Constructed Wetland System Research Articles

Change in microbial profile and environmental conditions in a constructed wetland system treating greywater.

The objective of this work was to verify the relationships between environmental conditions and microbial processes along a raw-light greywater flow in an improved constructed wetland (CW) system. Physicochemical analysis and high-throughput DNA sequencing were performed in the different zones to investigate the environmental conditions and microbial communities. The results showed that the system operated predominantly under anaerobic conditions, with redox potential (Eh) increasing from the inlet (-342.9 mV) to the outlet (-316.4 mV). Conversely, the chemical oxygen demand (COD) decreased along the greywater flow, suggesting negative correlation between these characteristics. The zones of the evapotranspiration and treatment tank (CEvaT) were characterized by lower community diversity and richness and by the presence of specific groups: Proteobacteria and Synergistetes related to the first steps of the conversion of organic carbon, in the bottom layer inside the anaerobic chamber (AnC); methanogens (Methanosaeta and Methanobacterium) and sulphate-reducing bacteria (Desulfovibrio, Desulforhabdus and Desulfomonile) in the middle layer; and microorganisms associated with the nitrogen cycle and oxygen release (Acinetobacter, Novosphingobium, Candidatus Nitrososphaera) in the top layer. On the other hand, the increase of the ORP and decrease of organic matter concentrations were associated with higher community diversity and richness in the middle layer of the CW, which showed higher abundance of microorganisms involved in methane (Methylobacterium and Candidatus Koribacter) and sulphur (Rhodoblastus and Thiobacillus) oxidation.

Seasonal Removal Efficiency and Degradation Products of Two Typical PPCPs in Subsurface Flow Constructed Wetlands

The pollution of surface waters by pharmaceuticals and personal care products (PPCPs) has aroused widespread concern. Constructed wetlands (CWs) have outstanding advantages in the removal of PPCPs; however, few studies have focused on the interaction of different types of PPCPs in CWs. In this study, two typical PPCPs[broad-spectrum antimicrobial agents triclosan (TCS) and non-steroidal anti-inflammatory drug diclofenac (DCF)] were selected as target pollutants and their removal behavior in subsurface flow CWs was analyzed. The effects of different seasons and influent conditions (i.e., single and combined addition of TCS and DCF) on removal efficiency was also examined. The main parameters of the CW system were as follows:the up-flow subsurface CW had a hydraulic load of 0.20 m·d-1 and a hydraulic residence time of 3 d with a continuous flow inlet. The initial influent concentration of PPCPs was 80 g·L-1 for TCS and 25 g·L-1 for DCF. The results showed that the average removal efficiencies for TCS and DCF in summer (91.72% and 85.86%, respectively) were significantly higher than in winter (52.88% and 32.47%, respectively). Independent sample t-tests confirmed that there was no significant difference in the removal efficiency of TCS and DCF under the different influent conditions (single and combined addition). The degradation products of TCS and DCF were also no different between the influent systems, and the representative degradation products of TCS were not detected in all systems. The main degradation products of DCF in the different systems were 3,5-dichlorobenzoic acid and m-dichlorobenzene. The two studied PPCPs showed no significant antagonism and competition effects at trace levels.

Potensi Bakteri Pereduksi Sulfat dan Jenis Bahan Organik dalam Pengolahan Air Asam Tambang menggunakan System Constructed Wetland Tanaman akar Wangi (Vetiveria zizanioides L)

Acid mine drainage (AMD) is a waste product from coal mining process. Acidic waste will impose a serious environmental issue such as organism annihilation and destruction of environmental ecosystem. Proper AMD management is required in order to restore polluted water to the proper standard condition. The Constructed Wetland system with Akar Wangi (Vetiveria zizanioides L.) and various organic growth medium compositions and sulphate-reducing bacteria and the composition of the media for several types of organic matter with sulfate-reducing bacteria (SRB) inoculation as stimulant was deemed a promising solution. This study was designed in randomized block design (RBD) consisted of nine treatments with three replicates. The treatments were: (A) = without organic matter and without SRB inoculation (control), (B) = 100% compost, (C) = 100% sawdust, (D) = 50% compost + 50% sawdust, (E ) = no organic matter + SRB inoculation (105 MPN ml-1), (F) = 100% compost + SRB inoculation, (G) = 100% sawdust + SRB inoculation, H = 50% compost + 50% sawdust + SRB inoculation, I = 75% compost + 25% sawdust + SRB inoculation. Results showed that 100% compost and SRB application increased polluted water pH. Application of 100% sawdust with or without SRB inoculation gave the highest reduction in sulfate content. SRB also has the potential to increase the height of Akar Wangi plant.

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.

Promotion of full-scale constructed wetlands in the wine sector: Comparison of greenhouse gas emissions with activated sludge systems

The aim of this study was to quantify and compare greenhouse gas (GHG) (i.e. carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4)) emissions from two full-scale winery wastewater and sludge treatment systems (i.e. constructed wetlands (CWs) and activated sludge system) located in Galicia (Spain). GHG fluxes were measured using the static chamber method in combination with an on-site Fourier transform infrared spectroscopy (FTIR) gas analyser in the CWs system. These on-site innovative techniques proved to be very accurate and reliable. In the activated sludge treatment systems, the floating chamber method in combination with the FTIR gas analyser was used. Measurements were carried out during the vintage season, when winery wastewater has the highest flow and loads, and the rest of the year. Emission rates of CO2, N2O and CH4 in the CWs units (i.e. vertical flow, horizontal subsurface flow and sludge treatment wetlands) ranged from 1.35E+02 to 7.54E+04, 1.70E-01 to 3.09E+01 and − 3.05E+01 to 1.79E+03 mg m−2 day−1, respectively. In the case of the activated sludge units (i.e. reactor, secondary settler and sludge storage tank) emission rates of CO2, N2O and CH4 ranged from 1.56E+04 to 1.43E+05, 1.13E+01 to 4.75E+01 and 2.52E+01 to 1.01E+03 mg m−2 day−1, respectively. Seasonally, daily and instantaneous variability in emissions as well as spatial variability was found. Comparing CWs with the activated sludge system, surface emission rates were lower in the CWs system in both seasons considered. Results highlighted that CWs are suitable technologies that can help to reduce GHG emissions associated with winery wastewater treatment.

Effect of filter media and hydraulic retention time on the performance of vertical constructed wetland system treating dairy farm wastewater

This study deals with the dairy wastewater treatment using laboratory scale vertical flow (VF) constructed wetlands with the <i>Canna indica</i> plantation over wetland beds due to phytoremediation capabilities. Three laboratory scale VF CWs (CW-A, CW-B and CW-C) each with an area of 0.135 m2 filled with gravel (CW-A: 20 mm; CW-B:10 mm gravel) and sand (CW-C) receiving 0.04 m3 d-1 dairy wastewater were operated for the wastewater purification. Each unit was operated at three hydraulic retention times (HRTs) i.e. 12 h, 24 h and 48 h for assessing its effect on wastewater purification . Among all units, removal rates fluctuated as: total suspended solids (TSS): 64.2–74.5%; biochemical oxygen demand (BOD): 45.3 – 63.1%; ammonium nitrogen (NH4–N): 29.6 – 56.5% and phosphate phosphorous (PO4–P): 20.5 – 57.8% at different HRTs. Increase in HRT showed better removal of pollutants in all CWs. Moreover, maximum removal of pollutants excluding TSS and NH4-N was achieved in CW-B at 48 h HRT. CW-B with similar HRT provided maximum removal of PO4-P (57.8%), BOD (63.1%) and chemical oxygen demand (COD): 67.4%. Increase in the size of filter media, from sand (0.25 mm) to 20 mm gravel resulted in higher removal of NH4 -N from wastewater.

Constructed wetlands operated as bioelectrochemical systems for the removal of organic micropollutants

The removal of organic micropollutants (OMPs) has been investigated in constructed wetlands (CWs) operated as bioelectrochemical systems (BES). The operation of CWs as BES (CW-BES), either in the form of microbial fuel cells (MFC) or microbial electrolysis cells (MEC), has only been investigated in recent years. The presented experiment used CW meso-scale systems applying a realistic horizontal flow regime and continuous feeding of real urban wastewater spiked with four OMPs (pharmaceuticals), namely carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBU) and naproxen (NPX). The study evaluated the removal efficiency of conventional CW systems (CW-control) as well as CW systems operated as closed-circuit MFCs (CW-MFCs) and MECs (CW-MECs). Although a few positive trends were identified for the CW-BES compared to the CW-control (higher average CBZ, DCF and NPX removal by 10–17% in CW-MEC and 5% in CW-MFC), these proved to be not statistically significantly different. Mesoscale experiments with real wastewater could thus not confirm earlier positive effects of CW-BES found under strictly controlled laboratory conditions with synthetic wastewaters.

Constructed wetlands for polishing oil and gas produced water releases.

Produced water (PW) is the largest waste stream associated with oil and gas (O&G) operations and contains petroleum hydrocarbons, heavy metals, salts, naturally occurring radioactive materials and any remaining chemical additives. In some areas in Wyoming, constructed wetlands (CWs) are used to polish PW downstream of National Pollutant Discharge Elimination System (NPDES) PW release points. In recent years, there has been increased interest in finding lower cost options, such as CWs, for PW treatment. The goal of this study was to understand the efficacy of removal and environmental fate of O&G organic chemical additives in CW systems used to treat PW released for agricultural beneficial reuse. To achieve this goal, we analyzed water and sediment samples for organic O&G chemical additives and conducted 16S rRNA gene sequencing for microbial community characterization on three such systems in Wyoming, USA. Three surfactants (polyethylene glycols, polypropylene glycols, and nonylphenol ethoxylates) and one biocide (alkyldimethylammonium chloride) were detected in all three PW discharges and >94% removal of all species from PW was achieved after treatment in two CWs in series. These O&G extraction additives were detected in all sediment samples collected downstream of PW discharges. Chemical and microbial analyses indicated that sorption and biodegradation were the main attenuation mechanisms for these species. Additionally, all three discharges showed a trend of increasingly diverse, but similar, microbial communities with greater distance from NPDES PW discharge points. Results of this study can be used to inform design and management of constructed wetlands for produced water treatment.

Treatment of wastewater with modified constructed wetland system as a tertiary treatment unit

Incorporation of constructed wetlands into the sewage treatment process is done in order to mimic processes found in the natural ecosystems where wetland plants and their associated microorganisms remove pollutants from wastewater. Vegetation in a wetland provides a substrate upon which microorganisms can grow, and break down organic materials. These organisms and natural chemical processes are responsible for approximately 90% of pollutant removal and waste breakdown in nature. This research work has been undertaken with a view to integrating the natural ecosystem into the existing treatment plant on a large scale, which will be instrumental in minimising the use of machineries and reducing high investment and operating cost as well as energy consumption. The greywater can be reused for purification but the currently adopted process to obtain a secondary water source is complicated and expensive. The conventional process constructed wetlands can be used as a tertiary treatment unit of sewage treatment process.

Effect of constructed wetland system on aquaculture wastewater by ecological treatment

In this study, an integrated ecological system was constructed to treat small scattered aquaculture wastewater in southern rural areas of China. The water outlet of 4 level wetlands was continuously monitored from July to December in 2017. Results showed the average concentrations of total nitrogen (TN), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3-N), total phosphorus (TP) and chemical oxygen demand (COD) were 43.64mg/L, 17.53mg/L, 1.71mg/L, 1.66mg/L and 51.39mg/L in the average effluent concentration of grade I wetland, respectively, and 8.35mg/L, 4.42mg/L, 0.24mg/L, 0.26mg/L, 21.32mg/L in the average effluent concentration of grade IV wetland, respectively. The removal rates were 81%, 75%, 86%, 85% and 59% for TN, NH4+-N, NO3-N, TP and COD in the integrated ecological system, respectively. The effluents from the integrated ecological system met the requirements of “Discharge Standard of Pollutants for Livestock and Poultry Breeding” (GB 18596-2001) and achieved “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant” (GB 18918-2002) the center two levels to discharge the standard. Obviously, the integrated ecological system could work efficiently in treating the rural scattered aquaculture wastewater, and also possess merits of low construction and operation costs and simple management method, which will be benefited to its application in the southern rural regions of China.

Treatment of wastewater with modified constructed wetland system as a tertiary treatment unit

Treatment of wastewater with modified constructed wetland system as a tertiary treatment unit

Acclimation performance of constructed wetland coupled with microbial fuel cell for ammonia treatment of wastewaters at high loading rate

Global challenges on water and energy crisis have pressurized on water treatment industry to put into practice advanced technologies for ensuring a suitable supply of either water or energy services. Compared with other biological treatment technologies, constructed wetland (CW) is widely considered as an efficient eco-technology for wastewater treatment with the advantages of low cost, simple operation and maintenance. Microbial fuel cell (MFC) technology is the recently emerging approach in environmental engineering. The integration of MFCs within vertical up-flow CW systems (VSF-CW) as a sustainable technology, therefore, could provide dual benefits in nitrogen removal of wastewaters and energy recovery simultaneously. This study has preliminarily evaluated the acclimation performance of VSF-CW-MFC systems at the high loading rate (4.2 mg COD/h.L; COD:N = 10:1) of domestic wastewaters containing ammonia. Results demonstrated the potential of VSF-CW-MFC systems in achieving electricity generation and ammonia removal of domestic wastewaters at the high loading rate. The plant presence and influent pH of 7.0 could improve the performance efficiency. Average removal efficiencies of NH4+ and COD in planted microcosms with the influent pH of 7.0 were 43.4% and 79%, respectively.

KINETICS OF PHOSPHATE REMOVAL FROM DOMESTIC WASTEWATER BY CONSTRUCTED WETLAND WITH JOYWEED (Alternanthera sp.)

This study aims to determine the dynamics of phosphate removal process in domestic wastewater through wastewater treatment mechanism of constructed wetland with Joyweed (Alternanthera sp.). The experiment was conducted in batches with a retention time of 12 days, the treatments were designed to evaluate the effect of depth of the water with and without Alternanthera sp. on the ability to remove phosphate in wastewater. After 12 days of operation, all experiments reduced phosphate concentration in the effluent. The highest phosphate removal efficiency is at day 9 (about 69\%). Two kinetic equations of first-order and second-order are used to determine the trend of PO43- removal process in the system. The second-order kinetic equation is more suitable for treating PO43- in domestic wastewater by surface flow constructed wetland system. The results of this study show the potential of domestic wastewater treatment of Alternanthera sp. in the constructed wetland.

Correction to: Treatment of tannery wastewater in a pilot scale hybrid constructed wetland system in Arequipa, Peru

In the list of author surnames, an author name was incorrectly stated in the original print and online files. The correct list of author names for this article should appear as:

Removal efficiency of fecal coliform at different type of constructed wetland systems namely VSSF, HSSF and SF

The study was conducted during 2015 to evaluate removing effciency of feacal coliform form wastewater by three type of constructed wetland systems. These systems nemaly Vertical subsurface flow (VSSF), Horizontal subsarface flow (HSSF) and surface flow (SF). The total mean removal efficiency of fecal coliform after five days of treatment reached 68.43% and for each system was 70.26%, 68.19% and 66.69% for HSSF, VSSF and SF respectively.Also, the rsults recorded remving effciency of 55.93% when the loding rate was 25 % and it reached about 63.65% when the loading rate was 50%. The total mean of removal efficiency of fecal coliform achieved in April was 56.22% while the total mean removal efficiency was 62.01% in May for the same systems. The statical analysis showed a siginficant deffriences of fecal coliform removing among resident time and system type, while, there was no significant deffriences among loading rate percenatge. Keywords: Constructed wetland, Fecal Coliform, Horizontal subsarface flow system, Vertical subsarface flow, Surface flow.

Performance of three type of constructed wetland systems for treating municipal waste water

Performance of three type of constructed wetland systems for treating municipal waste water

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.

Evaluation of the functionality of a constructed wetland system under semidesert and saline conditions

Objective: Evaluate the functionality of a constructed wetland used to treat the wastewater from a school by recording water inflow and outflow, in addition to the local conditions that affect its operation and compliance with environmentalregulations.Design/methodology/approach: Verification of the installation specifications; programmed measurements of the inflowoutflowwater balance and ambient temperature; and analysis of the salinity effect and wetland performance.Results: The high evapotranspiration at the site contributed to the decrease in the resident volume of water within the wetland, causing water stress to the vegetation, not complying with the regulation about the reduction/elimination of water pollutants.Study limitations/implications: The high daytime temperature significantly decreased the daily inflow volume of wastewater, even after adding the precipitation water, which affects the biological activity of the vegetation; therefore, the study was performed on half of the wetland surface. Thus, the wetland was unable to reduce the pollutants to safe levels.Findings/conclusions: The amount of recovered treated water is minimal. The inflow is five times lower than the designed flow of the construction. The weekly log was appropriate to observe fluctuations in the water balance and its effect on the vegetation within the wetland.

Technological Reliability and Efficiency of Wastewater Treatment in Two Hybrid Constructed Wetlands in the Roztocze National Park (Poland)

The paper presents the results of a 3-year study on the technological reliability and the efficiency of typical domestic wastewater treatment in two hybrid constructed wetland systems (CWs) located in the area of the Roztocze National Park (Poland). The studied objects consist of an initial settling tank and a system of two beds of the vertical flow (VF) and horizontal flow (HF) (VF–HF) type with reed and willow. The wastewater flow rate in the constructed wetlands systems (CWs) was 0.4 and 1.0 m3/d, respectively. During the study period (2017–2019) 20 series of analyses were performed and 60 wastewater samples were collected. Based on the obtained results the effects of pollutant removal and the technological reliability were determined, which were specified with the Weibull method. The average efficiency of biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) removal was 96–99%. Slightly lower effects were obtained in the case of total phosphorus (TP) removal (90–94%), as well as for total suspended solids (TSS) (80–87%) and total nitrogen (TN) (73–86%) removal. The analysed CWs were characterised by 100% technological reliability for BOD5 and COD, as well as a good reliability for TSS and TP (87–100%) but slightly lower for TN removal (35–89%). Hybrid CWs of VF–HF type should be recommended to use in protected areas for wastewater treatment and water resources quality protection.

Removal of pollutants from abattoir wastewater using a pilot-scale bamboo constructed wetland system

Wastewater from abattoir sources in urban areas can adversely affect the environment and cause health problems. This research investigated the ability of a bamboo constructed wetland system (BCWS) using Bambusa vulgaris, to treat wastewater from abattoir by removing nutrients and organics. This study adopted pilot scale reactors with bed dimension of 1 m length x 1 m width x 1 m depth to simulate a horizontal sub-surface flow constructed wetland and planted with six strands of bamboo plants. Parameters analyzed include the nutrients (in the form of phosphate and nitrate) and the organics (in the form of Chemical oxygen demand, COD and Biochemical oxygen demand, BOD). The effluent analysis that were carried out within a 28-day retention period showed that there was a very good decrease in the nutrient pollutant parameters; phosphate (99.6 %), nitrate (98.5 %). The organics showed a lesser performance with a 39.3 % removal efficiency for COD and 49.9 % removal efficiency for BOD. Bamboo can be used in a BCWS for low cost green technology in urban areas and can be improved upon by increasing the number of bamboo shoot in order to have a larger root system.