响应面法优化复合缓释碳源填料的制备及其脱氮特性

Optimization for preparation of composite slow-release carbon source filler by response surface methodology and its denitrification characteristics

针对污水处理厂出水普遍存在有机碳源不足的问题,以湿地植物菖蒲(Acorus calamus)和β-羟基丁酸与β-羟基戊酸共聚物(PHBV)为原料优化制备复合填料。采用响应面法Box-Behnken Design模型研究了碳源质量配比、冷冻及交联时间等关键参数对填料有机物(以TOC计)释放特性的影响。结果表明,冷冻时间单因素、质量配比-交联时间组合因素对释碳性能的影响显著。静态浸出实验结果表明,该填料具备优良的碳源缓释特征,有机碳释放量和平均释放速率分别为(35.27±1.50)mg·g^(-1)和(0.88±0.05)mg·(g·d)^(-1),释碳过程遵循二级动力学和Ritger-Peppas动力学模型。实验条件下,在初始NO_(3)^(-)-N质量浓度为5~20 mg·L^(-1)的反硝化批次实验中,生物脱氮效果优良,NO_(3)^(-)-N平均去除率为84.42%~92.20%。BET表征结果表明优化制备填料的比表面积为3.05 m^(2)·g^(-1),孔径为26.38 nm。扫描电镜(SEM)和荧光激发发射矩阵(EEM)分析结果表明,优化制备填料表面粗糙多孔,有利于微生物的生长利用与附着,浸出液有机物主要为类蛋白类物质等,具有良好的脱氮微生物可利用性。复合填料实现了持续释碳和生物脱氮过程的协同,可为基于碳源填料强化的污水深度脱氮技术研发提供参考。

In response to the prevalent issue of inadequate organic carbon content in the effluent of urban wastewater treatment plants,the composite slow-release carbon source fillers were developed with Acorus calamus,a natural wetland plant,andβ-hydroxybutyric acid andβ-hydroxyvaleric acid copolymer(PHBV)as primary materials.The Box-Behnken Design model within the response surface methodology was utilized to study the impact of various mass ratios,freezing time,cross-linking time,and other key preparation parameters on the release properties of organic matter(measured in terms of TOC).The results indicated that both freezing time and the mass ratio-crosslinking time combination factors had a significant impact on carbon release properties.The results of the static leaching experiments indicated that the filler could slowly release carbon source with an average organic carbon release rate of(0.88±0.05)mg·(g·d)^(-1)and a total organic carbon release of(35.27±1.50)mg·g^(-1).The carbon release behavior followed both second-order kinetic and Ritger-Peppas kinetic models.In denitrification batch experiments with initial NO_(3)^(-)-N concentrations ranging from 5 mg·L^(-1)to20 mg·L^(-1),the biological denitrification effect was good with an average NO_(3)^(-)-N removal rate of 84.42%to92.20%.The BET characterization indicated that the optimally prepared filler had a specific surface area of3.05 m^(2)·g^(-1)and a pore size of 26.38 nm.The scanning electron microscopy(SEM)and the fluorescence excitation-emission matrix(EEM)analysis results indicated that the surface of the optimally prepared filler was rough and porous,which was conducive to the utilization of microbial growth and their attachment.The leachate organic matter consisted mainly of proteins,and they were available for microbial denitrification.The composite fillers demonstrated the combined effect of continuous carbon release and biological nitrogen removal processes,and can provide a reference for advanced denitrification technology from wastewater based on the carbon source fillers enhancement.