焦化废水预处理及其特征污染物的变化分析

摘要

焦化废水是典型的有毒/难降解工业有机废水,表现出高浓度、多相、多组分共存的性质,需对其进行预处理以保证后续生物处理系统高效稳定的运行.本文结合实验数据与工程实例,重点分析了重力沉降、蒸氨/脱酚、混凝/气浮、臭氧氧化单元工艺作为预处理技术对焦化废水原水中特征污染物的分离去除情况.研究发现:经过90min重力沉降,56.05％的悬浮颗粒和46.54％的油分得到分离;接着,将初始pH=10的废水蒸氨50min后,在pH=9、T=30℃、R=1∶4、n=3的条件下采用磷酸三丁酯-30％煤油进行萃取脱酚,氨氮和苯酚的去除率分别为69.85％和76.02％;随后,在FeSO4投加量为1500mg/L、初始pH=9的混凝/气浮反应中,硫化物、氰化物以及氨氮的去除率分别为89.93％、60.68％和2.95％;最后,在臭氧浓度为14mg/L±1 mg/L、初始pH=10、反应时间为80min的臭氧氧化反应中,硫化物、氰化物以及氨氮的去除率分别达到94.92％、91.05％和47.26％.上述研究结果对于焦化废水预处理工艺的进一步优化具有指导意义,同时认为,这类废水预处理技术的优化与应用需要综合考虑相分离、产品分离和有毒物质的转化这3个层面有效性与经济性的结合.%Coking wastewater contains toxic refractory compounds in high loads,distributed between liquid and suspended solids.The pretreatment including gravity sedimentation,ammonia stripping/phenol extraction,coagulation/air floatation and ozonation was applied prior to biological treatment providing its effective performance.The removal of characteristic pollutants was studied in each pretreatment process.The results showed that 56.05％ of suspended solids and 46.54％ oil content were removed in 90min gravity sedimentation.Ammonia was stripped for 50min,and phenol was extracted using mixture of tributyl phosphate with 30％ kerosene at pH=9,T=30℃,R=1 ∶ 4,n=3.Ammonia and phenol were recovered for 69.85％ and 76.02％,respectively.At the FeSO4 dosage of 1500mg/L and initial pH=9,coagulation/air floatation removed sulfide,cyanide and ammonia for 89.93％,60.68％ and 2.95％,respectively.At the concentration of gaseous ozone 14mg/L±1mg/L and initial pH =10,sulfide,cyanide and ammonia were degraded as a result of 80min ozonation for 94.92％,91.05％ and 47.26％,respectively.The results obtained in the study may serve the optimization of the pretreatment process,targeting the purification performance and the economic efficiency with the separation of phases,the recovery of chemical products and the transformation of toxic pollutants.