剩余污泥超声预处理后水解酸化特性

为探讨剩余污泥超声预处理后的水解酸化特性,考察了0.6 W/mL、5 min和1 W/mL、5 min 2种超声预处理条件下污泥水解酸化过程有机质、氮、磷的释放情况。实验结果表明,2种超声预处理均可促进污泥水解酸化,并且0.6 W/mL比1 W/mL的超声预处理更有利于SCOD的释放、VFAs的产生以及氮和磷的释放;水解酸化初期,超声预处理比未经超声预处理的污泥在有机质、氮、磷释放率上差异非常明显,随着水解酸化的进行,有机质和氮释放率差异仍很明显,而磷释放程度逐渐接近;经0.6 W/mL超声预处理,污泥水解酸化3 d后,SCOD释放率、VFAs浓度、TN释放率和NH4+-N释放率分别是未经处理污泥的1.85、2.63、1.85和1.41倍,而TP和PO43--P释放率较未经处理污泥仅分别多2.44和1.23个百分点。研究表明,控制适宜的声能密度、超声时间和水解酸化进程是超声预处理强化剩余污泥水解酸化效果的关键。

Hydrolysis and acidification characteristics of excess sludge after ultrasonic pretreatment

In order to explore the hydrolysis-acidification characteristics of the excess sludge after the ultrasonic pretreatment, the releases of organic matter, nitrogen and phosphorus in the hydrolysis-acidification phase of the sludge were investigated under two ultrasonic pretreatment conditions of 0.6 W/mL with 5 min and 1 W/mL with 5 min. The experimental results showed that, both ultrasonic pretreatments were able to accelerate the hydrolysis and acidification of the sludge, and the ultrasonic pretreatment at 0.6 W/mL was more helpful to release SCOD, to produce volatile fatty acids (VFAs) and to release nitrogen and phosphorus than that at 1 W/mL. In the beginning of the hydrolysis-acidification phase, the differences in the release rates of organic matter, nitrogen and phosphorus of the sludge between with ultrasonic pretreatment and without ultrasonic pretreatment were extremely obvious. With the progress of the hydrolysis and acidification, the differences in the release rates of organic matter and nitrogen were still very obvious, while the release degrees of phosphorus approached the same. The SCOD release rate, VFAs concentration, TN release rate and NH⁺₄-N release rate of the sludge with ultrasonic pretreatment at 0.6 W/mL were 1.85 times, 2.63 times, 1.85 times and 1.41 times that of the sludge without ultrasonic pretreatment in three-day hydrolysis acidification phase, respectively, meanwhile TP release rate and PO^3-₄-P release rate of the former sludge were only 2.44 percents and 1.23 percents higher than that of the latter sludge. This research indicated that controlling the appropriate ultrasonic energy density, sonication time and the hydrolysis-acidification progress was the key for the ultrasonic pretreatment to strengthen the hydrolysis-acidification performances of the excess sludge.