Abstract: Water-treatment flocculants are being developed from traditional to inorganic, from inorganic to organic,from natural organic to synthetic organic, from synthetic organic to modified natural organic,from inorganic or organic to inorganic organic,and from chemical to biological with ecological safety.In order to promote the rapid development and practical application of water-treatment flocculants,the research progress and application situation of flocculants for water treatment at home and abroad were reviewed.In particular,the characteristics of two important flocculant types,chemical and microbiological flocculants,as well as their application processes in water treatment were summarized,their development orientations were analyzed and evaluated,and the future research directions aimed to overcome the current shortages in developing and applying flocculants in China were put forward.

Key words: Mikania micrantha, Volatile oil, Insects, Biological activity