世界城市人口的不断增加，给即将到来的下个世纪带来了一些极为严重的环境问题——最显而易见的是，到2Z25年，必须为5亿城市居民（是目前的两倍）提供安全、纯净的用水。1997年，LjNU（联合国大学）在东京组织了一个主题为“对世纪的城市用水”的讨论会，会议云集了8位世界顶 The growing urban population in the world brings some very serious environmental problems to the coming century - most obviously, it is imperative to provide 500 million urban residents (twice the current level) with security by 225, Pure water. In 1997, LjNU (UNU) organized a symposium in Tokyo titled “Urban Water for Centuries”, which brought together 8 world tops