French vertical-flow constructed wetland design: adaptations for tropical climates

2015 ◽  
Vol 71 (10) ◽  
pp. 1516-1523 ◽  
Author(s):  
P. Molle ◽  
R. Lombard Latune ◽  
C. Riegel ◽  
G. Lacombe ◽  
D. Esser ◽  
...  
Keyword(s):  
Constructed Wetland ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Tropical Climate ◽  
Design Guidelines ◽  
Local Context ◽  
Vertical Flow ◽  
National Quality ◽  
Vertical Flow Constructed Wetland ◽  
Different Seasons

The French Outermost Regions are under tropical climate yet still have to comply with both French and EU regulations. French vertical-flow constructed wetland systems appear well adapted to the technical specifics of these regions but their adaptation to tropical climate requires new design guidelines to be defined (area needed, number of filters, type of plants, material to be used, etc.). A study was started in 2008, with backing from the national water authorities, to implement full-scale experimental sites and assess the impacts of local context on design and performances. This paper reports the monitoring results on three vertical-flow constructed wetlands fed directly with raw wastewater (known as the ‘French system’) in Mayotte and French Guiana. The plants, now in operation for between 1 and 6 years, range from 160 to 480 population equivalent (p.e.). Monitoring consisted of 28 daily composite flow samples in different seasons (dry season, rainy season) at the inlet and outlet of each filter. Performances are benchmarked against French mainland area standards from Irstea's database. Results show that performances are improved by warmer temperature for chemical oxygen demand (COD), suspended solids (SS) and total Kjeldahl nitrogen (TKN) and satisfy national quality objectives with a single stage of filters. Treatment plant footprint can thus be reduced as only two parallel filters are needed. Indeed, warm temperatures allow faster mineralization of the sludge deposit, making it possible to operate at similar rest and feeding period durations. Systems operated using one twin-filter stage can achieve over 90% COD, SS and TKN removal for a total surface of 0.8 m²/p.e.

scholarly journals Pilot-scale study of vertical flow constructed wetland combined with trickling filter and ferric chloride coagulation: influence of irregular operational conditions

2015 ◽  
Vol 71 (7) ◽  
pp. 1088-1096 ◽  
Author(s):  
B. Kim ◽  
M. Gautier ◽  
G. Olvera Palma ◽  
P. Molle ◽  
P. Michel ◽  
...  
Keyword(s):  
Constructed Wetland ◽  
Phosphorus Removal ◽  
Water Saturation ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Saturation Level ◽  
Vertical Flow ◽  
Trickling Filter ◽  
Operational Conditions ◽  
Vertical Flow Constructed Wetland

The aim of this study was to characterize the efficiency of an intensified process of vertical flow constructed wetland having the following particularities: (i) biological pretreatment by trickling filter, (ii) FeCl3 injection for dissolved phosphorus removal and (iii) succession of different levels of redox conditions along the process line. A pilot-scale set-up designed to simulate a real-scale plant was constructed and operated using real wastewater. The influences of FeCl3 injection and water saturation level within the vertical flow constructed wetland stage on treatment performances were studied. Three different water saturation levels were compared by monitoring: suspended solids (SS), total phosphorus (TP), dissolved chemical oxygen demand (COD), ammonium, nitrate, phosphate, iron, and manganese. The results confirmed the good overall efficiency of the process and the contribution of the trickling filter pretreatment to COD removal and nitrification. The effects of water saturation level and FeCl3 injection on phosphorus removal were evaluated by analysis of the correlations between the variables. Under unsaturated conditions, good nitrification and no denitrification were observed. Under partly saturated conditions, both nitrification and denitrification were obtained, along with a good retention of SSs. Finally, under saturated conditions, the performance was decreased for almost all parameters.

Effects of a saturated layer and recirculation on nitrogen treatment performances of a single stage Vertical Flow Constructed Wetland (VFCW)

2013 ◽  
Vol 68 (7) ◽  
pp. 1461-1467 ◽  
Author(s):  
S. Prigent ◽  
J. Paing ◽  
Y. Andres ◽  
F. Chazarenc
Keyword(s):  
Constructed Wetland ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Single Stage ◽  
Vertical Flow ◽  
Saturated Layer ◽  
Vertical Flow Constructed Wetland ◽  
Hydraulic Load ◽  
Nitrogen Concentrations ◽  
Kjeldahl Nitrogen

Upgrades to enhance nitrogen removal were tested in a 2 year old pilot vertical flow constructed wetland in spring and summer periods. The effects of a saturated layer and of recirculation were tested in particular. Two pilots (L = 2 m, W = 1.25 m, H = 1.2 m), filled with expanded schist (Mayennite®), were designed with hydraulic saturated layers of 20 and 40 cm at the bottom. Each pilot was fed with raw domestic wastewater under field conditions according to a hydraulic load of 15–38 cm d−1 (i.e. 158–401 g COD (chemical oxygen demand) m−2 d−1) and to recirculation rates ranging from 0% up to 150%. The initial load during the first 2 years of operation resulted in an incomplete mineralized accumulated sludge leading to total suspended solids (TSS), COD and biochemical oxygen demand (BOD5) release. A 40 cm hydraulic saturated layer enabled an increase of 5–10% total nitrogen (TN) removal compared to a 20 cm saturated layer. Recirculation allowed the dilution of raw wastewater and enhanced nitrification in a single stage. A design of 1.8 m² pe−1 (48 cm d−1, 191 g COD m−2 d−1) with a 40 cm saturated layer and 100% recirculation enabled the French standard D4 (35 mg TSS L−1, 125 mg COD L−1, 25 mg BOD5 L−1), nitrogen concentrations below 20 mg TKN (total Kjeldahl nitrogen) L−1 and 50 mg TN L−1, to be met.

Experiences from the full-scale implementation of a new two-stage vertical flow constructed wetland design

2013 ◽  
Vol 69 (2) ◽  
pp. 335-342 ◽  
Author(s):  
Guenter Langergraber ◽  
Alexander Pressl ◽  
Raimund Haberl
Keyword(s):  
Constructed Wetland ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Full Scale ◽  
Vertical Flow ◽  
Effluent Water ◽  
Two Stage ◽  
Vertical Flow Constructed Wetland ◽  
Hydraulic Load ◽  
Public Holidays

This paper describes the results of the first full-scale implementation of a two-stage vertical flow constructed wetland (CW) system developed to increase nitrogen removal. The full-scale system was constructed for the Bärenkogelhaus, which is located in Styria at the top of a mountain, 1,168 m above sea level. The Bärenkogelhaus has a restaurant with 70 seats, 16 rooms for overnight guests and is a popular site for day visits, especially during weekends and public holidays. The CW treatment system was designed for a hydraulic load of 2,500 L.d−1 with a specific surface area requirement of 2.7 m2 per person equivalent (PE). It was built in fall 2009 and started operation in April 2010 when the restaurant was re-opened. Samples were taken between July 2010 and June 2013 and were analysed in the laboratory of the Institute of Sanitary Engineering at BOKU University using standard methods. During 2010 the restaurant at Bärenkogelhaus was open 5 days a week whereas from 2011 the Bärenkogelhaus was open only on demand for events. This resulted in decreased organic loads of the system in the later period. In general, the measured effluent concentrations were low and the removal efficiencies high. During the whole period the ammonia nitrogen effluent concentration was below 1 mg/L even at effluent water temperatures below 3 °C. Investigations during high-load periods, i.e. events like weddings and festivals at weekends, with more than 100 visitors, showed a very robust treatment performance of the two-stage CW system. Effluent concentrations of chemical oxygen demand and NH4-N were not affected by these events with high hydraulic loads.

scholarly journals Phytoremediation of Heavy Metals From Mixed Domestic Sewage Through Vertical- Flow Constructed Wetland Planted with Canna Indica and Acorus Calamus

2020 ◽  
Vol 15 (3) ◽  
pp. 430-440
Author(s):  
Mahesh Prasad Barya ◽  
Deepak Gupta ◽  
Reetika Shukla ◽  
Tarun Kumar Thakur ◽  
Virendra Kumar Mishra
Keyword(s):  
Heavy Metals ◽  
Constructed Wetland ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Acorus Calamus ◽  
Vertical Flow ◽  
Canna Indica ◽  
Treated Sewage ◽  
Wide Range ◽  
Vertical Flow Constructed Wetland

The removal of contaminants from sewage wastewater through constructed wetlands is becoming increasingly popular worldwide. Constructed wetland (CW) is a man-made structure for wastewater treatment that uses natural processes associated with wetland vegetation, soils, and their associated microbial combinations. This study investigated the performance of experimental vertical flow constructed wetland (VFCW) cells to remove heavy metals (HMs) from primary treated sewage. The primary treated sewage was collected from the sewage treatment plant (STP) in the campus of Indira Gandhi National Tribal University, Amarkantak, India. Sewage wastewater samples were collected from all cells of the experimental VFCW and analyzed for four heavy metals (Zn, Fe, Cu, and Cr). The plant species results show that the removal efficiency of the Canna indica L. for Zn, Fe, Cu, and Cr was 95%, 92%, 96%, and 93 % and Acorus calamus L.were 89 %, 80 %, 91 %, and 47 % respectively. These macrophytes with the substrate (gravel and sand) have presented a wide range of tolerance to all the selected metals and therefore can be used for field-scale constructed wetland removal of heavy metals from sewage wastewater.

Treatment of domestic wastewater by vertical flow constructed wetland planted with umbrella sedge and Vetiver grass

2013 ◽  
Vol 68 (6) ◽  
pp. 1345-1351 ◽  
Author(s):  
Suwasa Kantawanichkul ◽  
Somsiri Sattayapanich ◽  
Frank van Dien
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetland ◽  
Plant Biomass ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Nitrogen Accumulation ◽  
Vertical Flow ◽  
Vetiver Grass ◽  
Vetiveria Zizanioides ◽  
Vertical Flow Constructed Wetland

The aim of this study was to investigate the efficiency of wastewater treatment by vertical flow constructed wetland systems under different hydraulic loading rates (HLR). The comparison of two types of plants, Cyperus alternifolius (Umbrella sedge) and Vetiveria zizanioides (Vetiver grass), was also conducted. In this study, six circular concrete tanks (diameter 0.8 m) were filled with fine sand and gravel to the depth of 1.23 m. Three tanks were planted with Umbrella sedge and the other three tanks were planted with Vetiver grass. Settled domestic wastewater from Chiang Mai University (chemical oxygen demand (COD), NH4+-N and suspended solids (SS) of 127.1, 27.4 and 29.5 mg/L on average, respectively) was intermittently applied for 45 min and rested for 3 h 15 min. The HLR of each tank was controlled at 20, 29 and 40 cm/d. It was found that the removal efficiency of the Umbrella sedge systems was higher than the Vetiver grass systems for every parameter, and the lowest HLR provided the maximum treatment efficiency. The removal efficiency of COD and nitrogen in terms of total Kjeldahl nitrogen (TKN) was 76 and 65% at 20 cm/d HLR for Umbrella sedge compared to only 67 and 56% for Vetiver grass. Nitrogen accumulation in plant biomass was also higher in Umbrella sedge than in Vetiver grass in every HLR. Umbrella sedge was thus proved to be a suitable constructed wetland plant in tropical climates.

scholarly journals Unsteady state series CSTR modeling of removal of ammonia nitrogen from domestic wastewater treated in a vertical flow constructed wetland

2020 ◽  
Vol 10 (1) ◽  
pp. 868
Author(s):  
Alejandro Rincón ◽  
Gloria Yaneth Florez ◽  
Fredy E. Hoyos Velasco
Keyword(s):  
Constructed Wetland ◽  
Reaction Rate ◽  
Treatment Plant ◽  
Domestic Wastewater ◽  
Rate Coefficients ◽  
Water Volume ◽  
Model Parameters ◽  
Vertical Flow ◽  
Unsteady State ◽  
Vertical Flow Constructed Wetland

This work shows simulation results for subsurface vertical flow constructed wetland (VFCW) using a series CSTR model. The VFCW considered received the outflow from a domestic wastewater treatment plant. In addition, it was planted with Cyperus sp. and filter media was unsaturated. The model was based on an unsteady state mass balance for ammonia, nitrites, and nitrates, using one to three series CSTRs. Nitrogen transformation mechanisms considered were ammonification, nitrification, plant uptake and denitrification. The following effects were evaluated: the number of reacting CSTRs from one to three; the occurrence of the reaction in second and third CSTRs for the case that three CSTRs hold; the use of either equal or different values of reaction rate parameters between CSTRs; and the discretization of the reaction rate parameters. The inflow and outflow measurements of ammonium, nitrites, and nitrates were used for model calibration. The estimated parameters included the reaction rate coefficients and reactor water volume. The coefficient of determination (R2) evidenced a satisfactory capability of simulating outlet pollutant concentrations. Two and three reacting CSTRs achieved similar R2 value (0.54-0.55), whereas one reacting CSTR achieved an R2 of 0.39, and three CSTRs with reaction only in the first tank achieved an R2 of 0.42. Discretization of the nitrification rate for the case of two reacting CSTRs led to an R2 of 0.94. The parameter sensitivity analysis revealed a significant effect of model parameters on the R2 value.

First stage of the French vertical flow constructed wetland system: experiments with the reduction of surface area and number of units

2014 ◽  
Vol 5 (1) ◽  
pp. 50-55 ◽  
Author(s):  
E. S. Manjate ◽  
L. C. O. Lana ◽  
D. C. Moraes ◽  
G. R. Vasconcellos ◽  
G. R. M. Maciel ◽  
...  
Keyword(s):  
Constructed Wetland ◽  
Oxygen Demand ◽  
Feeding Strategies ◽  
Attractive Alternative ◽  
Second Phase ◽  
Vertical Flow ◽  
Full System ◽  
Mean Values ◽  
Vertical Flow Constructed Wetland ◽  
Removal Efficiencies

Small vertical-flow constructed wetland units comprising the first stage of the French system were studied in Brazil for the treatment of raw sewage. Planted and unplanted units and different feeding strategies were tested. In the first phase, hourly batches of a daily flow of 13 m3 d−1 were applied over three alternating units, resulting in an average hydraulic loading rate (HLR) on the full system of 0.15 m3 m−2 d−1. A second phase, aimed at reducing land requirements, kept the same daily flow and batch frequency, but used two alternating units, resulting in a HLR on the full system of 0.22 m3 m−2 d−1. Removal efficiencies were very good when the system operated with three units, with mean values of 82% for biochemical oxygen demand (BOD), 81% for chemical oxygen demand (COD), 85% for total suspended solids (TSS) and 59% for NH4+-N. With two units, the equivalent values were 74% for BOD, 59% for COD, 67% for TSS and 51% for NH4+-N. There were significant differences in the median removal efficiencies of COD and TSS. No significant differences were found between planted and unplanted units for most constituents. In both phases, the overall good performance and the simplicity of the system make this treatment process a very attractive alternative for developing countries.

Water Budget of Constructed Wetland System with Subsurface Vertical Flow in Sub-Humid Tropical Climate

2015 ◽  
Vol 1 (5) ◽  
pp. 235-242
Author(s):  
Édio Damásio da Silva Júnior ◽  
Rogério de Araújo Almeida ◽  
Elisa Rodrigues Siqueira ◽  
Ábio Roduvalho da Silva
Keyword(s):  
Constructed Wetland ◽  
Water Budget ◽  
Tropical Climate ◽  
Vertical Flow ◽  
Humid Tropical Climate ◽  
Wetland System
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