Artificial vegetation island (AVI), which is mimicry of natural floating island, is one of ecotechnology for water quality improvement and restoration of disturbed aquatic ecosystem, and AVIs were launched in Lakes Paldang and Paro, Lakes of Korea to test their effectiveness. In Lake Paldang, an eutrophic lake, AVI could be acting as nutrients remover, but efficiencies was not clearly observed, but under the AVI, fish and zooplankton were more abundant than bulk lake water. In oligotrophic Lake Paro, where littoral zone was perfectly destroyed, AVI was installed as substitute for littoral zone. By microbial activities, Iris and other macrophytes on AVI were growing well and fishes were coming. We conclude that AVIs could be launched for partial restoration of disturbed ecosystem of oligotrophic and eutrophic lakes.

비점오염원으로부터 오염된 소하천에서 영양염류를 제거하기 위하여 식물플랑크톤 배양 장치를 설치하고 운영하였다. 식물플랑크톤 배양조에서 식물플랑크톤 정치배양 결과, 식물플랑크톤의 연속배양을 위한 배양조의 체류시간을 3일로 결정하였으며 TP는 70%, TN은 44%가 제거됨을 확인하였다. 연속배양 결과 45일 동안 배양조에 유입된 TP의 53.9%, TN의 53.1%가 식물플랑크톤에 의한 흡수와 슬러지로 제거되었다. 식물플랑크톤이 성장하면서 배양조의 pH와 용존산소농도는 각각 평균 10.8, 16mg L-1이었다. 결국 비점오염원에 오염된 하천수의 영양 염류는 식물플랑크톤의 사체와 화학반응으로 생성된 침전물로 제거되었다. 비교적 설치가 간단하고 경제성이 높은 식물플랑크톤 배양법의 높은 현장적용 가능성을 확인하였다.

Among the functions of ecosystem, nutrients cycle is the most important for sustaining natural system. But in modernized and industrialized countries, the product consumes the resources and make wastes. This means that valuable resources are turning to waste through product. Waste water is one of the product from the valuable resources, so waste water is no more waste and it can be used as valuable resources for other process by using natural ecosystem. By the conventional wastewater treatment systems, the “zero discharge” could not be achieved by several factors. Shortage of resources is one of the reasons. Secondly, by the environmental engineering, the pollutants are only transformed from one medium to another. Thirdly, for eliminating the pollutants, fossil fuel must be used, which means another pollution. Self-designed and solar energy based ecotechnology could be an alternative method which solve the local, regional and global environmental problems properly should be found out. Already ecotechnology was defined as “the design of human society with it natural environment for the benefit of both”. By using the functions of ecosystem, such as food web, energy flow, nutrients cycles and homeostasis, pollutants can be eliminated, concentrated and transformed to nature. The major purpose of mechanical wastewater treatment systems is focused on the large quantity of domestic wastewater. But, small quantity of domestic wastewater is not concerned by public treatment because economic and technical difficulty. However, for improvement of water quality of streams and rivers, the small quantity of domestic wastewater must be purified. Here, some eco-technologies for water quality improvement installed in Korea are introduced. The artificial wetland, artificial food web and artificial vegetation island are installed in polluted and ecologically disturbed areas. These methods are not perfectly solving the environmental problems, and they are acting as alternative methods for clean up of polluted and restoration of disturbed ecosystems.