Effectiveness and Temporal Variation of a Full-Scale Horizontal Constructed Wetland in Reducing Nitrogen and Phosphorus from Domestic Wastewater (original) (raw)
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Water Air and Soil Pollution, 2011
A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH 4+) decreased from 4.6 to 1.7 mg L−1, nitrate (NO 3−) decreased from 6.8 to 5.3 mg L−1, total N (TN) decreased from 14.6 to 10.1 mg L−1, and total P (TP) decreased from 1.6 to 1.1 mg L−1. Average removal efficiencies (loading basis) for NO 3−, NH 4+, TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH 4+. Results from mesocosm experiments indicated that NH 4+ was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO 3− was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2–4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH 4+ and P can be maximized in the pond while NO 3− requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant.
Nitrogen removal in integrated constructed wetland treating domestic wastewater
Proceedings of 2nd Irish International Conference on Constructed Wetlands for Wastewater Treatment and Environmental Pollution Control, 2010
Abstract: The nitrogen (N) removal performance of a 3.25 ha Integrated Constructed Wetland (ICW) treating domestic wastewater from Glaslough village in County Monaghan, Ireland, is evaluated in this study. The ICW consists of two sludge ponds and five shallow vegetated wetland cells. Influent and effluent concentrations of two N species, namely, ammonia-nitrogen (NH3-N) and nitrate-nitrogen (NO3-N) measured weekly over two years, together with hydrology of the ICW provided the basis for this evaluation. The influent wastewater typically contained 34 mg/L NH3-N and 6 mg/L NO3-N. Effluent from the ICW typically contained < 1 mg-N/L for both species. Concentration removal efficiencies were high and consistently averaged 99 % for NH3-N and 94 % for NO3-N. Average areal N loading rate (245 mg m-2 d-1 NH3-N and 52 mg m-2 d-1 NO3-N) had a significant linear relationship with areal N removal rate (240 mg m-2 d-1 and 49 mg m-2 d-1, respectively) for both species. The areal first-order N removal rate constants in the ICW averaged 14 m/yr. for NH3-N and 11 m/yr. for NO3-N. Temperature coefficients (θ) for N reduction in the ICW were low, and suggested that the variability in N removal by the ICW was independent of temperature."
Environmental science and pollution research international, 2015
To investigate the long-term nitrogen treatment efficiency in vertical-flow (VF)-horizontal-flow (HF) hybrid constructed wetlands (CWs), the nitrogen removal efficiency under different seasons, N loads, and three operating stages (representing age of the wetland) were evaluated over a 12-year period. The average total nitrogen (TN) removal efficiencies in the effluent during the operation period were in the following order: summer (75.2 %) > spring (73.4 %) ≒ autumn (72.6 %) > winter (66.4 %). The removal efficiencies of TN in summer, autumn, and spring were generally higher than those in winter. At different stages of operation (years), the average TN removal rates in the effluent were in the following order: middle stage (73.4 %; years 2006-2009) > last stage (72.0 %; years 2010-2013) > beginning stage (70.1 %; years 2002-2005). In VF-HF CWs, the amount of average TN removal (mg N m(-2) day(-1)) over the 12-year period was in the order of summer (5.5) ≒ autumn (5.1) &g...
Seasonal Applicability of Three Plant Constructed Wetlands for Nutrient Removal in Pilot Scale
2016
The main objective of this study was to compare the removal efficiency of nutrients using Lactuca sativa, Medicago sativa and Phragmites australis in subsurface flow constructed wetlands with horizontal flow. In order to test water quality, fabricated reactors designed and the plants cultivated in the soil while their root were inside the wastewater. A long time study carried out from spring till end of autumn (9 months) in order to evaluate the difference in removal rate based on the seasonal changes. The highest removal rate was during summer which followed by spring and autumn. Thus, the effect of plants on the removal efficiency of organic matter (COD, BOD), TSS and nutrient (P and TN) appeared to be dependent on the seasonal growth. Phragmites australis the most sensitive species in order the removal of nutrient from wastewater.
Nutrient removal from aquaculture wastewater using a constructed wetlands system
Aquaculture, 2002
Nutrient removal is essential for aquaculture wastewater treatment to protect receiving waters from eutrophication and for potential reuse of the treated water. A pilot-scale wastewater treatment system consisting of a free water surface (FWS) and a subsurface flow (SSF) constructed wetlands arranged in series was operated for around 8 months. The study was conducted to examine system start-up phenomena and to evaluate system performance in removing inorganic nitrogen and phosphate from aquaculture wastewater under various hydraulic loading rates (1.8 to 13.5 cm day−1). The wetlands system showed rapid start-up behaviors in which process stabilities were achieved in the following sequence: phosphate removal in the SSF without an adaptation period, nitrogen removal in the SSF after 1 month, nitrogen removal in the FWS after 2 to 3 months, phosphate removal in the FWS after 3 months, and vegetation cover in both wetlands after 7 months of operation. Nitrogen removals were excellent, with efficiencies of 86% to 98% for ammonium nitrogen (NH4–N) and 95% to 98% for total inorganic nitrogen (TIN). Removal efficiencies were affected little by the hydraulic loading trials. Phosphate removal of 32% to 71% occurred, with the efficiencies being inversely related to hydraulic loading. The FWS wetland removed most inorganic nitrogen, whereas the SSF wetland removed phosphate at a rate equal to or even greater than the FWS. Removal of ammonium and nitrite (effluent concentrations <0.3 mg NH4–N l−1 and 0.01 mg NO2–N l−1) were sufficient for recycle in the aquaculture system without danger of harming the fish.
Temperature influence on nitrogen removal in a hybrid constructed wetland system in Northern Italy
The objective of this research was to investigate the efficiency and seasonal performance of a full-scale hybrid constructed wetland system (HCW) in reducing total nitrogen (TN), ammonia nitrogen (NH4-N) and nitrate nitrogen (NO3-N). HCW with a total area of about 130 m2 and hydraulic load of 2 m3/day was composed of three subsurface flow vertical systems (VF), working in parallel and one horizontal (HF) connected in series. The system was loaded daily with synthetic wastewater having an average concentration of TN of 250 mg/L (about 125 mg/L of NH4-N and 125 mg/L of NO3-N). Water samples were collected and analyzed from May to July 2011 and from January 2012 to July 2012. Variations were observed in nutrient removal performance related to temperature. During the whole monitoring period median reduction efficiency (RE) in the HCW was TN 95%, NH4-N 95% and NO3-N 93%, although three sub-periods characterized by different performances have been observed. During the first period (from May to July 2011) the RE was positive for the three nitrogen forms considered, whereas from January to the end of March 2012 the RE was lower, particularly for TN and NO3-N. From April 2012, when the temperature rose above 14.8 C, there was an increase in the performance that reached the 2011 values. Internal production of NO3-N was observed, mainly in the VF systems between January and March 2012. The median removals of mass pollutants per m2 of HCW per day were TN 3.1 g/m2/d, NH4-N 1.5 g/ m2/d, NO3-N 1.5 g/m2/d. Segmented regression analysis identified a breakpoint at 14.2 C for wastewater temperature that caused variations in TN and NO3-N concentration reduction performances. According to this approach the abatement was always positively correlated with temperature, but different regression slopes were obtained below and above the breakpoint. In particular, with lower temperature the abatement of NO3-N and TN increased by 1.7 and 2.0% per C of temperature increase; with temperature higher than 14.2 C the increase in abatement due to increased temperature was sharper, especially for NO3-N.
Water Science and Technology, 2014
Nitrogen (N) transformations and removal in integrated constructed wetlands (ICWs) are often high, but the contributions of various pathways, including nitrification/denitrification, assimilation by plants and sediment storage, remain unclear. This study quantified the contributions of different N removal pathways in a typical multi-celled ICW system treating domestic wastewater. Findings showed near complete average total N retention of circa 95% at 102.3 g m−2 yr−1 during the 4-year period of operation. Variations in total N and NH4–N removal rates were associated with effluent flow volume rates and seasons. According to the mass balance estimation, assimilation by plants and sediment/soil storage accounted for approximately 23% and 20%, respectively, of the total N load removal. These were the major N removal route besides microbial transformations. Thus, the combination of plants with high biomass production offer valuable opportunities for improving ICW performance. The retriev...