Subsurface Flow Constructed Wetland System Research Articles

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.

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.

Impact of clogging on accumulation and stability of phosphorus in the subsurface flow constructed wetland

Substrate clogging is one of the major operation challenges of subsurface flow constructed wetlands (SSF-CWs). And the phosphorus (P) removal performance and stability of P accumulation of SSF-CWs would be varied with the development of substrate clogging. In this study, three horizontal SSF-CWs microcosms with different clogging degrees were conducted to explore the mechanism of P accumulation behavior influenced by substrate clogging. Increase in clogging degree resulted in hydraulic retention time (HRT) diminution and adsorption sites increase, which jointly led to reduced P removal efficiency at low clogging degree (L-CW), however, higher P removal efficiency was obtained as adsorption sites increase offset HRT diminution at high clogging degree (H-CW). Substrate adsorption was the primary removal pathway in all SSF-CW systems. It accounted for 77.86 ± 2.63% of the P input in the H-CW, significantly higher than the control (60.08 ± 4.79%). This was attributed to a higher proportion of Fe/Al–P accumulated on the substrate of H-CW, since clogging aggravated the anaerobic condition and promoted the generation of Fe ions. The increase in clogging degree also elevated the release risk of the accrued P in SSF-CWs, since Fe/Al–P was considered bioavailable and readily released under environmental disturbance. The obtained results provide new insights into the P transport and transformation in SSF-CWs and would be helpful to optimize substrate clogging management.

Development and Design of Laboratory Scale Subsurface Flow Constructed Wetland System

Wetlands have traditionally functioned as a natural filtration system. Constructed wetlands (CWs) are a cost-effective and efficient green technology for treating many different types of wastewaters. The efficiency of constructed wetland depends upon the type of media, vegetation, effluent concentration, and applied hydraulic load. The objective of the present paper is to Development and Design a laboratory scale constructed wetland system. The important considerations in the design are the size of the wetland, aspect ratio, depth of each layer, and slope. The length, width, and height of the CWs are 1.2 m; 0.3 m; and 0.65 m; respectively. The total volume of CWs is 0.234 m3 and the treatment section in the system consists volume of 0.135 m3. Twelve sampling points are provided to collect the water from the different layers (media) of the wetland. An aeration pipe is provided at the bottom of CWs. With the laboratory scale constructed wetland system, we can analyze the different types of wastewater.

EFISIENSI PENYISIHAN KADAR BOD PADA LIMBAH CAIR TAHU MENGGUNAKAN TANAMAN BAMBU AIR DENGAN SISTEM SUB SURFACE FLOW CONSTRUCTED WETLAND

The tofu industry in Indonesia is growing very rapidly due to the high public demand for tofu.. Most of the tofu industries in Indonesia are household-scale industries that are not equipped with waste treatment so that processing is needed, one of which is Phyto-treatment. In this research, tofu wastewater treatment is carried out using a water bamboo plant (Equisetum hyemale) through a sub-surface flow constructed wetland system. This study aims to eliminate the levels of organic pollutants in the tofu wastewater which can be seen from the levels of BOD (biological oxygen demand) and to determine the effect of the number of plants and the type of media on the BOD levels. The test was Phyto-treatment carried out for 20 days with a residence time of BOD testing on days 5, 10, 15, and 20. Based on the results of the study, the efficiency of removing BOD levels on day 20 in the X1Y1, X2Y1, X1Y2, and X2Y2 reactors was 40.93%, 79.10%, 26.53%, and 53.61%, respectively. The efficiency of removal of the highest BOD levels was found in the X2Y1 Reaktor. Meanwhile, based on the results of statistical tests using two-way ANOVA, it can be concluded that the number of plants and the type of media had a significant effect on the BOD levels

The Partial Contribution of Constructed Wetland Components (Roots, Gravel, Microorganisms) in the Removal of Phenols: A Mini Review

Constructed wetlands (CW) have attracted growing interest in wastewater treatment research in the last 20 years, and have been investigated intensively worldwide. Many of the basic processes occurring in CWs have been qualitatively established; however, much quantitative knowledge is still lacking. In this mini review, the proportionate contributions of the different system components to removal of contaminants are examined. The main objective of this mini review is to provide a more in-depth assessment of the interactions between the porous bed, plants, and microorganisms during the removal of organic contaminants from the water in a subsurface flow CW system. In addition, a unique technique to study the partial contribution to the total removal of contaminants in a CW is described. Future studies in this field will expand our knowledge of any synergistic or antagonistic interactions between the components and facilitate improved CW construction and operation. Here, phenol will be used as a model industrial organic contaminant to illustrate our current understanding of the contributions of the different components to total removal. I will also discuss the various factors influencing the efficacy of bacteria, whether planktonic or as biofilm (on porous bed or plant roots), in subsurface flow CWs.

Removal of heavy metals in subsurface flow constructed wetlands: Application of effluent recirculation

This study reports four heavy metals, i.e., Zinc (Zn), Chromium (Cr), Nickel (Ni), and Lead (Pb) removal from landfill leachate employing two-hybrid subsurface flow constructed wetland systems; each system included a vertical flow (VF) followed by a horizontal flow (HF) wetland. The wetland systems were packed with organic (coco-peat) or construction (brick, sand) materials and planted with Phragmites australis or Chrysopogon zizanioides ( Vetiver ). Both systems were operated under without, and with effluent recirculation protocols. Cr, Ni, and Pb concentration were 2–73 mg/kg, 3–12 mg/kg, and 0.00004–27 mg/kg, respectively in Phragmites ; 8–34 mg/kg, 3–15 mg/kg, and 0.00004–14 mg/kg, respectively in Vetiver. Organic carbon (C) and iron (Fe) of the coco-peat, brick allowed media-based metals removal in VF wetlands; such accumulation was not quantified in sand-based HF wetlands. Zn, Cr, Ni, Pb removal percentages increased between 75 and 98%, 29 and 41%, 14 and 48%, 23 and 26%, respectively, in VF wetlands during the effluent recirculation period (compared with removal performances of without recirculation phase). Removal percentages were reduced in HF wetlands during the recirculation period. Overall, Zn, Cr, Ni, Pb removal percentages in the two-hybrid wetlands ranged between 20 and 97%, 95 and 99%, 55 and 73%, 69 and 83%, respectively.

Evaluation of Tannery Wastewater Treatment by Integrating Vesicular Basalt With Local Plant Species in a Constructed Wetland System

Tannery wastewater is composed of a complex mixture of organic and inorganic components from various processes that can critically pollute the environment, especially water bodies if discharged without treatment. In this study, integrated vesicular basalt rock and local plant species were used to establish a horizontal subsurface flow constructed wetland system and to investigate the treatment efficiency of tannery wastewater. Four pilot units were vegetated with P. purpureum, T. domingensis, C. latifolius, and E. pyramidalis, and a fifth unit was left unvegetated (control). The constructed wetland units in horizontal subsurface flow systems were effective in removing total chromium (Cr), chemical oxygen demand (COD), and 5-day biological oxygen demand (BOD5) from the inflow tannery wastewater. The removal efficiency reached up to 99.38, 84.03, and 80.32% for total Cr, COD, and BOD5, respectively, in 6 days of hydraulic retention time (HRT). The removal efficiency of total suspended solid (TSS), total phosphorus (TP), and nitrate (NO3−) of the constructed wetland units reached a maximum of 70.59, 62.32, and 71.23%, respectively. This integrated system was effective for treating tannery wastewater, which is below the Ethiopian surface water standard discharge limit set to BOD5 (200 mg L−1), COD (500 mg L−1), total Cr (2 mg L−1), NO3− (20 mg L−1), TSS (50 mg L−1), and TP (10 mg L−1).

Performance of a Pilot-Scale Constructed Wetland and Medium-Term Effects of Treated Wastewater Irrigation of Arundo donax L. on Soil and Plant Parameters

On marginal lands in the Mediterranean basin, giant reed (Arundo donax L.) represents one of the most interesting perennial crops due to high levels of biomass production. Considering periodic water shortage during the summer months in this area, the reuse of treated wastewater (TWW) would seem to be a good opportunity for the growth of the species. The aim of this study was to assess the medium-term effects of irrigation using freshwater (FW) and TWW on soil characteristics and growth in giant reed plants. TWW was obtained from a pilot-scale horizontal subsurface flow constructed wetland system (HSSF CWs) with a total surface area of 100 m2. A split-plot design for a two-factor experiment was used with three replications. Medium-term TWW irrigation increased organic matter and plant nutrients in the soil; however, pH was not affected. Plants irrigated with TWW showed greater growth (+10.49% in height, +12.75% in stem diameter, +11.51% in above-ground biomass) than those irrigated with FW. The higher heating value of crop residues ranged between 16.83 (FW-irrigated plants) and 17.00 MJ kg−1 (TWW-irrigated plants). Results show that HSSF CWs produces TWW, which can be an alternative source of water for growing giant reed with high biomass performance.

Simulation and optimization of hydraulic performance of small baffled subsurface flow constructed wetland.

The water body inside the constructed wetland is affected by various factors, and the flow state is relatively complicated. There will always be a certain degree of low velocity area and rapid outflow phenomenon, which makes part of the space in the wetland unable to be effectively used. Based on Computational Fluid Dynamics (CFD) technology, this paper uses Fluent's porous media model and discrete phase model to establish a hydrodynamic model of up and down baffled subsurface flow constructed wetland system. The internal flow field of the wetland is simulated, and the hydraulic performance of different baffle settings and substrate laying methods in the wetland is systematically evaluated. The results show that when the number of baffles is the same, the hydraulic efficiency is higher when the first baffle is located on the lower part of the substrate. Compared with the position of the baffle, the increase in the number of baffles does not significantly improve the hydraulic efficiency of the constructed wetland. The substrate layer thickness ratio has a significant effect on the two parameters of the variance of the hydraulic residence time distribution (σ2) and the flow divergence (σ02). By increasing the thickness of the middle substrate, the low flow rate phenomenon caused by the small porosity substrate area of the upper layer and the rapid outflow phenomenon of the lower substrate can be improved to a certain extent, the utilization efficiency of the middle substrate layer is improved, and the hydraulic performance is increased. The research results are of great significance for improving the utilization of wetland space and ensuring its efficient decontamination and purification function.

Performance efficiency and water quality index of a two-stage horizontal subsurface flow constructed wetland system polishing anaerobically treated brewery effluent

The disposal of untreated or partially treated brewery wastewater can cause pollution problems to the receiving water bodies. The objective of this study was to evaluate the effectiveness of a two-stage horizontal subsurface flow constructed wetland (HSSFCW) system planted with Cyperus alternifolius and Typha latifolia in polishing an up-flow anaerobic sludge blanket (UASB) reactor treating brewery effluent in Kombolcha, Northern Ethiopia. The system was integrated with the UASB reactor, and its performance efficiency was monitored for a year using standard methods. The first-order kinetic model was used to correlate the influent and effluent pollutant concentrations and estimate the areal rate constant (kA) by fitting the experimental data to the model. The HSSFCW's water quality index (WQI) and oxygen transfer rate (OTR) were also calculated. The findings showed that HSSFCW removed 89% total suspended solids (TSS), 92% chemical oxygen demand (COD), 83.6% total nitrogen (TN), 92.9% ammonium – nitrogen (NH4+ − N), 74.4% total phosphorous (TP), and 79.5% orthophosphate (PO43−). Literature comparable OTR values were obtained for each HSSFCW stage with a total OTR value of 23.5 g−2d−1. Effluent concentrations of COD, TN and NH4+ − N were reasonably correlated (R2 ≥ 0.85) to influent concentrations. The calculated kA (md-1) for TSS, COD, TN, NH4+ − N, TP, and PO43− were 0.26, 0.26, 0.11, 0.18, 0.08, and 0.08, respectively. Further polishing of the effluent with two-stage HSSFCW has shifted the WQI from a good to excellent water quality rating and thus, can be used as a sustainable polishing technique for agro-process wastewaters.

Evaluation of irrigation suitability potential of brewery effluent post treated in a pilot horizontal subsurface flow constructed wetland system: implications for sustainable urban agriculture

The use of untreated or partially treated wastewater reuse for urban and peri-urban agricultural irrigation is a common practice in developing countries like Ethiopia. Such practices, however, pose significant environmental and public health risks. The objective of this study was to evaluate the irrigation suitability of anaerobic digestion brewery effluent (ADBE) and two-stage horizontal subsurface constructed wetland post-treated ADBE (CWPBE). A series of pot experiments were conducted in a plastic - greenhouse system arranged in three sets of irrigation schemes: Treatment Group1 (TG1): municipal pipe tap water (MPTW) irrigated pots; Treatment Group2 (TG2): ADBE irrigated pots, and Treatment Group3 (TG3): CWPBE irrigated pots. Pots packed with the same amount of sandy clay loam soil and local tomato seeds sown were irrigated following an updated tomato irrigation schedule derived from the FAO CROPWAT stimulation model for 120 days. The findings from key irrigation water quality parameters showed that the CWPBE achieved the prescribed irrigation water standards with values of pH (7.4 ± 0.15), electrical conductivity (1.9 ± 0.11 dS.m−1), total suspended solids (25 ± 4.17 mgL-1), chemical oxygen demand (185.1 ± 1.66 mgL-1), total nitrogen (17.4 ± 0.7 mgL-1), total phosphorous (8.8 ± 0.26 mgkg-1), calcium (10.5 ± 3.6 mgkg-1), magnesium (4.9 ± 0.98 mgkg-1), sodium (4.4 ± 1.51 mgkg-1), potassium (2.3 ± 1.15 mgkg-1), sodium adsorption ratio (1.6 ± 0.34), and total coliform (8 ± 0.16×10−5 CFU/100 mL). Moreover, tomato plants grown in TG3 attained higher growth such as number of leaves (85.6 ± 4.68), plant height (92.2 ± 1.29 cm), stem diameter (13.1 ± 2.35 cm) and leaf area (35.5 ± 1.03 cm2) as well as higher biomass (61.2 ± 1.33 kgm−2) and fruit (46.4 ± 3.51 kgm−2) yields over other treatment groups. The results revealed that irrigation waters significantly improved both growth and yield parameters of tomato plants with the ascending order of TG1 < TG2 < TG3. Moreover, CWPBE showed minima short-term residual effect on soil physicochemical properties as compared to ADBE, and thus, it has potential suitability for agricultural irrigation reuse.

Post treatment of anaerobically treated brewery effluent using pilot scale horizontal subsurface flow constructed wetland system

The anaerobic process is considered to be a sustainable technology for the treatment of wastewaters rich in organic matter mainly due to its lower energy consumption and production of value-added products such as biogas and organic fertilizer. However, it cannot be seen as providing ‘complete’ environmental solution as its treated effluents would typically not meet the desired discharge limits in terms of residual carbon, nutrients and other pollutants. This has given impetus to subsequent post treatment in order to meet the environmental standards and protect the receiving water bodies and environment. The aim of this study was to evaluate the post-treatment potential of a pilot scale two-stage horizontal subsurface flow constructed wetland (HSSFCW) system planted with Cyperus alternifolius and Typha latifolia, respectively, for enhanced removal of residual carbon and nutrient from an up-flow anaerobic sludge blanket (UASB) reactor treated brewery effluent. A pilot scale two-stage HSSFCW was integrated with the UASB reactor, and its performance efficiency was assessed for the removal of total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), ammonium–nitrogen (NH4–N), total phosphorous (TP), and orthophosphate (PO43−). Macrophytes aboveground biomass and nutrient accumulation potential were also determined following standard methods. The results from this study showed that Cyperus alternifolius planted CW cell removed 68.5% TSS, 74.2% COD, 55.7% TN, 68.6% NH4–N, 41.1% TP and 48.1% PO43−. Moreover, further polishing with Typha latifolia planted CW cell enhanced the removal efficiencies to 89% TSS, 92% COD, 83.6% TN, 92.9% NH4–N, 74.4% TP, and 79.5% PO43−. Strong linearity and Pearson correlation was found between macrophyte biomass and nutrient accumulation in each CW cell (Cyperus alternifolius: R2 = 0.91, r = 0.97 for TN; R2 = 0.92, r = 0.96 for TP; and Typha latifolia: R2 = 0.96, r = 0.98 for TN and TP), and showed substantial nutrient reduction with cumulative nutrient accumulation of 1290 gTNm−2 and 708.7 gTPm−2 in the complete system. The performance of the pilot CW system as a tertiary treatment for brewery wastewater showed that the effluent meets the permissible discharge standards throughout the year excluding phosphorous.

The removal of arsenic and metals from highly acidic water in horizontal subsurface flow constructed wetlands with alternative supporting media

A laboratory-scale horizontal subsurface flow constructed wetland system was used to quantify the arsenic removal capacity in the treatment of highly acidic, arsenic and metal-rich water: pH ≈ 2, Fe ≈ 57 mg/L, Pb ≈ 0.9 mg/L, Zn ≈ 12 mg/L. The system was operated in two stages, being As ≈ 2.1 mg/L in stage one, and ≈ 3.7 mg/L in stage 2. Limestone and zeolite were employed as main supporting media to build non-vegetated and vegetated cells with Phragmites australis. The system was very effective in the removal of arsenic and iron (> 96%), and lead (> 94%) throughout the whole experimental period, having the four treatment types a similar performance. The main effect of the media type was on the pH adjustment capacity: limestone cells were able to raise the pH to ≈ 7.1, whereas zeolite cells raised it to ≈ 3.8. The contribution of plant uptake to the overall removal of As, Fe and Zn was minor; accounting for less than 0.02%, 0.07% and 0.7% respectively. As such, pollutants were mainly retained in the wetland beds. Our results suggest that limestone is recommended over zeolite as wetland medium mainly due to its neutralization capacity.

Effects of Irrigation with Different Sources of Water on Growth, Yield and Essential Oil Compounds in Oregano.

Aromatic plants can benefit from the use of treated wastewater to satisfy their water requirements, but the effects on the essential oil yield and quality need an assessment. The aims of this study were to assess the effects of freshwater and treated wastewater obtained from a Sicilian (Italy) pilot-scale horizontal subsurface flow constructed wetland system on plant growth and yield, essential oil yield and composition of oregano (Origanum vulgare ssp. hirtum (Link) Ietswaart) and soil characteristics. The system had a total surface area of 100 m2 and was planted with giant reed and umbrella sedge. An experimental open field of oregano was set up close to the system. Two years and two different sources of irrigation water were tested in a split-plot design for a two-factor experiment. Treated wastewater was characterized by higher values of mineral and organic constituents than freshwater. The results highlight that short-term irrigation with freshwater and treated wastewater, in both years, led to increased plant growth, dry weight and essential oil yield of oregano plants. However, it did not significantly affect the essential oil content and composition in comparison with the control. Furthermore, the year and source of irrigation water did not significantly vary the chemical composition of the soil. Our results suggest that treated wastewater can be considered an alternative to freshwater for the cultivation of oregano due to the fact that it does not greatly influence the yield quality and quantity of this species in the short-term.

Comparison of first-order kinetic models for sewage treatment in horizontal subsurface-flow constructed wetlands

ABSTRACT There are several techniques for sizing horizontal subsurface-flow constructed wetlands systems (CWs), and mathematical models have been frequently used for this purpose because they more accurately represent the liquid behaviour in these reactors. The P-k-C* model has already been used in the prediction of organic matter removal in CWs, but it has been little explored in the literature. On other hand, the model proposed by Chan and Chu [Modeling the reaction kinetics of Fenton’s process on the removal of atrazine. Chemosphere. 2003;51(4):305–311] was not known for prediction of organic matter removal in CW systems. In the present work, the kinetic data for chemical oxygen demand (COD) removal of 28 horizontal subsurface-flow constructed wetlands were used to compare the performance of two pseudo-first-order kinetic models (P-k-C* model and model from Chan and Chu. The comparisons of nonlinear regressions were performed considering Akaike information criterion (AIC), root-mean-square error (RMSE), and adjusted coefficient of determination (). In general, both models were able to provide good predictions of relative remaining concentration (C/C 0). However, the Chan and Chu model produced higher adjustment coefficients, showing the potential to be used in modelling and simulation of the degradation kinetics of organic matter in wetlands.

Vegetation contribution on phosphorus removal in constructed wetlands

Constructed wetlands have been proven as efficient natural-like technologies to treat different wastewater types. However, phosphorus (P) removal with these systems is still a challenge due to their low performance. This study aims to compare, in microcosm subsurface flow constructed wetland system, the PO4-P apparent balance of five macrophytes (Carex elata All., Juncus effusus L., Phalaris arundinacea L. var. picta, Phragmites australis (Cav.) Trin., and Typha latifolia L.) and an unvegetated control to evaluate plants' contribution in P removal. Compared with unvegetated systems, plant presence increased the PO4-P removal between 5.4% (P. arundinacea) and 9.4% (C. elata). Only T. latifolia was able to remove more than the PO4-P load (13.05 g m−2) whereas the removal reached 86.2%, 48.1%, 37.6% and 36.0% for P. aundinacea, C. elata, J. effusus and P. australis, respectively. Considering the total P load (51 g m−2), its removal from wastewater reached the highest value with T. latifolia (21.8% of inlet quantity) whereas the other species had an average removal value of 6.5%. The biennial study indicates: 1) T. latifolia as the best solution to remove PO4-P from the wastewater being able to remove more than PO4-P load (1.5 times); 2) P. aundinacea as other possible choice able to remove about 86% of PO4-P load.

STUDI STABILITAS SISTEM SUB SURFACE FLOW CONSTRUCTED WETLAND (SSF-CW) MENGGUNAKAN TANAMAN MELATI AIR DAN MEDIA TANAM ZEOLIT DALAM MENURUNKAN LOGAM Hg

Amalgamation to gold in artisanal small scale generally uses mercury (Hg) that decrease the quality of environment especially water. A study of mercury artisanal small scale gold mine waste water was conducted by utilizing simple technology using Sub Surface Flow - Constructed Wetland (SSF-CW) system. This system is a combination of phytoremediation methods using Echinodorus palaefolius plant with zeolite as growth media. The purpose of this study was to determine the stability of SSF-CW in reducing Hg concentration in water. This SSF-CW system model has dimensions of 820 mm x 320 mm x 585 mm consisting of 3 zones, namely the inlet zone, the reaction zone and the outlet zone. The study was conducted with an initial HgCl2 waste concentration of 14.94 mg / L which was carried out in two stages, continuous and batch for 12 hours and lasted for 3 days for each stage. Effluent samples were taken every 0 hours, 4 hours, 8 hours, and 12 hours for mercury concentration analysis using Direct Mercury Analyzer (DMA). The result showed that SSF-CW could support the process of reducing Hg concentration n wastewater with removal efficiency of 98.99%. Echinodorus had the ability to accumulate metals with a BCF value of 9,117. and the accumulation of Hg in the zeolite (as growth media) was still far from the saturated capacity to absorb mercury

Coliform removal in a constructed wetland system used in post-swine effluent treatment

This study evaluated the efficiency of a constructed wetland system (CWS) in removing total coliforms (TC) and thermotolerant coliforms (ThC) of swine wastewater, as a complementary treatment to an anaerobic system. At Stage 1, the experimental system was combined using a vertical flow constructed wetland system (VFCWS) cultivated with Tifton 85 grass in series with a horizontal subsurface flow constructed wetland system (HFCWS1) cultivated with Taboa. In HFCWS1, the hydraulic detention times (HDT) were 4.7, 3.1 and 2.3 days and the surface application rates (SAR) were 294, 319 and 397 kg ha-1 d-1 of COD, in Phases I, II and III, respectively. At Stage 2, the experimental system was combined using a horizontal subsurface flow constructed wetland system (HFCWS2) cultivated with Tifton 85 grass, HDT were 6.1, 2.0 and 0.5 days and the SAR were 850, 656 and 6.34 kg ha-1 d-1 of COD, in Phases I, II and III, respectively. In Stage 1, it was verified that the VFCWS was more efficient in coliform removal when compared to HFCWS1. When only HFCWS were compared, coliform removal in Stage 1 was between 1 and 2 log units in HFCWS1. In the stage 2, the HFCWS2 was more limited, with the highest removal efficiencies during Phase I of 1.6 and 0.8 log units for TC and ThC, respectively. In general, the association resulted in efficiencies that ranged from 96.4 to 99.0% for TC, 94.2 and 97.6% for ThC, equivalent to the average removal of 1.2 to 2 log units, considered satisfactory.

Treatment of landfill leachate with laboratory scale vertical flow constructed wetlands: plant growth modeling

The main purpose of this study was to investigate the removal of ammonia, orthophosphate, and COD present in landfill leachate using vertical subsurface flow constructed wetland systems (VFCW). The effect of different types of plants (Typha latifolia and Canna indica) in the removal of pollutants was also investigated. The systems were operated identically at a flow rate of 5 l/day and a hydraulic retention time (HRT) of 22 days in the T. latifolia reactor (R1), C. indica reactor (R2), and Control reactor (R3). Concentration-based average removal efficiencies for R1, R2, and R3 were NH4-N; 60.0%, 56.0%, and 46, COD; 81.0%, 84.0%, and 79.0%, PO4-P; 45.0%, 46.0%, and 32.0%, respectively. These results show that the model is a good predictive tool for determining the plant lengths using the growth equations. It is also revealed that the Logistic and Cubic models are suitable for the R1 and R2 reactors.