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污染控制技术及原理

The influence of phosphate on the performance of the flocculant produced by Paenibacillus polymyxa GA1

基金项目：国家重点基础研究“973”发展计划项目(No.2005CB724203);国家自然科学基金资助项目(No.50478053);湖南省自然科学基金资助项目(No.04JJ3004,05JJ2004);湖南省科技计划项目(No.05FJ3001)

摘要：考察了一株高效产絮凝剂微生物多粘类芽孢杆菌Paenibacillus polymyxa GA1(以下简称GA1)的发酵培养基以及培养基各组分的絮凝性.实验结果表明,培养基中K₂HPO₄、KH₂PO₄在CaCl₂存在、pH值中性偏碱时对各种废水均有一定的絮凝性,在GA1所产絮凝剂(以下简称MBFGA1)絮凝废水的过程中起重要作用,且作用离子为PO₄^3-和Ca²⁺;这两种离子在pH值中性偏碱时能有效降低高岭土悬液的ξ电位绝对值到接近零,使胶体脱稳;PO₄^3-和Ca²⁺形成絮状沉淀后,能网捕脱稳颗粒,进而在MBFGA1桥联作用下使颗粒结团沉降完成絮凝.发酵培养基虽有一定絮凝性,但效果不佳,处理后上清液颗粒平均粒径远大于发酵液处理,且絮体、泥饼性质差异大,不利于工业应用和后续处理.硫酸钡亦有一定的助凝效果,但因沉淀本身性质差异,其效果劣于磷酸钙.

Abstract：Paenibacillus polymyxa GA1(GA1)produces a bioflocculant with high flocculating activity. Flocculation activities of the culture medium and each of its components were measured. Different wastewater samples could be flocculated by K₂HPO₄ and KH₂PO₄ in the culture medium with CaCl₂ when pH>7.0. K₂HPO₄ and KH₂PO₄ were the key factors when the wastewater was treated by the microbial flocculant produced by GA1(MBFGA1).The contributing ions were PO₄^3- and Ca²⁺. The Abs olute value of kaolin's zeta potential could be brought down by these two ions to about 0, hence the stabilization of the colloid was broken. The unstable grains could be captured by the floccule of calcium phosphate, then the grains coagulated with MBFGA1 and settled. Although the wastewater could be flocculated by the culture medium alone, the effect was poor. The average granularity of kaolin was much bigger than that treated by fermentation and the floc properties are inappropriate for industrial conditions. Kaolin could also be flocculated with the help of BaSO₄, but because of the difference of deposition, the effect was not as good as Ca 3(PO₄)₂.