脉冲电促催化氧化对剩余污泥脱水性能影响

Effect of Pulse Electrocatalytic Oxidation on Dewatering Performance of Excess Sludge

以双氧水为氧化剂、铁板为电极,研究高频脉冲电对污泥脱水性能及成分的影响。考察污泥pH值、双氧水投加量以及电解时间、电流密度、脉冲电频率等因素对污泥比阻、滤饼含水率、滤液COD值的影响;利用傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)对污泥进行表征,对比处理前后污泥热值、总氮和主要重金属含量的变化。结果表明:在脉冲电作用下,铁电极释放亚铁离子对过氧化氢氧化污泥具有催化作用;随电解时间延长和电流密度增大,污泥比阻和滤饼含水率均下降,滤液COD增大;在pH值为3~5的介质中,当双氧水投加量为0.5mL/100g污泥、脉冲频率为2.5kHz、电流密度为20mA/cm^(2)、处理时间30min时,污泥比阻减小到3.5×10^(10)m/kg,滤饼含水率降到75%以下,污泥中总氮含量降低35.01%,铅铁铜锌等重金属去除率在14.77%~84.72%;污泥基本结构无明显变化,保留原污泥95.34%的热值。

With hydrogen peroxide as oxidant and iron sheets as electrodes,the effect of high-frequency pulse electricity on the dewaterability and composition of sludge was studied in this paper.It also investigated the influences of various factors,such as the pH value of sludge,the dosage of hydrogen peroxide,electrolysis time,current density and pulse frequency,on the specific resistance of sludge,the moisture content of filter cake and the COD value of filtrate.The sludge was characterized by FT-IR and SEM and the changes of the calorific value,total nitrogen and contents of main heavy metals of sludge before and after treatment were studied.The results showed that the ferrous ions released from the iron electrodes had catalytic action on H_(2)O_(2) oxidatingsludge using pulse electrolyty.With the increase of electrolysis time and current density,the resistance of sludge and the moisture content of filter cake decreased,while the COD value of filtrate increased.In a pH 3-5 medium,when the dosage of hydrogen peroxide was 0.5 mL in 100 g of sludge with pulse frequency 2.5 kHz and current density 20 mA/cm^(2),the specific resistance of sludge was reduced to 3.5×10^(10)m/kg and the moisture content of filter cake less than 75%after 30 minutes.The total nitrogen in sludge decreased by 35.01%,and the removal rate of heavy metals such as lead,iron,copper,and zinc ranged from 14.77%to 84.72%.Meanwhile,the basic structure of sludge had no significant change and the calorific value of the original sludge was retained at 95.34%.