Hybrid constructed wetlands for highly polluted river water treatment and comparison of surface- and subsurface-flow cells

The main purpose of this study was to treat organic pollutants, nitrogen and phosphorus in polluted river water by the use of constructed wetland (CW) systems. A laboratory experiment research was conducted on subsurface flow constructed wetland systems operated in vertical flow (VF) and horizontal flow (HF) mode. The systems were unplanted and hydraulic retention times were identically 2.7 days. The average removal efficiencies for HFCW and VFCW were NH+ 4-N 64.9% and 75.2%, NO- 3-N 92.3% and 40.1%, COD 97.5% and 90.1%, TP 94.6% and 96.2%, respectively. The removal of NH+ 4-N and NO- 3-N in the different CW units were in order of VFCW (drained) > VFCW (flooded) > HFCW and HFCW > VFCW (flooded) > VFCW (drained), respectively. When the water level in the VFCW was changed, an obvious fluctuation of the effluent NH+ 4-N and NO- 3-N concentrations was observed.

Download Full-text

Nutrient Removal from Polluted River Water by Combining Vertical and Horizontal Subsurface Flow Constructed Wetlands

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.663.1029 ◽

2013 ◽

Vol 663 ◽

pp. 1029-1032 ◽

Cited By ~ 1

Author(s):

Cheng Xin Qin ◽

Gang He ◽

Yu Huan Duan ◽

Xiao Ping Pang ◽

Zong Lian She

Keyword(s):

River Water ◽

Removal Rate ◽

Subsurface Flow ◽

Ammonia Removal ◽

Polluted River ◽

Main Layer ◽

Second Stage ◽

N Removal ◽

Different Depths ◽

Horizontal Subsurface Flow

A lab-scale hybrid constructed wetland system was constructed to purify polluted river water. The system was composed of a first stage of the vertical subsurface flow filter, followed by a second stage of horizontal subsurface flow bed. Both beds used furnace slag with a size of 4-60 mm for the main layer. The system was continuously fed. Different depths of unsaturated layer (0 cm, 15 cm and 30 cm) in vertical filter were tested. The unsaturated layer of 30 cm in vertical filter presented the most effective ammonia removal of 89.1%, while lowest NO3--N removal rate of 74.1% for the system. High TN removal efficiencies (77.3%-81.0%) could be observed during operation of three depths. The removals of COD and TP were in the range of 97.1%-98.4% and 76.4%-88.9%, respectively.

Download Full-text

Numerical Simulation as a Tool to Improve Subsurface-Flow Constructed Wetlands for Water Treatment

Water Resources Quality ◽

10.1007/978-3-642-56013-2_5 ◽

2002 ◽

pp. 83-99

Author(s):

G. Langergraber ◽

R. Haberl ◽

J. Laber

Keyword(s):

Numerical Simulation ◽

Water Treatment ◽

Constructed Wetlands ◽

Subsurface Flow ◽

Subsurface Flow Constructed Wetlands

Download Full-text

Effect of corn cobs as external carbon sources on nitrogen removal in constructed wetlands treating micro-polluted river water

Water Science & Technology ◽

10.2166/wst.2019.156 ◽

2019 ◽

Vol 79 (9) ◽

pp. 1639-1647 ◽

Cited By ~ 2

Author(s):

Lu-ji Yu ◽

Tao Chen ◽

Yanhong Xu

Keyword(s):

Organic Carbon ◽

River Water ◽

Constructed Wetlands ◽

Carbon Sources ◽

Oxygen Demand ◽

Ammonia Nitrogen ◽

Flow Mode ◽

Low Carbon ◽

Polluted River ◽

Corn Cobs

Abstract Micro-polluted river water is characterized as having limited biodegradability, low carbon to nitrogen ratio and little organic carbon supply, all of which makes it hard to further purify. Two bench scale constructed wetlands (CWs) with a horizontal subsurface flow mode were set up in the laboratory to evaluate their feasibility and efficiency on denitrification with and without corn cobs as external carbon sources. Micro-polluted river water was used as feed solution. The CW without corn cobs substrates possessed a good performance in removing chemical oxygen demand (COD, <40 mg/L) and ammonia nitrogen (NH3-N, <0.65 mg/L), but less efficiency in removing total nitrogen (TN) and nitrate nitrogen (NO3-N). In marked contrast, the CW with 1% (w/w) corn cobs substrates as external carbon sources achieved a significant improvement in the removal efficiency of TN (increased from 34.2% to 71.9%) and NO3-N (increased from 19% to 71.9%). The incorporation of corn cobs substrates did not cause any obvious increase in the concentrations of COD and NH3-N in the effluent. This improvement in the denitrification efficiency was owing to the released organic carbon from corn cobs substrates, which facilitated the growth of abundant microbes on the surface and pores of the substrate. The open area of the used corn chips is larger than that of the pristine ones, and corn cobs can continue to provide a carbon fiber source for denitrification.

Download Full-text