N discharges from wastewater treatment plants (WWTPs) is necessary. Upgrading WWTPs from conventional activated sludge (CAS) to biological nutrient removal (BNR) is the most common measure to lower levels of effluent N. However, in spite of successful N reduction through such upgrades, eutrophication persists in numerous urban waters. In this study, we investigated why decreased N discharge resulting from upgrading CAS to BNR, particularly predenitrification BNR, cannot necessarily alleviate eutrophication. Our laboratory reactor study demonstrated that compared to CAS effluent N, predenitrification BNR effluent N contains less dissolved inorganic N (DIN) but more dissolved organic N (DON), especially low molecular weight DON (LMW-DON). Bioassay-based experimental and numerical analyses found that effluent N has dissimilar phytoplankton-stimulating potency depending on its chemical forms. In particular, effluent LMW-DON showed significantly greater potency than effluent DIN. This difference in potency makes predenitrification BNR effluent N more productive for causing primary production than CAS effluent N. These results indicate that the impact of effluent N on eutrophication should be evaluated based on not only the total quantity but also the qualitative aspect of N. • Lab reactor and bioassay were used to assess impact of effluent N on eutrophication. • Predenitrification effluent N had less DIN but more DON than CAS effluent N. • DON showed significantly greater potential for primary production than DIN. • Predenitrification BNR effluent N was more productive N than CAS effluent N. [ABSTRACT FROM AUTHOR]

Wastewater is a potential environmental source of Clostridium difficile, although a direct link with community-acquired C. difficile infection (CA-CDI) in humans has not yet been established. The present study was performed to determine the occurrence of C. difficile in two types of wastewater treatment plants (WWTPs) in Isfahan, Iran. A total of 95 samples were taken from a conventional activated sludge treatment plant and a waste stabilization ponds system, and analyzed for the presence of C. difficile. C. difficile was found in 13.6% (3/22) of digested sludge samples. However, no C. difficile was detected in inlet and outlet samples or in raw sludge of activated sludge. C. difficile was also detected in 5% (2/40) of the samples from waste stabilization ponds. Polymerase chain reaction (PCR) analysis showed that all strains of C. difficile detected were toxigenic (tcdB gene positive). This study shows that C. difficile was present in WWTPs, which might constitute a potential source of community-acquired C. difficile infection.

Energy consumption and sludge production minimization represent rising challenges for wastewater treatment plants (WWTPs). The goal of this study is to investigate howenergy is consumed throughout the whole plant and how operating conditions affect this energy demand. A WWTP based on the activated sludge process was selected as a case study. Simulations were performed using a pre-compiled model implemented in GPS-X simulation software. Model validationwas carried out by comparing experimental and modeling data of the dynamic behavior of the mixed liquor suspended solids (MLSS) concentration and nitrogen compounds concentration, energy consumption for aeration, mixing and sludge treatment and annual sludge production over a three year exercise. In this plant, the energy required for bioreactor aeration was calculated at approximately 44% of the total energy demand. A cost optimization strategy was appliedby varying the MLSS concentrations (from1 to 8 gTSS/L)while recordingenergy consumption, sludge production and effluent quality. An increase of MLSS led to an increase of the oxygen requirement for biomass aeration, but it also reduced total sludge production. Results permit identification of a key MLSS concentration allowing identification of the best compromise between levels of treatment required, biological energy demand and sludge production while minimizing the overall costs. [ABSTRACT FROM AUTHOR]

The potential of a membrane bioreactor (MBR) system to treat Fischer-Tropsch (FT) reaction water from gas-to-liquids (GTL) industries was investigated and compared with the current treatment system: a conventional activated sludge system followed by an ultrafiltration (CAS-UF) unit. The MBR and the CAS-UF systems were inoculated with municipal activated sludge and operated in parallel for 645 days with four interruptions using synthetic FT reaction water. Both treatment systems achieved a removal efficiency of 98 ± 0.1% within 60 days after inoculation, the COD influent concentration was 1014 ± 15 mg L. This suggests that MBRs form a suitable alternative to CAS-UF systems for the treatment of FT reaction water from the GTL industries. Moreover, the total fouling rates ( F ) of the membranes used from day 349 till the end were assessed. The average F was 7.3 ± 1.0 10 m day for CAS-UF membranes and 2.8 ± 00.7 10 m day for MBR-MT membranes. This indicates that MBR systems for the treatment of FT reaction water from the gas-to-liquids industries are less prone to fouling than CAS-UF systems. [ABSTRACT FROM AUTHOR]

Despite decades of micropollutant (MP) monitoring at wastewater treatment plants (WWTPs), we lack a fundamental understanding of the time-varying metabolic processes driving MP biotransformations. To address this knowledge gap, we collected 24-h composite samples from the influent and effluent of the conventional activated sludge (CAS) process at a WWTP over 14 consecutive days. We used liquid chromatography and high-resolution mass spectrometry to (i) quantify 184 MPs in the influent and effluent of the CAS process; (ii) characterize temporal dynamics of MP removal and biotransformation rate constants; and (iii) discover biotransformations linked to temporally variable MP biotransformation rate constants. We measured 120 MPs in at least one sample and 66 MPs in every sample. There were 24 MPs exhibiting temporally variable removal throughout the sampling campaign. We used hierarchical clustering analysis to reveal four temporal trends in biotransformation rate constants and found MPs with specific structural features co-located in the four clusters. We screened our HRMS acquisitions for evidence of specific biotransformations linked to structural features among the 24 MPs. Our analyses reveal that alcohol oxidations, monohydroxylations at secondary or tertiary aliphatic carbons, dihydroxylations of vic-unsubstituted rings, and monohydroxylations at unsubstituted rings are biotransformations that exhibit variability on daily timescales.

Emerging global threats, such as climate change, urbanization and water depletion, are driving forces for finding a feasible substitute for low cost-effective conventional activated sludge (AS) technology. On the other hand, given their low cost and easy operation, nature-based systems such as constructed wetlands (CWs) and waste stabilization ponds (WSPs) appear to be viable options. To examine these systems, a 210-day experiment with 31 days of peak load scenario was performed. Particularly, we conducted a deliberate strategy of experimentation, which includes applying a preliminary study, preliminary models, hypothetical tests and power analysis to compare their removal efficiencies and resilience capacities. In contrast to comparable high removal efficiencies of organic matter—around 90%—both natural systems showed moderate nutrient removal efficiencies, which inferred the necessity for further treatment to ensure their compliance with environmental standards. During the peak period, the pond treatment systems appeared to be the most robust as they indicated a higher strength to withstanding the organic matter and nitrogen shock load and were able to recover within a short period. However, high demand of land—2.5 times larger than that of AS—is a major concern of the applicability of WSPs despite their lower operation and maintenance (O&M) costs. It is also worth noting that initial efforts on systematic experimentation appeared to have an essential impact on ensuring statistically and practically meaningful results in this comparison study.

Very little information on the occurrence and fate of multiple classes of antimicrobials in the aquatic environment is reported for the Southeast Asian region. This study provides the first and comprehensive data on the occurrence of ten different classes of antimicrobials in wastewater samples for Singapore. Among the investigated antimicrobials, 19 out of 21 target compounds were detected in 100% of the collected raw influent samples. Concentrations of the detected antimicrobials in raw influent varied from 23.8 to 43,740 ng/L. Removal of antimicrobials by conventional activated sludge (CAS) and membrane bioreactor (MBR) systems at a local wastewater treatment plant was evaluated. MBR exhibited better performance over CAS for most target antimicrobials. Beta-lactam, glycopeptide, and fluoroquinolone classes were largely eliminated by biological wastewater treatment processes, whereas trimethoprim and lincosamides appeared to be persistent. Effects of physicochemical properties and chemical structures of target antimicrobials on their removal efficiencies/mechanisms during wastewater treatment process were also discussed. [ABSTRACT FROM AUTHOR]

Flocculent settling (stokesian) is predominant within ideally operating clarifiers, and the shift to ‘slower’ hindered settling (non-stokesian) causes both failure and poor effluent quality. Therefore, a new metric for settling characteristics was developed and classified as Limit of Stokesian Settling (LOSS). The technique consisted of determining the total suspended solids (TSS) concentration at which mixed liquor settling characteristics transition from stokesian to non-stokesian settling. An image analytical technique was developed with the aid of MATLAB ® to identify this transition. The MATLAB tool analyzed RGB images from video, and identified the presence of an interface by a dramatic shift in the Red indices. LOSS data for Secondary activated-sludge systems were analyzed for a period of 60 days at the Blue Plains Advanced Wastewater Treatment Plant. LOSS for secondary systems typically occurred between 600 and 700 mg TSS/L but reached 1000 mg TSS/L for a good settling secondary sludge and 500 mg TSS/L for a poor settling secondary sludge, settling quality was based on hindered settling rates. In addition, LOSS was collected for granular systems seeded with cyclone underflow from Strass Wastewater Treatment Plant, it was observed that LOSS was higher for granular systems ranging from 1600 to 5500 mg TSS/L for low and high levels of granulation, respectively. The monovalent to divalent cation ratio (M/D) was increased with the addition of sodium ions to deteriorate settling properties. Samples adjusted with higher M/D consistently had 100 mg TSS/L (15%) decrease in LOSS from the control. LOSS numbers collected experimentally were validated with the Takacs et al. (1991) settling model. When compared to flux curves with small changes in sludge matrix, LOSS was proven to be faster at characterizing hindered settling velocity and was less erratic. This is the first time a measurement method has been developed to characterize the transition from stokesian to non-stokesian settling. Additionally, this is the first step in developing new metrics to predict clarifier failure, and determine effluent quality through the development of flocculent settling metrics. [ABSTRACT FROM AUTHOR]

The inoculation of conventional activated sludge is a prospective option against transferring anaerobic ammonium oxidation (ANAMMOX) biomass from a currently existing ANAMMOX process in places where large amounts of ANAMMOX biomass are not available. In this study, poly(vinyl alcohol)/sodium alginate gel beads were utilized as an immobilization system to entrap activated sludge. Despite the longer start-up periods than those in previous examples using the ANAMMOX inoculum, the acclimation of ANAMMOX bacteria in the gel beads was successful. The maximum nitrogen removal rate of 1.12 kg N/m 3 -day was established at a nitrogen loading rate of 1.26 ± 0.04 kg N/m 3 -day with a total nitrogen removal efficiency of 88.9%. The exponential growth rate in the initial phase was enhanced by a higher nitrogen loading rate. The area-to-volume ratio of the gel beads was the significant control factor for the lag period, showing an inverse relationship due to the internal mass transport limitation. Based on the 16S rRNA gene, a sharp increase in the amount of ANAMMOX bacteria was identified along with an increase in the nitrogen removal rate. The responsible ANAMMOX bacteria were the species related to Candidatus ‘Brocadia sinica’. [ABSTRACT FROM AUTHOR]

The relative strengths of membrane bioreactors (MBR) versus conventional activated sludge (CAS) processes have long been debated, but never compared systematically at full scale. To this end, we monitored full-scale wastewater treatment performance and mixed-liquor characteristics (sludge biomass, extracellular polymeric substances (EPS), supernatant with molecular weight and hydrophilic/hydrophobic distribution) for parallel MBR and CAS (via oxidation ditch—OD), for a year. Ammonia and suspended solids were better removed by MBR; temperature affected ammonia removal in OD. At low temperatures, sludge settlement declined in both processes, but solid–liquid separation via membrane filtration continued, although the membrane fouled. EPS characteristics were similar, and organic components in EPS and supernatant varied seasonally, in both processes. MBR had a lower production rate, but higher concentration, of supernatant organics and accumulated large molecular-weight polysaccharides. Ammonia removal was correlated with tightly bound proteinaceous EPS. Polysaccharides, in loosely bound EPS and supernatant, were responsible for effective settlement (OD), and membrane fouling (MBR). These results demonstrate how mixed liquor intermediates process and performance, and that performance depends on effective solid–liquid separation. MBRs excel when stringent requirements for pollutant-removal and extreme environmental conditions exist. The much cheaper OD remains competitive under less demanding conditions. [ABSTRACT FROM AUTHOR]

Dissolved organic nitrogen (DON) has become a growing concern due to its contribution to eutrophication and nitrogenous disinfection byproducts (N-DBPs) formation. However, information of DON in membrane bioreactors (MBRs) is very limited. In this study, occurrence, transformation and fate of DON in an MBR system were systematically investigated. MBR sludge showed a larger hydrolysis rate of particle organic nitrogen (PON) and also a higher transformation rate of DON to nitrate compared to conventional activated sludge (CAS). For long-term experiments, MBR achieved higher DON removal efficiency at low temperature than CAS; however, at high temperature, the effluent DON concentrations were almost the same in both systems. Batch tests on DON biodegradability showed that DON concentration increased and large molecular weight DON accumulated after 3-h aeration at low temperature, while DON concentration continuously decreased with the increase of aeration time at high temperature. The obtained results provide insights in DON removal in MBRs for meeting increasingly stringent regulations in terms of nitrogen removal. [ABSTRACT FROM AUTHOR]

The efficacy of three different wastewater treatment configurations, conventional activated sludge (CAS), nitrifying activated sludge (NAS) and biological nutrient removal (BNR) for removal of selected micropollutants from authentic wastewater was investigated. The processes were also characterized based on their proficiency to reduce the estrogenic activity of the influent wastewater using the in vitro recombinant yeast assay. The removal efficiency of trimethoprim improved with the complexity of the three treatment process configurations. Ibuprofen, androstendione, sulfamethoxazole, nonylphenol, estrone and bisphenol-A had moderate to high removals (>65%) while carbamazepine and meprobamate remained recalcitrant in the three treatment process configurations. The removal of gemfibrozil was better in the NAS than in BNR and CAS treatment configurations. The yeast estrogen screen (YES) assay analyses showed an improvement in estrogenicity removal in the BNR and NAS treatment configurations as compared to the CAS treatment configuration. Comparing the estrogenic responses from the three treatment configurations, the removal efficiencies followed the order of BNR= NAS>CAS and all were greater than 81%. [ABSTRACT FROM AUTHOR]

Pharmaceutical and personal care products (PPCPs) can evade degradation in sewage treatment plants (STPs) and can be chronically discharged into the environment, causing concern for aquatic organisms, wildlife, and humans that may be exposed to these bioactive chemicals. The ability of a common STP process, conventional activated sludge (CAS), to remove PPCPs (caffeine, di(2-ethylhexyl)phthalate, estrone, 17α-ethinylestradiol, ibuprofen, naproxen, 4-nonylphenol, tonalide, triclocarban and triclosan) from a synthetic wastewater was evaluated in the present study. The removal of individual PPCPs by the laboratory-scale CAS treatment plant ranged from 40 to 99.6%. While the efficiency of removal for some compounds was high, remaining quantities have the potential to affect aquatic organisms even at low concentrations. Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to influent recreated model wastewater with methanol (IM, solvent control) or with PPCP cocktail (IC), or CAS-treated effluent wastewater with methanol (EM, treated control) or with PPCP cocktail (EC). Alterations in hepatic gene expression (evaluated using a quantitative nuclease protection plex assay) and plasma vitellogenin (VTG) protein concentrations occurred in exposed fish. Although there was partial PPCP removal by CAS treatment, the 20% lower VTG transcript levels and 83% lower plasma VTG protein concentration found in EC-exposed fish compared to IC-exposed fish were not statistically significant. Thus, estrogenic activity found in the influent was retained in the effluent even though typical percent removal levels were achieved raising the issue that greater reduction in contaminant load is required to address hormone active agents. [ABSTRACT FROM AUTHOR]

Abstract: Diclofenac (DCF) is a common anti-inflammatory pharmaceutical that is often detected in waste wasters, effluents and surface waters. Recently, DCF was included in the watch list of substances in EU that requires its environmental monitoring in the member states. DCF is also known to harmfully affect several environmental species already at concentrations of ≤1μg/l. This review focuses on the occurrence and fate of DCF in conventional wastewater treatment processes. Research done in this area was gathered and analyzed in order to find out the possibilities to enhance DCF elimination during biological wastewater treatment. More precisely, human metabolism, concentrations in wastewater influents and effluents, elimination rates in the treatment train, roles of sorption and biotransformation mechanisms during the treatment as well as formation of transformation products are reported. Additionally, the effect of process configuration, i.e. conventional activated sludge (CAS), biological nutrient removal (BNR), membrane bioreactor (MBR) and attached-growth bioreactor, and process parameters, i.e. solids retention time (SRT) and hydraulic retention time (HRT) are presented. Generally, DCF is poorly biodegradable which often translates into low elimination rates during biological wastewater treatment. Only a minor portion is sorbed to sludge. MBR and attached-growth bioreactors may result in higher elimination of DCF over CAS or BNR. Long SRTs (>150d) favor the DCF elimination due to sludge adaptation. Longer HRTs (>2–3d) could significantly increase the elimination of DCF during biological wastewater treatment. Bioaugmentation could be used to enhance DCF elimination, however, this requires more research on microbial communities that are able to degrade DCF. Also, further research is needed to gain more information about the deconjugation processes and biotic and abiotic transformation and the nature of transformation products. [Copyright &y& Elsevier]

This paper compares the removal performances of two complete wastewater treatment plants (WWTPs) for all priority substances listed in the Water Framework Directive and additional compounds of interest including flame retardants, surfactants, pesticides, and personal care products (PCPs) ( n = 104). First, primary treatments such as physicochemical lamellar settling (PCLS) and primary settling (PS) are compared. Similarly, biofiltration (BF) and conventional activated sludge (CAS) are then examined. Finally, the removal efficiency per unit of nitrogen removed of both WWTPs for micropollutants is discussed, as nitrogenous pollution treatment results in a special design of processes and operational conditions. For primary treatments, hydrophobic pollutants (log K > 4) are well removed (>70 %) for both systems despite high variations of removal. PCLS allows an obvious gain of about 20 % regarding pollutant removals, as a result of better suspended solids elimination and possible coagulant impact on soluble compounds. For biological treatments, variations of removal are much weaker, and the majority of pollutants are comparably removed within both systems. Hydrophobic and volatile compounds are well (>60 %) or very well removed (>80 %) by sorption and volatilization. Some readily biodegradable molecules are better removed by CAS, indicating a better biodegradation. A better sorption of pollutants on activated sludge could be also expected considering the differences of characteristics between a biofilm and flocs. Finally, comparison of global processes efficiency using removals of micropollutants load normalized to nitrogen shows that PCLS + BF is as efficient as PS + CAS despite a higher compactness and a shorter hydraulic retention time (HRT). Only some groups of pollutants seem better removed by PS + CAS like alkylphenols, flame retardants, or di-2-ethylhexyl phthalate (DEHP), thanks to better biodegradation and sorption resulting from HRT and biomass characteristics. For both processes, and out of the 68 molecules found in raw water, only half of them are still detected in the water discharged, most of the time close to their detection limit. However, some of them are detected at higher concentrations (>1 μg/L and/or lower than environmental quality standards), which is problematic as they represent a threat for aquatic environment. [ABSTRACT FROM AUTHOR]

Abstract: An upflow dynamic membrane separation (DMS) process was developed for organic matter recovery from low-strength municipal wastewater. During the operation of 300days, 81.6% of organic matter recovery rate on average was achieved at a high membrane flux of 60L/(m2 h). Chemical analyses and batch assays revealed that the recovered organic matter (ROM) had larger carbon to nitrogen mass ratio (C/N) and higher fermentation potential compared to the waste activated sludge. The transformation of the organic matter occurred in the DMS process, which was related to the polyferric sulfate (PFS) coagulation, anaerobic metabolism and membrane retention. The recovery of soluble organic matter was facilitated by the coagulation, and the transformation was observed in the sludge zone due to the anaerobic metabolism. Although the dynamic membrane was less efficient to remove the small molecules, it allowed a sound retention of particulate fractions and biopolymers, enabling a relatively high ROM recovery in the DMS process. Furthermore, the net operation expenditure for the novel wastewater treatment paradigm employing the DMS process was about 0.24kWh/m3, much lower than that (1.10kWh/m3) for the conventional membrane bioreactor treatment technology. These results indicated that the upflow DMS process was a promising approach for sustainable wastewater treatment. [Copyright &y& Elsevier]

This work reports the performance of a laboratory scale membrane bioreactor (MBR) and a conventional activated sludge (CAS) treating a real industrial-municipal mixed wastewater, spiked with 17-b estradiol (E2) in micrograms amounts. In order to compare the steady- state conditions of both systems, different sludge retention times (SRT) of 10 and 20 days were applied, while the other operational parameters were maintained unchanged. Results regarding the removal of chemical oxygen demand (COD), nitrogen and E2 have been assessed with statistics analysis using the Mann-Whitney test. MBR outperforms the CAS treatment in terms of COD and nitrogen removal, and the increase in the SRT generally improves the performance of each system. However, E2 was almost completely eliminated in both systems and SRTs applied, leading to removal rates above 99%. Thus, this study shows that the biological elimination of E2 is not directly related to the nitrification rate, and other process or operational parameters should be of importance. [ABSTRACT FROM AUTHOR]