MgFe类水滑石法强化混凝深度处理猪场尾水及混凝污泥特性研究

Advanced treatment of piggery wastewater via enhanced coagulation with Mg/Fe layered double hydroxides and analysis of the coagulation sludge properties

为了深度处理经二级生化处理后的猪场尾水,采用Mg Fe类水滑石法强化混凝猪场尾水。考察了不同pH值、Mg与Fe摩尔配比[n(Mg∶Fe)]等混凝条件对猪场尾水常规指标以及其中微量重金属[Zn^(2+)、Cu^(2+)、Cr(Ⅵ)]和兽用抗生素(磺胺甲基异恶脞,SMX)等去除效果的影响,并利用X射线衍射(XRD)、扫描电镜(SEM)和傅立叶转换红外(FTIR)等技术对混凝污泥特性进行分析,制备了催化材料,进行了混凝污泥资源化利用初探。结果表明:当猪场尾水初始pH>6.5时,TP、浊度和Cr(Ⅵ)去除率分别在95%、80%和35%以上。当初始pH值进一步调节至大于8.0时,MgFe类水滑石对Zn^(2+)和Cu^(2+)去除率可达85%以上,对SMX去除率在75%以上;Mg与Fe摩尔配比对各水质指标去除效果影响不大。混凝污泥主要形成的矿物相有类水滑石与磷酸铁矿物。通过煅烧混凝污泥制备高级氧化催化剂,发现在相同过硫酸氢钾(PMS)投加量的条件下,700℃限氧热解混凝污泥制得的催化剂比同条件下利用人工合成MgFe类水滑石制得的催化剂具有更高的催化活性。研究结果可为养猪处理废水与混凝污泥资源化利用研究提供支持。

After the second stage of biochemical treatment, piggery wastewater still contains a high level of contaminants, and further pro- cessing is required.The effects of initial pH and Mg/Fe molar ratio on the removal of water contaminants were investigated in this study. The coagulation precipitates were analyzed via X-ray diffraction （XRD）, scanning electron microscopy（ SEM ）, and Fourier transform infrared spectroscopy（FTIR）, and the coagulation sludge was cycled as a kind of catalyst for the first step of resource utilization. The results showed that when the initial pH value of the piggery wastewater was above 6.5, the removal rates of TP and Cr（ Wl ） and the reduction of turbidity reached over 95%, 35%, and 80%, respectively. When the pH value was higher than 8.0, the removal rates of Zn2＋ and Cu2＋ reached over 85%, and the removal rate of SMX could reach over 75%. However, the Mg/Fe molar ratio had little effect on coagulation. Analysis of the coagulation sludge showed that mainly layered double hydroxides and iron phosphate minerals were formed. At last, we prepared catalysts with coagulation sludge under the conditions of 700 ℃ and limited oxygen and found that with the same amount of potassium monopersulfate （PMS） addition, catalysts prepared with coagulation sludge had higher catalytic activity than those prepared with Mg-Fe LDHs. This finding shows the great potential of the obtained coagulation sludge in resource utilization.