热碱-EDTA耦合法强化污泥破解及效果分析

Strengthening sludge disintegration by thermal alkali-EDTA coupling method and its effect analysis

采用热碱-EDTA耦合法进一步提升热碱法破解污泥的效果,以期减少碱量和热能的消耗。选用影响污泥破解效果的pH、温度和EDTA投加量等因素设计L16(45)的正交实验,在得出最佳污泥破解条件下,对比考察了热碱法和热碱-EDTA耦合法破解污泥的效果。结果表明,热碱-EDTA耦合法相比热碱破解法,破解后SCOD、TN、TP、多糖和蛋白质溶出量分别提高了14.7%、5.6%、9.9%、3.6%和25.9%,污泥残渣中VS的含量(21.93%)也小于热碱破解法(29.68%),破解液中分子质量小于400 Da的小分子物质占比(40.68%)大于热碱破解的对应结果(32.34%)。通过污泥粒径测定和SEM观察发现,热碱-EDTA耦合法破解的污泥粒径分布峰值响应小于热碱破解,污泥固体分散性优于热碱破解。通过分析可知,热碱-EDTA耦合法可以提高中低温条件下热碱破解的有机物溶出率和有机物水解性能,降低污泥残渣中VS的相对含量,热碱-EDTA耦合法相比热碱法强化了污泥的破解效果。

The thermal alkali-EDTA coupling method was used to further disintegrate the sludge,in order to reduce the consumption of alkali and heat energy.The orthogonal test of L16(45)was designed with five factors e.g.,pH,temperature,solid-liquid ratio,reaction time and EDTA dosage,which affected the sludge disintegration effect.Under the optimized sludge disintegration conditions,the effects of the sludge disintegration were compared between the thermal alkali and the thermal alkali-EDTA coupling methods.The results showed that compared with the thermal alkali disintegration treatment,the release amounts of SCOD,TN,TP,polysaccharide and protein from thermal alkali-EDTA coupling disintegrated sludge increased by 14.7%,5.6%,9.9%,3.6% and 25.9%,respectively.The thermal alkali-EDTA coupling disintegration led to less VS content in the residual sludge than that by the thermal alkali disintegration(21.93% versus 29.68%).Besides,the proportion of small molecule(<400 Da)in the lysate by the thermal alkali-EDTA coupling disintegration was higher than that by the thermal alkali disintegration(40.68% versus 32.34%).Sludge floc size measurement and SEM observation demonstrated that thermal alkali-EDTA coupling disintegrated sludge had smaller response value in sludge particle size distribution and better flocs dispersion than the thermal alkali disintegration.The above results indicated that the thermal alkali-EDTA coupling method can improve the dissolution rate and the hydrolysis property of organic matter under the medium and low temperature conditions,and further reduce the relative VS content in sludge residue.Obviously,the thermal alkali-EDTA coupling method can strengthen the sludge disintegration effect compared with the thermal alkali method and show a promising prospect.