Fuzzy mathematics-based sludge stability evaluation of adding different proportions of lime
添加不同比例的石灰对污泥稳定化的模糊评价

Alkaline treatment,although being recognized as a safe and secure method,was restricted in China for lacking of efficient equipment which not only consumed large quantities of lime but also lowed sludge stabilization.After using independently developed efficient mixer,5%,7%,10%,12% and 15% of industrial lime was added into dewatered sludge,changes of temperature,pH,fecal coliform and odor intensity were assayed,sludge stability was evaluated by using fuzzy mathematics.The results show that adding different proportions of industrial lime,sludge temperature increased from the original 30℃ to 32.0,36.0,39.2,41.0 and 43.3℃;pH also increased from the original 6.5 to 12;fecal coliform reduced from the original 1.08 × 10-8 g/MPN to 0.01 g/MPN;odor intensity dropped from five to two;fuzzy comprehensive evaluation achieved a high degree of sludge stability.Therefore,sludge stabilization can be realized by the addition only of 5% of lime.