Review of Constructed Wetlands Applied in Water Pollution Control in Taiwan

Water pollution is a serious problem in Taiwan. Large amounts of pollutants from different point- and nonpoint-sources are discharged into both natural and artificial water bodies, including rivers, lakes, ponds, reservoirs and coastal water. Contaminated water affected the supply of water in living, industry and agriculture in Taiwan. Wetlands are lands where the water surface is near the ground surface for long enough each year to maintain saturated soil conditions, along with the related vegetation. There are many valuable functions of wetlands including providing habitat for reproduction, feeding, and resting for organisms, flood attenuation, groundwater recharge, sediment entrapment, and water quality purification. Constructed wetlands are thus used as wastewater treatment facilities through the function of water quality purification of wetlands. Besides, this natural treatment system was found more economical than conventional mechanical treatment system for water pollution control. In Taiwan, the research work on constructed wetlands was begun from several years ago conducted by several researchers in the project supported by National Science Council. Different types of water bodies, including contaminated river water, aquaculturing pond water, sewage, industrial wastewater, and storm water, were tested using microcosm or macrocosm constructed wetland systems for their removal efficiencies of different types of pollutants. The results of this three-year research project showed that the effluents from constructed wetlands exhibited high potential for water reuse, which was beneficial for sustainable use of water resource in Taiwan.