Removal and speciation of heavy metals along the treatment path of wastewater in subsurface-flow constructed wetlands

2003 ◽  
Vol 48 (5) ◽  
pp. 307-313 ◽  
Author(s):  
P.E. Lim ◽  
K.Y. Mak ◽  
N. Mohamed ◽  
A. Md. Noor
Keyword(s):  
Constructed Wetlands ◽  
Metal Removal ◽  
Anodic Stripping Voltammetry ◽  
Subsurface Flow ◽  
Typha Latifolia ◽  
Domestic Wastewater ◽  
Antagonistic Effect ◽  
Metal Species ◽  
Dissolved Metals ◽  
Subsurface Flow Constructed Wetlands

This study was conducted to: (1) evaluate the performance of constructed wetlands in removing Zn, Pb and Cd, respectively, and Zn, Pb, Cd and Cu in combination and (2) investigate the speciation patterns of the dissolved metals differentiated according to their detectability by anodic stripping voltammetry (ASV) and their lability towards Chelex resin along the treatment path of metal-containing wastewater in horizontal subsurface-flow constructed wetlands. Four laboratory scale wetland units planted with cattails (Typha latifolia) were operated outdoors for six months. Three of the units were, respectively, fed with primary-treated domestic wastewater spiked with Zn(II), Pb(II) and Cd(II) whilst the fourth was spiked with a combination of Zn(II), Pb(II), Cd(II) and Cu(II). The results demonstrate that a metal removal efficiency of over 99% was achievable for wetland units treating the metals singly or in combination provided the sorption capacity of the media was not exceeded. When treating the metals in combination, an antagonistic effect, more significantly for Pb and Cd, on the sorptive metal uptake by media was observed. Based on the metal speciation patterns, the wetland system seemed to be capable of maintaining the ASV-labile metal species at relatively low level (<10%) before media exhaustion.

Field-Scale Studies of Subsurface Flow Constructed Wetlands for Stormwater Quality Enhancement

1997 ◽  
Vol 32 (1) ◽  
pp. 101-118 ◽  
Author(s):  
Q.J. ROCHFORT ◽  
W.E. Watt ◽  
J. Marsalek ◽  
B.C. Anderson ◽  
A.A. Crowder
Keyword(s):  
Organic Carbon ◽  
Constructed Wetlands ◽  
Suspended Solids ◽  
Nutrient Loading ◽  
Subsurface Flow ◽  
Reaction Rates ◽  
Pollutant Removal ◽  
Order Kinetic ◽  
Dissolved Metals ◽  
Subsurface Flow Constructed Wetlands

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.

Reciprocating constructed wetlands for treating industrial, municipal and agricultural wastewater

2001 ◽  
Vol 44 (11-12) ◽  
pp. 399-405 ◽  
Author(s):  
L. Behrends ◽  
L. Houke ◽  
E. Bailey ◽  
P. Jansen ◽  
D. Brown
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Environmental Protection Agency ◽  
Subsurface Flow ◽  
Domestic Wastewater ◽  
High Strength ◽  
Time Frequency ◽  
Operating Technique ◽  
Tennessee Valley ◽  
Subsurface Flow Constructed Wetlands

Scientists at the Tennessee Valley Authority (TVA), and in collaboration with the U.S. Environmental Protection Agency (EPA), are continuing to develop and refine an innovative wastewater treatment system referred to as reciprocating subsurface-flow constructed wetlands. Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands, such that contiguous cells are filled and drained on a frequent and recurrent basis. This operating technique turns the entire wetland system into a fixed-film biological reactor, in which it is possible to control redox potential in alternating aerobic and anaerobic zones. Reciprocating systems enable manipulation of wastewater treatment functions by controlling such parameters as hydraulic retention time, frequency of reciprocation, reciprocation cycle time, depth of reciprocation, and size and composition of substrate. These improved wetland technologies have been used for treating municipal/domestic wastewater, high strength animal wastewater, and mixed wastewater streams containing acids, recalcitrant compounds, solvents, antifreeze compounds, heavy metals, explosives, and fertilizer nutrients. Results from selected treatability studies and field demonstrations will be summarized with respect to conceptual design and treatment efficacy.

scholarly journals Evaluation of Ageratum conyzoides in field scale constructed wetlands (CWs) for domestic wastewater treatment

2017 ◽  
Vol 75 (10) ◽  
pp. 2268-2280 ◽  
Author(s):  
A. S. Tilak ◽  
Suhas P. Wani ◽  
A. Datta ◽  
M. D. Patil ◽  
M. Kaushal ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Typha Latifolia ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Fecal Coliforms ◽  
Pistia Stratiotes ◽  
Field Scale ◽  
Ageratum Conyzoides ◽  
Canna Indica

Ageratum conyzoides were evaluated in field scale subsurface flow constructed wetlands (CWs) to quantify its nitrogen (N) and phosphorus (P) uptake and compare with wetland plants (Pistia stratiotes, Typha latifolia and Canna indica). The two-field scale subsurface flow CWs, located in the International Crops Research Institute for Semi-Arid Tropics, received wastewater from an urban colony. The CW1 and CW2 had the same dimensions (length:10 m, width:3 m, total depth:1.5 m and sand and gravel:1 m), similar flow rates (3 m3/d), hydraulic loading rates (HLRs-10 cm/d) and hydraulic retention time (HRT-5 days) from July 2014–August 2015. The vegetation in both CWs consisted of Pistia stratiotes, Typha latifolia, Canna indica, and Ageratum conyzoides, respectively. The CW1 (% reduction with respect to concentrations) reduced total suspended solids (TSS) (68%), NH4-N (26%), NO3-N (30%), soluble reactive P (SRP) (20%), chemical oxygen demand (COD) (45%) and fecal coliforms (71%), while the CW2 (%-reduction with respect to concentrations) reduced TSS (63%), NH4-N (32%), NO3-N (26%), SRP (35%), COD (39%) and fecal coliforms (70%). Ageratum conyzoides can be used in combination with Pistia stratiotes, Typha latifolia and Canna indica to enhance removal of excessive N, P and fecal coliforms from domestic wastewater.

Performance evaluation of planted and unplanted subsurface-flow constructed wetlands for the post-treatment of UASB reactor effluents

2009 ◽  
Vol 60 (12) ◽  
pp. 3025-3033 ◽  
Author(s):  
Filipe Lima Dornelas ◽  
Matheus Boechat Machado ◽  
Marcos von Sperling
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Typha Latifolia ◽  
Post Treatment ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Horizontal Subsurface Flow ◽  
Subsurface Flow Constructed Wetlands ◽  
Belo Horizonte

A system comprised by a UASB (Upflow Anaerobic Sludge Blanket) reactor followed by two horizontal subsurface-flow constructed wetlands in parallel was evaluated for the treatment of the wastewater generated in the city of Belo Horizonte, Brazil (50 inhabitants each unit). One unit was planted (Typha latifolia) and the other was unplanted. Influent and effluent samples were collected for a period of seven months. The systems were able to produce final effluents with low concentrations of organic matter and suspended solids, but showed not to be efficient in the removal of nutrients. Mean effluent concentrations for the planted and unplanted units were, respectively: BOD: 15 and 19 mg/L; COD: 42 and 64 mg/L; TSS: 3 and 5 mg/L; TN: 27 and 33 mg/L; N-NH3: 25 and 29 mg/L; P Total: 1.2 and 1.5 mg/L. The planted wetland presented effluent concentrations and removal efficiencies significantly (Wilcoxon matched-pairs test, 5% significance level) better than the unplanted unit for most constituents. The study shows that horizontal subsurface-flow constructed wetlands can be effectively used as a post-treatment option for the effluent from UASB reactors.

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