城市污水处理厂污泥臭氧减量技术研究

通过半连续式实验考察了臭氧投加量和初始pH对剩余污泥臭氧处理的影响.结果表明,随着臭氧投加量的增加,污泥溶解率增加,有机质、氮、磷等物质释放到污泥液相中;最佳臭氧投加量控制在约150 mg·g-1(以SS计),污泥溶解率可达约26%;污泥臭氧减量应在初始pH中性或偏碱性条件下进行,此时污泥溶解率较高,有利于有机质和氮的溶出.臭氧处理后污泥回流至生物处理系统对微生物的生物活性、COD和TN的去除效果无显著影响,但由于系统中无剩余污泥排放,导致TP的去除效果明显下降.臭氧处理后污泥上清液的Ca(OH)2除磷实验发现,较高的钙磷摩尔比对上清液除磷有利;当其值控制在10.0左右时,TP的去除率大于80%.

Sludge reduction by ozone in municipal wastewater treatment plants

Semi-continuous mode experiments were adopted to examine the effects of ozone dose and initial pH on the sludge reduction by ozone. The results indicated that, as the ozone dose increased, the sludge solubilization ratio increased and the organic compounds, nitrogen and phosphorus were gradually released into the water phase of sludge. The optimal ozone dose was around 150 mg·g^-1 (in SS), at which the sludge solubilization ratio could reach about 26%. An initial neutral or alkaline pH value favored the sludge reduction, under which a high sludge solubilization ratio was obtained and the release of organic compounds and nitrogen was enhanced. The recycling of ozonated sludge to biological treatment system had no obvious impact on the microbial activity and the removal efficiencies of COD and TN, while the removal efficiency of phosphorus declined obviously because of the zero discharge of excess sludge from the biological treatment system. The experimental results of phosphorus removal from ozonated sludge supernatant by Ca(OH)₂ indicated that a high Ca/P molar ratio was beneficial for phosphorus removal; when this ratio was controlled at about 10.0, the removal efficiency of TP could reach more than 80%.