With the stricter sewage discharge standards and higher environmental quality requirements, the development of advanced treatment technology of piggery tail water (the effluent of biochemical unit) is particularly urgently needed. We used dual coagulation with Na⁺ modified zeolite (NMZ) and Mg²⁺/Fe³⁺ chloride to remove COD, TP, NH₃N and turbidity from piggery tail water. Thereafter, the on-site coagulation sludge was oxygen-limited pyrolyzed, and the pyrolyzed sludge (PS) showed a great capacity to adsorb and remove Cd²⁺ from water. Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) analysis showed that abundant new binding sites were generated after pyrolysis, and the surface morphology of PS composites were examined by scanning electron microscopy (SEM). The results confirmed the presence of NMZ, Mg/Fe metal oxides, biochar and phosphates in PS composites, leading to a synergistic effect for high efficient Cd²⁺ removal. The Cd²⁺ adsorption on the composite PS500 (sludge pyrolyzed at 500 °C) can be well expressed by Langmuir isotherm model with theoretical maximum adsorption capacity of 139.28 mg g⁻¹. The adsorption behaviors of PS500 were affected by solution pH, coexisting ions and humic acids. Hence, dual coagulation with NMZ-Mg/Fe chloride is one of the effective methods for the advanced treatment of piggery wastewater, and the coagulation product can be utilized to remove Cd²⁺, which is beneficial to reduction of environmental pollution and resource recovery.

随着更严格的污水排放标准和更高的环境质量要求，迫切需要开发猪尾水（生化单元的出水）的先进处理技术。我们使用Na ⁺改性沸石（NMZ）和Mg ²⁺ / Fe ³⁺氯化物进行双重混凝，以去除猪尾水中的COD，TP，NH ₃ N和浊度。此后，现场凝结污泥被氧限制热解，并且热解污泥（PS）表现出很大的吸附和去除Cd ^{2+的能力。}从水。傅立叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）分析表明，热解后产生了大量新的结合位点，并通过扫描电子显微镜（SEM）检查了PS复合材料的表面形态。结果证实了PS复合材料中存在NMZ，Mg / Fe金属氧化物，生物炭和磷酸盐，从而导致了高效去除Cd ²⁺的协同效应。Langmuir等温模型可以很好地表达复合PS500（在500°C下热解的污泥）对Cd ^2+的吸附，理论最大吸附量为139.28 mg g ^-1。溶液的pH值，共存离子和腐殖酸会影响PS500的吸附行为。因此，用NMZ-Mg / Fe氯化物进行双重混凝是猪场废水深度处理的有效方法之一，该混凝产物可用于去除Cd ²⁺，有利于减少环境污染和资源回收。