Constructed Wetlands Research Articles

Significant negative impact of human activities on carbon storage in the Yellow River Delta over the past three decades

With the increasing intensification of human activities, significant changes in land use and land cover (LULC) have posed a severe threat to the carbon storage capacity of wetland ecosystems. A deep understanding of this impact is crucial for protecting regional ecosystems and promoting sustainable development. This study utilized the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and the human activity intensity (HAI) index to conduct detailed grid analysis and global analysis of carbon storage through creating fishnet system and explored the complex relationship between carbon storage and HAI in the Yellow River Delta (YRD), China. The results indicated that over the past 30 years, natural wetlands such as meadow wetlands and salt marshes in the study area had undergone significant degradation due to escalating human activities, while artificial wetlands and non-wetland areas expanded. Concurrently, the total regional carbon storage had declined by 2.08 Tg, representing a significant drop of 8.22 % in the YRD from 1990 to 2020. Among them, dry land, as the primary land type, served as the most crucial carbon pool. Additionally, the human activity intensity of land surface (HAILS) increased significantly, with a growth rate of 37.27 %. HAI mapping revealed a continuous expansion of areas with high HAI. In contrast, the Yellow River Delta National Nature Reserve (YRDNNR) maintained relatively low HAI. Correlation analysis further showed the significant negative correlation (p < 0.01) between carbon storage and HAI, with r values of grid analysis ranging from −0.1395 to −0.0344, while that for global analysis was −0.9643, respectively. This reflected the spatial heterogeneity and agglomeration effects of data analysis across different scales. This study provides valuable insights for achieving the “dual carbon” goals and supporting the conservation and management of wetland ecosystems.

Urine luck: Environmental assessment of yellow water management in buildings for urban agriculture

The increasing global demand for agricultural production poses challenges to maintain the needs for critical fertilizers such as nitrogen. This study explores the potential of human urine as a source of renewable nitrogen for fertilizer production. Through a life cycle assessment, three different urine management strategies were compared: (S1) an artificial wetland, (S2) an on-site lab-scale aerobic reactor for nitrogen recovery, and (S3) a centralized wastewater treatment plant. While scenario S2 had the highest impacts in 6 out of 8 categories, an advantage in marine eutrophication was identified. S2 showed high energy demand (750 kg MJ-eq) and ecotoxicity (602 kg 1.4-DCB-eq.) mainly due to energy requirements. Nitrogen production exceeded 2.3 times the yearly nitrogen demands of the building tomato production. Upscaling S2 reduces impacts up to 2 times, lowering the payback time from 29 to 13 years. Therefore, implementing large-scale nitrogen recovery systems in cities is encouraged.

Innovations in Phytoremediation: Application of Artificial Wetlands for the Contaminated Water Treatment and Heavy Metals Removal

Objective: The objective of this study was a review to compile research on phytoremediation methods—including phytoextraction, rhizofiltration, phytostabilisation, phytodegradation, and phytovolatilisation—using primary sources to address heavy metal contamination in water. Theoretical Framework: The study is a basic investigation that includes a contextualization regarding the water issue, as well as the treatment of wastewater. A description of the characteristics and quality indicators of water was carried out, along with the importance of the removal of contaminants such as heavy metals using different technologies like phytoextraction, rhizofiltration, phytostabilization, phytodegradation, and phytovolatilization. This led to a detailed description of artificial wetland techniques as a viable and sustainable alternative. Method: The methodology adopted for this research includes data collection and compilation of existing information; regarding the different techniques related to wastewater treatment with artificial wetlands, these systems utilize natural processes involving vegetation, soil, and microbial activity to remove contaminants from water. More than 100 articles have been legally downloaded, and systematised in the database to paraphrase sentences and cite appropriately. Results and Discussion: Phytoremediation is an environmentally friendly technical choice because of its low cost to remediate water and soil contamination through methods of phytoextraction, rhizofiltration, phytostabilisation, phytodegradation and phytovolatilisation for organic contaminants, pesticides, oil waste, heavy metals, antibiotics, etc. It is relevant to choose transgenic plant methods to insert DNA genes and conduct molecular mechanisms through experimental optimisation studies for lightened growth and hyperaccumulation of heavy metals, generating space for metal and biomass storage, and prior knowledge of the physiology and biochemical processes of the plants. Research Implications: The results can be applied or influence practices in environmental protection using Phytoremediation, which is based on a natural technique of plants and their microbiota associated with roots and tissues, endophytic bacteria as Aeromonas sp, Pseudomonas sp, Bacillus sp, Sinorhizobium meliloti, Chryseomonas sp, Curtobacterium sp, Sphingomonas sp, Erwinia sp, Flavimonas sp retain contaminants. On the other hand, aquatic macrophytes such as Lemna spp, Typha spp, Potamogeton spp, Azolla filiculoides, Ceratophyllum demersm, Eichhornia crassipes, and Phragmites australis constitute an effective and feasible complementary alternative for the treatment of contaminated waters. Originality/Value: This study contributes to the literature There are different phytoremediation methods such as phytoextraction, rhizofiltration, phytostabilisation, phytodegradation, and hytovolatilisation for organic contaminants, pesticides, petroleum waste, heavy metals, pharmaceutical antibiotics, etc. Each of the elements has specific applications depending on the conditions of the place and the type of contaminants in an ecosystem.

Integrated respiratory toxicity of municipal wastewater to human bronchial epithelial cells and 3D bronchospheres

Respiratory symptoms have been reported in wastewater treatment workers and residents living close to sewage treatment plant. However, toxicological research about the respiratory hazards of municipal wastewater is scarce. The present study aims to gain insight into the comprehensive respiratory hazards induced by the contaminant mixtures in municipal wastewater. The integrated respiratory hazards of effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TTP), and a constructed wetland (CW) were evaluated using normal human bronchial epithelial cells (NHBE) bioassay, and toxicity reduction efficiency of various treatment techniques was analyzed. Effluents caused cytotoxicity, oxidative damage, inflammation response with the increased levels of IL-6 and CXCL8, and impaired barrier integrity with decreased expressions of ZO-1 and occludin in NHBE. Further, the effluents inhibited the development of 3D bronchospheres, increased irregular surface and cell debris, and suppressed the formation of luminal structures. TTP E effluent significantly increased the expression of MUC5AC in bronchospheres. The integrated biomarker response (IBR) of the influent was removed by 40.2% at SWTPs, 18.2% at TTP, and 36.6% at CW, respectively. The IBR of the final effluents from SWTPs, TTP, and CW were 7.2, 7.7, and 7.7, respectively. Significant correlation with toxicity biomarkers was frequently observed for stearyl alcohol, o-cresol, phenanthrene, butylated hydroxytoluene, and dimethyl phthalate. The present study provided human relevant evidence concerning the adverse respiratory effects associated with discharge. The necessity for deep water treatment, performance optimization, and the potential means were suggested for improving water quality and protecting respiratory health.

Demonstration scale treatment of drainage canal water in the Nile Delta through a combination of facultative lagoons and hybrid constructed wetlands

Drainage canal water (DCW), a mixture of Nile water, drainage water and municipal wastewater, is largely used for irrigation in the Nile Delta. Facultative lagoons (FL) and constructed wetlands (CWs) represent interesting options for DCW treatment before its agricultural re-use, but very few studies investigated their implementation in Egypt. This work aimed at developing at demonstration scale (250 m3 d-1) a FL+CW treatment train capable to turn DCW into an effluent reusable in agriculture. Three types of hybrid CWs were tested in parallel for 530 days. The combination of FL with a cascade hybrid CW, operated at a 200 L d-1 m-2 surface loading rate, led to medium-to-high removal efficiencies (suspended solids 90%, total nitrogen 84%, phosphate 80%, COD 67%, faecal coliforms 2.2 Log) and surface removal rates (COD 47.5 t y-1 ha-1, total nitrogen 10.9 t y-1 ha-1, faecal coliforms 1.5 1011 MPN y-1 ha-1). The effluent, compliant with class C of EU 2020/741 regulation, is potentially reusable to irrigate numerous Egyptian crops. The results show that the combination of FLs with cascade hybrid CWs has a great potential for the treatment of DCW and low-strength municipal wastewater, with near-zero energy consumption, null consumption of chemicals and a land requirement varying between 1.1% and 1.5% of the agricultural land irrigated with the treated DCW.

Simultaneous removal of vanadium and nitrogen in two-stage vertical flow constructed wetlands: Performance and mechanisms.

Vanadium (V(V)) and nitrate, as co-concomitant pollutants in water bodies, pose potential threats to the eco-environment and human health. This study was to reveal the feasibility of simultaneous removal of V(V) and nitrate in the series-wound vertical flow constructed wetlands (CWs) with iron ore (B-CWs)/manganese ore (C-CWs)-wood substrates. The results showed that B-CWs could achieve efficient V(V) and NO3--N removal with the influent of 2 and 10 mg/L (V(V)/NO3--N=1:5), respectively. With the increase of V(V)/NO3--N ratio (V(V)/NO3--N=1:1), B/C-CWs exhibited better combined pollution removal. Even when nitrate was removed (V(V)/NO3--N=1:0), the systems could maintain a good capacity for V(V) removal. High V(V) (20 mg/L) significantly inhibited V(V) removal, with a slight recovery of the performance as the decrease of V(V) influent. High NO3--N concentration (10 mg/L) effectively enhanced V(V) removal and restored C-CWs to the better level. V(IV) precipitates/oxides were the main reducing end-products. High abundance of V(V)-reducing bacteria and iron/manganese cycling pumps ensured efficient V(V) removal.

Floating Treatment Wetlands Made of HDPE and PET Can Be Sources of Microplastics

Floating Treatment Wetlands Made of HDPE and PET Can Be Sources of Microplastics

Application of dairy wastewater as substrate for bioremediation of coal mine drainage in planted horizontal flow constructed wetland

Coal mine drainage (CMD) is an environmental threat due to its high volume, low pH, presence of toxic metals, and absence of biodegradable organics. The present study aims to treat CMD in a horizontal sub-surface flow constructed wetland (CW) using dairy wastewater as an organic source. CW was planted with Typha angustifolia. Characteristics of synthetic CMD were (except pH, all unit mg/L) pH 1.9; Fe: 100, SO 4 2 − : 1,000, Mn: 6, Zn: 5, Co: 1, Ni: 1, and Cr: 1. CMD was mixed with synthetic dairy wastewater (pH: 5.05, COD: 2,700 mg/L, BOD: 1,600 mg/L) in the ratio of 3:1. Alkalinity of 120–190 mg/L CaCO3 was generated and effluent pH improved from 2.2 to 6.6. Metals precipitated as metal sulfide or hydroxide. Sulfate removal was hindered due to the synergistic toxicity of several metals. Except for Mn, all other effluent parameters were within the discharge limit for disposal in inland surface water.

Ornamental Plant Growth in Different Culture Conditions and Fluoride and Chloride Removals with Constructed Wetlands

Natural water resources often contain fluorides and chlorides due to wastewater discharge; however, excessive exposure to fluorides can pose health risks to humans. Elevated chloride levels can negatively affect aquatic fauna and disrupt the reproductive rates of plants. This study assessed constructed wetlands (CWs) featuring monocultures (including Canna hybrid, Alpinia purpurata, and Hedychium coronarium) and polycultures (combinations of species from the monoculture systems) of ornamental plants (OPs) to evaluate their efficiency in removing fluorides and chlorides. The results revealed that the ornamental plants flourished in the CW conditions without sustaining any physical damage. C. hybrid demonstrated the longest roots and the highest volume, as well as greater height compared to other species. However, this did not affect the ion removal efficiency. In polyculture systems, 42.2 ± 8.8% of fluoride was removed, a result that was not significantly different (p &gt; 0.05) from the removal rates observed in monocultures of C. hybrid (42.5 ± 7.5%), H. coronarium (36.8 ± 7.0%), or A. purpurata (30.7 ± 7.9%). For chloride, a similar pattern emerged, with 32.4 ± 4.8% removed in constructed wetlands (CWs) using a polyculture of ornamental plants, a figure that was also not significantly different (p &gt; 0.05) from the removal percentages in monocultures of C. hybrid (29.1 ± 5.3%), H. coronarium (28.1 ± 5.0%), or A. purpurata (32.0 ± 5.7%). Our results indicate that CWs with polyculture species contribute to pollutant removal at levels comparable to those found in monoculture systems. However, polyculture systems offer enhanced aesthetic appeal and biodiversity, incorporating various ornamental flowering plants. The use of this eco-technology for removing fluoride and chloride pollutants helps prevent river contamination and associated health issues.

Accelerated Indirect Photodegradation of Organic Pollutants at the Soil-Water Interface.

Indirect photolysis driven by photochemically produced reactive intermediates (PPRIs) is pivotal for the transformations and fates of pollutants in nature. While well-studied in bulk water, indirect photolysis processes at environmental interfaces remain largely unexplored. This study reveals a significant acceleration of indirect photodegradation of organic pollutants at the soil-water interface of wetlands. Organic pollutants experienced ubiquitously enhanced indirect photodegradation at the soil-water interfaces, with rates 1.41 ± 0.01 to 4.27 ± 0.03-fold higher than those in bulk water. This enhancement was observed across various natural and artificial wetlands, including coastal wetlands and rice paddies. In situ mapping indicated that soil-water interfaces act as hotspots, concentrating both organic pollutants and PPRIs by 9.30- and 4.27-folds, respectively. This synchronized colocation is the primary cause of the accelerated pollutant photolysis. Additionally, the contribution of each PPRI species to pollutant photolysis and a coupled transformation pathway at the soil-water interface significantly differed from those in bulk water. For instance, the contribution of singlet oxygen to metoxuron photolysis increased from 10.1% in bulk water to 44.4% at the soil-water interface. Our study highlights the rapid indirect photolysis of organic pollutants at the soil-water interfaces, offering new insights into the natural purification processes in wetlands as "Earth's kidneys."

Effects of Earthworm Density on Greenhouse Gas Emissions from Constructed Wetlands with Different Plant Configurations

Effects of Earthworm Density on Greenhouse Gas Emissions from Constructed Wetlands with Different Plant Configurations

Experimental Study on the Removal of Pollutants from Domestic Wastewater in a Strongly Constructed Wetland with an Applied Electric Magnetic Field

The addition of physical field enhancement measures to improve the purification effect of vertical flow artificial wetlands has gradually become popular. In this study, a vertical flow artificial wetland system reinforced by electric and magnetic fields was constructed. These fields were first optimized using finite element 3D simulation software to obtain the optimal electric and magnetic field parameters. Then, the pollutant removal effects and changes in microbial community structure were comparatively analyzed. The optimal electromagnetic field parameters (applied voltage of 15 V and applied magnetic field of 20 mT) resulted in significantly enhanced removal rates of chemical oxygen demand (COD), nitrate nitrogen (NH4+-N), total phosphorus (TP), and orthophosphorus (PO43−-P) in wastewater, with rates of 74.47%, 45.44%, 89.85%, and 90.04%, respectively. These rates were notably higher than those observed in the vertical flow artificial wetland system. The microbial community structure analysis revealed that the vertical flow constructed wetland with enhanced electric and magnetic fields exhibited (EM-VFCW) a more diverse and complex microbial community structure. Notably, the abundance of bacteria capable of removing NH4+-N and COD, including Aspergillus, Fusarium, and Actinobacteria, was significantly elevated.

Sustainability Prediction by Evaluating the Emergy of a Co-Treatment System for Municipal Wastewater and Acidic Water Using Intermittent Electrocoagulation

The objective of this research was to evaluate the sustainability of a co-treatment system that combines Municipal Wastewater (MW) and Acid Mine Drainage (AMD) through the technique of intermittent electrocoagulation, applied as an advanced solution to improve contaminant removal efficiency and optimize energy balance. Four scenarios were analyzed: Treatment I (with a 1/7 ratio of urban wastewater to AMD), Treatment II (which includes an artificial wetland), Treatment IIIa (which introduces electrocoagulation to enhance sulfate removal and pH regulation), and Treatment IIIb (which employs a 1/15 ratio of AMD to eutrophic water). The methodology focused on calculating key sustainability indicators such as the Net Yield Ratio (EYR), Emergy Inversion Ratio (EIR), Environmental Loading Ratio (ELR), and Sustainability Index (SI), in order to assess the impact of each technology on the energy efficiency and environmental load of the system. The results showed that, although Treatment IIIa was effective in contaminant removal, the EIR increased to 0.18 and the ELR rose to 0.62, indicating a higher reliance on non-renewable inputs due to increased energy demand. However, Treatment IIIb, which combines electrocoagulation with eutrophic water, significantly improved the sustainability of the system, achieving an SI of 2.31 and an ELR of 1.22, reflecting a reduction in energy efficiency due to intensive use of external resources, but overall greater sustainability compared to the other scenarios. This research concludes that intermittent electrocoagulation, when integrated with synergistic resources like eutrophic water, can enhance contaminant removal efficiency and improve the use of renewable resources, minimizing environmental load and increasing the sustainability of wastewater treatment systems.

WATER INHABITING BIRDS OF MAIGANGA POST COAL MINING PONDS AND ARTIFICIAL WETLAND

Wetlands play a significant role in bird conservation and generally support biological diversity. Historically, bird community assessment has been employed in monitoring and identifying areas for conservation actions. In this study, we examined two post mining ponds and one artificial wetland in Maiganga Coal Mine, Gombe State for wetland avifauna. We focused on water birds (i.e. bird species that depend wholly or partially on water and wetland ecosystems for their survival). Survey was conducted during the onset of dry season in October 2021 to September 2022. Point count technique was used for the survey. A total of 626 individuals of 23 species from 19 genera, 10 families and 6 bird Order were recorded. The White-faced whistling duck was the most abundant bird species and was restricted to the active-mine pond (AMP). AMP was the most diverse of the three water bodies surveyed. However, some species were exclusive to either of the three sites. Similarly, AMP was the most abundant site with 426 individuals from 16 bird species, followed closely by the sedimentation pond with 147 individuals drawn from 15 bird species. The results suggest that water depth, age of establishment and surrounding vegetation structure could be a major determinant of bird species composition and abundance in the study area. The study highlights the importance of restorative actions aimed at recovering modified landscapes, through tree planting and creation of wetlands. This is evident in the presence of waterbirds in Maiganga, a location that was previously devoid of perennial water bodies and...

Unveiling synergistic enhancement mechanism of nitrogen removal in surface flow constructed wetlands: Utilizing iron scraps and elemental sulfur as integrated electron donors

Lacking electron donors generally causes poor denitrification performance in constructed wetlands (CWs). In this study, iron scraps (ISs) and elemental sulfur (S0) were employed as electron donors in different surface flow constructed wetlands (SFCWs): control (C-SF), ISs added (Fe-SF), S0 added (S-SF), and ISs and S0 combined (Fe + S-SF) to investigate the performance and mechanism of nitrogen (N) removal through continuous flow and batch experiments. The impact of hydraulic retention times (HRTs) and temperatures on N removal was explored. The combined use of ISs and S0 significantly improved nitrate (NO3− -N) removal in Fe + S-SF compared to the other SFCWs. During the 3-d HRT at 25 °C, the average NO3− -N removal efficiency in Fe + S-SF reached the highest value of 71.66 ± 12.54%, reducing NO3− -N concentrations from 12.03 mg/L to 3.47 mg/L. The results of the batch experiments revealed an N removal pattern that aligned with the findings of the continuous flow experiment. The microbial community analysis revealed a selective enrichment of key functional genera (e.g., Ferritrophicum and Dechloromonas), contributing to enhanced N removal in Fe + S-SF. These findings suggest that the synergistic use of ISs and S0 can achieve better denitrification efficiency and potentially be utilized for enhanced N removal from low C/N wastewater.

The effect of leaf leachates addition on denitrification in subsurface flow constructed wetlands is shaped by the bed substrate type

In constructed wetlands (CWs), bed substrate and leaf leachates from vegetation may correct the low C/N ratio that constrains heterotrophic denitrification and nitrate removal from irrigated agricultural drainage water. However, the interactive effects of bed substrate type and leaf leachates on denitrification are still unknown. By focusing on a CWs pilot plant, we designed a laboratory experiment to evaluate i) wether denitrification potential rates varied among bed substrates: calcareous gravel (a conventional substrate), gravel+soil from a natural wetland (silty loam Solonchak, 1.5 % of organic C) and gravel+biochar from pyrolyzed ornamental plants (75 % of organic C); and ii) the response of denitrification within each bed substrate to the addition of their respective leaf leachates. We found that denitrification potential rates were lower in gravel beds (0.011 ± 0.006 μgN2O-N gDM−1 h−1) than those observed with the addition of biochar (0.06 ± 0.03) and especially soil (0.78 ± 0.04), with soil being the most advantageous option. Besides, leaf leachates addition boosted denitrification rates in all cases. Nevertheless, the effect of leachates was relatively higher in gravel beds than in the other substrates (15 times higher vs. 2 and 4 times with soil and biochar, respectively). Our outcomes highlight limited denitrification when using gravel substrate not only by low C but also due to essential macro- and micro-elements, and support the role of plant leaves as internal and self-sustainable source of nutrients.

Effect of integrated microbial fuel cell in a two-stage vertical flow constructed wetland for piggery wastewater treatment and resource recovery by photobioreactor

ABSTRACT This study developed a nature-based pilot-scale technology for simultaneous piggery WW treatment and resource recovery potential. The technology comprised a two-stage vertical flow constructed wetland (2-VFCW) integrated with a microbial fuel cell (MFC) and microalgal photobioreactor. The first and second stage was an unsaturated and saturated type, respectively. The bioelectricity generation was optimised by investigating the suitable electrode zonation, hydraulic retention time (HRT) and WW loading rate. The 2-VFCW-MFC-treated effluent was studied to grow microalgae for biomass production. The 2-VFCW-MFC showed better treatment efficiency than the 2-VFCW, possibly due to enhanced microbial activity on the electrode surface, leading to improved organic matter degradation and electron transfer to the cathode, enhancing NO3− and PO43− reduction. The 2-VFCW-MFC with electrode zonation of 20 cm (cathode) and 60 cm (anode) and HRT of 76 h, 48 min showed the highest open-circuit voltage of 291.83+13.53 mV and WW treatment efficiency. The highest algal biomass of 21,323.34+8,316.26 mg/L (wet weight) was produced at HRT of 96 h, then entered the death phase. Comparatively, the 2-VFCW-MFC showed higher WW treatment efficiency than 2-VFCW at 2 L/day by 23.24% COD, 27.43% TOC, 33.05% PO43−, 13.51% NO3−, 8.14% TN, except TAN (22.71%).

Decentralized sanitation alternatives in cities of the global south—A case of constructed wetlands in Bulawayo, Zimbabwe

Constructed wetlands have emerged as a sustainable alternative for decentralized wastewater treatment in developing countries which face challenges with urbanization and deteriorating infrastructure. This paper discusses the key factors affecting the implementation of constructed wetlands in developing countries. A case study research design was adopted, which focused on Bulawayo, Zimbabwe. A mixed-method approach was adopted for the study. Spatial analysis was conducted to identify potential sites for constructed wetlands in the city of Bulawayo. Semi structured interviews were conducted, with relevant stakeholders, such as town planners, civil engineers, NGO representatives, community leaders, and quantity surveyors. The findings reveal that political reforms, public acceptance, land availability, and funding are crucial for the successful implementation of constructed wetlands. Additionally, four sites were identified as the most favorable preliminary locations for these systems. The paper captures all the key factors relevant to the implementation of constructed wetlands (CWs) with a closer look at policy and the role it plays in the adoption of decentralized wastewater treatment systems. Formulating policy around the decentralized sanitation systems was considered imperative to the success of the systems whether in implementation or in operation. The paper adds to knowledge in the subject of sustainable wastewater treatment alternatives for developing countries. However, further research can be conducted with a different methodology to ascertain the applicability of the systems in developing urban cities considering other important aspects in the implementation of wastewater treatment systems.

Study on the Functions and Design Techniques of Urban Parks in the Context of Post-1949 Urban Development - Case Study of Xian, China

The urban park is an important part of the urban green space system and an essential factor in promoting sustainable development and urban transformation. The functions and corresponding design methods of urban parks also reflect the background and development requirements of different periods. In response to the requirements of urban development in different periods, parks in Xian have gradually changed from a single function of recreation to a function of cultural exchange and, in recent years, to a function of habitat protection. In order to better discuss and analyze characteristics and provide inspiration for further study, the article aims to divide the period from 1949 to 2020 into four stages according to the historical background, and make a comparative analysis according to the corresponding overall planning requirements and examples. The study will combine data with field visits to representative parks from four periods and analyze the relevance of their design and impact to the requirements of the times.The renovation of ancient gardens lays the foundation for the construction of parks, the protection and development of cultural heritage sites increases the role of parks in cultural construction, and the development and construction of ecological wetlands increases the function and role of parks in the construction of ecological civilisation. It can be concluded that the function of the park is also correspondingly related to its design approach.

Optimizing the final rest period of sludge treatment wetlands: Assessment of biosolids quality

Wastewater Treatment Plants (WWTPs) generate a substantial amount of sludge as a residue of the wastewater treatment process. The management of this sludge requires the adoption of cost-effective and environmentally friendly techniques. Sludge Treatment Wetlands (STW) have emerged as an effective means to manage and treat sludge, resulting in the production of biosolids suitable for agricultural purposes. This study aimed to ascertain the optimal operation in terms of final rest period for STWs in the Mediterranean region to boost the production of biosolids for agricultural applications. Two WWTPs in Spain were monitored for a period of 9 months, during which several physic-chemical parameters were monitored to determine the optimal final rest period. The findings revealed that, when sludge feeding period was stopped in summer, a final rest period of 6 months was sufficient to reach biosolids suitable for agricultural re-use. These biosolids displayed a content of 53% total solids (TS), a mineralization rate of 40% volatile solids (VS/TS), a stabilization degree (SD) of 40%, and a high nutrient content. Moreover, the presence of heavy metals, pathogens, antimicrobial resistance genes (ARGs), antibiotics, and pesticides was generally low. Overall, this study demonstrates that, in the Mediterranean Region, 6 months of rest period starting in summer are appropriate for sludge treatment wetlands to effectively generate biosolids with suitable characteristics to be safely re-used as a bio-based fertilizer.