涂装工艺含磷废水的特征及其污染控制研究

【作者】 雷育涛；

【导师】 罗建中；

【作者基本信息】 广东工业大学 ， 环境工程， 2005， 硕士

【摘要】 涂装是表面工程的重要内容,涂装预处理产生的磷化废水无机磷含量高,化学需氧量和生化需氧量相对较低,用生化法处理难以达到废水排放标准的要求。富营养化污染已成为目前所面临的重大环境问题,多数富营养化水体中控制因素为磷,因此废水的除磷对防止水体富营养化尤为重要。涂装预处理过程是涂装生产主要的污染产生环节、能耗环节、水耗环节,环境污染问题也最严重,是涂装生产推行清洁生产的关键因素所在。 本研究对冰箱涂装工艺锌系磷化废水的特征及其污染控制进行了研究,提出了化学沉淀法除磷、除锌和降低COD值等污染的处理方法,从机理上深入探讨了pH对锌系磷化废水去锌除磷的影响,考察了不同药剂、不同的投加量、不同的pH值条件下对除磷的影响。首次从清洁生产角度改造涂装表面预处理工艺,从源头上削除污染,减少磷化药剂的投加量,减少废水和相关污染物的排放等来提高企业的经济效益。 本论文首先从理论上探讨了沉淀的原理及其影响因素,主要探讨了用Fe²⁺、Fe³⁺和Ca²⁺为沉淀剂除磷时的最佳pH,理论计算结果表明,以Fe²⁺为沉淀剂,pH不应大于3.95;以Fe³⁺为沉淀剂,pH不应大于3.20;只考虑以Ca²⁺为沉淀剂除去PO₄^3-时,pH以高为好。另外,要除去废水中的锌,pH以8.0～10为宜。 进水TP浓度为9.63mg/L～9.68mg/L时,离心分离预处理锌系磷化废水,可除去部分的悬浮物磷酸盐,但去除效果不明显,离心转速为3000r/min,离心时间8min后,对TP的去除率最高也只有10.07%。 本实验以Fe²⁺、Fe³⁺、Ca²⁺为沉淀剂,以PAM为混凝剂,用H₂SO₄、NaOH或Ca（OH）₂调节废水的pH值,通过对沉淀前后废水TP的变化、COD的变化的研究,表明Fe²⁺、Fe³⁺、Ca²⁺盐对锌系磷化废水的处理具有良好的除磷和除COD效果。TP浓度为11.97mg/L时,Fe₂（SO₄）₃的加入量为0.25kg/t废水,PAM的加入量为0.005kg/t废水,出水TP为0.44mg/L,低于一级排放标准0.5mg/L要求;废水TP浓度为12.44mg/L,FeSO₄的加入量为0.2kg/t废水,PAM的加入量为0.005kg/t废水,出水TP为0.21mg/L,大大低于一级排放标准的要求;废水TP浓度为12.24mg/L,CaCl₂的加入量为0.36kg/t废水,以Ca（OH）₂调节废水的pH,PAM的加入量为0.005kg/t废水,pH为10.72时,出水TP为0.47mg/L,达到了一级排放标准的要求。更多还原

【Abstract】 Painting is a very importent infact thing in surface treatment. TP concentration is very high, but COD and BOD are relatively low of the phosphatizing wastewater from painting surface pretreatment. Eutrophication becomes serious environmental problem these days, and the major factor is phosphate for eutrophication. Therefore, we consider it even more important to remove phosphate from wastewater for entrophication control. Painting surface pretreatment process is the key factor to practice cleaner production for painting, due to the fact that it yield most of the pollutant, and it consumes most of the energy, most of the fresh water.Phosphatizing wastewater with zinc from refrigerator painting process was studied about character and pollution control. Some pollution treatment methods about phosphate and zinc removal by chemical precipitation method, reducing COD were also discussed in this thesis. It was mainly studied the effect of phosphate and zinc removal under different reagents, different add-on quality, different pH and so on. It’s the first time that cleaner production was used in painting surface pre-treatment process. It can improve economic benefit applying cleaner production, reducing discharged pollutant and phosphatizing reagents in painting surface pre-treatment process.It discussed the theory of precipitation and its influential factor, the best pH range on theory, while treating phosphatizing wastewater with Fe²⁺, Fe³⁺ and Ca²⁺ as precipitator.The results indicated that pH shouldn’t exceed 3.95 with Fe²⁺, pH shouldn’t exceed 3.20 with Fe³⁺. And higher pH will be better while using Ca²⁺ to remove PO₄^3-. To remove zinc from wastewater, for the pH, 8.0-10 will be better.The TP of wastewater with an inlet concentration of 9.63mg/L⁹.68mg/L, some phosphate can be removed by centrifugation, but it has little purpose, only 10.07% of the TP removed, with 3000r/min, after 8min.In this experiment, we made Fe²⁺、 Fe²⁺、 Ca²⁺ as precipitator, PAM as coagulation, regulated pH of wastewater by adding H₂SO₄, NaOH or Ca（OH）₂, studied the change of TP and COD before and after precipitation. It was indicated that Fe²⁺、 Fe²⁺、 Ca²⁺ had a good effect to phosphate removal and COD removal of phosphatizing wastewater with zinc. When inlet TP is 11.97mg/L, added 0.25kg Fe₂（SO₄）₃ per one ton wastewater, 0.005 kg PAM per one ton wastewater, then outlet TP was 0.44mg/L. When inlet TP is 12.44mg/L, if we added 0.2kg更多还原