Stages Of Wastewater Treatment Research Articles

Identification of microbial groups in the aeration tanks of secondary wastewater treatment stage

Microbes are prevalent in wastewater, degrading organic matter that impact the environment. In recent years, wastewater treatment plants have been used to process treated water for domestic purposes, sustaining groundwater resources for the future. The current study assessed the present microbial species in the aeration tanks for the secondary wastewater treatment stage in the Sulaibiya Wastewater Treatment and Reclamation Plant, Kuwait. Biweekly wastewater samples were collected for a period of three months from October 2022 to December 2022 from the aeration tanks. The collected wastewater samples were analyzed for microbiological parameters including total coliform, fecal coliform, Salmonella, and E. coli. Further, the microbial species were identified using the Biolog Omnilog Instrument. The results indicated that a total of 45 bacterial species isolates were identified with the most dominant genus being Bacillus with twenty-one isolates. Though Bacillus is common in aeration tanks, the presence of Bacillus thuringiens/cereus is rare and their existence could be due to the change in climatic conditions such as rainfall, dust and wind. Therefore, the study recommends that all microbial groups should be identified at all treatment stages including, primary, secondary, tertiary, and advanced treatment stages to ensure the complete removal of microbes.

To what extent do water reuse treatments reduce antibiotic resistance indicators? A comparison of two full-scale systems

Water reuse is an essential strategy for reducing water demand from conventional sources, alleviating water stress, and promoting sustainability, but understanding the effectiveness of associated treatment processes as barriers to the spread of antibiotic resistance is an important consideration to protecting human health. We comprehensively evaluated the reduction of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in two field-operational water reuse systems with distinct treatment trains, one producing water for indirect potable reuse (ozone/biologically-active carbon/granular activated carbon) and the other for non-potable reuse (denitrification-filtration/chlorination) using metagenomic sequencing and culture. Relative abundances of total ARGs/clinically-relevant ARGs and cultured ARB were reduced by several logs during primary and secondary stages of wastewater treatment, but to a lesser extent during the tertiary water reuse treatments. In particular, ozonation tended to enrich multi-drug ARGs. The effect of chlorination was facility-dependent, increasing the relative abundance of ARGs when following biologically-active carbon filters, but generally providing a benefit in reduced bacterial numbers and ecological and human health resistome risk scores. Relative abundances of total ARGs and resistome risk scores were lowest in aquifer samples, although resistant Escherichia coli and Klebsiella pneumoniae were occasionally detected in the monitoring well 3-days downgradient from injection, but not 6-months downgradient. Resistant E. coli and Pseudomonas aeruginosa were occasionally detected in the nonpotable reuse distribution system, along with increased levels of multidrug, sulfonamide, phenicol, and aminoglycoside ARGs. This study illuminates specific vulnerabilities of water reuse systems to persistence, selection, and growth of ARGs and ARB and emphasizes the role of multiple treatment barriers, including aquifers and distribution systems.

CONTROL MODEL OF THE WASTEWATER TREATMENT PROCESS

The main stages of biological wastewater treatment are studied, existing models and control of these processes are analyzed, methods for solving the system of differential equations and the disadvantages of each model when used for control purposes are shown. To find the optimal mode using models of the biological treatment process, various criteria are used. The parameters and variables of the process of biological wastewater treatment by microorganisms in aeration tanks are determined - control and exciting influences, as well as input and output quantities, and a system of differential equations connecting them is established. The feasibility of using MatLAB software for building an analytical model and its solution, and Simulink for visual modeling is shown. Keywords: wastewater, model, aero tank, biological treatment, management.

Determinants of microbial colonization on microplastics through wastewater treatment processes: The role of polymer type and sequential treatment

This study examines the microbial colonization characteristics of microplastics (MPs) in wastewater treatment plants (WWTPs), focusing on polymer types (High-Density Polyethylene (HDPE) and Polyethylene Terephthalate (PET)) and various stages of wastewater treatments. Through individual and sequential deployment approaches, the research aimed to identify the determinants of bacterial colonization on MPs, whether they were introduced at each stage of treatment individually or in sequence from primary to tertiary stages. The study revealed that the stage of wastewater treatment profoundly influenced bacterial colonization on the polymer types MPs, with bacterial attachment being largely niche-specific. HDPE showed increased sensitivity to wastewater composition, leading to selective biofilm formation. For instance, in HDPE, Firmicutes accounted for 25.1 ± 0.04 % during primary treatment, while Alphaproteobacteria increased significantly in the tertiary treatment to 19.8 ± 0.1 %. Conversely, PET exhibited a stochastic pattern of bacterial colonization due to differences in surface hydrophilicity. Additionally, in sequential deployments, a notable shift towards stochastic bacterial attachment on MPs, particularly with HDPE was observed. The Shannon diversity values for MP biofilms were consistently higher than those for wastewater across all stages, with PET showing an increase in diversity in sequential deployments (Shannon diversity: 5.01 ± 0.03 for tertiary stage). These findings highlight the critical role of MPs as carriers of diverse bacteria, emphasizing the necessity for strategies to mitigate their impact in WWTPs. This study presents a significant advancement in our understanding of the interactions between MPs and microbial populations in WWTP environments.

Correlation between odour and hydrogen sulphide concentrations from municipal wastewater treatment plant immissions

The study focused on odours generated by hydrogen sulphide (H2S) immissions from a municipal wastewater treatment plant in a city of 2 million people. Odour awareness was vital to monitor environmental pollution and human’s safety. H2S was released from decomposition of organic matter, sulphites (SO32-) and sulphates (SO42-) by anaerobic microorganisms used in the biological stage of wastewater treatment. H2S was responsible for odours coming from the treatment plant. Long exposure (8 hours) to 2-5 ppm causes headaches and watery eyes, and 50 ppm irritates the airways. Maximum permissible concentrations for H2S are 0.006 ppm (24 hours) and 0.011 ppm (30 minutes). In Romania there are no limits on the concentration of odours. The sludge pumping station from the wastewater treatment plant registered the highest odour concentration at 36.000 OUE/m3, with significant levels of H2S primarily found there. Nevertheless, the activated sludge aeration system effectively eliminated around 99% of the H2S through degradation and absorption processes. The correlation between H2S and odour has been proved by a direct proportional relationship with a ratio of 25.000. Experimental determinations and mathematical modelling, using the Aermod View program, contributed to a deeper understanding of the impact of odours on the environment and on sensitive receptors, showed maximum odour concentrations of 38.8 ouE/m3 at the site of the municipal wastewater treatment plant and 5 ÷7 ouE/m3 at receptors, but without affecting residential areas.

Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Feces and Wastewater Treatment System in Swine Farms, Thailand

The antimicrobial resistance (AMR) problem is one that demands urgent interventions to minimize the rapid spread in humans, animals and the environment. Extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-Ec) could spread from livestock farms to environment or circulate in farms via wastewater. This study aimed to quantify and characterize ESBL-Ec in swine feces and wastewater samples collected from 2 conventional swine farms with wastewater treatment systems. Microbiological analysis was performed on fecal and wastewater samples, and the concentration of cefotaxime (CTX)-resistant bacteria, indicative of ESBL-Ec, was determined across different stages of wastewater treatment. Additionally, ESBL-Ec was isolated and identified from fresh feces, swine house wastewater, and treated wastewater from covered lagoons and photosynthetic ponds. Results indicated a higher concentration of CTX-resistant bacteria in the wastewater in the early process of wastewater treatment. However, CTX-resistant bacteria were not detected in the final photosynthetic pond in one of the 2 farms. ESBL-Ec was identified in fresh feces from swine houses and wastewater treatment plants in both farms. Further antimicrobial susceptibility testing revealed diverse resistance patterns among the ESBL-Ec isolates, with tetracycline and gentamicin demonstrated the highest resistance rates. The ESBL genes identified belonged to the CTX-M-14, CTX-M-17 and CTX-M-55. This study demonstrated the presence of ESBL-Ec in swine feces and wastewater, emphasizing the importance of effective wastewater treatment before discharging to limit the spread of AMR bacteria. HIGHLIGHTS ESBL producers was isolated from fecal and wastewater samples from swine farms The wastewater treatment system could reduce cefotaxime-resistant bacteria CTX-M-14, CTX-M-17 and CTX-M-55 genes were detected in swine farms, Thailand GRAPHICAL ABSTRACT

Multidrug-resistant plasmid RP4 inhibits the nitrogen removal capacity of ammonia-oxidizing archaea, ammonia-oxidizing bacteria, and comammox in activated sludge

In wastewater treatment plants (WWTPs), ammonia oxidation is primarily carried out by three types of ammonia oxidation microorganisms (AOMs): ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and comammox (CMX). Antibiotic resistance genes (ARGs), which pose an important public health concern, have been identified at every stage of wastewater treatment. However, few studies have focused on the impact of ARGs on ammonia removal performance. Therefore, our study sought to investigate the effect of the representative multidrug-resistant plasmid RP4 on the functional microorganisms involved in ammonia oxidation. Using an inhibitor-based method, we first evaluated the contributions of AOA, AOB, and CMX to ammonia oxidation in activated sludge, which were determined to be 13.7%, 41.1%, and 39.1%, respectively. The inhibitory effects of C2H2, C8H14, and 3,4-dimethylpyrazole phosphate (DMPP) were then validated by qPCR. After adding donor strains to the sludge, fluorescence in situ hybridization (FISH) imaging analysis demonstrated the co-localization of RP4 plasmids and all three AOMs, thus confirming the horizontal gene transfer (HGT) of the RP4 plasmid among these microorganisms. Significant inhibitory effects of the RP4 plasmid on the ammonia nitrogen consumption of AOA, AOB, and CMX were also observed, with inhibition rates of 39.7%, 36.2%, and 49.7%, respectively. Moreover, amoA expression in AOB and CMX was variably inhibited by the RP4 plasmid, whereas AOA amoA expression was not inhibited. These results demonstrate the adverse environmental effects of the RP4 plasmid and provide indirect evidence supporting plasmid-mediated conjugation transfer from bacteria to archaea.

Enhancing Ecological Efficiency in Biological Wastewater Treatment: A Case Study on Quality Control Information System

This study aimed to improve the control system of the biological stage of wastewater treatment using the quality control information system to support the concept of environmental efficiency management. In this case, the object of the study was the treatment facilities of Sumy city (Ukraine). For automatic control of wastewater quality, pH, oxidation reduction potential (ORP), electrical conductivity, and temperature indicators were taken, as well as hydrobiological analysis of activated sludge and mathematical modelling. The pH of wastewater at the input system has systematically unacceptable values (above 8.5 were recorded). Unacceptable concentrations of sulphur-containing toxicants arrive at the entrance of treatment facilities (0.22–1.3 mg/L). The response of activated sludge biocenosis to increasing concentrations of hydrogen sulphide in wastewater was analysed. Furthermore, a mathematical model of monoculture population growth, with two factors that affect population growth (nutrient concentration and monoculture production concentration), was implemented for the initial assessment of possible negative effects on wastewater treatment. The differential equation of the population dynamics of the i-th species of microorganisms in activated sludge was described. The applied system of automated monitoring of wastewater parameters with expert assessment of activated sludge and a unified mathematical model of approaches allows for a complex system of decision-making support to be realised. However, this requires the construction of mathematical models that would take into account the cause–effect relations that operate under conditions of incomplete technological information and the potential presence of emergencies due to natural disasters and military activities.

Industrial Wastewater Indirect Discharges in Integrated Pollution Prevention and Control Perspective: A Case Study of Prague

Wastewater discharge is one of the sources of environmental pollution. Wastewater pollution originates, inter alia, in industrial wastewater. After treatment, industrial wastewater can be discharged directly into the receiving water body or indirectly into a sewerage network terminated by the concluding stage of wastewater treatment. In the Czech Republic, indirect wastewater discharges are obeyed by the contractual relationship between the wastewater producer and the sewerage network operator. General limits for indirectly discharged wastewater are not set by any national legislation. The aim of this paper is a description of industrial wastewater discharged into the municipal sewerage system in Prague and possibilities of setting limits for installations undertaking the industrial activities listed in Annex I of the Integrated Prevention Act. The study showed that 72% of installations discharge industrial wastewater indirectly. The majority are energy plants that produce boiler blowdown wastewater. More than 80% of wastewater from studied installations is treated by one central wastewater treatment plant. The studied installations are equipped with a wastewater neutralization unit. However, despite the existence of the legislative framework to propose limits for studied installations, only two installations covered by BAT conclusions with relevant BAT-AELs for indirect discharges to the receiving water body were determined. Generally, a small percentage of installations can be limited by an integrated permit due to an inconsistent approach to the issue of indirect discharges from installations under the scope of the Integrated Prevention Act.

Assessment of Prickly Pear Fruit Peel Mucilage in Form of Gel as a Green Coagulant for the Tertiary Treatment of Domestic Wastewater.

The application of natural coagulants derived from food byproducts in domestic wastewater tertiary treatment, which contains a number of impurities as suspended colloidal particles, has a potential use as essential substitutes for traditional inorganic coagulants. These biomaterials are a sustainable and environmentally friendly alternative that can be used to improve water quality and human health. In this study, prickly pear (PP) fruit peel mucilage gel was evaluated as a novel coagulant for the tertiary stage of domestic wastewater treatment. Jar tests were performed on residual raw water at the inlet (influent) and outlet (effluent) of the tertiary wastewater treatment (constructed wetland) with a coagulant dose of 12 mg L-1 at a pH of 13. The efficiency of green (i.e., mucilage) and inorganic chemical (i.e., FeCl3) coagulants was compared on the basis of turbidity and color removal. The flocs produced by the coagulants were characterized structurally by FTIR spectroscopy and Zeta potential analysis and morphologically by scanning electron microscopy (SEM). The results showed that the turbidity and the color removal efficiency of the mucilage compared to the FeCl3 at the outlet of the treatment (effluent) were practically the same, reaching 94% turbidity and 85-87% color removal efficiency with both coagulants. The structure and morphology of the flocs generated by the coagulants showed a higher content of organic matter trapped in the flocs. The floc formation observed mechanisms were adsorption/bridging for mucilage and charge neutralization for FeCl3. The results of this study demonstrated that the PP mucilage green coagulant can be used to enhance the quality of treatment of domestic wastewater in an eco-friendly and biodegradable manner.

Study of HAZOPs in the Screening Unit of the Industrial Gas Wastewater Treatment Plant

The filtration is the final stage of industrial gas wastewater treatment for clean water generation. Filtration is an operation of separating solid and liquid materials by filter medium. In filtration process the driving force such as pressure difference by gravitation or rotary power cause the feed to flow. The process parameters in the filtration process need to be monitored and controlled because deviation or abnormality of the process parameters will cause operating failures. This condition requires a more in-depth identification so that the risks of operating failures can be minimized. HAZOPs is a method to identify hazard that caused by deviation of parameters using guide words. Steps of the research consisted of early survey, literature study, and filling the HAZOPs worksheet such as determine study node, deviation, parameter, guideword, risk evaluation, and risk control. The results of the study show that there were four potential deviations from three parameters which were flow, pressure, and temperature. Risk values analysed were medium and low. Recommendation of the system are adding alarm, valve, changing filter regularly, and scheduling the routine maintenance.

Life Cycle Assessment of an Industrial Laundry: a Case Study in the Italian Context

The high volumes of wastewater from industrial laundry with known toxicological concerns represent a relevant source of pollution for water bodies. Moreover, the unavailability of a detailed and specific Life Cycle Inventory (LCI) referring to the use of detergent within the laundry system could undermine the overall quality of the environmental assessment. This is related to the use of a substitutional product or proxy dataset for specific processes like the use of detergents. Laundry services are also known as highly energy consuming sites. This paper thus aims to make a Life Cycle Inventory (LCI) and Assessment (LCA) for an industrial laundry to provide the environmental profile for an Italian case study. The primary data input to finalize the LCI came from data collected directly from an Italian industrial laundry, integrated with literature, data provided from supporting databases (i.e. Ecoinvent 3.8), and data specifically obtained from the technical datasheets of detergents. The industrial laundry system considers the product’s overall supply chain: extraction and manufacturing of raw materials, including the detergent, transportation and logistics, the industrial process associated with the laundry activity, wastewater treatment, recirculation packaging, and final disposal stages. The calculated environmental profiles refer to the functional unit of 1 kg of linen washed by a standard washing cycle. The system boundaries of this study include the production stages of the process. The analysed activities are the transportation for the delivery and collection of linen, the purchase of raw materials, and the sanitization and washing processes. SimaPro 9.2 software and the ReCiPe 2016 H method are used for the LCA study. The baseline scenario has been compared with an alternative scenario introducing renewable energy technology (i.e. solar PV panel). The result shows a total impact of 12.77 mPt. The most impacting activities are the washing phase (4.62 mPt), the ironing phase (4.29 mPt), and the drying phase (1.56 mPt). The greatest impact in the washing phase is caused by the use of detergents and washing products. It is observed that most of the impacts fall into the categories of ‘Global Warming, Human Health’, ‘Fine Particulate Formation’, ‘Carcinogenic Human Toxicity’, ‘Non- Carcinogenic Human Toxicity’, ‘Fossil Resource Scarcity’. The midpoint category with the highest impact is ‘Fine Particulate Formation’ with a value of 5.18 mPt. The alternative scenario introducing renewable energy technology (i.e. solar PV panel) reduces the impact by 19.7 %. Sensitivity analyses have been performed to evaluate the LCA model’s uncertainty, with specific reference to the washing agents, the transportation of raw materials, and the energy consumption.

Characteristics and Risk Assessment of PAH Pollution in Soil of a Retired Coking Wastewater Treatment Plant in Taiyuan, Northern China.

We analyzed the soil at the site of a former coking wastewater treatment plant on redeveloped land in Taiyuan, northern China, in an attempt to detect the presence of 16 types of priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency (US EPA) and evaluate the potential pollution risks. The results show that the total proportion of PAHs in the surface soil of the redeveloped land ranged from 0.3 to 1092.57 mg/kg, with an average value of 218.5 mg/kg, mainly consisting of high-ring (5-6 rings) components. Characteristic ratio analysis indicated that the pollution was mainly related to the combustion of petroleum, coal, and biomasses. The wastewater treatment units operated according to the following treatment train: advection oil separation tank, dissolved air flotation tank, aerobic tank, secondary sedimentation tank, and sludge concentration tank. Our study found that pollution resulting from low-ring PAHs mainly appeared in the advection oil separation tank during the pre-wastewater treatment stage, while medium-ring PAH contamination mainly occurred in the dissolved air floatation tank, aerobic tank, and secondary sedimentation tank during the middle stages of wastewater treatment. High-ring PAH contamination primarily appeared in the sludge concentration tank in the latter stage of wastewater treatment. Based on our assessment of the ecological risk using the Nemerow Comprehensive Pollution Index and the toxicity equivalent factor (TEF) method, we determined that individual PAHs in the study area exceeded acceptable levels and the total amount of pollution was potentially harmful to the ecological environment. In addition, the comprehensive lifetime cancer risk for different populations resulting from exposure to the soil in the study area was determined to be within acceptable limits based on the average PAH concentrations.

Antibiotic Resistance and Genetic Variability of Acinetobacter spp. from Wastewater Treatment Plant in Kokšov-Bakša (Košice, Slovakia).

This study investigated the genetic variability and antibiotic resistance of Acinetobacter community depending on the stage of wastewater treatment in Kokšov-Bakša for the city of Košice (Slovakia). After cultivation, bacterial isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and their sensitivity to ampicillin, kanamycin, tetracycline, chloramphenicol and ciprofloxacin was examined. Acinetobacter spp. and Aeromonas spp. dominated bacterial populations in all wastewater samples. We identified 12 different groups based on protein profiling, 14 genotypes by amplified ribosomal DNA restriction analysis and 11 Acinetobacter species using 16S rDNA sequence analysis within Acinetobacter community, which showed significant variability in their spatial distribution. While Acinetobacter population structure changed during the wastewater treatment, the prevalence of antibiotic-resistant strains did not significantly vary depending on the stage of wastewater treatment. The study highlights the role of a highly genetically diverse Acinetobacter community surviving in wastewater treatment plants as an important environmental reservoir assisting in the further dissemination of antibiotic resistance in aquatic systems.

Mass flow and consumption calculations of pharmaceuticals in sewage treatment plant with emphasis on the fate and risk quotient assessment

In Egypt, pharmaceuticals consumption increased dramatically owing to the population growth and the unrestricted sale manner. Accordingly, the occurrence and fate of nine common pharmaceutical active compounds (PhACs) were scrutinized at a sewage treatment plant (STP) in Giza, Egypt. The levels of these PhACs were assessed in different the wastewater treatment stages and dewatered sludge phase using high-performance liquid chromatography coupled with photodiode arrays detector. The average concentrations of the total PhACs detected in influent, primary sedimentation effluent (PSE) and final effluent (FE) were 227, 155 and 89 µg L−1, respectively. The overall removal efficiency of the individual PhACs ranged from 18 to 72% removal. The occurrence trend revealed that biodegradation and adsorption are the concurrently removal mechanisms of the studied PhACs. The overall consumption per day in West of Greater Cairo was estimated based on influent concentration of STP. Sulfamethoxazole, paracetamol and diclofenac were detected with the highest levels in the influent of STP, PSE and FE as well as in the dewatered sludge. Furthermore, the high concentrations of these compounds in the sludge confirm the adsorption pathway removal of theses PhACs. The risk quotient (RQ) assessment for the detected PhACs in FE is greatly higher than the predicted non-effect concentration (PNEC). Conclusively, the FE of STP is considered a risky source for PhACs in adjacent surface water.

Efficiency of Wastewater Treatment from Iron, Copper and Nickel Ions by Sorbent from Water Purification Sludge

An analysis was made of the purification efficiency of three-component model solutions containing various amounts of iron, copper and nickel ions, and industrial wastewater containing the same amount of the above ions, using a sorbent obtained from sludge from a water treatment site. It has been established that in three-component model solutions, depending on the initial concentration, the efficiency of purification from iron ions is from 40 to 90 %, copper ions from 80 to 100 %, nickel ions from 90 to 100 %. In industrial wastewater, the efficiency of cleaning from iron ions is above 50 %, copper ions above 70 %, nickel ions from 60 to 80 %, depending on their initial concentration. It is shown that the use of this sorbent is promising for use in industrial enterprises both at the initial and final stages of wastewater treatment from iron, copper and nickel ions.

Wastewater-based surveillance of COVID-19 and removal of SARS-CoV-2 RNA across a major wastewater treatment plant in San Antonio, Texas

This study contributes to the collective evaluation of SARS-CoV-2 RNA persistence and removal along the wastewater treatment stages of a treatment plant in San Antonio, Texas.

Performance of Constructed Wetland on the Removal of Nutrient in Domestic Wastewater Using Chrysopogon Zizanioides

In this study, a native wild plant, Chrysopogon zizanioides (C-zi), was used in a wetland system to treat household wastewater. The root system of the C-zi is comprised of primary roots, secondary roots, and filamentous roots that all extend vertically deep into the soil rather than spreading horizontally. Depending on the concentration of the influent water, the water entering the vetiver-containing tank was stored for 3 to 5 days. These results demonstrated C-superior zi's ability to degrade organic waste as well as nutrients. COD, BOD, phosphorus, and ammonia are all removed with a high degree of effectiveness (82%, 82%, 80%, and 76%, respectively) in both stages of domestic wastewater treatment. The plant's roots had grown from 5 to 30 centimeters in length over the course of three months. In aspects of wastewater treatment and high biomass growth in wetland system, it was proposed that the use of C-zi is favorable.

Evaluation of the Richness, Species Diversity, and Biosafety of Saprotrophic Fungal Communities in Constructed Wetlands and Biological Wastewater Ponds

The present study was focused on the characterization of the biocenotic diversity of saprotrophic fungi, taking into account the impact of various treatment systems and technological stages as well as the physicochemical properties of wastewater. The biodegradation potential, the hazard posed to humans, animals, and the environment, and the effectiveness of elimination of propagules were evaluated. The most effective elimination of fungal propagules was recorded in hybrid constructed wetland systems with horizontal (HF-CW) and vertical (VF-CW) wastewater flow, especially in the VF-HF objects. The fungal communities present in wastewater from small constructed wetland (CW) and wastewater stabilization ponds (WSP) were dominated by ubiquitous terrestrial molds accompanied by a minimal number of yeasts. The similarity of the species composition of the fungal communities between the treatment plants was generally low, whereas the species diversity together with the population size was very high at the various stages of wastewater treatment. Species with potential pathogenicity to humans and animals accounted for over 45%, i.e., were classified as BioSafety Level 1 and 2 (BSL-1 and BSL-2 groups), and potentially phytopathogenic fungi represented 31.5% of the mycobiota species composition. The dynamics of fungal growth were correlated with the content of organic pollutants and nutrients (nitrogen and phosphorus) and with oxygen deficiency. The accumulation of nitrates corresponded to the decline in the frequency of fungi in treated wastewater. The lowest efficiency of the removal of fungi was exhibited by the biological wastewater stabilization ponds.

Bacterial Resistance to β-Lactam Antibiotics in Municipal Wastewater: Insights from a Full-Scale Treatment Plant in Poland.

This study investigated enzymatic and genetic determinants of bacterial resistance to β-lactam antibiotics in the biocenosis involved in the process of biological treatment of wastewater by activated sludge. The frequency of bacteria resistant to selected antibiotics and the activity of enzymes responsible for resistance to β-lactam antibiotics were estimated. The phenomenon of selection and spread of a number of genes determining antibiotic resistance was traced using PCR and gene sequencing. An increase in the percentage of bacteria showing resistance to β-lactam antibiotics in the microflora of wastewater during the treatment process was found. The highest number of resistant microorganisms, including multi-resistant strains, was recorded in the aeration chamber. Significant amounts of these bacteria were also present in treated wastewater, where the percentage of penicillin-resistant bacteria exceeded 50%, while those resistant to the new generation β-lactam antibiotics meropenem and imipenem were found at 8.8% and 6.4%, respectively. Antibiotic resistance was repeatedly accompanied by the activity of enzymes such as carbapenemases, metallo-β-lactamases, cephalosporinases and β-lactamases with an extended substrate spectrum. The activity of carbapenemases was shown in up to 97% of the multi-resistant bacteria. Studies using molecular biology techniques showed a high frequency of genes determining resistance to β-lactam antibiotics, especially the blaTEM1 gene. The analysis of the nucleotide sequences of blaTEM1 gene variants present in bacteria at different stages of wastewater treatment showed 50-100% mutual similarity of.