Abstract: Based on the 1961-2005 meteorological data from thirty three stations in Huaihe River basin, and by using fuzzy mathematics and spatial interpolation methods, the climate suitability of double-cropping rice in this basin were studied. Temperature and recipitation were the key climate factors affecting the growth of doublecropping rice, and the climate suitability of both early and late rice had strong regional characters. The climate suitability of early rice decreased from central plain area to east coast and west mountain area, whereas that of late rice decreased from south area to north area. Temperature suitability increased at a rate of 0.01 (10a)^-1, suggesting that temperature had positive effects on the growth and development of double-cropping rice in Huaihe River Basin. Sunlight suitability decreased at a rate higher than 0.02 (10a)^-1. The overall climate suitability had a decreasing trend.

Key words: Combined flocculants, Flocculent performance, Wastewater treatment, COD, Turbidity, Environmental safety