化学沉淀法脱除焦化废水中的氨氮

【作者】 王香平；

【导师】 史世庄；

【作者基本信息】 武汉科技大学 ， 化学工艺， 2004， 硕士

【摘要】 本文综述了现有氨氮废水处理技术，针对现有的焦化废水处理工艺和氨氮不达标的现状，开发了化学沉淀法作为焦化废水处理系统的一个有益的补充，以解决氨氮超标的问题。 采用武钢焦化公司不同部位的废水，研究了化学沉淀剂、pH值、反应温度、试剂投加量等因素对氨氮脱除效果的影响。探讨了在工业上应用的可能性。 实验结果表明：三组化学沉淀剂（MgCl₂·6H₂O和Na₂HPO₄·12H₂O、MgO和H₃PO₄、Mg（OH）₂和H₃PO₄）都能有效地脱除焦化废水中的氨氮，而以MgCl₂·6H₂O和Na₂HPO₄·12H₂O脱除效果最好。 理论分析和计算表明，脱除氨氮沉淀反应的最佳pH值为8.89，且与氨氮初始浓度无关；而适宜范围随着氨氮初始浓度的增加而增大。试验结果表明，脱除氨氮沉淀反应的最佳pH值范围为8.5～9.5。 反应温度对氨氮脱除效果有较大的影响，反应温度升高，氨氮脱除率降低。 化学沉淀剂投加量以按化学计量系数n(Mg²⁺)：n（NH₄⁺）：n(PO₄^3-)=1：1：1时脱除氨氮的效果最好。增加投加量不但不会提高氨氮脱除率，反而增加操作费用和造成P的二次污染。 当试验条件控制在pH值为8.5～9.5、常温、化学沉淀剂摩尔比为n(Mg²⁺)：n（NH₄⁺）：n(PO₄^3-)=1：1：1时，可将氨氮浓度在500mg／L以下的混沉池水与均合池水脱至15mg／L以下，从而达标排放，氨氮脱除率达95％以上。而蒸氨废水的氨氮脱除率只有75％左右。 实验和探讨表明，化学沉淀法可以作为焦化废水现有一段曝气法焦化污水处理工艺的一个有效补充，可在均合池或混沉池投加化学沉淀剂使氨氮指标达到排放标准。更多还原

【Abstract】 Existing technologies for treating with wastewater containing ammonia nitrogen are reviewed in the paper. According to existing technologies for treating with coking wastewater and present situation on which ammonia nitrogen can’ t meet the need of discharging standard, chemical precipitation used to improve the technology and solve the ammonia nitrogen problem is developed.Using coking wastewater from WISCO, various factors affecting on ammonia nitrogen removal rate such as chemical precipitators, pH value, reaction temperature, dosages etc. are researched. The possibility of application the chemical precipitation to industry production is investigated.Research results have shown that, three sets of chemical precipitators (MgCl2 6H20 and Na2HP04 12H20,MgO and H3P04, Mg(OH)2 and H3P04)can be used to remove the ammonia nitrogen effectively, but when MgCl2 6H20 and Na2HP04 12H20 are used, removal rate of ammonia nitrogen is highest.Theoretical analyses and calculation show that, optimum pH for removing ammonia nitrogen is 8. 89, besides the pH is independent of original concentration of ammonia nitrogen, but applicable range of the PH become broader with increase of original concentration of ammonia nitrogen. Experimentation shows that the range of optimum pH for removing ammonia nitrogen is 8. 5-9. 5.Reaction temperature has effect on removal of ammonia nitrogen. The reaction temperature rises, removal rate of ammonia nitrogen lowers.When the dosage of chemical precipitators is according to stoichiometric coefficient n(Mg2+) : n(NH4+) : n (P043-) =1 : 1 : 1, removal rate of ammonia nitrogen is highest. If increasing the dosage, operation cost would increase and secondary contamination of phosphorus would be produced.On the condition of pH 8.5-9.5, dosage n(Mg2+) : n(NH4+) : n (P043-) =1 : 1 : 1 and room temperature, ammonia nitrogen of coking wastewater from settling pond and from regulating pond with concentration less than 500mg/L can be lowered to less than 15mg/L and discharged on meeting the discharge standard, and the removal rate of ammonia nitrogen is up to more than 95%. But the removal rate of wastewater from distillation of ammonia is only 75%.Investigation and discussion show that the chemical precipitation is an effective means to improve the existing technologies for treating with coking wastewater, the chemical precipitators are added into regulating pond or settlingpond to cause the index of ammonia nitrogen to meet the discharge standard.更多还原