碳中和愿景下碳化污泥吸附耦合铁盐混凝处理污水

Combination of sludge-derived-carbon adsorption and coagulation of iron salt for sewage treatment under the vision of carbon neutrality

以市政污水处理厂剩余污泥为原料,经连续高速污泥碳化系统脱水、干化和缺氧干馏处理后,可制得碳化污泥吸附剂。通过检测碳化污泥的基本特征参数、粒度分布、元素组成、水溶物和重金属离子表征其物理化学特性,并用碳化污泥吸附与三氯化铁混凝耦合处理污水。结果表明,碳化污泥的孔容积、比表面积和碘值分别为0.10 cm^(3)/g、140 m^(2)/g和515.2 mg/g,颗粒粒径主要分布在1.0~5.7 mm,碳质量分数接近50%,最大碳氢质量比(C/H)为39.09,且碳化过程实现了剩余污泥中重金属离子的固定化,溶出物质量浓度和重金属离子质量浓度均低于水处理相关标准指标值,可被安全应用于污水处理。利用碳化污泥吸附耦合铁盐混凝对市政污水进行深度处理,在三氯化铁、碳化污泥投加量分别为15 mg/L和4 g/L时,污水中COD、NH3-N、TP和浊度的去除率分别为59.38%、28.20%、59.41%和91.84%。碳化污泥吸附与铁盐混凝的协同作用,不仅可提高污水中各类污染物的去除率,而且可减少33.33%的三氯化铁投加量。

Using the excess sludge from municipal sewage treatment plant as raw material,sludge-derived-carbon adsorbent was prepared by dehydration,drying and anoxic retorting through continuous high-speed carbonizing system.The physical and chemical characteristics of sludge-derived-carbon were examined in terms of the basic parameters,the particle size distribution,elemental composition,dissolved matter and heavy metal ion contents.Furthermore,the removal rates of pollutants for sewage treatment were also investigated through the combination of sludge-derived-carbon adsorption and coagulation of ferric chloride.The results showed that the pore volume,specific surface area and iodine value of sludge-derived-carbon could reach 0.10 cm^(3)/g,140 m^(2)/g and 515.2 mg/g,respectively.And the particle sizes of sludge-derived-carbon were mainly 1.0-5.7 mm.The carbon mass fraction of sludge-derivedcarbon was close to 50%,and the maximum mass ratio of carbon to hydrogen(C/H)was 39.09.As the immobilization of heavy metals in the carbonization process,the mass concentration of dissolved matter and heavy metal ions of sludge-derived-carbon were lower than the relevant standard of water treatment,which could be safely applied to sewage treatment.The municipal sewage was further treated by sludge-derived-carbon adsorption coupled with ferric salt coagulation.When the dosage of ferric chloride and sludge-derived-carbon were 15 mg/L and 4 g/L,the removal efficiencies of COD,NH3-N,TP and turbidity reached to 59.38%,28.20%,59.41%and 91.84%,respectively.The removal rates of pollutants could be improved significantly by means of the synergistic effect of sludge-derived-carbon adsorption and coagulation of iron salt.Meanwhile,the dosage of ferric chloride had been reduced by 33.33%.