Biological Treatment Technologies Research Articles

Biological two-stage treatment technology for mitigating mining-related heavy metal pollution in Georgian rivers

ObjectivesThe study aimed to investigate heavy metal contamination (copper, arsenic, manganese) in Georgian rivers affected by mining and develop a two-stage water purification technology using Spirulina (Arthrospira platensis) and trehalose lipid (TRL). This technology offers a sustainable and efficient solution to mitigate environmental and health hazards from mining-related pollution, improving river ecosystems and public health.Data DescriptionThis study examines the current state of the Kvirila, Lukhuni, Kazretula, and Mashavera rivers in terms of heavy metal pollution. Data were collected from field application of a two-stage purification process. Initial assessments showed heavy metal concentrations exceeding local regulatory limits (საქართველოს საკანონმდებლო მაცნე. გარემოსდაცვითი ტექნიკური რეგლამენტების დამტკიცების თაობაზე. Environmental Technical Regulations Approval. www.matsne.gov.ge/en/document/view/2196792?publication=0&scroll=0. Accessed 22 Aug 2024.). The purification process involved a 72-h incubation in a primary tank, followed by membrane filtration and the addition of biomass with trehalose lipid (TRL) in a secondary tank. Post-treatment data revealed significant reductions in manganese and copper concentrations, bringing them below permissible thresholds. These data highlight the effectiveness of the two-stage purification technology in removing heavy metal contaminants from water sources impacted by industrial pollution. The findings demonstrate the potential of this technology to improve sustainable water management practices and provide scalable solutions for communities facing similar water quality challenges.

Application of Decentralized Wastewater Treatment Technology in Rural Domestic Wastewater Treatment

The management of domestic wastewater in rural areas has always been challenging due to characteristics such as the wide distribution and dispersion of rural households. There are numerous domestic sewage discharge methods used in rural areas, and it is difficult to treat the sewage. To address this problem, decentralized wastewater treatment systems (DWTSs) have been installed around the globe to reuse and recycle wastewater for non-potable uses such as firefighting, toilet flushing, and landscape irrigation. This study compares the currently implemented treatment processes by investigating them from the point of view of their performance and their advantages and disadvantages to provide new ideas for the development of rural wastewater treatment technologies. According to conventional treatment technologies including activated sludge (OD, A/O, A/A/O, SBR), biofilm (biofilter, MBBR, biological contact oxidation, biofluidized bed) and biogas digesters, natural biological treatment technologies including artificial wetlands (surface flow, vertical flow, horizontal submerged flow artificial wetlands), soil percolation systems (slow, fast, subsurface percolation and surface diffusion) and stabilization pond technology and combined treatment technologies are categorized and further described.

Research on Coal Mine Environmental Pollution Management and Ecological Restoration Technology

This paper analyses the current situation of environmental pollution in coal mines, its causes, and its impact on the ecological environment, and systematically researches the management of environmental pollution in coal mines and ecological restoration technology. The paper analyses the main categories of coal mine environmental pollution, including water pollution, air pollution, and solid waste pollution, and discusses the causes of these pollution and their destructive effects on the ecological environment. Immediately after that, the article elaborates on the treatment technologies of coal mine environmental pollution, including physical, chemical and biological treatment technologies for water pollution control, blocking, adsorption and covering technologies for air pollution control, and landfill, incineration and resource utilization strategies for solid waste disposal. This paper also discusses coal mine ecological restoration techniques, including species selection and allocation for vegetation restoration, vegetation restoration models, physical, chemical and biological methods for soil improvement, and engineering, vegetation and agricultural measures for soil and water conservation. Through the research of this paper, the researchers aim to provide scientific basis and technical support for the management of coal mine environmental pollution and ecological restoration and to promote the restoration of the ecological environment in mining areas and the sustainable development of the coal industry.

Robust nitrogen removal via nitrification-partial denitrification / anammox to co-treat acrylic fiber wastewater and sewage without external carbon

Acrylic fiber (AF) wastewater is characterized by high levels of ammonia nitrogen, refractory organic compounds, and toxic substances, making biological nutrient removal challenging. Conventional biological treatment technologies are often ineffective due to the complex composition, high toxicity, and low C/N ratios of AF wastewater. In this study, a two-stage nitrification-partial denitrification/anammox (N-PDA) process was firstly developed for the combined treatment of AF wastewater and domestic sewage, which integrated nitrification-SBR(N-SBR) and partial denitrification/anammox-UASB (PDA-UASB). The N-SBR achieved stable nitrification (ARE=100 %, HRT=4.2 h) with increasing ratios of AF wastewater, while the PDA-UASB utilized organic carbon from domestic sewage to simultaneously remove nitrate (91.7 mg/L) and ammonium (66.3 mg/L) through the PDA pathway (HRT=11.3 h). After 200 days, the relative abundance of Candidatus Brocadia increased from 0.6 to 5.4 %, ensuring robust nitrogen removal performance. The system achieved effluent ammonium and total nitrogen concentrations below 1.0 mg/L and 15.0 mg/L, respectively, with a total nitrogen removal rate of 87 %. This study demonstrates the N-PDA process as an efficient, energy-saving, and cost-effective solution for treating AF wastewater without the additional organic carbon sources, enhancing nitrogen removal efficiency and operational stability.

Insights into the role of electrochemical stimulation on sulfur-driven biodegradation of antibiotics in wastewater treatment

The presence of antibiotics in wastewater poses significant threat to our ecosystems and health. Traditional biological wastewater treatment technologies have several limitations in treating antibiotic-contaminated wastewaters, such as low removal efficiency and poor process resilience. Here, a novel electrochemical-coupled sulfur-mediated biological system was developed for treating wastewater co-contaminated with several antibiotics (e.g., ciprofloxacin (CIP), sulfamethoxazole (SMX), chloramphenicol (CAP)). Superior removal of CIP, SMX, and CAP with efficiencies ranging from 40.6 ± 2.6 % to 98.4 ± 1.6 % was achieved at high concentrations of 1000 μg/L in the electrochemical-coupled sulfur-mediated biological system, whereas the efficiencies ranged from 30.4 ± 2.3 % to 98.2 ± 1.4 % in the control system (without electrochemical stimulation). The biodegradation rates of CIP, SMX, and CAP increased by 1.5∼1.9-folds under electrochemical stimulation compared to the control. The insights into the role of electrochemical stimulation for multiple antibiotics biodegradation enhancement was elucidated through a combination of metagenomic and electrochemical analyses. Results showed that sustained electrochemical stimulation significantly enriched the sulfate-reducing and electroactive bacteria (e.g., Desulfobulbus, Longilinea, and Lentimicrobiumin on biocathode and Geobactor on bioanode), and boosted the secretion of electron transport mediators (e.g., cytochrome c and extracellular polymeric substances), which facilitated the microbial extracellular electron transfer processes and subsequent antibiotics removal in the sulfur-mediated biological system. Furthermore, under electrochemical stimulation, functional genes associated with sulfur and carbon metabolism and electron transfer were more abundant, and the microbial metabolic processes were enhanced, contributing to antibiotics biodegradation. Our study for the first time demonstrated that the synergistic effects of electrochemical-coupled sulfur-mediated biological system was capable of overcoming the limitations of conventional biological treatment processes. This study shed light on the mechanism of enhanced antibiotics biodegradation via electrochemical stimulation, which could be employed in sulfur-mediated bioprocess for treating antibiotic-contaminated wastewaters.

Evaluation of a Greenhouse Ecosystem to Treat Craft Beverage Wastewater

An aerated greenhouse ecosystem, often referred to as a Living Machine®, is a technology for biological wastewater treatment within a greenhouse structure that uses plants with their roots submerged in the wastewater. This system has a small footprint relative to traditional onsite wastewater treatment systems and constructed wetland, can treat high-strength wastewater, and can provide a high level of treatment to allow for reuse for purposes such as irrigation, toilet flushing, and landscape irrigation. Synthetic and actual craft beverage wastewaters (wastewater from wineries, breweries, and cideries) were examined for their treatability in bench-scale greenhouse ecosystems. The tested wastewater was high strength with chemical oxygen demands (COD) concentrations of 1120 to 15,000 mg/L, total nitrogen (TN) concentrations of 3 to 45 mg/L, and total phosphorus (TP) concentrations of 2.3 to 90 mg/L. The COD, TN, and TP concentrations after treatment ranged from below 125 to 560 mg/L, 1.5 to 15 mg/L, and below 0.25 to 7.8 mg/L, respectively. The results confirm the ability of the aerated greenhouse ecosystem to be a viable treatment system for craft beverage wastewater and it is estimated to require 54 and 26% lower hydraulic retention time than an aerobic lagoon and a low temperature, constructed wetland, respectively, the types of systems that would likely be used for this type of wastewater for onsite locations.

Resource utilization of sewage sludge as a nitrogen self-doped carbon quantum dot for specific detection of Fe3+ and Hg2+

With the widespread application of sewage biological treatment technology, a large amount of sewage sludge is generated during the sewage treatment process, which not only poses a threat to the environment but also results in wastage of C and N resources. In this study, the nitrogen self-doped fluorescent carbon dots (N-CDs) with an average particle size of 3.43 nm were synthesized green through a two-stage hydrothermal method. It was found that N-CDs can detect Fe3+ through internal filtration effect (IFE), with a linear detection range of 0–250 μM and a detection limit of 2.207 μM. Furthermore, N-CDs can also serve as a “turn off–on” probe for monitoring Hg2+, with a linear detection range of 2–10 μM and a detection limit of 0.989 μM. Interestingly, oxygen-containing groups were shown to be sensitive to Hg2+, which has been demonstrated for the first time. Moreover, the practical application of N-CDs as a double ion sensor in the detection of Fe3+ and Hg2+ has achieved good results for real power plant wastewater.

Emerging trends in POME treatment and applications: chemical and biotechnological aspects

Globally, environmental challenges are growing more and more significant. Changes in soil have been caused by the years-long discharge and careless disposal of palm oil mill effluent (POME). A systematic review explored emerging trends in POME treatment and applications, with a focus on recent, innovative methods for POME treatment with biological and chemical treatment technologies, chemical and biotechnological approaches. The review highlighted several key findings, including the efficiency and cost-effectiveness of these approaches, their ability to reduce environmental impacts, and their potential to recover resources such as energy and nutrients. Quantitative information on the efficacy of these approaches was also provided. Based on these findings, the review concludes that the aforementioned approaches can significantly improve POME treatment and offer a promising way to reduce environmental impacts and recover resources. However, further research is needed to optimize and scale up these approaches, as well as to assess their long-term sustainability. In addition, it is important to consider the social, economic, and environmental factors that may affect the successful implementation of these approaches.

Salt stimulates sulfide−driven autotrophic denitrification: Microbial network and metagenomics analyses

Sulfur autotrophic denitrification (SADN) is a promising biological wastewater treatment technology for nitrogen removal, and its performance highly relies on the collective activities of the microbial community. However, the effect of salt (a prevailing characteristic of some nitrogen−containing industrial wastewaters) on the microbial community of SADN is still unclear. In this study, the response of the sulfide−SADN process to different salinities (i.e., 1.5 % salinity, 0.5 % salinity, and without salinity) as well as the involved microbial mechanisms were investigated by molecular ecological network and metagenomics analyses. Results showed that the satisfactory nitrogen removal efficiency (>97 %) was achieved in the sulfide−SADN process (S/N molar ratio of 0.88) with 1.5 % salinity. In salinity scenarios, the genus Thiobacillus significantly proliferated and was detected as the dominant sulfur−oxidizing bacteria in the sulfide−SADN system, occupying a relative abundance of 29.4 %. Network analysis further elucidated that 1.5 % salinity had enabled the microbial community to form a more densely clustered network, which intensified the interactions between microorganisms and effectively improved the nitrogen removal performance of the sulfide−SADN. Metagenomics sequencing revealed that the abundance of functional genes encoding for key enzymes involved in SADN, dissimilatory nitrate reduction to ammonium, and nitrification was up−regulated in the 1.5 % salinity scenario compared to that without salinity, stimulating the occurrence of multiple nitrogen transformation pathways. These multi−paths contributed to a robust SADN process (i.e., nitrogen removal efficiency >97 %, effluent nitrogen <2.5 mg N/L). This study deepens our understanding of the effect of salt on the SADN system at the community and functional level, and favors to advance the application of this sustainable bioprocess in saline wastewater treatment.

Monitoring of enteropathogenic Gram-negative bacteria in wastewater treatment plants: a multimethod approach

The wastewater treatment processes are associated with the emission of microbial aerosols, including enteropathogenic bacteria. Their presence in this work environment poses a real threat to the health of employees, both through the possibility of direct inhalation of the contaminated air and indirectly through the pollution of all types of surfaces with such bioaerosol particles. This study aimed to investigate the prevalence of enteropathogenic bacteria in the air, on surfaces, and in wastewater samples collected in four wastewater treatment plants (WWTPs). The effectiveness of conventional culture-biochemical, as well as spectrometric and molecular methods for the rapid detection of enteropathogenic bacteria at workstations related to particular stages of wastewater processing, was also evaluated. Bioaerosol, surface swab, and influent and effluent samples were collected from wastewater plants employing mechanical–biological treatment technologies. The air samples were collected using MAS-100 NT impactor placed at a height of 1.5 m above the floor or ground, simulating aspiration from the human breathing zone. Surface samples were collected with sterile swabs from different surfaces (valves, handles, handrails, and coveyor belts) at workplaces. The raw influent and treated effluent wastewater samples were aseptically collected using sterile bottles. The identification of bacterial entheropathogens was simultaneously conducted using a culture-based method supplemented with biochemical (API) tests, mass-spectrometry (MALDI TOF MS), and molecular (multiplex real-time PCR) methods. This study confirmed the common presence of bacterial pathogens (including enteropathogenic and enterotoxigenic Escherichia coli, Salmonella spp., Campylobacter spp., and Yersinia enterocolitica) in all air, surface, and wastewater samples at studied workplaces. Higher concentrations of enteropathogenic bacteria were observed in the air and on surfaces at workplaces where treatment processes were not hermetized. The results of this study underline that identification of enteropathogenic bacteria in WWTPs is of great importance for the correct risk assessment at workplaces. From the analytical point of view, the control of enteropathogenic bacterial air and surface pollution using rapid multiplex-PCR method should be routinely performed as a part of hygienic quality assessment in WWTPs.

Application and effect evaluation of membrane bioreactor technology in municipal wastewater treatment

Due to the increasing amount of urban sewage and improved standards in sewage discharge, simple traditional biological sewage treatment fails to meet the needs of municipal sewage treatment. Therefore, to treat wastewater more efficiently, the process of combining biofilm technology with traditional biological wastewater treatment appeared. This paper analyzes the advantages and problems of the combined processes of membrane separation technology and traditional biological sewage treatment technology from and perspective of complementary processes, and puts forward relevant measures to alleviate membrane fouling. The study found that Membrane Bioreactor (MBR) technology occupies a small area, and has a better sewage effluent quality and strong stability, also the sludge output is low. Anaerobic Membrane Bioreactor (AnMBR) technology can increase the effectiveness of removing organic matter and enable resource reuse, which satisfies the demand for low energy consumption. Membrane Aeration Bioreactor (MABR) technology involves bubble-free aeration that greatly improves the quality of sewage effluent, and the production of sludge in MABR technology decreases. Anaerobic ammonium nitrogen membrane bioreactor technology can enhance the efficiency of Anammox bacteria, and the energy consumption and economic cost of this technology are low. Although these membrane combination processes can effectively treat sewage, they can easily be limited by factors such as temperature, microbial communities, and membrane fouling. This paper provides guiding opinions for decision makers in the field of urban sewage treatment so that they can apply appropriate sewage treatment technology to local municipal sewage treatment, promoting the sustainable development of sewage treatment.

Reservoir Desilting and Treatment of Silted Sediment

This paper aims to explore the significance and methods of sediment treatment in reservoirs. It first analyzes the impact of sediment on protective engineering, highlighting how sediment reduction exacerbates soil erosion and riverbed siltation, directly threatening the safety of protective engineering. Next, it introduces the application of compound fingerprint identification method in sediment source analysis, which accurately identifies sediment sources by comprehensively considering multiple characteristics, providing crucial scientific basis for protective engineering. The paper then discusses three main sediment treatment methods: mechanical dredging technology, sedimentation tank treatment, and biological treatment. Mechanical dredging technology is simple and efficient but suffers from issues like noise and high maintenance costs. Sedimentation tank treatment effectively improves water quality, while biological treatment technology has recently gained significant attention for purifying water bodies using microorganisms and plants, enhancing ecological quality. In conclusion, the paper emphasizes the importance of selecting suitable treatment methods based on specific conditions to achieve maximum efficiency and cost-effectiveness.

Response surface methodology for process optimization in livestock wastewater treatment: A review

With increasing demand for meat and dairy products, the volume of wastewater generated from the livestock industry has become a significant environmental concern. The treatment of livestock wastewater (LWW) is a challenging process that involves removing nutrients, organic matter, pathogens, and other pollutants from livestock manure and urine. In response to this challenge, researchers have developed and investigated different biological, physical, and chemical treatment technologies that perform better upon optimization. Optimization of LWW handling processes can help improve the efficacy and sustainability of treatment systems as well as minimize environmental impacts and associated costs. Response surface methodology (RSM) as an optimization approach can effectively optimize operational parameters that affect process performance. This review article summarizes the main steps of RSM, recent applications of RSM in LWW treatment, highlights the advantages and limitations of this technique, and provides recommendations for future research and practice, including its cost-effectiveness, accuracy, and ability to improve treatment efficiency.

Global occurrence of organic micropollutants in surface and ground water: Highlighting the importance of wastewater sanitation to tackle organic micropollutants

The occurrence, fate and distribution of organic micropollutants (OMPs) in different water matrices is of increasing concern due to the negative effects towards flora, fauna and human health. This metadata study provides an updated picture of the global occurrence of OMPs in freshwater and wastewater in five geographical regions, and illustrates how socioeconomic factors are key elements that influence the concentration of these OMPs in the different water matrices. The study also aims to provide a collated database of OMPs removal efficiencies achieved by the different biological treatment technologies. Our findings demonstrated that OMPs like acetaminophen, ibuprofen, and triclosan are present globally in freshwater (> 500 ng/L) and wastewater (> 10, 000 ng/L), and at relatively higher concentrations than the other evaluated OMPs. Significant correlations between OMPs concentration in wastewater versus freshwater demonstrated wastewater to be a potential source of certain OMPs to the freshwater environment. This was further confirmed through correlation between OMPs concentration and socioeconomic factors like infrastructure index and governance index in both wastewater and freshwater. These results highlighted the importance of wastewater sanitation to control and reduce OMPs dissemination in the environment. Thus, various types of biological wastewater treatment processes including activated sludge processes, biofilm processes, wetland and lagoon, and membrane bioreactor were analyzed for their OMP’s removal efficiencies. Findings demonstrated that advanced processes like membrane bioreactors (MBR) may not always outperform other low-costs biotechnologies in the treatment of OMPs (e.g., bisphenol A removal by activated sludge with anoxic and oxic zone, AS-AAO was 93% versus MBR at 89%). But rather, the removal efficiency will depend on pollutant properties and certain operational parameters such as hydraulic retention time, treatment capacity, and removal efficiency of total suspended solids.

Effects of nitrate reduction on the biotransformation of 1H-1,2,4-triazole: Mechanism and community evolution

Due to the refractory of 1 H-1,2,4-triazole (TZ), conventional anaerobic biological treatment technology is usually restricted by low removal efficiency and poor system stability. In this study, TZ biodegradation and nitrate reduction was coupled to improve the removal efficiency of TZ from polluted wastewater. Batch assay was performed with pure culture strain Raoultella sp. NJUST42, which was reported to have the capability to degrade TZ in our previous study. Based on batch assay result, complete removal of TZ could be achieved in the presence of nitrate, whereas only 50% of TZ could be removed in the control system. Long-term stability experiment indicated that the relative abundance of microorganisms (Bacteroidetes_vadinHA17, Georgenia, Anaerolinea, etc) was obviously enhanced under nitrate reduction condition. During long-term period, major intermediates for TZ biodegradation such as [1,2,4]Triazolidine-3,5-diol, hydrazine dibasic carboxylic acid and carbamic acid were detected. A novel TZ biotransformation approach via hydration, TZ-ring cleavage, deamination and oxidation was speculated. PICRUSt1 and KEGG pathway analyses indicated that hydration (dch), oxidation (adhD, oah, pucG, fdhA) of TZ and nitrate reduction (Nar, napA, nrfA, nirBK, norB, nosZ) were significantly enhanced in the presence of nitrate. Moreover, the significant enrichment of TCA cycle (gab, sdh, fum, etc.) indicated that carbon and energy metabolism were facilitated with the addition of nitrate, thus improved TZ catabolism. The proposed mechanism demonstrated that TZ biodegradation coupled with nitrate reduction would be a promising approach for efficient treatment of wastewater contaminated by TZ.

Removal of RNA viruses from swine wastewater using anaerobic membrane bioreactor: Performance and mechanisms

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23–76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.

Nitrogen and phosphorus removal from synthetic aquaculture water through electrocoagulation

In this research, we utilized multivariate analysis to evaluate the efficient removal of nitrogen and phosphorus from synthetic aquaculture water using the electrocoagulation process. The elimination of nitrogen and phosphorus is a critical issue in various wastewater treatment plants and aquaculture systems, especially in instances of intensive or super-intensive cultivation. To avert the buildup of pollutants in the water, be it within internal recirculation systems or bodies of water receiving effluents from rearing tanks, it is imperative to employ treatment methodologies designed to effectively eliminate nitrogen and phosphorus nutrients. These nutrients have the potential to induce eutrophication in aquatic ecosystems. However, conventional biological treatment technologies can be ineffective, as they often only remove one pollutant or the other. Furthermore, the individual operations for these systems are complex and require substantial space. Electrocoagulation is a compact and promising technology for treating aquaculture water and effluents for raw nutrient removal. In this context, our findings showcase the simultaneous removal of both nitrogen and phosphorus through the electrocoagulation method. The best treatment was verified for the highest electrical current density (74 A. m-2), the shortest distance between electrodes (4 cm), and the lowest electrolysis time (50 min). In these conditions, the efficiency removal in ammonia nitrogen and total phosphorus were 30.5% and 100% respectively. Keywords: electrochemical treatment, eutrophication, water pollution control.

The impact of ozone treatment on the removal effectiveness of various refractory compounds in wastewater from petroleum refineries

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms. These challenges can be overcome by using ozone (O3) as a standalone or as a pretreatment to the biological treatment. Ozone was used in this study to degrade the organic pollutants in the heavily contaminated PRW from a refinery in Mpumalanga province of South Africa. The objective was achieved by treating the raw PRW using ozone at different ozone treatment times (15, 30, 45, and 60 min) at a fixed ozone concentration of 3.53 mg/dm3. The ozone treatment was carried out in a 2-liter custom-designed plexiglass cylindrical reactor. Ozone was generated from an Eco-Lab-24 corona discharge ozone generator using clean, dry air from the Afrox air cylinder as feed. The chemical oxygen demand, gas chromatograph characterization, and pH analysis were performed on the pretreated and post-treated PRW samples to ascertain the impact of the ozone treatment. The ozone treatment was effective in reducing the benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds in the PRW. The 60-min ozone treatment of different BTEX pollutants in the PRW resulted in the following percentage reduction: benzene 95%, toluene 77%, m + p-xylene 70%, ethylbenzene 69%, and o-xylene 65%. This study has shown the success of using ozone in reducing the toxic BTEX compounds in a heavily contaminated PRW.

Effects of Hydrothermal Pretreatment and Anaerobic Digestion of Pig Manure on the Antibiotic Removal and Methane Production.

Whether advanced biological waste treatment technologies, such as hydrothermal pretreatment (HTP) integrated anaerobic digestion (AD), could enhance the removal of different antibiotics remains unclear. This study investigated the outcome of antibiotics and methane productivity during pig manure treatment via HTP, AD, and HTP + AD. Results showed improved removal efficiency of sulfadiazine (SDZ), oxytetracycline (OTC), and enrofloxacin (ENR) with increased HTP temperatures (70, 90, 120, 150, and 170°C). OTC achieved the highest removal efficiency of 86.8% at 170°C because of its high sensitivity to heat treatment. For AD, SDZ exhibited resistance with a removal efficiency of 52.8%. However, OTC and ENR could be removed completely within 30days. When HTP was used prior to AD, OTC and ENR could achieve complete removal. However, residual SDZ levels reduced to 20% and 16% at 150 and 170°C, respectively. The methanogenic potential showed an overall upward trend as the HTP temperature increased. Microbial analysis revealed the antibiotics-induced enrichment of specific microorganisms during AD. Firmicutes were the dominant bacterial phylum, with their abundance positively correlated with the addition of antibiotics. Methanobacterium and Methanosarcina emerged as the dominant archaea that drove methane production during AD. Thus, HTP can be a potential pretreatment before AD to reduce antibiotic-related risks in manure waste handling.

Performance of full-scale rural wastewater treatment plants in the reduction of antibiotic-resistant bacteria and antibiotic resistance genes from small-city effluents

The main objective of this study was to evaluate the performance of full-scale rural wastewater treatment plants (WWTPs) in the reduction of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from small-city effluents. Twenty full-scale WWTPs in rural Chile with different biological treatment technologies (vermifiltration (VF), activated sludge (AS) and biodisc (BD)) and disinfection treatments (chlorination (Cl) and UV irradiation (UV)) were monitored and studied in two campaigns: Campaign 1 (20 WWTPs) and Campaign 2 (6 WWTPs). In both campaigns, the rural WWTPs improved the water quality of the effluents very significantly (90%, 70%, and 40% reductions in TU, COD, and NH4+-N, respectively) and reduced ARB and ARG loads by 2–4 log units. All three biological treatments contributed to the final quality of the effluents, especially in terms of microbiological parameters, with statistically indistinguishable efficiencies between them. These results show the importance of rural WWTPs in improving the water quality of urban effluents while reducing microbiological risk and the spread of antibiotic resistance into the environment. The study demonstrates the utility of a non-centralized, self-managed wastewater treatment scheme that can be implemented in many sparsely populated areas around the world.