Constructed wetlands for textile wastewater remediation: A review on concept, pollutant removal mechanisms, and integrated technologies for efficiency enhancement

Abstract Two subsurface flow constructed wetlands were tested for pollutant removal performance in conjunction with an on-line stormwater detention pond, in Kingston Township, Ontario. The 4.9 m2 wetland cells were filled with 9 mm limestone gravel, and planted with cattail, common reed and spike rush. Changes in nutrient (total organic carbon, PO43- and NH4+), suspended solids and metal (Cu, Pb, Zn) concentrations were used to assess performance. Contaminant removal occurred through a combination of physical, chemical and biological means. As with any biological system, variation in performance of stormwater wetlands can be expected to occur as a result of fluctuations in contaminant loading, contact time and ambient environmental conditions. Storm pond effluent was delivered in continuous flow through the wetlands (during baseflow and event conditions), with a detention time of 1 to 3 days. The wetlands were able to maintain removal rates of up to 39% for orthophosphate even during the more severe conditions of fall dieback. Average removal of suspended solids (46%) and dissolved metals (Cu 50%) remained similar throughout all tests. Organic carbon was reduced by less than 10% during these tests. Low nutrient levels in the pond effluent were supplemented by spiking with sources of carbon, nitrogen and phosphorus during pulsed loading conditions. Daily sampling produced a time series, which illustrated the rates of decline in concentration of nutrients. First order kinetic assimilation rates ranged from 1.7 d-1 for NH4002B to 0.12 d-1 for organic carbon, which were noticeably lower when compared with municipal and industrial wastewater treatment rates. Three methods of sizing stormwater wetlands (impervious surface area, volumetric load and kinetic reaction rates) were compared using the same design storm and data from this study. From this comparison it was seen that the kinetic sizing approach proved to be the most versatile, and allowed for adaptation to northern climatic conditions and anticipated nutrient loading.

Download Full-text

Area-based speciation kinetic analysis of the multipollutant removal in Constructed Wetlands to enhance its treatment efficiency

Environmental Science Water Research & Technology ◽

10.1039/d1ew00027f ◽

2021 ◽

Author(s):

Manoj Kumar ◽

Rajesh Singh

Keyword(s):

Wastewater Treatment ◽

Kinetic Analysis ◽

Constructed Wetlands ◽

Municipal Wastewater ◽

Zero Order ◽

Pollutant Removal ◽

Municipal Wastewater Treatment ◽

Treatment Efficiency ◽

First Order ◽

Present Study Area

In the present study area-based, pollutant removal kinetic analysis was considered using the Zero-order, first-order decay and efficiency loss (EL) models in the constructed wetlands (CWs) for municipal wastewater treatment....

Download Full-text

Evaluation of herbicide (persistent pollutant) removal mechanisms through hybrid membrane bioreactors

Bioresource Technology ◽

10.1016/j.biortech.2015.10.041 ◽

2016 ◽

Vol 200 ◽

pp. 795-803 ◽

Cited By ~ 12

Author(s):

Dimuth Navaratna ◽

Li Shu ◽

Veeriah Jegatheesan

Keyword(s):

Hybrid Membrane ◽

Membrane Bioreactors ◽

Pollutant Removal ◽

Persistent Pollutant ◽

Removal Mechanisms

Download Full-text

Treatment performances of French constructed wetlands: results from a database collected over the last 30 years

Water Science & Technology ◽

10.2166/wst.2015.089 ◽

2015 ◽

Vol 71 (9) ◽

pp. 1333-1339 ◽

Cited By ~ 30

Author(s):

A. Morvannou ◽

N. Forquet ◽

S. Michel ◽

S. Troesch ◽

P. Molle

Keyword(s):

Constructed Wetlands ◽

Oxygen Demand ◽

Pollutant Removal ◽

Vertical Flow ◽

Removal Rates ◽

Waste Stabilization Ponds ◽

Small Communities ◽

Technical Department ◽

In Series ◽

High Chemical Oxygen Demand

Approximately 3,500 constructed wetlands (CWs) provide raw wastewater treatment in France for small communities (<5,000 people equivalent). Built during the past 30 years, most consist of two vertical flow constructed wetlands (VFCWs) in series (stages). Many configurations exist, with systems associated with horizontal flow filters or waste stabilization ponds, vertical flow with recirculation, partially saturated systems, etc. A database analyzed 10 years earlier on the classical French system summarized the global performances data. This paper provides a similar analysis of performance data from 415 full-scale two-stage VFCWs from an improved database expanded by monitoring data available from Irstea and the French technical department. Trends presented in the first study are confirmed, exhibiting high chemical oxygen demand (COD), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) removal rates (87%, 93% and 84%, respectively). Typical concentrations at the second-stage outlet are 74 mgCOD L−1, 17 mgTSS L−1 and 11 mgTKN L−1. Pollutant removal performances are summarized in relation to the loads applied at the first treatment stage. While COD and TSS removal rates remain stable over the range of applied loads, the spreading of TKN removal rates increases as applied loads increase.

Download Full-text

Pollutant removal mechanisms in a bio-diatomite dynamic membrane reactor for micro-polluted surface water purification

Desalination ◽

10.1016/j.desal.2012.02.021 ◽

2012 ◽

Vol 293 ◽

pp. 38-45 ◽

Cited By ~ 28

Author(s):

Huaqiang Chu ◽

Bingzhi Dong ◽

Yalei Zhang ◽

Xuefei Zhou ◽

Zhenxun Yu

Keyword(s):

Surface Water ◽

Water Purification ◽

Membrane Reactor ◽

Pollutant Removal ◽

Dynamic Membrane ◽

Removal Mechanisms

Download Full-text

Hydraulic tracer studies in a pilot scale subsurface flow constructed wetland

Water Science & Technology ◽

10.2166/wst.1997.0195 ◽

1997 ◽

Vol 35 (5) ◽

pp. 189-196 ◽

Cited By ~ 7

Author(s):

Andrew C. King ◽

Cynthia A. Mitchell ◽

Tony Howes

Keyword(s):

Dispersion Model ◽

Plant Root ◽

Subsurface Flow ◽

Plug Flow ◽

Pilot Scale ◽

Pollutant Removal ◽

Tracer Studies ◽

Operational Strategies ◽

Design Procedures ◽

Removal Mechanisms

Current design procedures for Subsurface Flow (SSF) Wetlands are based on the simplifying assumptions of plug flow and first order decay of pollutants. These design procedures do yield functional wetlands but result in over-design and inadequate descriptions of the pollutant removal mechanisms which occur within them. Even though these deficiencies are often noted, few authors have attempted to improve modelling of either flow or pollutant removal in such systems. Consequently the Oxley Creek Wetland, a pilot scale SSF wetland designed to enable rigorous monitoring, has recently been constructed in Brisbane, Australia. Tracer studies have been carried out in order to determine the hydraulics of this wetland prior to commissioning it with settled sewage. The tracer studies will continue during the wetland's commissioning and operational phases. These studies will improve our understanding of the hydraulics of newly built SSF wetlands and the changes brought on by operational factors such as biological films and wetland plant root structures. Results to date indicate that the flow through the gravel beds is not uniform and cannot be adequately modelled by a single parameter, plug flow with dispersion, model. We have developed a multiparameter model, incorporating four plug flow reactors, which provides a better approximation of our experimental data. With further development this model will allow improvements to current SSF wetland design procedures and operational strategies, and will underpin investigations into the pollutant removal mechanisms at the Oxley Creek Wetland.

Download Full-text

Using one filter stage of unsaturated/saturated vertical flow filters for nitrogen removal and footprint reduction of constructed wetlands

Water Science & Technology ◽

10.2166/wst.2017.115 ◽

2017 ◽

Vol 76 (1) ◽

pp. 124-133 ◽

Cited By ~ 4

Author(s):

Ania Morvannou ◽

Stéphane Troesch ◽

Dirk Esser ◽

Nicolas Forquet ◽

Alain Petitjean ◽

...

Keyword(s):

Constructed Wetlands ◽

Oxygen Demand ◽

Pollutant Removal ◽

Operating Conditions ◽

Vertical Flow ◽

Saturated Layer ◽

Recirculation Rate ◽

Total Filtration ◽

Filtration Area ◽

Stage System

French vertical flow constructed wetlands (VFCW) treating raw wastewater have been developed successfully over the last 30 years. Nevertheless, the two-stage VFCWs require a total filtration area of 2–2.5 m2/P.E. Therefore, implementing a one-stage system in which treatment performances reach standard requirements is of interest. Biho-Filter® is one of the solutions developed in France by Epur Nature. Biho-Filter® is a vertical flow system with an unsaturated layer at the top and a saturated layer at the bottom. The aim of this study was to assess this new configuration and to optimize its design and operating conditions. The hydraulic functioning and pollutant removal efficiency of three different Biho-Filter® plants commissioned between 2011 and 2012 were studied. Outlet concentrations of the most efficient Biho-Filter® configuration are 70 mg/L, 15 mg/L, 15 mg/L and 25 mg/L for chemical oxygen demand (COD), 5-day biological oxygen demand (BOD5), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN), respectively. Up to 60% of total nitrogen is removed. Nitrification efficiency is mainly influenced by the height of the unsaturated zone and the recirculation rate. The optimum recirculation rate was found to be 100%. Denitrification in the saturated zone works at best with an influent COD/NO3-N ratio at the inflet of this zone larger than 2 and a hydraulic retention time longer than 0.75 days.

Download Full-text