Constructed Wetland System Research Articles

Constructed Wetlands as Nature-Based Solutions for Wastewater Treatment in the Hospitality Industry: A Review

The hospitality industry is increasing its awareness of how the integration of nature-based solutions can decrease its environmental impact while maintaining or increasing the service level of the sector. Constructed wetlands (CWs) constitute a promising sustainable solution for proper in situ domestic wastewater treatment. This literature review elucidates the status of CWs implementation in the hospitality industry to help foster the exchange of experiences in the field and deliver examples of approaches in different contexts to support future applications of this technology. Most of the studies reported in the literature were conducted in Europe, but studies emanating from Asia and South America are also available. The design of CWs, the horizontal and vertical subsurface flow CWs (HSFCW, VSFCW), and hybrid systems have been reported. The average removal efficiencies of the systems ranged from 83 to 95% for biochemical oxygen demand, 74 to 94% for chemical oxygen demand, 78 to 96% for total suspended solids, 75 to 85% for ammonium, 44 to 85% for ammonia, 50 to 73% for nitrate, 57 to 88% for total Kjeldahl nitrogen, 51 to 58% total nitrogen, and 66 to 99% for total phosphorus. The majority of the systems were implemented as decentralized treatment solutions using HSFCWs, with the second most common design being the hybrid CW systems in order to reduce area requirements, increase treatment efficiency, and prevent clogging. Overall, CWs are a promising sustainable solution which may support access to adequate sanitation worldwide as well as safe wastewater recycling and reuse, leading to more sustainable tourist destinations.

Influence of nitrogen sources on wastewater treatment performance by filamentous algae in constructed wetland system

Although filamentous algae have the characteristics of high nutrient assimilation ability, and adaptation to different conditions, studies on their role in water purification of constructed wetlands (CWs) are limited. In this study, the wastewater treatment capacity under different nitrogen sources was explored by constructing a filamentous algal CW (FACW) system. Results confirmed the fast and stable operation efficiency of the FACW system. Ammonia nitrogen was preferred in Cladophora sp. absorption and assimilation. The nutrient consumption rate (NCR) for total nitrogen (TN) of AG was 2.65 mg g−1 d−1, much higher than that of nitrate nitrogen (NG) (0.89 mg g−1 d−1). The symbiosis of bacteria and Cladophora sp. Contributed to pollutant removal. A stable and diverse community of microorganisms was found on Cladophora sp. Surface, which revealed different phylogenetic relationships and functional bacterial proportions with those attached on sediment surface. In addition, temperature and light intensity have great influence on the purification ability of plants, and low hydraulic retention time is beneficial to the cost-effective operation of the system. This study provides a method to expand the utilization of wetland plants and apply large filamentous algae to the purification of wetland water quality.

Enhanced removal of antibiotic and antibiotic resistance genes by coupling biofilm electrode reactor and manganese ore substrate up-flow microbial fuel cell constructed wetland system

Manganese ore substrate up-flow microbial fuel cell constructed wetland (UCW-MFC(Mn)) as an innovative wastewater treatment technology for purifying antibiotics and electricity generation with few antibiotic resistance genes (ARGs) generation has attracted attention. However, antibiotic purifying effects should be further enhanced. In this study, a biofilm electrode reactor (BER) that needs direct current driving was powered by a Mn ore anode (UCW-MFC(Mn)) to form a coupled system without requiring direct-current source. Removal efficiencies of sulfadiazine (SDZ), ciprofloxacin (CIP) and the corresponding ARGs in the coupled system were compared with composite (BER was powered by direct-current source) and anaerobic systems (both of BER and UCW-MFC were in open circuit mode). The result showed that higher antibiotic removal efficiency (94% for SDZ and 99.1% for CIP) in the coupled system was achieved than the anaerobic system (88.5% for SDZ and 98.2% for CIP). Moreover, electrical stimulation reduced antibiotic selective pressure and horizontal gene transfer potential in BER, and UCW-MFC further reduced ARG abundances by strengthening the electro-adsorption of ARG hosts determined by Network analysis. Bacterial community diversity continuously decreased in BER while it increased in UCW-MFC, indicating that BER mitigated the toxicity of antibiotic. Degree of modularity, some functional bacteria (antibiotic degrading bacteria, fermentative bacteria and EAB), and P450 enzyme related to antibiotic and xenobiotics biodegradation genes were enriched in electric field existing UCW-MFC, accounting for the higher degradation efficiency. In conclusion, this study provided an effective strategy for removing antibiotics and ARGs in wastewater by operating a BER-UCW-MFC coupled system.

The influence of pollutantson plant growth and treatment efficiency of horizontally-constructed wetlands

Constructed wetlands (CWs) have been widely used for wastewater treatment due to advantages such as low cost and easy operation. However, pollutant concentrations directly affect treatment efficiency by inhibiting plant and microbial growth. This study aims to evaluate the relationship between pollutant concentrations, tolerance of plants, and treatment efficiency of horizontal subsurface flow (HSF) CWs receiving synthetic wastewater. The results showed that Cyperus alternifoliusL. grew well in conditions with concentrations of chemical oxygen demand (COD) and NH4+ up to 75 and 125 mg/l, respectively, and pH 5-8. The lowest treatment efficiency was 56.7% at an initial COD concentration of 1000 mg/l. There were several dead plants in the CWs with a NH4+ concentration of 200 mg/l. When the initial COD and NH4+ concentrations were in the range of 500-750 and 75-125 mg/l, respectively, the treatment efficiencies of organic matter (COD) and NH4+ were 82.5-85.1 and 31-69.7%, respectively. The pH value was stable at a neutral level during the treatment process. The concentration ranges of COD (500-750 mg/l) and NH4+ (75-125 mg/l) were the optimal thresholds for pollution control while also ensuring normal plant growth. This study serves as a basis for considering wastewater characteristics in the design of HSF CW systems in practice.

Influence of loading rates and feeding conditions on hybrid constructed wetlands integrated with microbial fuel cells

The present study had as objective to evaluate the influence of different operation conditions on two treatment systems composed of anerobic biofilter (AF) and hybrid constructed wetlands (CWs). Both treatment lines had as the first treatment stages an 1450 L AF unit and a CW designed as a Floating Treatment Wetland. Then, a pump directed half of the wastewater flow for each of the treatment lines. One of the lines was composed of a Vertical Flow CW incorporated with microbial fuel cells (CW-MFC), called Configuration 1 (C1), whereas the other line consisted of a Vertical Flow CW (VFCW) and a Horizontal Flow CW (HFCW), named Configuration 2 (C2). The treatment system was fed with wastewater generated in a university campus and monitored for 13 months, with three operation conditions tested: 3 pulses per day with 50 L each (20.5 L/m2day); 4 pulses with 75 L each (41 L/m2day) and 6 pulses with 75 L each (61.6 L/m2day). In addition, the potential bioenergy generated was monitored. For the last operation condition, C1 efficiently reduced BOD5 (88.7%) and turbidity (84.4%). On the other hand, for the nutrients the treatment efficiencies were lower, with 40.3% (TP) and 46.6% (N−NH3). Overall, similar results were obtained with the C2, with mean removal efficiencies of BOD5 (87.3%), turbidity (93.1%), and lower TP (10.4%) reduction. The treatment performance presented similar tendencies even with the changes in loading rates and in hydraulic retention times. Regarding the voltage monitoring, a peak of 687 mV was obtained considering a mean loading rate of 15.6 gCOD/m2day, whereas the maximum power density was 0.25 mW/m. Future research should focus on reducing the internal resistance of the CW system, thus increasing the bioelectricity generated and in treating wastewater with higher organic matter content.

The efficacy of Vetiveria zizanioides in horizontal subsurface flow constructed wetland for treating textile wastewater

Textile wastewater discharged into rivers often triggers a decrease in water quality and causes harm to its aquatic ecosystem. Textile wastewater, which may contain nutrients, organic compounds, and heavy metals, can be managed using a constructed wetland system. Vetiver grass is known for its ability in treating polluted waters, though the information related to its potential in controlling textile wastewater pollution in riparian areas is still limited. This study aimed to determine the efficacy of a pilot scale constructed wetland system using vetiver grass (Vetiveria zizanioides) for the removal of several pollutants in a riparian area polluted by textile wastewater. The wastewater flowed horizontally through the sub-surface layer of the system with a hydraulic retention time of two days. The wastewater was diluted to 20%. Three systems were made by varying the porous size of planting media using coarse gravel, fine gravel, and sand. The systems were then run for three months. Of the three constructed wetland systems, the highest removal efficiency (RE) was achieved for the NH4 + parameter with an average removal efficiency higher than 60%. The highest nutrient RE was achieved by the system with sand in the growing media, with NH4 + RE of more than 80%. RE values were fluctuating until the end of the experiment, which might occur because the system was not yet stable. It may take longer operation time to get a better system performance in removing the pollutants contained in the textile industry waste.

Efficacy Evaluation of Silty-Sandy Soil and Chrysopogon zizanioides to Attenuate Doxycycline from Wastewater in a Constructed Wetland System

Efficacy Evaluation of Silty-Sandy Soil and <i>Chrysopogon zizanioides</i> to Attenuate Doxycycline from Wastewater in a Constructed Wetland System

Constructed wetlands for the treatment of combined sewer overflow upstream of centralized wastewater treatment plants

Combined sewer overflows (CSOs) constitute nowadays a major environmental concern, representing one of the main untreated sources of pollution for receiving water bodies. Additional, in recent years, the frequency and intensity of CSOs have increased due to the growing urbanisation and climate change. Although there is no single effective strategy, one of the most promising approaches for the control and treatment of CSOs can be found in nature-based solutions (NBS), such as constructed wetlands (CWs). Despite the demonstrated potential of CWs to treat CSOs, the only data reported in the literature refer to CSO-CW systems located along the sewerage network. This research represents, to the best of our knowledge, the first monitoring of a full-scale CSO-CW designed to treat the combined sewer overflow upstream of the WWTP located in Carimate, in the province of Como (Italy). The system is a multistage CW, composed by a 1st vertical subsurface flow (VF) stage (total area of 8500 m2) and a 2nd free water surface (FWS) stage (total area of 4500 m2). The observed removal rates during the 3 years monitoring campaign (mean values equal to 83.2%, 64.6%, 63.8% for COD, TP, and N-NH4+ respectively) confirmed the treatment efficiency of CW system for all the investigated parameters, consistent with literature data for CSO-CWs in line with the sewerage network, despite its large scale and different hydraulic characteristics. Furthermore, the system also provides additional ecosystem services such as flood mitigation (average CSO interception of 82%), enhancement of biodiversity and a low operational and maintenance cost.

Use of climbing and ornamental plants in vertical flow constructed wetlands treating greywater

This study focuses on the use of climbing ornamentals and ornamental plants for greywater treatment in vertical flow constructed wetlands. Different design parameters, such as substrate (sand or vermiculite), the use of saturation zone, and plant species (Trachelospermum jasminoides, Lonicera japonica, Callistemon laevis) were evaluated for optimal removal of studied pollutants. Results revealed that, regarding the tested substrates, sand with or without saturation zone presented significantly higher removal rates for turbidity (94 ± 5 %) and Chemical Oxygen Demand: (96 ± 7 %) than vermiculite (Turbidity: 54 ± 23 %; Chemical Oxygen Demand: 73 ± 29 %). Moreover, slightly higher removal rates were recorded in vegetated systems compared to unvegetated systems. According to the findings, all examined plants survived and grew in vertical flow constructed wetlands receiving up to 204 mm of greywater per day. However, L. japonica and C. laevis are more well-adapted to such constructed wetland systems compared to T. jasminoides. Overall, the application of climbing and ornamental plants in vertical flow constructed wetlands for greywater treatment in buildings seems like a very promising option to improve the aesthetic appearance of the systems and consequently increase public acceptance.

Phytoremediation of Domestic Sewage in Constructed Wetland Integrated with Cultivation of Chlorella sp.: A Novel Technique for Remediation and Resource Recovery

Domestic sewage-based constructed wetland (CW) showed that the effluent from CW-system contain enough plant nutrients and enhanced the growth of microalgae. Hence, a pilot CW system employing Typha latifolia in domestic sewage, integrated with the cultivation wild type Chlorella sp. was investigated. Phytoremediation at 48 hours of detention time caused significant changes in its physicochemical properties and the generated effluent was notably attractive for the cultivation of microalgae. The microalga was grown in 6 treatments: treated-mixotrophic (T1), treated-heterotrophic (T2), treated-autotrophic (T3), control-mixotrophic (T4), control-heterotrophic (T5) and control-autotrophic (T6) conditions for 8 days inside an incubator. The results suggested that phytoremediation effluents integrated with mixotrophic cultivation of microalgae, utilising both light and carbon sources could be the most efficient, environmentally safe, sustainable and novel technique for synergistic resource generation and bioremediation.

A preliminary experimental study simulating evapotranspiration process in TEvap tanks cultivated with different forages

ABSTRACT The evapotranspiration tank (TEvap) is a ‘zero-discharge’ ecotechnology for toilet water disposal. This work refers to a preliminary study to evaluate the influence of forages and the addition of a vertical soil strip on evapotranspiration (ET), electrical conductivity (EC) and pH in TEvap receiving fresh water. The factors studied were the forages and the soil strip, resulting in four treatments with three replications. Two plant growing seasons, cycle 1 and cycle 2, were monitored, during which the variables were measured every three and seven days, respectively. Weather variables were used to estimate the reference evapotranspiration and determine the TEvap coefficient (KTEvap). The accumulated ET for TEvap with Capiaçu was 27.93% and 45.89% greater than for TEvap cultivated with Tifton-85 during the first and second cycles, respectively. There were no significant differences in ET for TEvap with and without the soil strip. BRS Capiaçu also showed lower values for EC and pH. High values were obtained for KTEvap: 2.37 and 1.76 for TEvap cultivated with BRS Capiaçu and Tifton-85 grass, respectively. Considering the period of this study, the minimum area for ‘zero-discharge’ would be 5.70 m2 inhab−1 and 7.77 m2 inhab−1 by TEvap planted with BRS Capiaçu and Tifton-85 grass, respectively. Due to its greater capacity for evapotranspiration, it can be concluded that the BRS Capiaçu forage is suitable for a ‘zero-discharge’ constructed wetland systems. It is suggested that further, more-thorough studies be carried out to design a ‘zero-discharge’ TEvap, considering different weather conditions, crops and inlet toilet water. HIGHLIGHTS Evapotranspiration tank (TEvap) is a ‘zero discharge’ ecotechnology for disposing toilet water; A preliminary study was conducted to simulate the evapotranspiration in TEvap receiving fresh water; Two forages – Cynodon spp. (Tifton-85 grass) and Pennisetum spp. (BRS Capiaçu) – were cultivated in the tanks; 5.70 m2 inhab−1 were estimated for evapotranspiration with BRS Capiaçu and 7.77 m2 inhab−1 with Tifton-85 grass.

Application of hybrid vertical flow constructed wetland systems to treatment of greywater for their use to irrigation in rural areas

Access to water supply is currently one of the biggest social and economic challenges in many parts of the world. Iran is currently experiencing serious water problems. One of the appropriate solutions to overcome the existing challenge is to pay attention to alternative water sources such as treated greywater. In the present study the performance of greywater treatment system consists of a vertical flow constructed wetland followed by column filled with combined inexpensive adsorbents in a series was investigated. The absorption capacity of incinerator bottom ash (IBA), rice husk, pumice, dried stems of Phragmites Australis (PA) and activated carbon (as control) absorbents were assessed by analyzing the quality of the influent and effluent streams through testing COD, PO4−3, NO3−, EC and TSS in greywater. After evaluating the treatment capacity of the above absorbents, it was concluded that IBA and dried stems of PA are the most effective material to reach the irrigation water quality. Then, using them, a hybrid pilot-scale experimental system was designed to study the treatment of greywater. This hybrid system efficiently removes COD, NO3− –N and PO4−3 by up to 90.35%, 100% and90.2%, respectively.

Manganese ore enhanced polycyclic aromatic hydrocarbons removal in constructed wetlands: Insights into the key removal mechanism and main driving factor

Substrates are vital to efficiently remove polycyclic aromatic hydrocarbons (PAHs) in constructed wetlands (CW). However, the critical role of the substrate in the system is still not fully understood due to the unclear PAHs removal mechanism and particularly the main driving factor affecting PAHs removal. In this study, four vertical-flow CWs with different typical substrate types (A: quartz sand, B: quartz sand + granular activated carbon, C: quartz sand + ceramsite, and D: quartz sand + manganese ore) were established to investigate the treatment performance and mechanism of CW systems. Satisfactory and stabilized PAHs removal was achieved in CW-D during the operation period of 120 days, which significantly increased the removal of PAHs by 23.80%–31.18% compared with control group. Microbial degradation was revealed to dominate PAHs removal in CWs, and the enhanced proportion of microbial degradation (21.12%-35.43%) in CW-D led to the higher PAHs removal compared with other CWs. Further analysis showed that altered extracellular polymeric substances and Mn cycle improved the electron transfer capacity, and strengthened the interaction between plants and microorganisms in CW-D. Microbial analysis showed that the abundance of key PAH-degrading microorganisms and microbial metabolic gene expression were enhanced in CW-D, which supported the increased microbial degradation of PAHs. Additionally, root length and microbial diversity were two driving factors affecting PAHs removal rather than specific surface area based on the structural equation modeling analysis. This study provides comprehensive insights into the key role of suitable substrates for PAHs removal as well as the related mechanism and driving factors of PAHs removal in CWs.

Analysis of changes on substrates filling constructed wetland systems after landfill leachate treatment - FTIR study

A rapid and inexpensive method, Fourier transform infrared spectroscopy (FTIR), can be used to identify impurities and determine the functional groups responsible for the sorption of specific ions. The FTIR method has already been used in research. However, there is a lack of research on constructed wetland (CW) infill materials used to treat landfill leachate (LL). Therefore, the aim of this study was to verify the changes occurring in selected substrates (zeolite, expanded clay and bark) constituting vertical flow CW infill (VFCW) supplied with municipal LL. The principal component analysis carried out mainly showed differences in the results between the variants of the experiment with an infill of expanded clay and the others (for the values obtained at wave numbers in the range 1600-400 cm−1, in which most changes occurred). All peaks of the FTIR spectra of the pine bark filling the CW differ in location and intensity between the samples. In most cases, the stripes were elongated at exposure to 25% and 100% LL (compared to tap water). In all CW variants infill made of zeolite, peaks occurred at wave numbers within 1049-1012 cm−1, which were most likely caused by the presence of inorganic substances corresponding to clay minerals, and to silica. The FTIR spectra for zeolites, do not show large differences between the different infill samples used for LL treatment (100% LL and 25% LL). In all CW variants with expanded clay infill, peaks in the 1250-900 cm−1 wave number region, possibly indicating the presence of polysaccharides and phosphodiesters. FTIR spectroscopy has proven to be a very useful tool for rapid grade assessment determination of changes occurring on selected substrates and the identification of contaminants that remained after treatment in VFCWs fed with LL.

The enhancement of nutrients removal performance in a vertical up-flow constructed wetland system using iron-carbon substrates

The reclaimed water was usually further treated by the constructed wetland (CW) to remove nitrogen and phosphorus before it was discharged to water bodies. In this work, the iron-carbon (Fe-C) substrate and plant-based carbon source were added to the vertical up-flow CWs to enhance the denitrification of reclaimed water. It was found that the removal efficiency of nitrate (NO3--N), total nitrogen (TN) and total phosphorus (TP) in the Fe-C amended CWs were significantly increased by 20–35%, 10–25%, and 10–35%. Moreover, the plant-based carbon source also contributed to TN and TP removal. The additional substrates also reduced the emission of NO2 and CH4 from the CWs. Finally, the microbial community was analyzed to disclose the mechanism involved in the enhanced performance of CWs. The enriched hydrogenotrophic and heterotrophic denitrifiers by the Fe-C substrates and pine bark contributed to the enhanced nitrification.

Rhizosphere microbial dynamics in response to Desmondesmus sp. ZM-3 and carbon footprint analysis in constructed wetland

As an emerging bioremediation process for sewage treatment, microalgae-based constructed wetlands (CWs) have received attention. However, few studies have explored the specific links between rhizosphere microorganisms and microalgae in depth, and few studies have considered the combined role of these two types of organisms in carbon emissions. In this study, Desmondesmus sp. ZM-3 and coupled CW systems were set up to explore microalgae and nitrogen-related microbial interactions and greenhouse gas (GHG) emission effects. The results indicated that the removal efficiencies of TN and NH4+-N in the coupled systems were significantly higher (13.07% and 9.31%, respectively) than those of the CWs. The ATP and electron transport system activity (ETSA) of rhizosphere microorganisms and the activities of enzymes involved in the nitrogen removal process were enhanced after dosing with ZM-3. Microbial community succession analysis showed that ZM-3 addition also promoted the growth of denitrifying bacteria, which became key taxa in the CW. Thus, microalgae and denitrifying bacteria could mutually contribute to the nitrogen transformation process. Furthermore, according to life cycle assessment (LCA), the CO2 emission equivalent was decreased by 4.6 CO2 eq./m3 in the coupled systems. Clean energy usage for power generation and a reduction in light duration are improvement strategies that could further minimize GHG emissions. These findings offer new insights into microalgae-based CWs for wastewater treatment.

Greywater treatment using vertical subsurface flow constructed wetland system

Wastewater (specifically greywater) treatment methods are vital especially in areas facing water shortage problems with arid climates. Constructed wetlands could play a strategic role in wastewater reclamation in arid regions. On one hand, the reliability is not high since its efficiency and the nutrients removal is low. On the other hand, the efficiency in removing the chemical oxygen demand is high. (Chemical Oxygen Demand, Dissolved Oxygen, Total Nitrogen, and Phosphate) were analyzed to study the effect on the removal efficiency if different substrates and hydraulic retention time (HRT) were varied. The systems were roughly identical except the main substrate in each was modified to be soil, gravel, or random packing. The best system, which is the system with soil substrate, resulted in a final average percent removal of 93% and 74% for chemical oxygen demand and total nitrogen, respectively. However, resulted in low percent removal for the orthophosphate. This system also gave the highest efficiency when the aeration period was the longest. The longer the aeration period the more oxygen is supplied and by this, microorganisms will be highly active and decompose the organic matter. While system three with random packing substrate had the least removal efficiency; yet operated the best for the removal of phosphorus. Generally, all the systems achieved the highest percent removal when the HRT for the wastewater spent inside the system was the shortest and aeration was the longest.

Assessment of Surfactant Removal Capacity and Microbial Community Diversity in a Greywater-Treating Constructed Wetland

Surfactants are among the main chemical contaminants in greywater (GW) and can cause severe health issues in humans and aquatic organisms. We assessed the performance of a multistage constructed wetland system (EvaTAC) for GW treatment and capacity of the microbial community in linear alkyl benzene sulfonate (LAS) biodegradation. Physicochemical analyses were performed over 497 d, and biomass samples were collected for high-throughput DNA sequencing. The system was predominated by anaerobic conditions and received an average chemical oxygen demand (COD) and LAS of 374 and 32 mg·L−1, with removal rates of 66% and 43%, respectively. A positive correlation between COD and LAS suggested COD as a design parameter for LAS removal. We identified microbial genera participating in hydrolysis, fermentation, syntrophy, acetogenesis, methanogenesis, surfactant degradation, and sulphate reduction. Among the 15 surfactant-degrading genera, Pseudomonas was predominant. Community richness and diversity indices were comparable between subsystems, with a slight decrease in diversity observed towards the outlet. Among the LAS degraders, Rhodopseudomonas palustris had the highest relative abundance of operational taxonomic unit (OTU)s in all samples and the highest richness in the anaerobic chamber. The patterns in microbial community composition and environmental conditions suggest that LAS biodegradation occurred throughout the EvaTAC system.

Microalgae-based constructed wetland system enhances nitrogen removal and reduce carbon emissions: Performance and mechanisms

Combination of constructed wetlands (CWs) and microalgae-based technologies has been proved as effective wastewater treatment option; however, little attention was paid to investigate the optimal combination ways. This study showed that the integrated system (IS) connecting microalgal pond with CWs exhibited improved pollutant-removal efficiencies and preferred carbon reduction effects compared to other alternatives such as coupled system or independent CWs. Microbial analysis demonstrated that core microorganisms (e.g., Acinetobacter and Thermomonas) of the IS were mostly associated with carbon, nitrogen, and energy metabolism. Based on co-occurrence networks, microbial quantity with denitrification function in the IS accounted for 71.01 % of the microorganism related to nitrogen metabolism, which was higher than that of 48.84 % in the independent CWs, indicating that the presence of microalgae in IS played important role in promoting biological denitrification. These findings provide insights into the microbial mechanism and highlights the complementary effects between microalgae and CWs.

Green metal oxides coated biochar nanocomposites preparation and its utilization in vertical flow constructed wetlands for reactive dye removal: Performance and kinetics studies

Major causes of water pollution in the ecosystem are pollutants such as dyes which are noxious. The present study was based on the synthesis of the green nano-biochar composites from cornstalk and green metal oxide resulting in Copper oxide/biochar, Zinc oxide /biochar, Magnesium oxide/biochar, Manganese oxide/biochar, biochar for removal of dyes combined with the constructed wetland (CW). Biochar Augmentation in constructed wetland systems has improved dye removal efficiency to 95% in order of copper oxide/biochar > Magnesium oxide/biochar > Zinc oxide/biochar > Manganese oxide/biochar > biochar > control (without biochar) respectively in wetlands. It has increased the efficiency of pH by maintaining pH 6.9–7.4, while Total Suspended Solids (TSS) removal efficiency and Dissolved oxygen (DO) increased with the hydraulic retention time of about 7 days for 10 weeks. Chemical oxygen demand (COD) and colour removal efficiency increased with the hydraulic retention time of 12 days for 2 months and there was a low removal efficiency for total dissolved solids (TDS) from control (10.11%) to Copper oxide /biochar (64.44%) and Electrical conductivity (EC) from control (8%) to Copper oxide /biochar (68%) with the hydraulic retention time of about 7 days for 10 weeks. Colour and chemical oxygen demand removal kinetics followed second and first-order kinetic. A significant growth in the plants were also observed. These results proposed the use of agricultural waste-based biochar as part of a constructed wetland substratum can provide enhanced removal of textile dyes. That can be reused.