Method for removing humic substances from an aqueous alkaline solution

A method for removing humic substances comprising lignin， other lignin type compounds and their disintegration products from an aqueous alkaline waste water from a bleaching of chemical pulp， which method comprises —obtaining an aqueous alkaline waste water comprising humic substances such as dissolved lignin， and —adding a high cationic starch having a charge density value of at least 1.8 meq/g dry matter of starch derivates determined at pH 7-7.5 to the alkaline waste water to precipitate humic substances.

一种用于从化学纸浆漂白工序产生的碱性含水废水中去除腐殖物质的方法，所述腐殖物质包含木质素、其他木质素类化合物及其降解产物。该方法包含以下步骤：
1. 获取含有腐殖物质（如溶解态木质素）的碱性含水废水；
2. 向该碱性废水中添加高阳离子淀粉（high cationic starch），其在pH 7~7.5条件下以淀粉衍生物干物质计的电荷密度不低于1.8毫当量/克（meq/g），以此使腐殖物质沉淀析出。