Tertiary Treatment Systems Research Articles

Impact of grazing by multiple Daphnia species on wastewater bacterial communities.

Understanding the dynamics of fecal bacterial communities is crucial for managing public health risks and protecting drinking water resources. While extensive research exists on how abiotic factors influence the survival of fecal microbial communities in water, less attention has been paid to the impact of predation by higher organisms, such as the widely distributed grazer Daphnia. Nevertheless, Daphnia plays a significant role in regulating bacterial communities in natural aquatic ecosystems, and recent studies highlighted its potential as a biofilter in alternative tertiary wastewater treatment systems. In this study, we investigated the influence of three different Daphnia species on a wastewater bacterial community, including fecal indicator bacterium E. coli. Using a microcosm setup to simulate the discharge of untreated sewage into surface water, we conducted in-depth analysis of bacterial community dynamics through sequencing the 16S rRNA gene. Our results revealed significant changes in microbial diversity and composition following exposure to Daphnia grazing, with variations observed among the three Daphnia species. D. pulicaria exerted the most pronounced impact on microbial diversity, followed by D. middendorffiana and D. mendotae. A total of 90 taxa exhibited significantly reduced relative abundance in the presence of Daphnia, with Firmicutes phylum being the most affected. At genus level, bacteria typically associated with wastewater (e.g., Zoogloea and Arcobacter) and gut microbiome constituents (e.g., Prevotella and Akkermansia) were notably affected by Daphnia exposure. The influence of Daphnia on bacterial community composition was most pronounced for D. pulicaria, while D. middendorffiana and D. mendotae primarily impacted community structure. Furthermore, we demonstrated that the microbial response to Daphnia exposure is phylogenetically conserved, potentially reflecting a grazing resistance or grazer feeding trait. Our findings shed new light on the role of Daphnia in controlling bacterial communities in polluted water bodies and underscore its potential as biofilter in wastewater treatment and reuse contexts.

Hybrid modelling framework for ozonation and biological activated carbon in tertiary wastewater treatment.

Despite water being a significant output of water and resource recovery facilities (WRRFs), tertiary wastewater treatment processes are often underrepresented in integrated WRRF models. This study critically reviews the approaches used in comprehensive models for ozone (O3) and biological activated carbon (BAC) operation units for wastewater tertiary treatment systems. The current models are characterised by limitations in the mechanisms that describe O3 disinfection and disinfection by-product formation, and BAC adsorption in multi-component solutes. Drawing from the insights from the current O3, BAC, and WRRF modelling approaches, we propose an integrated O3-BAC model suitable for simulating dissolved organic carbon (DOC) and micropollutants removal in the O3-BAC systems. We recommend a hybrid modelling approach in which data-driven models can be integrated to compensate for structural limitations in mechanistic models. The model is developed within the activated sludge model (ASM) framework for flexibility in coupling with other WRRF models and hence facilitates developing system-wide WRRF models for wastewater reclamation and reuse systems.

Performance evaluation of pilot phyto-vortex integrated system in the reduction of wastewater pollutants

Abstract Wastewater pollution remediation connects to goal 6 of the United Nations 17 Sustainable Development Goals (SDG) ensuring availability and sustainable management of water and sanitation for all. Conventional and advanced wastewater treatment are quite expensive to operate to fully comply with regulatory standards in the country. Phyto-vortex integrated system is an alternative tertiary wastewater treatment system that interfaces with an oil and grease skimmer and vortex technology, relying on green plants and a variety of soil substrates to remediate wastewater. The research evaluated the potential of the Phyto-vortex system and its performance in the reduction of domestic wastewater pollutants. Plants and soil substrates were selected via Analytic Hierarchy Process (AHP) using one-way sensitivity analysis. Common reed, Vetiver grass, and Canna Lily were planted in constructed reed beds with various soil matrices using substrates laid at different levels. The beds operate continuously as a horizontal subsurface flow treating 5 m3 of a sewage treatment effluent per day with 1-3 days hydraulic retention time (HRT). The vortex unit aerates the water for further removal of gaseous pollutants. Samples were taken at designated points for 18 weeks. Analysis of the results shows a maximum reduction of 92% for biochemical oxygen demand (BOD), 60 % for chemical oxygen demand(COD), and 70 % for total suspended solids (TSS). Concentration of identified heavy metals in the influent are within the regulatory standards except for a rise in zinc concentration which was 97% reduced in the system. The percentage reduction of pollutants varies each week with nitrates decreasing in the range of 50% to 99%, phosphates from 8% to 39.5%, and ammonia from 45.65% to 99%. Varying environmental conditions such as monsoon rains and extreme heat caused algal blooms and plant disease affecting the results. Lower temperatures and lower humidity favor a decrease in the levels of the pollutants while higher temperature, higher humidity favor an increase in the levels of Nitrates, Phosphates, and Ammonia. The overall results show an effective integrated system of phytoremediation coupled with a vortex unit in the reduction of wastewater pollutants.

Performance of bioretention systems by umbrella plant (Cyperus alternifolius L.) and common reed (Phragmites australis) for removal of microplastics

Domestic wastewater is one of the main sources of microplastic (MP) contamination in aquatic environment; however, most wastewater treatment plants (WWTPs) have not been designed for the removal of MPs. In this study, the release rate of MPs in the treated water from a WWTP into the river was estimated to be approximately 105 × 103 pcs/capita/day. Thus, bioretention systems are designed as tertiary wastewater treatment systems to reduce the number of MPs in water resources. The objective of this study was to evaluate the performance of bioretention systems using the umbrella plant (Cyperus alternifolius L.) and common reed (Phragmites australis) for MP removal. After 17 weeks, MPs were found in the common reed bioretention system. The common reed root system and substrate influence the MP retention process to a greater extent through physical filtration, substrate ratio, plant roots, and biofilms on the roots. Additionally, the common reed root system played an important role in the removal of low-density MPs. The accumulation of MPs in roots and root hairs inevitably impacts plants. The results showed that the common reed at a 3:2:9 ratio (gravel: sand: soil) had the highest relative height growth rate (RHGR) (1.8 mm cm−1 week−1). These results show that the HSFs–3 at a ratio of 3:2:9 was able to reduce the number of MPs, with an average removal efficiency of 62.89 % and 95.45 % for sizes >1000 µm, 89.21 % for sizes 500–1000 µm, and 44.16 % for sizes <500 µm. The highest average microbeads removal efficiency was 95.24 %. Our results suggest that plant bioretention using Horizontal Subsurface Flow system is an effective treatment for removing MPs from wastewater.

An Integrated Modified Anaerobic/Slow Sand Filter Tertiary Treatment System for Domestic Wastewater Treatment at a Single Family Level

An Integrated Modified Anaerobic/Slow Sand Filter Tertiary Treatment System for Domestic Wastewater Treatment at a Single Family Level

Biochar-integrated reactive filtration of wastewater for P removal and recovery, micropollutant catalytic oxidation, and negative CO2 e: Life cycle assessment and techno-economic analysis.

Life cycle assessment (LCA) and techno-economic analysis (TEA) models are developed for a tertiary wastewater treatment system that employs a biochar-integrated reactive filtration (RF) approach. This innovative system incorporates the utilization of biochar (BC) either in conjunction with or independently of iron-ozone catalytic oxidation (CatOx)-resulting in two configurations: Fe-CatOx-BC-RF and BC-RF. The technology demonstrates 90%-99% total phosphorus removals, adsorption of phosphorus to biochar for recovery, and >90% destructive removal of observed micropollutants. In this work, we conduct an ISO-compliant LCA of a 49.2 m3 /day (9 gpm) field pilot-scale Fe-CatOx-BC-RF system and a 1130 m3 /day (0.3 MGD) water resource recovery facility (WRRF)-installed RF system, modeled with BC addition at the same rate of 0.45 g/L to quantify their environmental impacts. LCA results indicated that the Fe-CatOx-BC-RF pilot system is a BC dose-dependent carbon-negative technology at -1.21 kg CO2 e/m3 , where biochar addition constitutes a -1.53 kg/m3 CO2 e beneficial impact to the process. For the WRRF-installed RF system, modeled with the same rate of BC addition, the overall process changed from 0.02 kg CO2 e/m3 to a carbon negative -1.41 kg CO2 e/m3 , demonstrating potential as a biochar dose-dependent negative emissions technology. Using the C100 100-year carbon accounting approach rather than Cnet reduces these CO2 e metrics for the process by about 25%. A stochastic TEA for the cost of water treatment using this combinatorial P removal/recovery, micropollutant destructive removal, and disinfection advanced technology shows that at scale, the mean cost for treating 1130 m3 /day (0.3 MGD) WRRF secondary influent water with Fe-CatOx-BC-RF using the C100 metric is US$0.18 ± US$0.01/m3 to achieve overall process carbon neutrality. Using the same BC dose in an estimation of a 3780 m3 /day (1 MGD) Fe-CatOx-BC-RF facility, the carbon neutral cost of treatment is reduced further to US$0.08 ± $0.01 with added BC accounting for US$0.03/m3 . Overall, the results demonstrate the potential of carbon negativity to become a water treatment performance standard as important and attainable as pollutant and pathogen removal. PRACTITIONER POINTS: Life cycle assessment (LCA) of a pilot scale tertiary biochar water treatment process with or without catalytic ozonation at a WRRF shows a carbon negative global warming potential of -1.21-kg CO2e/m3 while removing 90%-99% TP and >90% of detected micropollutants. Biochar-integrated reactive filtration use can aid in long-term carbon sequestration by reducing the carbon footprint of advanced water treatment in a dose-dependent manner, allowing an overall carbon-neutral or carbon-negative process. A companion paper to this work (Yu et al., 2023) presents the details related to the process operation and mechanism and evaluates the pollutant removal performance of this Fe-CatOx-BC-RF process in engineering laboratory pilot research and field WRRF pilot-scale water resource recovery trials. Techno-economic analysis (TEA) of this biochar catalytic oxidation reactive filtration process using Monte Carlo stochastic modeling shows a forecasted carbon-neutral process cost with low P and micropollutant removal as US$0.11/m3 ± 0.01 for a 3780-m3/day (1 MGD) scale installation with BC cost at US$0.03/m3 of that total. The results demonstrate the potential of carbon negativity to become a water treatmentperformance standard as important and attainable as pollutant and pathogen removal.

Thyroidkeeper: a healthcare management system for patients with thyroid diseases.

Thyroid diseases, especially thyroid tumors, have a huge population in China. The postoperative patients, under China's incomplete tertiary diagnosis and treatment system, will frequently go to tertiary hospitals for follow-up and medication adjustment, resulting in heavy burdens on both specialists and patients. To help postoperative patients recover better against the above adverse conditions, a novel mobile application ThyroidKeeper is proposed as a collaborative AI-based platform that benefits both patients and doctors. In addition to routine health records and management functions, ThyroidKeeper has achieved several innovative points. First, it can automatically adjust medication dosage for patients during their rehabilitation based on their medical history, laboratory indicators, physical health status, and current medication. Second, it can comprehensively predict the possible complications based on the patient's health status and the health status of similar groups utilizing graph neural networks. Finally, the employing of graph neural network models can improve the efficiency of online communication between doctors and patients, help doctors obtain medical information for patients more quickly and precisely, and make more accurate diagnoses. The preliminary evaluation in both laboratory and real-world environments shows the advantages of the proposed ThyroidKeeper system.

Harnessing the power of metal-organic frameworks to develop microplastic fouling resistant forward osmosis membranes

With the gradual increase of microplastics (MPs) in water and wastewater streams, it is imperative to investigate their removal using tertiary treatment systems to minimize and preferably prevent their entrance into aquatic environments. Forward osmosis (FO) is a non-pressurized membrane process with potential applications in MPs removal from wastewater. However, efficient application of FO systems relies on developing high-performance FO membranes with low fouling tendency. MPs are proven as emerging foulants in membrane systems, diminishing their performance and lifetime and this highlights the need to consider MP fouling in developing sustainable membranes. The current study focuses on a novel modification of thin film composite (TFC) FO membranes by MIL-53(Fe) as a water-stable and hydrophilic metal-organic framework. Experimental results demonstrated that the optimized FO membrane (0.2 wt% MIL-53(Fe)) achieved a significantly higher water flux (90% increase) with a 23% less reverse salt flux. The modified membrane also had significantly less flux decline in fouling experiments and higher flux recovery after physical cleaning compared to the control membrane affirming its higher antifouling efficiency. MIL-53(Fe) integration in the FO substrate proved to be a practical method for developing high-performance TFC FO membranes with improved antifouling properties against MPs and organic foulants.

The environmental assessment of tertiary treatment technologies for wastewater reuse by considering LCA uncertainty

Tertiary treatment methods can result in severe environmental impacts that should be taken into consideration when deciding about the best system for wastewater reuse applications beside technical and economic issues. Life cycle assessment (LCA) commonly is used for evaluating the environmental impacts of these methods. Given the importance of uncertainty analysis, it is still an uncommon practice in LCA researches in recent years, especially those focused on tertiary wastewater treatment technologies (TWWTTs). Therefore, the main purpose of this study is to investigate the parameter and input data uncertainty in LCA of TWWTTs. Considering huge amount of data collected for LCA from different sources with various precision, there is high uncertainty in obtained LCA results that could affect the ranking of different methods based on their environmental impacts. The Monte-Carlo based method is used for uncertainty analysis of LCA and it is investigated how it can affect the final ranking of tertiary treatment methods based on their environmental impacts. In present study, LCA is used to study the environmental impacts of 22 tertiary treatment systems used for further treatment of effluent of South of Tehran wastewater treatment plant (WWTP) located at the south of Tehran, Iran. The treated wastewater of this WWTP is planned to be used for different purposes including landscape irrigation and groundwater recharge as well as industrial and non-potable household (toilet flushing) usages. Among the 22 tertiary treatment systems, the best system for each application was chosen, based on the LCA results and the uncertainty of LCA.

Ozone reactor combined with ultrafiltration membrane: A new tertiary wastewater treatment system for reuse purpose

In the present research, a new technology using the application of ozone (O³) together with an ultrafiltration (UF) membrane was tested for the tertiary treatment of wastewater. The primary and secondary wastewater-treatment systems were a septic tank and anaerobic filter. The experiment was divided into two stages: the first including only the application of O3 in the reactor, and the second, inclusion of the UF membrane. During the first stage of the study, where only the ozone was applied, a time of 40 min was chosen, with removal levels for chemical oxygen demand (COD), five-day biochemical oxygen demand (BOD5), total organic carbon (TOC), turbidity and ammonium (NH4+) of 39.5%, 45.4%, 32.4%, 44.85% and 68.4% being recorded. During stage 2, the UF membrane inside the reactor was activated after 40 min of ozonation. The values for the removal of COD, BOD5, TOC, turbidity, NH4+ and total phosphorus were 89.13%, 95.41%, 82%, 93.4%, 14.75% and 79.67%, respectively. The use of O3 + UF removed 100% of total coliforms and viruses from the secondary wastewater. In accordance with North American and European guidelines, the water resulting from the treatment process is fit for reuse. The operating costs can vary between 0.859 € m-3 and 2.440 € m-3 depending on the cost per kWh in each country. The experiments were conducted under batch-mode conditions, further evaluations about the real scale operation would require a previous pilot stage that would develop more tools for operations specifications and their costs. The results recorded here show that the performance of this new reactor design is effective in the tertiary treatment of wastewater, and should be available for use in the near future.

Worldwide cases of water pollution by emerging contaminants: a review

Water contamination by emerging contaminants is increasing in the context of rising urbanization, industrialization, and agriculture production. Emerging contaminants refers to contaminants for which there is currently no regulation requiring monitoring or public reporting of their presence in our water supply or wastewaters. There are many emerging contaminants such as pesticides, pharmaceuticals, drugs, cosmetics, personal care products, surfactants, cleaning products, industrial formulations and chemicals, food additives, food packaging, metalloids, rare earth elements, nanomaterials, microplastics, and pathogens. The main sources of emerging contaminants are domestic discharges, hospital effluents, industrial wastewaters, runoff from agriculture, livestock and aquaculture, and landfill leachates. In particular, effluents from municipal wastewater treatment plants are major contributors to the presence of emerging contaminants in waters. Although many chemicals have been recently regulated as priority hazardous substances, conventional plants for wastewater and drinking water treatment were not designed to remove most emerging contaminants. Here, we review key examples of contamination in China, Portugal, Mexico, Colombia, and Brazil. Examples include persistent organic pollutants such as polychlorinated biphenyls, dibenzofurans, and polybrominated diphenyl ethers, in lake and ocean ecosystems in China; emerging contaminants such as alkylphenols, natural and synthetic estrogens, antibiotics, and antidepressants in Portuguese rivers; and pharmaceuticals, hormones, cosmetics, personal care products, and pesticides in Mexican, Brazilian, and Colombian waters. All continents are affected by these contaminants. Wastewater treatment plants should therefore be upgraded, e.g., by addition of tertiary treatment systems, to limit environmental pollution.

Are mangrove forests reliable sinks of heavy metals due to phytoremediation and other mechanisms? A Sri Lankan perspective

We present a viewpoint regarding the prospects in Sri Lanka (a tropical island nation) to depend on mangroves in the remediation of heavy metal laden coastal environments. Sri Lanka has a rich array of lagoons and estuaries (total extent of 1580.17 km2) with ideal brackish water habitats to allow mangrove proliferation and for more restoration works. Furthermore, our estimates of Total Potential Ecological Risk (PER < 150) indicate that ecological risk from metallic contamination of coastal sediments is low, which means mangrove ecosystems would be ideal natural treatment systems for such low polluting environments (but as final cum tertiary treatment systems only). Mangroves are neither metal hyperaccumulators nor good phytoremediators (no ability to take up more than 5000 mg/kg dry weight of a given metal or exhibit a bioconcentration factor ≥ 1000), which means not very effective for high polluting environments.

Water reuse for aquaculture: Comparative removal efficacy and aquatic hazard reduction of pharmaceuticals by a pond treatment system during a one year study

Aquaculture is increasing at the global scale, and beneficial reuse of wastewater is becoming crucial in some regions. Here we selected a unique tertiary treatment system for study over a one-year period. This experimental ecosystem-based approach to effluent management included a treated wastewater pond (TWP), which receives 100% effluent from a wastewater treatment plant, and an aquaculture pond (AP) that receives treated water from the TWP for fish production. We examined the fate of a wide range of pharmaceutically active compounds (PhACs) in this TWP-AP system and a control pond fed by river water using traditional grab sampling and passive samplers. We then employed probabilistic approaches to examine exposure hazards. Telmisartan, carbamazepine, diclofenac and venlafaxine, exceeded ecotoxicological predicted no effect concentrations in influent wastewater to the TWP, but these water quality hazards were consistently reduced following treatment in the TWP-AP system. In addition, both grab and passive sampling approaches resulted in similar occurrence patterns of studied compounds, which highlights the potential of POCIS use for water monitoring. Based on the approach taken here, the TWP-AP system appears useful as a tertiary treatment step to reduce PhACs and decrease ecotoxicological and antibiotic resistance water quality hazards prior to beneficial reuse in aquaculture.

Evaluation of Sand Filtration and Activated Carbon Adsorption for the Post-Treatment of a Secondary Biologically-Treated Fungicide-Containing Wastewater from Fruit-Packing Industries

In this work, a sand filtration-activated carbon adsorption system was evaluated to remove the fungicide content of a biologically treated effluent. The purification process was mainly carried out in the activated carbon column, while sand filtration slightly contributed to the improvement of the pollutant parameters. The tertiary treatment system, which operated under the batch mode for 25 bed volumes, resulted in total and soluble COD removal efficiencies of 76.5 ± 1.5% and 88.2 ± 1.3%, respectively, detecting total COD concentrations below 50 mg/L in the permeate of the activated carbon column. A significant pH increase and a respective electrical conductivity (EC) decrease also occurred after activated carbon adsorption. The total and ammonium nitrogen significantly decreased, with determined concentrations of 2.44 ± 0.02 mg/L and 0.93 ± 0.19 mg/L, respectively, in the activated carbon permeate. Despite that, the initial imazalil concentration was greater than that of the fludioxonil in the biologically treated effluent (i.e., 41.26 ± 0.04 mg/L versus 7.35 ± 0.43 mg/L, respectively). The imazalil was completely removed after activated carbon adsorption, while a residual concentration of fludioxonil was detected. Activated carbon treatment significantly detoxified the biologically treated fungicide-containing effluent, increasing the germination index by 47% in the undiluted wastewater or by 68% after 1:1 v/v dilution.

Penerapan Hibrid Sistem Biofilter dan Hidroponik Sebagai Alternatif Pengolahan Limbah Pemukiman Low Income People

Domestic wastewater will cause environmental problems, if there is no treatment either communally or household scale or in other words, the people directly dispose of their waste into water bodies. There are several environmentally friendly and fairly inexpensive waste treatment systems, namely the biofilter system. The processing of the wastewater with a biofilter system in several studies resulted in very good reduction of some parameters. This research does not only use biofilter, because it is possible there are still residual inorganic compounds such as nitrate and phosphate left over from processing biofilter systems. So that a tertiary treatment is still needed using a hydroponic system. The results of this study, namely the tertiary treatment system with hydroponics can reduce the residual anoganic compounds of phosphate, such as the outlets of kangkung (76.13%), spinach (44.9%) and lettuce (45.95%), while nitrates did not decrease. The parameters of TDS, TSS, COD and BOD were reduced with the efficiency removal of 15.15-19.60%, 51.20-88.52%, 49.00-63,27% and 30.49-58.68% respectively.

Amino acids, fatty acids, and peptides in microalgae biomass harvested from phycoremediation of swine wastewaters

Algae-based wastewater tertiary treatment systems have been drawing attention to eco-friendly companies due to high remediation effectiveness and production of valuable raw material. The amino acids, fatty acids, and peptides from microalgae harvested from a pilot-scale phycoremediation system treating swine wastewater were determined. The maximum microalgae concentration of 247 ± 3.4 mg L−1 was obtained after 11 days when phosphate and ammonium were completely removed. The AA content showed relatively high concentrations (as % of total protein) of essential amino acids such as leucine (4.1), lysine (2.5), phenylalanine (2.6), and threonine (2.4). The fatty acid profile was composed of 5.3% polyunsaturated (as C18:2 and C18:3) and ~ 10% of unsaturated (mainly C16:1 and C18:1). About 25 bioactive peptides related to antioxidative, anti-inflammatory, and anticarcinogenic properties were found. Therefore, microalgae biomass produced during phycoremediation of swine wastewaters seems promising as a source of alternative feedstock with high-added value molecules.

Methods of monitoring of waste water treatment efficiency

One major result of implementing the Water Frame Directive (WFD) for the water industry is the likelihood of more stringent requirements for the efficiency of removal of the pollutants included in the list of WFD priority substances. During the last decade, an ongoing debate on the technical aspects of water treatment and on the fate and effects of its constituents after discharge are taking place. Due to the recent development of analytical techniques, the knowledge about the chemistry and toxicology of the waste water has increased considerable. Characterization of the oil treatment efficiency by total petroleum hydrocarbon concentration (TPH) is not sufficient any more. Waste water before and after treatment should be characterized by toxicity and amounts of the individual compounds and mixtures which trigger the toxicity. In the situations where more efficient oil removal from waste water is required to meet the requirements, there are a number of treatment options available, including some tertiary ("polishing") treatment systems. New generation tertiary wastewater treatment system for removal or reducing of the oil compounds, including dissolved polycyclic aromatic hydrocarbons, bearing along most toxic potential, was developed under a Eureka funded project. The new waste water treatment system involves novel monitoring device to verify that the dissolved and bioavailable fraction of the contaminants are degraded, and that the final effluent is cleaner also from a toxicity point of view. Previous studies showed that more toxic compounds might be produced during the treatment process due to the transformation of the original chemicals. The monitoring device consists of a membrane-based diffusive, time integrative (2-30 days) sampler. The newly developed fast analytical method for the analysis of membrane extracts enable to give us information on the dissolved concentrations for more than 80 oil related compounds in the effluents as well as the toxicity results, by using standard bio-assay tests. Moreover the monitoring system is capable to accurately sample most of the WFD priority substances in waste water treatment effluent waters. lt was found that some of the compounds were effectively removed in waste water treatment plant (WWTP), but other compounds remained in the dissolved phase at the same concentrations. Furthermore, volatilization of low molecular weight PAHs during the treatment process was studied by means of the new monitoring system, resulting in the identification of significant release of WFD pollutants to the air. The changes in time-integrative toxicity during the treatment process were evaluated by standard ecotoxicity analysis using the same membrane extracts. The three bio-assays used were Daphnia magna, Microtox and Algal but also other organism- or cell test systems will be tested further. Our developed monitoring device is the state-of-art method for screening for environmental toxicity by integrating biologically and chemically based techniques for early warning and ecosystem health assessment purposes. It can provide invaluable information in highly polluted environments where bioindicator organisms would not survive or behave normally.

Acetaminophen micropollutant: Historical and current occurrences, toxicity, removal strategies and transformation pathways in different environments

Acetaminophen (ACT) is commonly used as a counter painkiller and nowadays, it is increasingly present in the natural water environment. Although its concentrations are usually at the ppt to ppm levels, ACT can transform into various intermediates depending on the environmental conditions. Due to the complexity of the ACT degradation products and the intermediates, it poses a major challenge for monitoring, detection and to propose adequate treatment technologies. The main objectives of this review study were to assess (i) the occurrences and toxicities, (2) the removal technologies and (3) the transformation pathways and intermediates of ACT in four environmental compartments namely wastewater, surface water, ground water, and soil/sediments. Based on the review, it was observed that the ACT concentrations in wastewater can reach up to several hundreds of ppb. Amongst the different countries, China and the USA showed the highest ACT concentration in wastewater (≤300 μg/L), with a very high detection frequency (81–100%). Concerning surface water, the ACT concentrations were found to be at the ppt level. Some regions in France, Spain, Germany, Korea, USA, and UK comply with the recommended ACT concentration for drinking water (71 ng/L). Notably, ACT can transform and degrade into various metabolites such as aromatic derivatives or organic acids. Some of them (e.g., hydroquinone and benzoquinone) are toxic to human and other life forms. Thus, in water and wastewater treatment plants, tertiary treatment systems such as advanced oxidation, membrane separation, and hybrid processes should be used to remove the toxic metabolites of ACT.

Evaluation of a constructed wetland for wastewater treatment: Addressing emerging organic contaminants and antibiotic resistant bacteria

The occurrence of emerging organic contaminants (EOCs) in wastewaters and the inability of the conventional wastewater treatments plants to deal with them have been pointed out several times over the last few years. As a result, remnants of those compounds released into the aquatic environment present a potential risk for public health. Constructed wetlands (CWs) have been proposed as environmentally friendly, low-cost alternative systems with satisfactory results for different types of contaminants. This study aimed to evaluate the efficiency of a CW system, planted with the halophyte Juncus acutus, to eliminate bisphenol A (BPA) and two antibiotics, namely ciprofloxacin (CIP) and sulfamethoxazole (SMX) under different operating conditions. The behavior of Escherichia coli and enterococcal populations in terms of changes in their resistance profile for the selected antibiotics and the abundance of two resistance genes (qnrA and sul1) were also examined. BPA and CIP were significantly removed by the CW, with an overall removal of 76.2% and 93.9% respectively and with the plants playing a vital role. In contrast, SMX was not significantly eliminated. Moreover, fluctuations in the antibiotic resistance profile of bacteria were observed. Treatment processes affected the response of the two selected bacterial indicators, depending on the conditions employed in each case. Furthermore, increased levels of resistance genes were monitored in the system effluent. This study indicates that CWs, as tertiary wastewater treatment systems, may demonstrate high removal rates for some but not all EOCs. This implies that each EOC identified in the feed stream should be tested assiduously by analyzing the final effluents before their reuse or discharge into water bodies.

Techno-economic analysis of a decentralized wastewater treatment plant operating in closed-loop. A Finnish case study

The study analyzes a potential to improve the local waste and wastewater management in a Finnish community. The Lappeenranta wastewater treatment plant (WWTP) is used as a case study. Two different technological setups are considered for improving the wastewater treatment plant. These are used to construct four alternative wastewater reclamation scenarios. The mass and energy balances for the considered scenarios are developed and used as input for the profitability evaluation. The utilization of the sewage sludge from the WWTP and municipal solid waste fraction that cannot be recycled for the generation of heat and electricity at the CHP plant is investigated with the aim to improve the economic performance of the wastewater treatment facility. The studied scenarios are initially compared based on their investment and operational costs. The cost of water treatment increases significantly in the case of the investigated tertiary treatment systems: higher amounts of chemicals and electricity are needed to improve the water quality. At the same time, the study indicates that the profitability of a WWTP integrated with a CHP plant can be reasonably high in a wide range of likely price scenarios for alternative wastewater purification systems. The results of the analysis showed a significant potential for the investigated wastewater reclamation systems to improve the efficiency of solid waste and wastewater management in the community.