Operation of the vertical subsurface flow and partly submersed stormwater wetland with an intermittent recycle

Self Cite

A B S T R A C TThis study was done to investigate the performance of vertical subsurface flow (VSF) wetlands with additional carbon sources in reducing the nitrogen in stormwater from livestock lots. Three experimental lab-scale VSF wetlands packed with woodchips were constructed. The wetlands were operated with number of dry days (NDD) of 2, 4, and 8, respectively, for a duration of 136 d. The average removal efficiencies of total nitrogen (TN) were 26.2, 34.1, and 50.0% at NDD as 2, 4, and 8, respectively. The average nitrogen removal rate based on woodchips volume was 3.6 g N m −3 d −1 for NDD of 2, 2.1 g N m −3 d −1 for NDD of 4, and 1.7 g N m −3 d −1 for NDD of 8. Nitrification and denitrification were the major mechanisms of nitrogen reduction in the studied wetlands. The contribution of other pathways to nitrogen removal was small. The removal of total Kjeldahl nitrogen (TKN) and TN was not affected by the influent pH, whereas the removal of TKN was enhanced by the increase in influent alkalinity. Nitrification was promoted by the abundant oxygen supplied during the course of recirculation, whereas denitrification might be suppressed to some degree by the oxygen.

Section: Nitrogen Removalmentioning

confidence: 66%

Nitrogen reduction in stormwater from livestock lots by vertical subsurface flow wetlands packed with woodchips

Niu

Park

Kwon

et al. 2014

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“…However, due to poor adsorption substrates used, the proportion of TP removal via adsorption was low. A study on VF equipped with different substrates in the runoff treatment by Chen et al [43] demonstrated under the same condition, volcanics received just 13.3% TP removal, much lower than woodchip (38.8%), pot gravel (64.4%), and synthetic fiber (74.5%).…”

Section: The Overall Performance Of Wetlandsmentioning

confidence: 94%

Influence of intermittent aeration and organic loading rate on lab-scale constructed wetland systems treating synthetic wastewater

Shi²,

Ma³

2015

A B S T R A C TBy coupling the intermittent characteristics of rural sewage discharge and solar energy density, the performance responses of lab-scale tidal flow constructed wetland (TF) and conventional vertical flow constructed wetland (VF) to different organic loading rates (OLRs) (166.3, 300.9, 451.2, 602.4, and 751.2 g/m 2 d) in synthetic domestic sewage treatment were investigated to study its feasibility to replace conventional aeration and reduce the dependence of wastewater treatment plants on the grid in this study. Artificial aeration was conducted based on simulating photovoltaic aeration. The increase in OLR promoted the removal performances for the chemical oxygen demand (COD) and ammonia-nitrogen (NH þ 4 -N) in TF, which could be up to 95.7 and 97.2%, respectively, under OLR of 751.2 g/m 2 d. Excess organic carbons inhibited NH þ 4 -N removal through competition for oxygen available in VF, where the COD removal efficiency could be 89.6% while low NH þ 4 -N removal (40%) was obtained under OLR 751.2 g/m 2 d. With the increase in OLR, the removal of total nitrogen (TN) was enhanced. A higher OLR can not only provide enough electron donors but also produce more anoxic regions for denitrification. The best TN removal was 77.5% in TF and 49.8% in VF, which occurred at OLR of 751.2 and 602.4 g/m 2 d, respectively. A drop of TN removal in VF was attributed to the lack of nitrate-nitrogen (NO À 3 -N) when reaching OLR of 751.2 g/m 2 d. The removal efficiency for total phosphorus was increased gradually with the increase in OLR. This paper suggests that appropriate control of OLR can achieve the optimal effect of pollutants removal, especially the elimination of TN.

“…Usually, it is the most expensive component of the wetland and a proper filter media should not be considered only for the efficient removal of pollutants but also in terms of cost regarding construction and maintenance. Therefore, locally available resources have always been selected because they are economically viable and acceptable for use in the fields [9].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the different filter media in vertical flow stormwater wetland

Chen

Cheng

Niu

et al. 2013

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A B S T R A C TThe performance of four different types of filter media, namely woodchip, pot gravel, synthetic fiber, and volcanic stone employed as the main media in a set of column vertical flow stormwater wetlands were evaluated in this study. The evaluation parameters were treatment performance, adsorption capacity, porosity, filtration type, plant growth, substance release, cost, and construction. For pollutant removal, all the media showed efficient reduction of total suspended solids (more than 80%). Similarly, all were efficient in organics removal except for woodchip but it had the highest total nitrogen removal efficiency for 40%. total phosphorous removal was high in synthetic fiber and pot gravel (75 and 65%, respectively) but it was poor in volcanic stone. Pot gravel showed the highest adsorption capacity followed by volcanic stone but their disposal cost may be a burden. Although synthetic fiber has the highest porosity, it was thought to be capable of only surface filtration due to its small pore size while the others were expected to be capable of in-depth filtration. In terms of cost, woodchip was the cheapest followed by pot gravel and volcanic stone, while synthetic fiber was the most expensive. Finally, in terms of construction, all the media are advisable for use except for volcanic stone due to its high loading that can increase construction cost and due to difficult management during construction as well as replacement.