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This study aimed to explore the nitrogen and phosphorus removal performance of the horizontal submerged constructed wetland (HSCW) with Ti-bearing blast furnace slag (T). Another two HSCWs, with the converter steelmaking slag (G) and the stone (S) as wetland substrates, respectively, were simultaneously running as control. The results showed that t...
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In the anaerobic digestion (AD) system, different additives are used to accelerate microorganism activities and increase biogas and methane production. In this study, the effect of different types of slag that emerge in the iron and steel industry on biogas production and methane yield was investigated. Blast furnace slag (BFS), steelmaking convert...
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... Regarding the influence of NPK (nitrogen, phosphorus and potassium) fertilizers on water quality, the moderate negative correlation between PO 4 3− and Ca 2+ and PO 4 3− and Mg 2+ suggests that the wetland is fulfilling the function of a biogeochemical reactor, where the PO 4 3− concentration tends to be controlled by its calcium phosphate (Ca 3 (PO 4 ) 2 adsorption and precipitation [66] and Mg 3 (PO 4 ) 2 and MgHPO 4 [67], which may also corroborate the low Ca 2+ and Mg 2+ water concentration. ...
Connectivity among water bodies is crucial for hydrological and ecological processes and fundamental for water management. Hydrochemistry and potentiometric studies on an isolated wetland allow to assess landscape influence, flow pathways, and subsurface connection. This study focuses on an isolated wetland over diabase on a topographic depression , with no visible river connection, and aims to determine the influence of rainfall and landscape on water composition and investigate subsurface flow toward the Santa Gertrudes stream. Water levels were monitored, and samples were collected from four wells during wet and dry seasons. Physical and chemical water parameters were measured, and ion concentrations determined. Pearson's correlations highlighted codependence between physical and chemical parameters and ions and Piper's diagram classified water composition. Six potentiometric maps were generated using interpolated hydraulic loads from monitoring campaigns. The findings show fluctuations in water level (0.11 to 0.93 m during wet periods and 1.25 to 1.79 m during dry periods), indicating rainwater directly affects water availability. Water composition was categorized as Sodium Bicarbonate and electrical conductivity values (greater than 100 µS/cm) may indicate that upstream wells are retaining salts from the surrounding crops. Strong positive correlation between sodium, bicarbonate and carbonate, and sulfate with electrical conductivity suggests simultaneous release of ions due to rock and soil mineral alteration. Potentiometric data reinforce the hypothesis of a subsurface connection between the studied area and the Santa Gertrudes stream. Future studies could benefit from expanding the monitoring network to include more GIWs and applying additional methods, such as isotope tracers.
... This biological uptake, facilitated by the specific metabolic activities of wetland vegetation, significantly contributes to reducing nitrogen levels in water. Additionally, the substrate composition of CWs, often designed with materials such as gravel, sand, and organic matter, fosters conditions conducive to denitrification [15]. Denitrifying bacteria found within the sediments of wetlands transform nitrate into nitrogen gas, thereby effectively eliminating nitrogen from the aquatic ecosystem [6,16]. ...
Nitrogen pollution in water environments has reached critical levels globally, primarily stemming from agricultural runoff, industrial discharges, and untreated sewage. The excessive presence of nitrogen compounds poses a significant threat to water quality, leading to adverse impacts on ecosystems and human health. Reaching a breakthrough in the technology of constructed wetlands (CWs) for mitigating nitrogen pollution is hindered by existing knowledge gaps regarding the mechanisms involved in the removal process. Reaching this understanding, we offer a comprehensive summary of current advancements and theories in this research field. Initially, bibliometric techniques were employed to identify yearly patterns in publications and areas of research focus. Subsequently, the chosen documents underwent statistical analysis using VOSviewer_1.6.20 to determine countries’ annual productivity, significant publication years, influential authors, keyword clustering analysis, and more. Finally, a comprehensive overview is provided on the elimination of nitrogen through CWs, encompassing insights into microbial communities and structure types. This analysis aims to uncover potential strategies for optimizing the rate of nitrogen removal. Furthermore, this study elucidates the current research trend concerning the nitrogen removal performance of CWs and identifies challenges and future research directions in this field.
... Steel slag, a by-product of the steel-making industry, has high CaO content and is suitable for phosphorus adsorption. Previous studies have shown that steel slag can effectively remove phosphorus by forming Ca-P precipitates in saturated CWs (Lu et al., 2021;Xu et al., 2019;Zhang et al., 2024). However, the hydrolysis of CaO-steel slag during prolonged flooding periods significantly increased the effluent pH (>9), which may adversely affected nitrifying and denitrifying bacteria. ...
... Some portions are composed of Ti, P, and other elements. After the adsorption, Si and Ca contents remain almost similar; however, the P content slightly increased due to some adsorption on the substrate media [34]. On the other hand, Ti and K content decreased due to macrophyte uptake [34]. ...
... After the adsorption, Si and Ca contents remain almost similar; however, the P content slightly increased due to some adsorption on the substrate media [34]. On the other hand, Ti and K content decreased due to macrophyte uptake [34]. Similarly, the elemental composition of soil reveals that the major portion of the soil is composed of Si (62.93 %) and Fe (17.08 %). ...
A continuous system of moving bed biofilm reactor (MBBR) integrated with horizontal subsurface flow constructed wetland (HSSFCW) followed by a sedimentation tank (PUMBBR-CW) was used for the removal of chemical oxygen demand (COD), ammonia (NH4+), and paracetamol. The removal performance of the reactor was analyzed by varying the initial concentration of the pollutants, hydraulic retention time (HRT), and COD to NH4+ ratio (C/N ratio). Polyurethane foam (PUF) waste was used as the bio-carrier in the MBBR system. Microbial degradation, plant uptake, and substrate adsorption were the most dominant removal mechanisms in the PUMBBR-CW. Further insights into the degradation mechanisms were investigated by characterizing the substrate and bio-carrier and analyzing the degradation by-products. More than 95 % of COD removal was achieved with 30.6 h HRT and 550 mg/L initial concentration at a C/N ratio of 10. At 30.6 h HRT and a C/N ratio of 4, 87 % NH4+ and 94 % paracetamol removal were achieved. The low C/N ratio favors paracetamol removal, as the microorganism uses paracetamol as the sole carbon source under low C/N conditions. Moreover, it was found that paracetamol was uptake and stored in the Canna indica L. plant leaves (216 µg/g). An artificial neural network (ANN) was developed to find the optimum operating condition with maximum removal efficiency. The PUMBBR-CW system effectively overcame the drawbacks of conventional wastewater technologies, such as high footprint, variable pollutant loads, and high maintenance. Hence, it can be used as a highly efficient method of treating wastewater.
... The average concentration in the analyzed effluent remained at 5.72 ± 0.19 mg L −1 . Comparable results have been reported in previous research [59], where Total Phosphorus concentrations in the effluent reached 0.3 mg L −1 with a removal rate of 98%. These results exhibit higher efficiency compared with those obtained in the present study ( Figure 10b). ...
... Table 4 The average concentration in the analyzed effluent remained at 5.72 ± 0.19 mg L −1 . Comparable results have been reported in previous research [59], where Total Phosphorus concentrations in the effluent reached 0.3 mg L −1 with a removal rate of 98%. These results exhibit higher efficiency compared with those obtained in the present study ( Figure 10b). ...
The aim of this research was to evaluate the efficiency of horizontal subsurface flow-constructed wetlands (HSSFWs) planted with Hippeastrum striatum and Heliconia lastisphata for the treatment of contaminated river waters by wastewater from the dairy industry (WDI) and domestic wastewater in tropical climates over a study period of 136 days. Cell with a real volume of 780,000 mL and a flow rate of 1.805 mL s−1. The hydraulic retention time was determined to be 5 days. 12 individuals of Hippeastrum striatum were planted at a distance of 20 cm from each other in one cell, while in another cell, 12 individuals of Heliconia spp. were planted. An adaptation period was determined for both species. Subsequently, the experiment was started, and the elimination percentages obtained were as follows: COD: 67.94 ± 1.39%, 63.17 ± 2.63%; TSS: 56.49 ± 5.73%, 48.78 ± 5.87%; N-NH4: 51.06 ± 2.16%, 50.80 ± 1.91%; TN: 44.36 ± 5.73%, 30.59 ± 5.87%; TP: 47.00 ± 5.32%, 35.57 ± 4.06%; DO: 50.23 ± 1.61%, 47.74 ± 1.34%; and pH: 6.81 ± 0.07, 6.52 ± 0.1, for Heliconia lastisphata and Hippeastrum striatum, respectively. These results demonstrate that both macrophyte species can be used for the treatment of wastewater from the dairy industry using HSSFWs; cheese factories could be involved in the development of constructed wetland systems to reduce the environmental impact of the industry.
... Similar results were also found in the previous study . Different from most freshwater wetlands, the soil types in the study area were mostly saline-alkali soil with low nutrients content and poor original soil fertility (Verhoeven and Setter, 2010;Ouyang et al., 2013;Xu et al., 2019). The soil salinity was reduced greatly and quickly during cultivation under the measures of drainage salinity and freshwater replenishment Xiao et al., 2022). ...
... Next, not all articles could be employed for further analysis because they were review articles, and certain articles did not contain data on N and P removal amounts. By reading the title, abstract, and text of the articles during screening, 27 articles (Huang and He, 2011;Wu et al., 2011;Xiong et al., 2011;Barca et al., 2013;Shilton et al., 2013;Barca et al., 2014;Ren et al., 2014;Shi et al., 2014;Cui et al., 2015;Ge et al., 2015;Hussain et al., 2015;Yun et al., 2015;Zhang et al., 2015;Blanco et al., 2016;Ge et al., 2016;Mohamed et al., 2016;Ahmad et al., 2017;Shi P. et al., 2017;Park et al., 2017;Yuan et al., 2017;Adera et al., 2018;Xu et al., 2019;Hamdan et al., 2020;Saeed et al., 2020;Wan et al., 2020) met our requirement and were finally selected for data analysis, which provided a highly uniform dataset and reliable results. Datasets of the substrate filling mode, plant cultivation, flow direction of CW, steel slag particle size (SSPS), temperature (T), hydraulic retention time (HRT), hydraulic loading rate (HLR), pH value (pH), influent concentration (C in ), total nitrogen (TN), NH 4 + -N, and TP removal amounts (ΔC = C in − C out ) were extracted from these articles, and some original data were modified. ...
... Subsurface SSCWs are most widely used according to the flow direction and are divided into unsaturated vertical flow (Huang and He, 2011;Wu et al., 2011;Xiong et al., 2011;Shilton et al., 2013;Ren et al., 2014;Shi et al., 2014;Cui et al., 2015;Hussain et al., 2015;Zhang et al., 2015;Blanco et al., 2016;Ge et al., 2016;Mohamed et al., 2016;Ahmad et al., 2017;Yuan et al., 2017;Adera et al., 2018;Hamdan et al., 2020;Saeed et al., 2020) and saturated horizontal flow (Barca et al., 2013;Barca et al., 2014;Ren et al., 2014;Cui et al., 2015;Ge et al., 2015;Park et al., 2017;Yuan et al., 2017;Adera et al., 2018;Xu et al., 2019; SSCWs. Next, vertical flow SSCWs require only Frontiers in Environmental Science | www.frontiersin.org ...
Wetlands, including peatlands, marshes, swamps, and coastal wetlands, contain more than 30% of terrestrial soil carbon on only 8% of the Earth’s land surface (Mitsch and Gosselink, 2007). Due to their specific biodiversity and ecosystem function, and linking terrestrial and aquatic systems, wetlands are key players in the most important ecosystem services, especially water regulation, nutrient retention, and carbon cycling. The accumulation of peat in wetlands not only results in high carbon stocks in these systems but also provides invaluable archives of past wetland biomes and regional environmental conditions (Yu et al., 2010). However, in recent decades, the area of wetlands is decreasing due to land use change and the residual wetlands are prone to degradation globally (Davidson et al., 2018). The remaining wetland area is also sensitive to global climatic change and faces many natural and anthropogenic disturbances, such as drainage, global warming,
fire, biological invasions, degradation, land use change, pollution impact, etc. (Battisti et al., 2016). However, the lack of clear definitions and limited data for the entire range of existing wetland ecosystems poses challenges to assessing ecosystem functions and biodiversity and thus limits our understanding of mitigating the numerous impacts. Thus, the purpose of this Research Topic is to bring together the latest research on wetland ecology and disturbance ecology to better understand wetland resilience, spanning over the entire range of possible
wetland systems and allowing for an isolated view of individual systems.
... 29 In a before and after treatment study it was reported that the blast furnace slag (98% removal) show similar results as BCB at a low (3mg/l) TP concentration. 33 Newer substrates like fragmented limestone demonstrated an average P removal of 67% that is lower than the BCB in a mesocosm level study. 34 The fly as ceramics also has equal potential (90% P removal) for P removal as BCB in the present study. ...
Phosphorous (P) entering into the water bodies through point and non-point sources is a causal agent for eutrophication. Nature Based Solutions (NBS) like Constructed Wetlands (CW) are cost effective methods for treating the grey waters in order to protect the water bodies form risk of eutrophication. The P removal efficiency of Constructed Wetlands (CW) can be improved by adding new substrate having potential P removal efficiency. The study
was conducted to determine the phosphorus removal from wastewater using Baked Clay Ball (BCB) media in Vertical Flow Reed Beds (VFRB). The BCB was prepared with a mixture of river clay and saw dust. The field and lab-scale experimentation were set and operated in batch feeding mode using institutional wastewater for four months. The VFRBs were filled with BCB and planted with locally available reed grass (Phragmites karka). The hydraulic retention period in VFRB was 48 hours. Prime goal of the experiment was
to investigate the Phosphorus (P) removal efficiency of the VRFBs apart from other conventional wastewater quality parameters. The concentration of phosphorus of the institutional wastewater was in the range of 27.3 mg/l to 16.3 mg/l. The average phosphorus removal efficiency of the VFRB 1 and 2 filled with BCB was 93.47%, while the average P removal efficiency of gravel filled VFRB 2 and 3 was 68.20%. Thus the experiment reflected that the BCB is a better media than the gravel for P removal. Therefore, the BCB may be used at a field scale to remove P from wastewater in constructed wetlands. Further, there is scope to develop new substrate materials focusing on its P retention capacity, long lasting performance and cost of the substrate to be applied in real treatment situations.
... Thus, effective and eco-friendly approaches with low-energy consumption have gained more attention (Zhao et al. 2017). Constructed wetland (CW) has been used widely for the treatment of municipal sewage as it is easy to operate and maintain, energy-efficient, and cost effective and has good adaptability to influent load fluctuation and visual aesthetic value (Kasak et al. 2018;Xu et al. 2019;Wang et al. 2021). Many factors influence the removal of pollutants. ...
Water scarcity is a worldwide problem. Recycled municipal wastewater is considered a useful alternative to the conventional types of water resources. In this study, a shallow constructed wetland (SCW) with porous filter material and Rotala rotundifolia was used for advanced municipal sewage treatment. The wetland without plant was set as the control (SCW-C). The pollutant removal performance of the system at different hydraulic retention times (HRTs) was investigated. The diversity of the microbial community was analyzed, and the fate of nutrients, mainly N and P, in the system was discussed. Results showed that SCW was efficient in pollutant removal. Effluent concentrations of chemical oxygen demand (COD), total phosphorus (TP), and ammonium nitrogen (NH4+-N) were 15.0–23.6, 0.19–0.28, and 0.83–1.16 mg/L, separately, with average removal efficiencies of 61.2%, 46.3%, and 88.1% at HRT 18 h, which met the requirements of type \(\mathrm{IV}\) water set by the environmental quality standards for surface water in China. The richness and evenness of the bacterial community were significantly higher in the plant-rooted SCW. They increased along with the system. The dominant genera in the system were phosphate-solubilizing bacteria, nitrifying bacteria, and denitrifying bacteria. The P in the influent mainly flowed to the substrate and plant. At the same time, most N was removed by nitrification and denitrification. These findings suggested that the SCW could remove pollutants from the municipal sewage effluent and meet the standard requirement at low HRT.
... However, the strong alkalinity of steel slag is not conducive to plant growth and microbial survival, and it leads to a high pH of the effluent, which is attributed to the low efficiency of N removal by plants and microbes. Although ion exchange adsorption between NH 4 + and metal ions (such as Al 3+ , Fe 2+ , and Mn 4+ ) in steel slag can remove some ammonium nitrogen (NH 4 + -N) (Xu et al., 2019), when compared with microbial nitrogen removal, the nitrogen removed by adsorption is limited. This makes simultaneously removing N and P efficiently in SSCWs difficult. ...
... Next, not all articles could be employed for further analysis because they were review articles, and certain articles did not contain data on N and P removal amounts. By reading the title, abstract, and text of the articles during screening, 27 articles (Huang and He, 2011;Wu et al., 2011;Xiong et al., 2011;Barca et al., 2013;Shilton et al., 2013;Barca et al., 2014;Ren et al., 2014;Shi et al., 2014;Cui et al., 2015;Ge et al., 2015;Hussain et al., 2015;Yun et al., 2015;Zhang et al., 2015;Blanco et al., 2016;Ge et al., 2016;Lu et al., 2016;Mohamed et al., 2016;Ahmad et al., 2017;Shi P. et al., 2017;Park et al., 2017;Yuan et al., 2017;Adera et al., 2018;Xu et al., 2019;Chen et al., 2020;Hamdan et al., 2020;Saeed et al., 2020;Wan et al., 2020) met our requirement and were finally selected for data analysis, which provided a highly uniform dataset and reliable results. Datasets of the substrate filling mode, plant cultivation, flow direction of CW, steel slag particle size (SSPS), temperature (T), hydraulic retention time (HRT), hydraulic loading rate (HLR), pH value (pH), influent concentration (C in ), total nitrogen (TN), NH 4 + -N, and TP removal amounts (ΔC = C in − C out ) were extracted from these articles, and some original data were modified. ...
... Under alkaline conditions, precipitation, depending on the content of CaO in the substrate, is the main removal mechanism; thus, P can be quickly removed. In contrast, under acidic conditions, P is removed mainly by adsorption, and the removal process is slow and lasting (Ahmad et al., 2017;Xu et al., 2019). Moreover, HRT is a significant factor influencing removal efficiency. ...
Steel slag substrate constructed wetlands (SSCWs) can effectively remove phosphorus (P) from sewage through Ca-P precipitation and adsorption. Nonetheless, the disadvantages of a high pH value of the effluent and low nitrogen (N) removal efficiency limit the practical application of SSCWs. To improve these shortcomings, plant cultivation and combining steel slag with other substrate materials have been applied in SSCWs. However, related studies have not obtained a unanimous consensus elucidating such improvements. To accurately evaluate improvements, we statistically analyzed the experimental data reported in 27 related papers and found that combining steel slag with other substrate materials in SSCWs significantly increased the removal amount of total nitrogen (TN) (51.58 mg TN/L) and ammonium nitrogen (NH4 ⁺-N) (74.15 mg NH4 ⁺-N/L) but reduced the removal amount of total phosphorus (TP) (7.76 mg TP/L). In these combined substrate SSCWs, plant cultivation could compensate for the decline in TP removal amount and improve upon the simultaneous removal of N and P (6.02 mg TP/L, 62.18 mg TN/L, and 69.16 mg NH4 ⁺-N/L). Moreover, compared with vertical flow SSCWs, horizontal flow enables plant-cultivated and combined substrate SSCWs to achieve a higher TP removal capacity (6.38 mg TP/L). In addition, operational parameters, including temperature, hydraulic retention time (HRT), pH value, and influent concentration, significantly affected the N and P removal capacity of SSCWs. Our research results provide a theoretical reference for the design and operation of SSCWs for efficient N and P removal.
... The average removal rates of nitrogen and phosphorus of other natural substrates were less than 70% [13,14]. Artificial substrates include industrial or construction wastes [15], agricultural wastes [16], and artificially designed new substrates [17] with significant nitrogen and phosphorus removal. Li et al. [18] compared the nitrogen and phosphorus removal performance of bricks, concrete, and three natural substrates. ...
Constructed wetlands (CWs) are generally used for wastewater treatment and removing nitrogen and phosphorus. However, the treatment efficiency of CWs is limited due to the poor performance of various substrates. To find appropriate substrates of CWs for micro-polluted water treatment, zeolite, quartz sand, bio-ceramsite, porous filter, and palygorskite self-assembled composite material (PSM) were used as filtering media to treat slightly polluted water with the aid of autotrophic denitrifying bacteria. PSM exhibited the most remarkable nitrogen and phosphorus removal performance among these substrates. The average removal efficiencies of ammonia nitrogen, total nitrogen, and total phosphorus of PSM were 66.4%, 58.1%, and 85%, respectively. First-order continuous stirred-tank reactor (first-order-CSTR) and Monod continuous stirred-tank reactor (Monod-CSTR) models were established to investigate the kinetic behavior of denitrification nitrogen removal processes using different substrates. Monod-CSTR model was proven to be an accurate model that could simulate nitrate nitrogen removal performance in vertical flow constructed wetland (VFCWs). Moreover, PSM demonstrated significant pollutant removal capacity with the kinetics coefficient of 2.0021 g/m2 d. Hence, PSM can be considered as a promising new type of substrate for micro-polluted wastewater treatment, and Monod-CSTR model can be employed to simulate denitrification processes.
