Specialist Group on Use of Macrophytes in Water Pollution ... - IWA

WETLAND FOR WATER POLLUTION CONTROL IN CHINA:
RECENT EXPERIENCES
J. Zhai, H.W. Xiao, J. Liu
Chongqing University, Faculty of urban construction and environmental engineering,
Chongqing 400045, P. R. China
E-mail: zhaijun@cqu.edu.cn; xiaohaiwen99@163.com; liujiede87@yahoo.com.cn
Environmental protection has aroused increasing awareness from citizens and government
officials in china. Based on the current underdeveloped economic situation and low energy
consumption concept, the wastewater treatment technologies with low investment and
operation cost are favourable in China. Wetland, as a treatment technology with low
construction and operation cost and great aesthetical value, has great potential on water
pollution control. In recent years, more and more wetlands have been constructed in china.
Generally, two types of wetlands are constructed in china, one is constructed wetland, and the
other is converted natural wetland. Constructed wetland is usually utilized for urban
municipal wastewater and rural wastewater treatment, polluted landscape water purification
or non-point pollution control. Converted natural wetland is mostly used for purifying the
runoff, buffering flood peak, creating the inhabitancy for creatures, and improving the urban
ecological environment. And it is generally constructed into Wetland Park. This report
presents a brief review of constructed wetlands (CWs) and converted natural wetlands
(CNWs) applied in China in the last three years.
1. Constructed wetlands
Seven newly constructed wetlands in China are introduced in this report. The basic
information for each of them, including the name and location, influent, and treatment
capacity for the seven CWs, is illustrated in table 1. And table 2 lists the treatment process,
HLR, plants in wetlands, and occupation area etc.
From the two tables, the influent for all the CWs can be classified into three kinds, the urban
municipal and rural wastewater for secondary treatment, the effluent of WWTP for advanced
treatment, and the polluted landscape water. The CWs were all constructed between 2008 and
2011, and the type of CW is all hybrids CW except Jiaoling CWs. The treatment capacity for
the landscape water is the largest, for the municipal and rural wastewater is smaller and for
the effluent of WWTP is smallest.
CWs for urban municipal and rural wastewater treatment are widely used in china in the past
three years. Because domestic wastewater accounts for most of the wastewater, the influent
of urban wastewater and rural wastewater is not constant in quality and quantity, in which the
concentration of SS is very high and organics are very low. Normally in south china, the
indexes for urban wastewater are BOD/(mg.L −1 ) 55–153, COD/(mg.L −1 ) 78–578,
SS/(mg.L −1 ) 22–541, NH3-N/(mg.L −1 ) 13–28, TN/(mg.L −1 ) 18–31, TP/(mg.L −1 ) 3–9. In most
applied cases, the effluent can meet the requirements of Discharge Standard ClassⅠB
(GB18918-2002)(COD 60 mgL −1 ; BOD 20 mg.L −1 ;SS 20 mg.L −1 ; NH3-N/(mg.L −1 ) 8;
TN/(mg.L −1 ) 20; TP/(mg.L −1 ) 1) or even higher standard after treating by CWs. The treatment
process of CWs includes stabilization pond or aeration pond, HSSF CW and VSSF CW etc.
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46 IWA <strong>Specialist</strong> <strong>Group</strong> on Use of Macrophytes in Water Pollution Control: Newsletter No. 37