Article

Comparison of interannual removal variation of various constructed wetland types.

Department of Biodiversity and Environmental Management, Faculty of Biologic and Environmental Sciences, University of León, Campus de Vegazana s/n, E-24071 León, Spain.
Science of The Total Environment (Impact Factor: 3.16). 05/2012; 430:174-83. DOI: 10.1016/j.scitotenv.2012.04.072
Source: PubMed

ABSTRACT Seven mesocosm-scale (1m(2)) constructed wetlands (CWs) of different configurations were operated outdoors for thirty-nine months under the same conditions to assess their ability to remove organic matter and nutrients from urban wastewaters. CWs differed in some design parameters, namely the presence of plants, the species chosen (i.e., Typha angustifolia or Phragmites australis), the flow configuration (i.e., surface flow or subsurface flow) and the presence/absence of a gravel bed. It was observed that, in general, removal efficiencies decreased with the aging of the system and that seasonality had a great influence on CWs. A comparison was made in order to figure out which kind of CW was more efficient for the removal of every pollutant in the long term. Planted systems were clearly better than unplanted systems even in winter. Efficiency differences among CWs were not extremely great, especially after a few years. However, some types of CWs were more adequate for the removal of certain pollutants. The effect of the aging on the main parameters involved in pollutant removal in CWs (temperature, pH, conductivity, dissolved oxygen concentration and redox potential) was assessed. The efficiency of CWs should not be evaluated based on short monitoring periods (1-2 years) after the start-up of the systems, but on longer periods.

0 Bookmarks
 · 
91 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Low cost filter materials for efficient waste water treatment in constructed wetlands are worldwide in demand. However, information on soil physical parameters needed for efficient treatment is scarce. We investigated 5 different lava and one fluviatile operating sand filters in Germany for their differences in pore size distribution spectra, specific inner surface area and cumulative pore volume. While these soil physical parameters did have an influence on purification capacity and hydraulic conductivity, differences in mineralogy (presence of zeolites), waste water distribution systems (baffle plates versus pipes) and loading rates were the dominating factors determining filter efficiency. Lava sands convince with high purification capacities during permanent loading rates of >100 mm d−1, average loading rates of 20 g COD m−2 d−1 (chemical oxygen demand) and approximate effective loading rates of up to 250 g COD m−2 d−1.
    Ecological Engineering 07/2014; 68:124–132. · 2.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Outdoor shallow wetland mesocosms, designed to simulate surface constructed wetlands to improve lagoon wastewater treatment, were used to assess the role of macrophytes in the dissipation of wastewater nutrients, selected pharmaceuticals, and antibiotic resistance genes (ARGs). Specifically, mesocosms were established with or without populations of Typha spp. (cattails), Myriophyllum sibiricum (northern water milfoil), and Utricularia vulgaris (bladderwort). Following macrophyte establishment, mesocosms were seeded with ARG-bearing organisms from a local wastewater lagoon, and treated with a single pulse of artificial municipal wastewater with or without carbamazepine, clofibric acid, fluoxetine, and naproxen (each at 7.6 μg/L), as well as sulfamethoxazole and sulfapyridine (each at 150 μg/L). Rates of pharmaceutical dissipation over 28 d ranged from 0.073 to 3.0 d− 1, corresponding to half-lives of 0.23 to 9.4 d. Based on calculated rate constants, observed dissipation rates were consistent with photodegradation driving clofibric acid, naproxen, sulfamethoxazole, and sulfapyridine removal, and with sorption also contributing to carbamazepine and fluoxetine loss. Of the seven gene determinants assayed, only two genes for both beta-lactam resistance (blaCTX and blaTEM) and sulfonamide resistance (sulI and sulII) were found in sufficient quantity for monitoring. Genes disappeared relatively rapidly from the water column, with half-lives ranging from 2.1 to 99 d. In contrast, detected gene levels did not change in the sediment, with the exception of sulI, which increased after 28 d in pharmaceutical-treated systems. These shallow wetland mesocosms were able to dissipate wastewater contaminants rapidly. However, no significant enhancement in removal of nutrients or pharmaceuticals was observed in mesocosms with extensive aquatic plant communities. This was likely due to three factors: first, use of naïve systems with an unchallenged capacity for nutrient assimilation and contaminant removal; second, nutrient sequestration by ubiquitous filamentous algae; and third, dominance of photolytic processes in the removal of pharmaceuticals, which overshadowed putative plant-related processes.
    Science of The Total Environment 01/2014; s 482–483:294–304. · 3.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Due to the nature of the phosphorus (P) removal mechanisms associated with constructed wetlands, the sus-tainability of P treatment is usually of high interest. As a result, a 4-year dataset from a typical multi-celled integrated constructed wetland (ICW) located at Glaslough in Co. Mon-aghan, Ireland was evaluated to determine the effects of long-term P loadings and hydrological inputs on P treatment. The ICW was intensively monitored year-round from February 2008 through March 2012 for total P and molybdate reactive phosphate (MRP). Domestic wastewater was loaded at 16.4± 0.96 g m 2 year −1 for total P and 11.2±0.74 g m 2 year −1 for MRP. Average mass reductions over the monitoring period were 91.4 and 90.1 %, respectively. The area-based kinetic coefficients (K (20)) of 11.8 for total P and 15.6 m year −1 for MRP indicated a high area-specific retention rate. The ICW appeared to have a sustained capacity for P adsorption and retention, but the treatment was influenced mainly by external hydrological inputs and fluctuations in wastewater loadings. Linear regression analyses showed a reduction in mass reten-tion of both total P and MRP with increased effluent flow volumes. Monthly mass reductions exceeded 90 % when the effluent flow volumes were less than 200 m 3 day −1 . When monthly effluent flow volumes exceeded 200 m 3 day −1 , none-theless, mass reductions became highly variable. Designs and management of ICW systems should adopt measures to limit external hydrological loadings in order to maintain sufficient P treatment.
    Environmental Science and Pollution Research 07/2014; · 2.76 Impact Factor

Full-text (2 Sources)

Download
102 Downloads
Available from
May 28, 2014