Clogging pattern in vertical-flow constructed wetlands: Insight from a laboratory study

Ge, Hua; Zhu, Wei; Zhao, Lei; Huang, Juan

doi:10.1016/j.jhazmat.2010.04.088

Cited by 73 publications

(22 citation statements)

References 23 publications

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“…Significant amounts of TS and chemical oxygen demand (COD) are retained in the wetland bed (at least 80% in most studies [9,11,13,[15][16][17]) via physical filtration. However, the excessive accumulation of sludge deposit deteriorates the infiltration capacity of the wetland bed and extends the ponding period during operation, which eventually leads to the system failure, known as substrate clogging [18]. Furthermore, the removal of nitrogen compounds is less effective [13,15].…”

Section: Introductionmentioning

confidence: 99%

Dewatering and Treatment of Septage Using Vertical Flow Constructed Wetlands

Tan

Tang

et al. 2017

Technologies

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Abstract:The vertical flow constructed wetland (VFCW) has become an attractive decentralised technology for septage treatment. One of the main purposes of the septage treatment is to reduce the volume of raw septage through dewatering, where the solids content is retained in the wetland bed and the water content is released. The retention of solids forms a layer of sludge deposit at the wetland surface, and the drained water, the so-called leachate, typically contains a lower solids content. This article reports the performance of dewatering and filtration of a pilot-scale VFCW designed for septage treatment. A comparison between two feeding strategies, hydraulic loading rate (HLR) and solids loading rate (SLR), is presented. The dewatering efficiency through drainage was found to be dependent on the solids load. The removal of total solids (TS) and chemical oxygen demand (COD) were excellent as the quality of leachate showed that more than 90% of TS and COD were retained in the system. This study reveals that the feeding based on SLR delivered a more sustainable performance for dewatering and solids removal. The build-up of sludge deposit significantly deteriorated the dewatering efficiency through drainage, but it tended to improve the filtration capacity.

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Section: Introductionmentioning

confidence: 99%

Dewatering and Treatment of Septage Using Vertical Flow Constructed Wetlands

Tan

Tang

et al. 2017

Technologies

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“…Filter media clogging caused by particulate solid accumulation and biofilm growth is the operational problem that CWs often encounter (Hua et al 2010;Zhao et al 2009). Therefore, in order to avoid an anticipated clogging of constructed wetlands, it is recommended that the sewage should be pretreated by physicochemical methods prior to discharge into the vertical flow wetlands (Joan et al 2007;Prochaska et al 2007).…”

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confidence: 99%

Study of a Novel Vertical Flow Constructed Wetland System with Drop Aeration for Rural Wastewater Treatment

Zou

Guo

Han

et al. 2011

Water Air Soil Pollut

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Constructed wetlands are recognized as a reliable technology for rural wastewater treatment. However, conventional constructed wetlands face problems with low pollutant removal efficiency and limited oxygen transfer capability. Therefore, a novel vertical flow constructed wetland (VFCW) system with drop aeration was developed in this study. Two pilot-scale vertical flow constructed wetlands of 0.75 m 2 each were constructed with the same dimensions and configuration but different media, one of which (named as CW 1 ) was filled with a 1:1 mixture (by weight) of zeolite and dolomite and the other (named as CW 2 ) with the same zeolite only. The oxygen transfer capability of a multilevel two-layer drop aeration device, organics and nitrogen removal of CW 1 and CW 2 , and pollutant distribution along the depths of CW 1 and CW 2 in different operational phases were studied. The results demonstrated that compared with the direct drop aeration process, the multilevel, two-layer drop aeration device supplied 2-6 mg/L higher dissolved oxygen per meter of drop height, and after installation of the six-level, two-layer drop aeration devices, the 5-day biochemical oxygen demand removal load was improved from 8.1 to 14.2 gm −2 day −1 for CW 1 . With regard to the different filter media, nitrogen removal was improved by the adsorption of zeolite in the first year, with 5-36% higher NH 4 + -N removal efficiency of CW 2 compared with that in CW 1 . Since it did not have a significant positive effect on phosphate removal, dolomite can be replaced by zeolite. The chemical oxygen demand removal mainly took place in the upper 15-cm filter layer in different operational phases, while nitrogen distribution along the depths of the VFCWs was different in different operational phases. In addition, as no operational problems occurred, the vertical flow constructed wetland system with drop aeration is an appropriate alternative for rural wastewater treatment, with numerous advantages of low capital and operation costs, no energy consumption, easy maintenance, high hydraulic loading rate, high pollutant removal efficiency, and no clogging.

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“…When considering absorptive basins as sites where rainwater might be stored, it was assumed that the deposits building them had good or average permeability. Darcy's formula [40] was used to check the filtration flow intensity in terms of volume, and hence the capacity of water for infiltration in the depressions, and then the necessary area was established that rain of various intensity would infiltrate. It turned out to range from 1,015 m 2 for normal rain to 26,825 m 2 for torrential rain.…”

Section: Resultsmentioning

confidence: 99%