Municipal Wastewater Treatment Research Articles

Pathogenic Escherichia coli Virulome in Top Soil Improvers and Irrigation Waters Devoted to Leafy Vegetable Production: Hazard Assessment From a Case Study in Italy

ABSTRACTTop soil improvers (TSIs) and reused water from municipal wastewater treatment plants (WWTPs) represent useful and sustainable sources of organic carbon and nutrients for agriculture. However, from their regular use, emerging Escherichia coli enterophatotypes, particularly Shiga toxin‐producing E. coli (STEC), were responsible for severe foodborne outbreaks from contaminated ready‐to‐eat vegetables. We report the hazard characterization of 31 top soil improvers (TSIs) and 15 irrigation water samples of different origins, sampled at the farm level. The increased PCR signals of the marker virulence genes stx1, stx2, aggR, aaiC, ipaH, lt, stp, and sth for enteropathogenic, enteroaggregative, enteroinvasive, enterotoxigenic, and Shiga toxin‐producing E. coli from post‐enrichment samples were considered proof of the presence of viable bacteria. Despite positive signals from TSI‐enriched samples, we isolated one enteropathogenic and one enterotoxigenic strain from the same pig slurry sample and one STEC strain carrying the enterotoxigenic heat‐stable enterotoxin from bovine slurry. From irrigation water samples, the most detected genes were stx1, stx2, and eae, followed by aggR, aaiC, ipaH, lt, stp, and sth, leading to one STEC (stx1+) isolation. E. coli pathotype virulotyping could be proposed to assess if combined TSI and water inputs would potentially lead to hybrid strains with shuffled virulence features to support safe and sustainable ready‐to‐eat vegetable production.

Vaal’s Microplastic Burden: Uncovering the Fate of Microplastics in Emfuleni Municipality’s Wastewater Treatment Systems, Gauteng, South Africa

Municipal wastewater treatment plants (WWTPs) in Gauteng, South Africa, are inadequately designed or optimized to effectively remove microplastics (MPs), resulting in approximately 80% of wastewater being discharged into aquatic ecosystems with insufficient treatment. This study evaluates the prevalence and abundance of MPs in municipal WWTPs and their subsequent introduction into receiving water bodies. Comprehensive sampling was conducted across three municipal WWTPs in the Emfuleni region of Gauteng province from October 2022 to July 2023. Initial MP identification and quantification were performed using light microscopy, while scanning electron microscope energy-dispersive X-ray spectroscopy (SEM/EDS) was employed to identify non-plastic particles and perform elemental analysis. The findings reveal significant seasonal variability in MP concentrations. The highest influent and effluent concentrations were recorded during October (spring), with influent values of 142 MPs/ℓ (WWTP 1), 124 MPs/ℓ (WWTP 2), and 132 MPs/ℓ (WWTP 3), and effluent concentrations of 120 MPs/ℓ (WWTP 1), 63 MPs/ℓ (WWTP 2), and 89 MPs/ℓ (WWTP 3). Conversely, the lowest MP concentrations were observed during April (autumn), with influent concentrations of 114 MPs/ℓ (WWTP 1), 141 MPs/ℓ (WWTP 2), and 78 MPs/ℓ (WWTP 3), and effluent concentrations of 99 MPs/ℓ (WWTP 1), 53 MPs/ℓ (WWTP 2), and 86 MPs/ℓ (WWTP 3). Fibers and filaments constituted the dominant MP morphology, primarily derived from polyester, nylon, and acrylic synthetic textiles. Dark-colored MPs, especially black, blue, and red particles, were predominant in the wastewater samples. This study underscores the critical role of WWTPs as conduits for MP contaminants into the environment and highlights the urgent need to develop and implement improved MP removal technologies in wastewater treatment systems. MP production is estimated to account for approximately 15–20% of total global plastic production, corresponding to an annual generation of approximately 52.5–80 million metric tons of MP. By addressing MP pollution, this research directly contributes to sustainability by promoting the protection of freshwater ecosystems, reducing anthropogenic pressures on aquatic biodiversity, and supporting the principles of sustainable development. The findings align with global and regional goals to enhance water quality management and promote sustainable urbanization practices in line with the United Nations Sustainable Development Goals (SDGs).

Inhibition of nitrifying bacteria from heterocyclic N-containing organic compounds from municipal sludge hydrothermal liquefaction

Hydrothermal liquefaction (HTL) is a thermochemical technology that converts wet biomass into biochar and biocrude at high temperatures and pressures. HTL can be utilized within municipal wastewater treatment to convert waste activated sludge (WAS) into valuable resources, but HTL by-products include an aqueous coproduct (ACP) that has been characterized for its biological toxicity, high ammonia, and presence of heterocyclic N-containing organic compounds (HNOCs). This study evaluated the inhibitory effects of the most prevalent HNOCs on autotrophic nitrifiers present in WAS, by determining the concentration that reduces ammonia uptake by 50 percent (IC50). 2-pyrrolidinone, pyrazine, and 2- piperidinone and their derivatives were the most prevalent HNOCs in ACP from WAS at concentrations of 8.98, 6.05, and 0.40 mM respectively. The IC50 of 2-pyrrolidinone and pyrazine were 5.2 × 10−5 and 2.0 × 10−3 mM, respectively. The IC50 of the ACP was 0.08% (%v/v). This corresponded to concentrations of 2- pyrrolidinone, pyrazine, and 2-piperidinone of 7.52 × 10−3, 5.07 × 10−3, and 3.36 × 10−4 mM, respectively. The impact of ACP storage was also tested. ACP stored for 15 weeks exhibited less inhibitory effects on the nitrifying community compared to ACP stored for 1 week. The % maximum ammonia uptake rate was reduced by 23% for the 15-week stored ACP, in contrast to 51% reduction for ACP stored for 1 week. Results of this study provide guidance for how ACP recycle can be incorporated at a wastewater treatment plant without inhibiting nitrification, enhancing the feasibility of using HTL as a solids processing technology.

Integration of Membrane Bioreactors in Wastewater Treatment Plants: Opportunities and Challenges

The integration of membrane bioreactors into municipal wastewater treatment plants is presented as a research topic. The escalating demand to comply with stringent effluent discharge limits and to adopt green water management approaches has fueled a surge in the interest of implementing membrane bioreactors (MBRs) in treatment plants (TPs). MBRs are an attractive alternative for effective wastewater treatment because it integrates biological treatment with membrane filtration processes to achieve high-quality effluent. This abstract presents some findings and issues of how MBBR can be used in treatment works for wastewater. The introduction of MBRs in wastewater treatment plants provides a range of benefits including high effluent quality, reduced sludge production, and improved water reuse potential. MBRs can also be used as an efficient and unobtrusive treatment option, being suitable in the urban context with limited land. In addition, MBRs are easily adaptable to current infrastructure for treatment, offering them a practical upgrade solution for existing systems. Nevertheless, the incorporation of MBRs also poses many difficulties such as high capital and maintenance costs, membrane fouling and cleaning, and special operating knowledge requirement. However, the hurdles must be overcome in order to make the benefits of MBR integration into the wastewater treatment plants compelling. In order to address the challenges, continuing developments in membrane technology, process optimization and cost reduction approaches are required. Such initiatives are best achieved by collaborative research and development by academia, industry and government agencies. Moreover, the emergence of standardized design and operational guidelines may assist in the dissemination of MBRs in treatment plants. In general, the incorporation of MBRs to wastewater treatment plants promises a solution for environment sustainable water management and treatment and, through continuing research and development, will serve an important function in addressing the water quality challenges of the future.

Intensive electron transfer of a single-atom Fe-based catalytic ceramic membrane for municipal wastewater treatment: The synergistic effects of nitrogen vacancy defect and ultrathin nanostructure.

Intensive electron transfer of a single-atom Fe-based catalytic ceramic membrane for municipal wastewater treatment: The synergistic effects of nitrogen vacancy defect and ultrathin nanostructure.

Acidophilic partial nitrification rapid startup and robustness validation for municipal wastewater treatment: Operation performance and microorganism insights.

Acidophilic partial nitrification rapid startup and robustness validation for municipal wastewater treatment: Operation performance and microorganism insights.

Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico

This study investigates the performance of large-scale ornamental treatment wetlands (TW) for the treatment of municipal wastewater in the municipality of Nautla, Veracruz, Mexico, specifically within a contaminated estuary in the Gulf of Mexico. The research employed a treatment wetland system that integrates mixed flow methods, including vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF), to optimize operational, maintenance, and energy costs. Over a monitoring period from 15 October 2022 to 17 September 2023, the system achieved remarkable efficiencies in the removal of chemical oxygen demand (COD), NH3-N, NH4-N, NO2-N, NO3-N, total nitrogen (TN), with removal rates of 93.37%, 93.37%,91.36%, 91.29%, 95.74%, 97.36%, 71.69%, 92.26% and 91.45%, respectively. The effluent complied with the water quality standards established by the official Mexican standard NOM-001-SEMARNAT-2021, demonstrating the effectiveness of this TW configuration in treating water characterized by high chemical oxygen demand, nitrogen, and phosphorus levels. The results are especially relevant for tropical climates, where high temperatures and humidity can affect microbial activity and nutrient cycling, potentially enhancing treatment performance and reducing construction and management costs. This research highlights the viability of ornamental treatment wetlands as a sustainable solution for wastewater treatment in tropical climates and provides valuable information for future implementation and design criteria.

Deciphering intricate associations between vigorous development and novel metabolic preferences of partial denitrification/anammox granular consortia within mainstream municipal wastewater.

Deciphering intricate associations between vigorous development and novel metabolic preferences of partial denitrification/anammox granular consortia within mainstream municipal wastewater.

A chemically enhanced primary treatment and anammox-based process for sustainable municipal wastewater treatment: The advantage and application prospects.

A chemically enhanced primary treatment and anammox-based process for sustainable municipal wastewater treatment: The advantage and application prospects.

Biodegradation of trimethoprim and sulfamethoxazole in secondary effluent by microalgae-bacteria consortium.

Biodegradation of trimethoprim and sulfamethoxazole in secondary effluent by microalgae-bacteria consortium.

Microplastics in German paper mills' wastewater and process water treatment plants: Investigation of sources, removal rates, and emissions.

Microplastics in German paper mills' wastewater and process water treatment plants: Investigation of sources, removal rates, and emissions.

How Rhodococcus ruber accelerated denitrification with soybean-processing wastewater as the electron donor.

How Rhodococcus ruber accelerated denitrification with soybean-processing wastewater as the electron donor.

Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River.

Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River.

Isotopically resolved fate and processes of nitrogen in a constructed wetland treating domestic effluent.

Isotopically resolved fate and processes of nitrogen in a constructed wetland treating domestic effluent.

Aeration strategies for microalgae in wastewater treatment: Enhancing pollutant removal and community dynamics.

Aeration strategies for microalgae in wastewater treatment: Enhancing pollutant removal and community dynamics.

Pilot-scale partial nitrification and anaerobic ammonium oxidation system for nitrogen removal from municipal wastewater

Partial nitrification has the advantages of saving energy and reducing the need for carbon sources in municipal wastewater treatment. However, for municipal wastewater with low ammonia, start-up and maintenance of partial nitrification is a worldwide challenge. Here we developed a pilot-scale double sludge system consisting of two sequencing batch reactors for partial nitrification (12 m2) and denitrification/anaerobic ammonium oxidation (denitrification/anammox, 8.4 m2) to treat municipal wastewater. Partial nitrification was maintained at no ammonium remaining with a nitrite accumulation rate of 87.7%. This study found that partial nitrification system effluent chemical oxygen demand increased from 24.8 mg L−1 to 64.9 mg L−1 accompanied by transformation from complete nitrification to partial nitrification. In the denitrification/anammox system, the reduction of nitrite to nitrogen required about 40% less carbon consumption than nitrate. High nitrogen removal was achieved with effluent total inorganic nitrogen of 2.7 mg L−1 without carbon addition. This work provided a pilot-scale demonstration of low-carbon high-nitrogen removal.

Biogas Production Modelling Based on a Semi-Continuous Feeding Operation in a Municipal Wastewater Treatment Plant

Anaerobic digestion is a common method for treating sewage sludge in municipal wastewater treatment plants (WWTPs). However, modelling this process can be very challenging due to the complexity of biochemical reactions. This paper presents a novel methodology that estimates biogas production from sewage sludge by considering the semi-continuous sludge-feeding process of the digester. In most WWTPs, the sewage sludge treatment operates in a dynamic process; therefore, using a time-dependent tool that represents this dynamic process is essential for accurately representing biogas production. The biogas production results from the proposed model are compared against the historical data for a large-scale WWTP located in Sydney, Australia. The proposed model shows great accuracy and follows the historical data trend very precisely. The average biogas production based on historical data for 2020, 2021, and 2022 was 37,337 m3/d, 31,695 m3/d, and 23,350 m3/d, whereas for the proposed model, it was 37,960 m3/d, 30,465 m3/d, and 23,080 m3/d. Over the three-year period, the average biogas production was 30,794 m3/d for historical data and 30,503 m3/d for the proposed model, which shows a great level of accuracy (R2 of 0.85 and average error of 4.64%) on the results of the proposed model and WWTP historical data.

Determination of microplastics in municipal wastewater treatment plant effluents and sludge using micro-Raman spectroscopy

Microplastics (MPs) increase global awareness due to their ubiquity, high concentration levels, and devastating effects on the aquatic environment. Wastewater treatment plants (WWTPs) are recognized as a significant source of microplastics in aquatic and terrestrial environments, particularly for plastics used in personal care products and textile fibers from the clothing industry. The focus of the present study was the determination of MP in wastewater and sewage sludge samples of WWTP of Ioannina city, according to their shape, size, concentration, and polymer type. A wet peroxide oxidation (WPO) method using 30% H2O2 and 0.05 M ferrous (II) solution was applied to the water effluent, while an enzymatic digestion method combined with WPO was employed to eliminate the organic matter and extract MPs from sludge samples. Micro-Raman spectroscopy coupled with appropriate software was applied to detect and quantify the microplastic particles. The outcomes from this study showed that the most representative shape of MP in effluent wastewater and sludge was fragments (66.7% and 75%, respectively), followed by fibers, spheres, and films. Polyamide (PA), p -acrylic acid (PAA), and p -acrylamide-co-p -acrylic acid (PAM-co-PAA) were the most abundant polymers (100% frequency of detection), followed by p -vinyl chloride (PVC), p -butyl methacrylate (PBMA), p -ethylene (PE), p -styrene (PS), p -propylene (PP), p -vinyl alcohol (PVA), and p -vinyl butyral (PVB) (20%-80% frequency of detection). The mean concentration of MPs in five sampling campaigns was 5.8 ± 0.6 particles/L in secondary WWTP effluents and 33.3 ± 8 particles/g in sludge. This study focused on monitoring campaign, in order to better understand the occurrence, impact, and risks associated with MPs on WWTPs.

Nutrient removal performance and microbial composition analysis in hybrid membrane bioreactor for municipal wastewater treatment.

The removal of nutrients from wastewater to reduce the toxicity of these compounds to the environment requires more space in wastewater treatment plants to establish anaerobic, anoxic and aerobic treatment stages. To address this limitation, researchers have developed practical, intensive hybrid treatment systems that enhance nutrient removal performance while requiring less space. However, the implementation of hybrid systems within a reactor introduces the interaction between the attached and suspended growth that can influence the microbial community structure and the performance of the system, so it is crucial to understand the composition of the microbial communities involved in hybrid growth to optimize control strategies in these systems. This study investigated the microbial community structure of the integrated moving bed membrane bioreactor (IMBMBR) system and its impact on nutrient removal in municipal wastewater. The findings demonstrated that the effluent quality was improved with the IMBMBR. The efficiency of removing COD, BOD5, and in the IMBMBR were 91 ± 4.0%, 95 ± 4.0%, 99 ± 0.2% and 24 ± 3.0%, respectively. The IMBMBR had better nitrite oxidation and complete nitrification by increasing the diversity and abundance of effective bacteria. The abundance of Proteobacteria, Bacteroidetes and Nitrospira was enhanced in IMBMBR. Coexistence of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in IMBMBR led to increased nutrient removal. The study results suggest that IMBMBR can be an effective process for nutrient removal, achieving quality standards that comply with legal requirements for wastewater in municipal and industries with limited space for establishing treatment facilities. Additionally, this process can be quickly implemented as an upgrade to existing wastewater treatment plants, avoiding the need to develop an entirely new system.

Emission, Nonindustrial Sources, and Multiple Degradation Pathways of Chlorinated-Methylsiloxanes in Municipal Wastewater Treatment Plants: One National Study in China.

This is the first study to investigate national emission characteristics and multiple degradation pathways of chlorinated-methylsiloxanes in municipal wastewater treatment plants (WWTPs) of China. Monochlorinated products of three primary methylsiloxane oligomers (D4, D5, and D6), namely, D3D(CH2Cl), D4D(CH2Cl), and D5D(CH2Cl), were detected (2.1-9.9 ng/L, df = 72.4-89.7%) in raw municipal wastewater from 29 WWTPs of 25 Chinese cities. Among these cities, the total emissions (1.1-19.9 μg·day-1·person-1) of chloromethylsiloxanes (∑chloromethylsiloxanes) and the chloromethylsiloxanes/methylsiloxanes ratios were positively related with per capita gross domestic product (r = 0.78 and 0.79, p < 0.01). Meanwhile, ∑chloromethylsiloxanes were also found in residential wastewater, swimming pool water, and medical wastewater treated by free chlorine or advanced oxidation, with national emission from these nonindustrial sources being about 5.7 tonnes, 2.7 kg, and 38.4 kg each year, respectively. Unlike their poor elimination (7.7-10.8%) during wastewater biotreatment process, both methylsiloxanes and chloromethylsiloxanes exhibited more obvious biodegradation (10.9-20.6%) during sludge digestion. Simulation experiments indicated that chloromethylsiloxanes were degraded 1.3-1.7 times faster (t1/2 = 74.3-137 days) than parent methylsiloxanes. Hydrolysis and dechlorination, respectively, contributed 54.5% and 27.7% to chloromethylsiloxanes degradation. Additionally, the hydrolysis product (CH2Cl)MeSi(OH)2 had a 1.5-2.8 times faster dechlorination rate than chloromethylsiloxanes, suggesting that Si-O hydrolysis may accelerate dechlorination of chloromethyl.