Affiliations: Faculty of Municipal and Environmental Engineering,
Harbin Institute of Technology, Harbin 150006, China | Longgang District Environmental Protection Agency of
Shenzhen City, Longgang District, Shenzhen 518000, China | Shenzhen Institute of Environment Science, Shenzhen
518000, China | Longtian Shatian Sewage Manage Co., Ltd., Shenzhen
518000 China
Abstract: The operational performance of a full-scale subsurface-flow
constructed wetland, which treated the mixed industrial and domestic wastewater
with BOD_5/COD mean ratio of 0.33 at Shatian, Shenzhen City
was studied. The constructed wetland system consists of screens, sump, pumping
station, and primary settling basin, facultative pond, first stage wetland and
secondary stage wetland. The designed treatment capacity is 5000
m^3/d, and the actual influent flow is in the range of <
2000 to > 10000 m^3/d. Under normal operational
conditions, the final effluent quality well met the National Integrated
Wastewater Discharge Standard (GB 8978-1996), with the following parameters
(mean values): COD 33.90 mg/L, BOD_5 7.65 mg/L, TSS 7.92
mg/L, TN 9.11 mg/L and TP 0.56 mg/L. Seven species of plants were selected to
grow in the wetland: Reed, Sweetcane flower Silvergrass, Great Bulrush, Powdery
Thalia and Canna of three colours. The growing season is a whole year-round.
The seasonal discrepancy could be observed and the plants growing in the
wetland are vulnerable to lower temperature in winter. The recycling of the
effluent in the first stage of the wetland system is an effective measure to
improve the performance of the wetland system. The insufficient DO value in the
wetland system not only had significant effect on pollutants removal in the
wetland, but also was unfavourable to plant growth. The recycling of effluent
to the inlet of wetland system and artificial pond to increase DO value of
influent to the wetland is key to operate the subsurface constructed wetland
steadily and effectively.
