多通道网状电极电化学预处理垃圾渗滤液反渗透浓缩液
Electrochemical pretreatment of landfill leachate RO concentrate with multi-channel mesh electrodes
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摘要: 反渗透(Reverse Osmosis,RO)因出水水质好、运行成本低等优势常用于垃圾渗滤液的处理,但产生的RO浓缩液具有COD高、色度高、盐分高、难降解等特点,其处理存在效果差、能耗和成本均较高等问题.本工作采用氧化钌/氧化铱涂层电极(RuO2/IrO2-Ti)的钛网为阳极,以304不锈钢电极为阴极,设计制作了6通道的电化学反应器,通过电化学氧化处理RO浓缩液,研究考查了电流密度、循环流速、比电极面积等参数对COD去除效果的影响,分析了电化学氧化去除难降解有机物并同时脱盐的过程机理与能耗.结果表明,在电流密度32.89 mA·cm-2,循环流速0.46 cm·s-1,比电极面积65.10 m2·m-3的条件下,电化学氧化处理RO浓缩液3 h,COD去除率可达68.0%,TOC去除率可达40.6%,脱盐率可达72.1%,去除单位质量COD能耗仅为常规的板状电极电化学反应器的25.5%.本工作可为垃圾渗滤液RO浓缩液的预处理提供新思路.Abstract: Reverse osmosis (RO) is widely used in the treatment of the municipal solid waste leachate because it has the advantage of high quality of treated effluent, low running cost, etc. However, the concentrate produced during the RO process has high COD, high color, high salt content and is extremely hard to be degraded. At present, the treatment of RO concentrate is rather costly, low efficient and high energy consumption. In order to solve these problems, a novel electrochemical treatment process of RO concentrate in a homemade six-channel electrochemical reactor with the RuO2/IrO2 coated titanium mesh anodes and the 304 stainless steel plate cathodes were proposed. The effect of operation parameters of the current density, liquid circulation velocity and specific electrode area on COD removal was investigated. The degradation mechanism of the refractory organics and the energy consumption of the electrochemical oxidation process were also analyzed and calculated. The results show the COD, TOC and salt removal efficiency was 68.0%, 40.6% and 72.1% respectively after electrochemical treatment for 3 hours under the optimal conditions of current density of 32.89 mA·cm-2, liquid circulation velocity of 0.46 cm·s-1, and the specific electrode area of 65.1 m2·m-3. Compared with the conventional electrochemical treatment process using plate electrodes, the per kilogram COD removal energy consumption of the proposed electrochemical process is only 25.5% of the former one. Therefore, this work could provide an alternative choice for the pretreatment of landfill leachate RO concentrate.
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