Wetland Treatment System Research Articles

Selection of suitable filter materials for subsurface flow constructed wetland systems for wastewater treatment in rice noodle handicraft village

This study aims to select suitable filter materials for Subsurface Flow Constructed Wetlands (SSF CW) to treat wastewater from rice noodle handicraft villages, based on a combination of new materials (plastic waste and rice husk) and traditional substrates (limestone, gravel, and sand). Four SSF CW models using different filter materials were tested during three months, including CW1 (limestone, gravel, and sand), CW2 (sand, plastic waste, and gravel), CW3 (sand + rice husk, limestone, and gravel), and CW4 (sand + rice husk, plastic waste, and gravel). The results indicated that CW3 and CW4 systems were more effective to plant growth. Replacing limestone with plastic waste did not show a significant difference in treatment efficiency (p > 0.05), however the addition of rice husk decreased the efficiency of organic matter treatment while increasing nutrient treatment efficiency (p < 0.05). The highest treatment efficiencies for TSS and COD were observed in CW1, at 83.89 ± 1.38 % and 79.56 ± 1.36 %, respectively. Meanwhile, the highest treatment efficiencies for TN, NH4+, and TP were recorded in CW4, at 80.14 ± 2.76 %, 88.39 ± 1.62 %, and 82.22 ± 2.51 %, respectively. The effluent water from all four SSF CW models met the Vietnamese standard for wastewater quality (QCVN 40:2011/BTNMT, column B). This study demonstrates the potential of using a combination of plastic waste, rice husk, and sand as suitable filter substrates for SSF CW in treating wastewater from rice noodle handicraft villages.

Current status of wastewater treatment through large-scale treatment wetlands in the State of Veracruz, Mexico

The use of treatment wetlands has increased globally in the last twenty years. In the State of Veracruz, Mexico, CONAGUA has only registered six wetland-based treatment plants. However, recent research has revealed the existence of additional wetland treatment systems in operation that were not listed in the CONAGUA inventory. The main objective of this study is to diagnose the current situation of wastewater treatment in the State of Veracruz, Mexico, and identify the large-scale treatment wetlands that exist in the region. The study will focus on the design and implementation characteristics of these wetlands. The research is qualitative and descriptive, based on publications between 2000 and 2023 from Google Scholar and databases published by CONAGUA. The information review process used a content analysis technique to identify the geographical location of the wetlands, their installation area, the type of wetland, the type and volume of treated water, the vegetation used, and the year of installation. The results identified 12 large-scale treatment wetlands currently in operation in the State of Veracruz, Mexico, which have different design characteristics. The main variations are in the type of plants used. Some of these wetlands have been in operation for periods ranging from 1 to 17 years, but there is no updated information regarding their current functioning. Thus, future research is suggested to focus on the situational diagnosis of these systems years after their installation.

Studies of Wastewater Management through Microbiology of Constructed Wetland

Constructed wetlands are distinguished by certain environmental factors that let many physical and biological processes to occur simultaneously. This is the outcome of a particular habitat that supports the development of microbes and hydrophytes, which are plants that can live in aquatic and semiaquatic environments and are capable of anaerobic, anaerobic, and aerobic environments. Their combined activity amplifies the processes of oxidation and reduction, which are in charge of eliminating and holding onto contaminants. Sorption, sedimentation, and absorption all aid in these processes. Treatment wetland systems have been employed in community management for more than 50 years because of these benefits. Constructed wetlands are becoming more and more popular for treating or pre-treating many kinds of industrial wastewater because of their benefits, cheap operating costs, and high removal efficiency. The paper examines how these facilities are being used worldwide to treat industrial wastewater. With a focus on particular and distinctive pollutants from industries, the conditions of usage and efficacy of pollutants removal from wastewater that degrades quickly and slowly were described. The article addressed the use of subsurface horizontal flow beds for the treatment of wastewater from various industrial processes, including the manufacturing of paper, oil, and coffee, as well as the food sector, which includes wineries and distilleries. Constructed wetlands are used in Poland to treat wastewater and milk processing sludge on a pilot size or to dewater sewage sludge generated in municipal wastewater treatment plants that handle household sewage with around 40% of wastewater from the dairy and fish industries. Constructed wetlands provide the so-called ecosystem function in addition to an adequate degree of treatment in every instance.

Seasonal Sulfur Redox Cycling in Two Constructed Wetlands with Insight on How They Age.

Long-term metal remediation in wetland treatment systems (WTSs) involves facilitating dissimilatory sulfate reduction to produce sulfide and mineralize metals in deep sediments. We evaluated seasonal sulfur cycling in two constructed wetlands (Maintained WTS constructed in 2007, and the Unmaintained WTS constructed in 2000) on the Savannah River Site in Aiken, South Carolina, USA. Significant interactions in sulfide concentration were observed between sediment depth, season, and wetland (F = 4.64, df = 11, P = 3.28 × 10 - 5). In the Maintained WTS, dissimilatory sulfate reduction dominated the surface sediments during the warm season (0-2cm depth, t=-2.66, P = 9.70 × 10 - 3), unlike the Unmaintained system. Sulfate concentrations in pore waters increased in the warm season (F = 7.84, df = 1, P = 6.50 × 10 - 3), contrary to expectations. Sulfur limitation in the Unmaintained WTS during the warm season correlated with increased sulfur assimilation in giant bulrush. Lower sulfide concentrations in surface sediments of the Unmaintained WTS illustrated aging effects. The Maintained WTS shows potential for managing erosion, pH reduction, and sulfur limitation observed in the older Unmaintained WTS.

Mitigating environmental pollution from tofu industry wastewater: Case of Suyanto Tofu Factory, Mojokerto

Background: This research investigates the impact of tofu industry wastewater on water environments at Suyanto Tofu Factory, Mojokerto. The tofu industry generates liquid waste containing high pH, Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD), potentially polluting local rivers. Despite Suyanto Tofu Factory having wastewater treatment facilities, these are currently non-functional, underscoring the urgent need for designing new wastewater treatment installations. Methods: In this context, the study aims to determine the volume of wastewater produced, analyze the levels of BOD, COD, TSS, and pH in the wastewater, and design sustainable wastewater treatment facilities using a Constructed Wetland system. Findings: This method is expected to minimize the environmental impact of tofu wastewater, protect surrounding aquatic ecosystems, and comply with environmental regulations. By proposing sustainable solutions, the research aims to enhance awareness and management of wastewater in the tofu industry, offering technology solutions appropriate to local conditions. Conclusion: In conclusion, implementing effective and sustainable wastewater treatment installations is crucial to safeguard water quality and river ecosystems around Suyanto Tofu Factory. Novelty/Originality of this Study: By proposing a Constructed Wetland system for tofu industry wastewater treatment, this research introduces an innovative, sustainable solution tailored to local conditions, potentially revolutionizing waste management practices in small-scale food industries.

Hydraulic characterization of a hybrid aerated vertical and horizontal treatment wetland

Characterizing the performance of any treatment wetland (TW) system requires a fundamental understanding of the hydraulic behavior of the system. In aerated treatment, the air supply increases complexity, and the internal behavior of TWs can vary according to the adopted aeration strategy. Understanding these changes can provide insights into an optimized operation for aerated TWs. In this sense, the present work characterizes the hydraulics of a hybrid vertical and horizontal aerated TW through parallel tracer testing under different aeration strategies (varying aeration duration and aeration between the different compartments). The tracer test was conducted using amino-G acid and salt on a pilot scale system and measured at the outlet and inside the system. These results are subsequently compared to a full-scale system of a similar design to assess the validity of the results on a larger scale. The results allowed a characterization of actual retention time, the estimated number of tanks-in-series (NTIS), the volume of dead zones, and the identification of the hydraulic behavior under different aeration conditions. The results indicated that decreasing aeration duration led to more heterogeneity within the filter, the aeration on the primary filter plays an important role in mixing, and the pilot scale results can be upscaled for a larger scale. It also highlighted the impact of aeration in the different compartments of this hybrid aerated wetland system, which can contribute to an accurate characterization of specific pollutant removal kinetics.

Influence of Four Veterinary Antibiotics on Constructed Treatment Wetland Nitrogen Transformation.

The use of wetlands as a treatment approach for nitrogen in runoff is a common practice in agroecosystems. However, nitrate is not the sole constituent present in agricultural runoff and other biologically active contaminants have the potential to affect nitrate removal efficiency. In this study, the impacts of the combined effects of four common veterinary antibiotics (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N treatment efficiency in saturated sediments and wetlands were evaluated in a coupled microcosm/mesocosm scale experiment. Veterinary antibiotics were hypothesized to significantly impact nitrogen speciation (e.g., nitrate and ammonium) and nitrogen uptake and transformation processes (e.g., plant uptake and denitrification) within the wetland ecosystems. To test this hypothesis, the coupled study had three objectives: 1. assess veterinary antibiotic impact on nitrogen cycle processes in wetland sediments using microcosm incubations, 2. measure nitrate-N reduction in water of floating treatment wetland systems over time following the introduction of veterinary antibiotic residues, and 3. identify the fate of veterinary antibiotics in floating treatment wetlands using mesocosms. Microcosms containing added mixtures of the veterinary antibiotics had little to no effect at lower concentrations but stimulated denitrification potential rates at higher concentrations. Based on observed changes in the nitrogen loss in the microcosm experiments, floating treatment wetland mesocosms were enriched with 1000 μg L-1 of the antibiotic mixture. Rates of nitrate-N loss observed in mesocosms with the veterinary antibiotic enrichment were consistent with the microcosm experiments in that denitrification was not inhibited, even at the high dosage. In the mesocosm experiments, average nitrate-N removal rates were not found to be impacted by the veterinary antibiotics. Further, veterinary antibiotics were primarily found in the roots of the floating treatment wetland biomass, accumulating approximately 190 mg m-2 of the antibiotic mixture. These findings provide new insight into the impact that veterinary antibiotic mixtures may have on nutrient management strategies for large-scale agricultural operations and the potential for veterinary antibiotic removal in these wetlands.

Bioenergy-producing two-stage septic tank and floating wetland for onsite wastewater treatment: Circuit connection and external aeration

This study designed a two-stage, electrode-integrated septic tank-floating wetland system and assessed their pollutant removal performances under variable operational conditions. The two-stage system achieved mean organic, nitrogen, phosphorus, and coliform removal percentages of 99, 78, 99, and 97%, respectively, throughout the experimental run. The mean metals (chromium, cadmium, nickel, copper, zinc, lead, iron, and manganese) removal percentages ranged between 81 and 98%. Accumulated sludge, filler media, and the hanging root mass contributed to pollutant removals by supporting physicochemical and biological pathways. The mean effluent organic concentration and coliform number across the two-stage system were 20 mg/L and 1682 CFU/100 mL, respectively, during the closed-circuit protocol, which was beneath the open-circuit-based performance profiles, i.e., 32 mg/L and 2860 CFU/100 mL, respectively. Effluent organic, nitrogen, phosphorus, metals, and coliform number ranges across the two-stage system were 9–17 mg/L, 13–24 mg/L, 1–1.5 mg/L, 0.001–0.2 mg/L, and 1410–2270 CFU/100 mL, respectively during intermittent and continuous aeration periods. The air supply rate differences influenced pollutant removal depending on the associated removal mechanisms. The non-aeration phase produced higher effluent pollutant concentrations than the aeration periods-based profiles. The overall mean power density production of the septic tank ranged between 107 and 596 mW/m3; 110 and 355 mW/m3 with the floating wetland. The bioenergy production capacity of the septic tank was positively correlated to external air supply rates. This study demonstrates the potential application of the novel bioenergy-producing septic tank-floating wetland system for wastewater treatment in decentralized areas.

Occurrence, fate and distribution of emerging organic pollutants in full-scale hybrid constructed wetlands treating municipal effluents

The presence of emerging organic pollutants (EOPs) in municipal wastewater has raised concerns regarding their potential impact on human health and the environment. Constructed wetlands (CWs) have been identified as an effective and environmentally friendly solution for removing EOPs from municipal wastewater at a reasonable cost. This study investigated the performance of a full-scale hybrid constructed wetlands (HCWs) treatment system in reducing a total of 59 different types of EOPs. Findings show that the efficiency of the HCWs system in removing EOPs varied significantly depending on the specific physical and chemical properties of the pollutants. Pharmaceuticals (PhACs), personal care products (PCPs), and endocrine-disrupting chemicals (EDCs) were observed to be more effectively removed compared to bactericides, pesticides, and flame retardants, with removal efficiencies exceeding 54 %. Furthermore, the efficiency of the HCWs system in EOPs removal was observed to be influenced by seasonal variations. Specifically, the removal rate of PhACs in the spring and summer seasons reached 54.08 % ± 3.91 % and 61.04 % ± 8.58 %. The choice of substrate and plant species used within the system exhibited a notable impact on its overall removal efficiency. Moreover, the reduction effectiveness of EOPs across different treatment units varied significantly. Among these units, the bidirectional cross-flow filtration unit demonstrated superior reduction capabilities for PhACs and EDCs, with concentration reductions of 89.62 % and 86.34 %, respectively. Overall, this research emphasizes the importance of considering the specific characteristics of the pollutants and the system components to optimize the performance of CWs for EOPs removal in municipal wastewater.

Evaluating The Potential of Hibiscus Rosa-Sinensis in Floating Wetland for The Remediation of Water Bodies Polluted with Domestic Sewage

The inadequate infrastructure for wastewater treatment in many regions has led to the contamination of surface water bodies and groundwater degradation. To address this issue, floating wetland treatment systems have emerged as a viable alternative for effective wastewater remediation. This study focuses exclusively on utilizing Hibiscus rosa-sinensis, a tropical ornamental plant, within the context of floating wetland treatment techniques for the remediation of domestic wastewater. The primary objective is to assess the nutrient and pollutant removal efficiency of Hibiscus rosa-sinensis in a laboratory-scale floating wetland system. Healthy Hibiscus rosa-sinensis plants were cultivated on identical floating rafts and placed in plastic tanks filled with domestic sewage for experimental investigation. Water quality analyses were conducted regularly, spanning 0, 3, 5, 10, 15, 20, and 25 days HRT. The results of this experimental investigation revealed that Hibiscus rosa-sinensis, when used in floating wetland treatment, exhibited significant removal efficiencies for various parameters, including turbidity, total suspended solids (TSS), total phosphorus (TP), ammonia, and dissolved oxygen (DO).These findings highlight the potential of Hibiscus rosa-sinensis plants as a practical component of floating wetland systems for removing nutrients and pollutants from domestic wastewater. This research underscores the viability of Hibiscus rosa-sinensis as a sustainable and environmentally friendly solution to address water pollution challenges, particularly in the context of floating wetland treatment.

Enhancement of nitrates removal in pilot-scale treatment wetland systems

ABSTRACT The primary objective of the present study is to enhance the denitrification process in constructed wetlands (CWs), employed as an ecological and natural technology for wastewater treatment. Eco-friendly approaches have been tested to improve the nitrate removal efficiency in pilot-scale subsurface flow CWs. Initially, the system’s performance was enhanced by using a natural substrate, namely cork, as a filter medium. Another approach is bio-inoculation into the rhizosphere of a bacterial strain with the potential capacity for nitrate removal, thereby reinforcing the synergy between the plant and microorganisms. Finally, the approaches were combined, and nitrate removal was assessed. The main results showed that the most effective nitrate removal from wastewater was achieved with cork (80%) compared to gravel (60%). Bio-inoculation into the rhizosphere of denitrifying bacteria significantly improved nitrate removal. Indeed, the nitrate removal rate by the inoculated CW filled with gravel, was higher than the non-inoculated system, with rates of 78% and 60%, respectively. Moreover, the highest removal rate of 99.77% was obtained with the inoculated system filled with cork.

Performance of a multi-stage hybrid wetland system for the treatment of a dairy effluent

This work evaluates the performance of a pilot-scale hybrid wetland (HW) system for the effluent treatment from a dairy industry, located in Santa Fe (Argentina). The system consists of three stages in a serial configuration: vertical flow (S1) – free water surface (S2) – horizontal subsurface flow (S3) wetlands. The HW was operated during nine months. Wastewater, plant and sediment samples were taken from the system. Main pollutant concentrations were determined in wastewater. N and P concentrations were determined in plant tissues and in sediments to evaluate the accumulation in the system. The mean COD, BOD, TN, and TP removals in the whole HW system were 91 %, 94 %, 76 %, and 64 %, respectively. Organic matter concentration decreased due to aerobic and anaerobic degradation processes in all stages, mainly in S2. S1 presented proper conditions for nitrogen compounds interconversions by ammonification and nitrification processes. The highest total nitrogen removal was achieved in S2. Plant uptake contributed significantly to nutrient retention in S2 and S3. In S2, sediment did not participate significantly in nutrient retention. Phosphorus removal showed the lowest system efficiency. The obtained results determine the system performance under site-specific conditions, which contributes to the scaling process of the treatment wetland.

A sustainable green solution to domestic sewage pollution: Optimizing floating wetland treatment with different plant combinations and growth media

Water quality degradation poses a global threat, with surface water resources bearing the brunt of pollution from various sources, including inadequately treated wastewater discharged from industrial and commercial processes. This discharge introduces a wide range of pollutants, compromising surface water quality and potentially contaminating groundwater. Floating Wetland Treatment (FWT) systems, particularly utilizing affordable and easy-to-construct bamboo rafts, emerge as a promising eco-technology offering a sustainable solution for rehabilitating water bodies polluted with inadequately treated domestic sewage. Research exploring the combined remediation potential of different plant combinations remains limited, although several studies demonstrate the efficacy of individual plant species in FWT systems. This study addresses this gap by evaluating the effectiveness of three terrestrial plant combinations (Canna indica, Chrysopogon zizanioides, and Hibiscus rosa-sinensis) supported by bamboo rafts in treating domestic wastewater. Among FWT methods, systems utilizing bamboo as floating rafts stand out due to their affordability, ease of construction, and adaptability to diverse plant species. FWT systems were meticulously designed with three plant combinations, utilizing soil and coco peat as growth media. Different FWT systems exhibited variations in their ability to remove several key water quality indicators. These variations were influenced by operational conditions, system design, plant selection, and growth media. Notably, the peat-based FWT system (FWT-BPCV) combining Canna indica and Chrysopogon zizanioides consistently demonstrated outstanding performance in reducing various pollutants, including total nitrogen (78.9 %), ammonia (90.2 %), total phosphorus (86.9 %), COD (92.8 %), BOD5 (94.8 %), TDS (70.7 %), TSS (93.6 %), turbidity (93.3 %), phosphate (73.2 %), electrical conductivity (62.5 %), and E. coli (78 %). This research suggests that FWT-BPCV is an eco-friendly wastewater treatment solution and an effective option for domestic wastewater treatment practices.

A pilot-scale electrocoagulation-treatment wetland system for the treatment of landfill leachate

In the present study, the technical feasibility of an electrocoagulation-treatment wetland continuous flow system, for the removal of organic matter from landfill leachate (LL), was evaluated. The response surface methodology (MSR) was used to assess the individual and combined effects of the applied potential and distance between electrodes, on the removal efficiency and optimization of the electrocoagulation process. The hybrid treatment wetland system consisted of a vertical flow system coupled to a horizontal subsurface flow system, both planted with Canna indica. For a chemical oxygen demand (COD) concentration - without pretreatment of 5142.8 ± 2.5 mg L−1, the removal percentage for the electrocoagulation system was 79.4 ± 0.16%, under the optimal working conditions (Potential: 20 V; Distance: 2.0 cm). The COD removal efficiency in the treatment wetland with Canna indica showed a dependence with the hydraulic retention time, reaching 59.2 ± 0.2 % over 15 days. The overall efficiency of the system was about 91.5 ± 0.02 % removal of COD. In addition, a decrease in the biochemical oxygen demand (94.8 ± 0.14%) and total suspended solids (88.2 ± 0.22%), also related to the contamination levels of the LL, were obtained. This study, for the first time, shows that the coupling of electrocoagulation together with a treatment wetland system is a good alternative for the removal of organic contaminants present in LL.

Performance evaluation of a pilot wetland system for wastewater treatment

Wetland systems are inexpensive and easy-to-operate wastewater systems and are widely used globally at different scales for the safe treatment of wastewater. This study aims to evaluate a pilot-scale vertical flow wetland system treating wastewater under different loadings. The wetland system was constructed using indigenous plants (Imperata cylindrical) and operated using actual wastewater for twelve-months. Samples from influent and effluent of the wetland system were collected weekly. They were analyzed for parameters listed in the Kuwait Environment Public Authority standards for reuse in irrigation, such as organic matter, nutrients, heavy metals, and microorganisms. The results showed that the high hydraulic loading rate (1.67 m3/m2.d) phase was more efficient than the low hydraulic loading rate (1.04 m3/m2.d) phase in terms of organics and nutrient removal efficiency. The range of the removal efficiency of organic matter in low and high loading rates was around 48.5–49.0% and 59.1–59.1%, respectively. In addition, the range of the removal efficiency of nutrients in low and high loading rates was around 43.7–67.7% and 24.7–76.6%, respectively. Moreover, the range of the removal efficiency of heavy metals under the low and high loading rates was − 134.3–93.8% and − 1545.7–92.6%, respectively. It was evident that he metals were leaching from the soil. Moreover, it was found that the system performance was closely linked to the ambient temperature effects during the start-up (r = 0.59) and high hydraulic loading (r = 0.43) phases for example. While ambient temperature has wider effects on wetland biota, its effects on the plants are more pronounced. In conclusion, wetland systems can be constructed using indigenous plants to treat office wastewater efficiently under the harsh climate conditions of Kuwait with adjustments in capacity, loading rates, and operational conditions.

Microbial degradation of naphthenic acids using constructed wetland treatment systems: metabolic and genomic insights for improved bioremediation of process-affected water.

Naphthenic acids (NAs) are a complex mixture of organic compounds released during bitumen extraction from mined oil sands that are important contaminants of oil sands process-affected water (OSPW). NAs can be toxic to aquatic organisms and, therefore, are a main target compound for OSPW. The ability of microorganisms to degrade NAs can be exploited for bioremediation of OSPW using constructed wetland treatment systems (CWTS), which represent a possible low energy and low-cost option for scalable in situ NA removal. Recent advances in genomics and analytical chemistry have provided insights into a better understanding of the metabolic pathways and genes involved in NA degradation. Here, we discuss the ecology of microbial NA degradation with a focus on CWTS and summarize the current knowledge related to the metabolic pathways and genes used by microorganisms to degrade NAs. Evidence to date suggests that NAs are mostly degraded aerobically through ring cleavage via the beta-oxidation pathway, which can be combined with other steps such as aromatization, alpha-oxidation, omega-oxidation, or activation as coenzyme A (CoA) thioesters. Anaerobic NA degradation has also been reported via the production of benzoyl-CoA as an intermediate and/or through the involvement of methanogens or nitrate, sulfate, and iron reducers. Furthermore, we discuss how genomic, statistical, and modeling tools can assist in the development of improved bioremediation practices.

Environmental and Agro-Economic Sustainability of Olive Orchards Irrigated with Reclaimed Water under Deficit Irrigation

Increasing the economic and environmental sustainability of irrigated agriculture is a vital challenge for the Mediterranean crop production sector. This study explores the effects of the adoption of reclaimed water (RW) as source of irrigation in conjunction with the application of deficit irrigation strategies in an olive orchard (different genotypes) located within the “Valle dei Margi” farmhouse (Eastern Sicily). Specifically, the RW was obtained in situ by treating the wastewater coming from the farmhouse throughout a nature-based treatment wetland system (TW). The effects of RW on crop water status (CWS) was assessed by conducting plant-based measurements (i.e., leaf water potential, Ψ; and leaves’ relative water content, RWC) and determining satellite-based biophysical indicators. An economic and environmental evaluation of the proposed sustainable irrigation practices was carried out using the life cycle assessment (LCA) approach. The RW quality showed high variability due to fluctuations in the number of customers at the farmhouse during the COVID-19 pandemic period. A strong impact on the variation in Ψ was observed among the olive orchard under the different water regimes, evidencing how CWS performances are conditioned by the genotype. However, no differences in leaves’ RWC and in satellite-based biophysical indicators were detected. Finally, the results of the LCA analysis underlined how the use of RW may permit us to obtain important economic and environmental gains, representing an added value for olive growing for operating in accordance to more sustainable development models.

Performance of lagoon and constructed wetland systems for tertiary wastewater treatment and potential of reclaimed water in agricultural irrigation

Climate change poses challenges to agricultural water resources, both in terms of quantity and quality. As an adaptation measure, the new European Regulation (EU) 2020/741 establishes different water quality classes for the use of reclaimed water in agricultural irrigation. Italy is also working on the definition of a new regulation on reclaimed water reuse for agricultural irrigation (in substitution of the current one) that will also include the specific requirements imposed by the European one. Nature-based Solutions (NBS) can be a cost-effective and environmentally friendly way to facilitate water reclamation and reuse. The present study reports the outcomes of a long-term monitoring campaign of two NBS (e.g., a constructed wetland (CW) and a lagoon system (LS)) comparing influent and effluent concentrations of different contaminants (e.g., E. coli, BOD5, TSS, TN and TP) with the threshold values imposed by the new regulations. The results showed that in both the case studies, E. coli (about 100 CFU 100 mL−1) and BOD5 (lower than 25 mg L−1) mean effluent concentration need to be further reduced in reclaimed water to be suitable for unlimited reuse. As a negative aspect, in both the monitored NBS, an increase in TSS mean concentration in the effluent was observed, up to 40 mg L−1 in the case of the LS, making reclaimed water unsuitable for agricultural reuse. The CW has proven to be more effective in nitrogen removal (the effluent mean concentration was 3.4 mg L−1), whereas the LS was better at phosphorus removal (with an effluent mean concentration of 0.4 mg L−1). Based on the results, recommendations were made to further improve the performance of both systems in order to have adequate water quality, even for class A. Furthermore, the capacity of reclaimed water to meet crop water and nutrient needs was analyzed, and total nitrogen removal rate coefficients were calculated for the design of future LSs.

Evaluating the attenuation of naphthenic acids in constructed wetland mesocosms planted with Carex aquatilis

Surface oil sands mining and extraction in northern Alberta’s Athabasca oil sands region produce large volumes of oil sands process–affected water (OSPW). OSPW is a complex mixture containing major contaminant classes including trace metals, polycyclic aromatic hydrocarbons, and naphthenic acid fraction compounds (NAFCs). Naphthenic acids (NAs) are the primary organic toxicants in OSPW, and reducing their concentrations is a priority for oil sands companies. Previous evidence has shown that constructed wetland treatment systems (CWTSs) are capable of reducing the concentration of NAs and the toxicity of OSPW through bioremediation. In this study, we constructed greenhouse mesocosms with OSPW or lab process water (LPW) (i.e., water designed to mimic OSPW minus the NAFC content) with three treatments: (1) OSPW planted with Carex aquatilis; (2) OSPW, no plants; and (3) LPW, no plants. The OSPW–C. aquatilis treatment saw a significant reduction in NAFC concentrations in comparison to OSPW, no plant treatments, but both changed the distribution of the NAFCs in similar ways. Upon completion of the study, treatments with OSPW saw fewer high-molecular-weight NAs and an increase in the abundance of O3- and O4-containing formulae. Results from this study provide invaluable information on how constructed wetlands can be used in future remediation of OSPW in a way that previous studies were unable to achieve due to uncontrollable environmental factors in field experiments and the active, high-energy processes used in CWTSs pilot studies.

Performance evaluation of a lab-scale subsurface flow-constructed wetland system for textile industry wastewater treatment.

This study compares biochar (BCW) systems' pollutant removal effectiveness to conventional subsurface flow (CCW) in constructed wetland systems to treat textile wastewater. The two systems were identical in construction, but the biochar was 0.1 m thick over gravel and sand (maximum flow rate of 0.021 m3 h-1) as the primary medium over CCW (flow rate of 0.02 m3 h-1). The results revealed that the BCW approach was more efficient than the CCW system (pebble over sand and gravels) in removing and lowering heavy metals below thresh hold limits such as Cr, Cd, Cu, Pb, Ni, and Zn. The alkaline nature of textile water achieves neutrality in both CCW and BCW. However, BCW is more efficient due to a larger active surface area and the ability to filter out more metal and organic ions. TDS reduction efficiency in BCW was 53.07%, compared to 40.04% in CCW. Heavy metal removal was 100% in BCW at 3 to 12 h, whereas it takes 6 to 24 h in CCW (82% for Cr to 93% for Cu). The quick removal of Na from textile wastewater by BCW was reversed and achieved equilibrium in 24 h in contrast to the CCW system (> 24 h). The findings obtained at the lab scale level demonstrated that the BCW system was more effective in reducing TDS, neutralizing the alkalinity of textile wastewater, and removing heavy metals. This study strongly supports the potential application of biochar-constructed wetlands for textile wastewater treatment.