Study On Algal Bioflocculant And Defluoridation Bioabsorbent Of Drinking Water

Flocculating is one of the most extensively used method among all water treatment methods. In contrast to inorganic flocculants and organic synthetic polymer flocculants, bioflocculant has advantages such as biodegradability and non-toxic to organisms. Among those microbial bioflocculants, algal bioflocculant production generated less wastewater due to the absence of organic carbon source in media, and hence cost-effective in production.Bioflocculants of Chlamydomonas reinhardtii were investigated with axenic algal culture. C. reinhardtii was found to produce significant amounts of bioflocculant. Flocculating activity by C. reinhardtii began in the middle of the exponential phase and maintained until the end of the stationary phase. The highest flocculating efficiency was 97.06%. The flocculating substances were effective anionic biopolymer for kaolin clay suspensions. The purified C. reinhardtii bioflocculants were consisted of 47.93% proteins and 35.43% carbohydrates. The optimum condition for bioflocculant production of C. reinhardtii was 15°C-25°C, 20-60μEm^-2s^-1 and pH 6-10. The bioflocculants produced by C. reinhardtii showed maximum activity from pH 2 to 10. The amount of CaCl₂ as co-flocculant at optimal concentration was 2.25mM.The flocculating test of wasterwater indicated that the effects of the flocculant of C. reinhardtii on purifying papermaking tobacco leaf wasterwater and whey wasterwater were unnotable; but it had some effect on turbidity removal of pulp and paper wasterwater. However, the flocculating mechanism and the optimum flocculation condition on various wastewater still need further research.Bio-F is a new type of defluoridation biomaterial developed in our lab. Due to low cost and long life performance, Bio-F has predominant advantage in defluoridation of drinking water. A series of experimental investigations comprised of static and dynamic experiments were carried out to study the defluoridation characteristics and influencing factors. The result indicated that the defluoridation capacity (DC) of this filter material was increased to significant level, which is over one time than activated clinoptilolite and activated alumina(AA). Through the comparison with bonechar(BC), AA and activated clinoptilolite, it showed properties of swift F adsorption velocity, stable regeneration, manganese and ferrum elimination, high safety, adaptable pH and no peculiar smell of effluent, showed promising perspective in application in countryside.