摘 要

本论文以南京某化工企业生产过程产生的含高浓度甲醛的工艺废水为研究对象，通过小试实验考察了尿素缩合法、石灰碱解法以及尿素缩合法-石灰碱解法组合工艺对废水中甲醛的去除效果。

论文首先通过单因素优化法对尿素缩合法的反应条件pH值、尿素投加量、缩合温度、反应时间等四个主要影响因素进行了操作参数优化。实验结果表明：当初始反应pH值为2-3、投加的尿素与甲醛的摩尔比为1.5：1、温度为75℃、水浴加热时间为2h时，废水中甲醛的降解率高达99%以上；

论文其次通过单因素优化法对石灰碱解法的反应条件石灰投加量、碱解反应温度、反应时间等三个影响因素进行了操作参数的优化。实验结果表明当温度为80℃、水浴加热时间为90分钟、投加的石灰与甲醛的摩尔比为1.2：1，废水中甲醛的降解率能达到99.5%以上。化工废水原水甲醛浓度为34631mg/L的甲醛废水处理后甲醛含量低至60mg/L，远低于文献报道的甲醛对微生物的抑制浓度。

论文最后还考察了尿素缩合法-石灰碱解法组合工艺对废水中甲醛的去除效果。组合工艺对尿素缩合法处理之后的废水继续进行处理，将废水处理成甲醛含量低于文献报道的甲醛微生物抑制浓度。

关键词：甲醛废水 尿素缩合法 石灰碱解法

Abstract

In this paper, the process wastewater with high concentration of formaldehyde produced in the production process of a chemical enterprise in Nanjing is studied The removal efficiency of Formaldehyde from wastewater by urea condensation, lime alkaline hydrolysis and Urea condensation-lime alkaline hydrolysis combined processes was investigated in a small scale experiment.

Firstly, the operation parameters of urea condensation were optimized by means of single factor optimization, which included pH value, urea dosage, condensation temperature and reaction time. The results showed that the degradation rate of Formaldehyde in wastewater was over 99% when the initial pH value was 2-3, the molar ratio of urea to formaldehyde was 1.5:1, the temperature was 75 ℃and the heating time was 2 hours.

Secondly, the operation parameters of lime-alkaline hydrolysis were optimized by single factor optimization method, including the reaction conditions of lime dosage, reaction temperature and reaction time. The results show that when the temperature is 80℃, the heating time of water bath is 90 minutes and the molar ratio of lime to Formaldehyde is 1.2:1, the degradation rate of Formaldehyde in wastewater can reach over 99.5% . The concentration of formaldehyde in the raw water of chemical industry was 34631mg/L, and the concentration of Formaldehyde in the treated wastewater was as low as 60 mg/L, which was much lower than the inhibition concentration of Formaldehyde to microorganism reported in the literature.

At last, the removal effect of Formaldehyde from wastewater by urea condensation and lime alkaline hydrolysis was investigated. The wastewater from urea condensation process was treated by the combined process, and the formaldehyde content was lower than the microbial inhibition concentration of Formaldehyde reported in literature.

Key words: Formaldehyde wastewater; urea condensation; lime alkaline hydrolysis

目录

摘要 I

Abstract II

第一章 绪论 1

1.1甲醛废水的来源和危害 1

1.2甲醛的理化性质 1

1.3甲醛废水的预处理方法 1

1.3.1物理法 1

1.3.2化学法 2

1.3.3生物法 4

1.4研究目的及内容 4

1.4.1研究目的 4

1.4.2研究内容 4

第二章 实验准备 7

2.1实验试剂与设备 7

2.2溶液配制 8

2.2.1甲醛储备液的配制 8

2.2.2乙酰丙酮溶液的配制 8

2.3实验分析方法 8

2.3.1方法原理 8

2.3.2标准曲线的绘制 9

2.4水质分析 9

2.4.1废水水质特点 9

2.4.2水质分析 9

第三章 石灰法处理高浓度甲醛废水 11

3.1 石灰法原理 11

3.2 石灰投加量对石灰法降解甲醛效果的影响 11

3.3反应温度对石灰法降解甲醛效果的影响 12

3.4反应时间对石灰法降解甲醛效果的影响 13

3.4小结 15

第四章　尿素缩合法处理高浓度甲醛废水 17

4.1尿素缩合法原理 17

4.1.1传统理论——合成体型结构的脲醛树脂 17

4.1.2糖醛理论——合成Uron环结构的脲醛树脂 18

4.2尿素投加量对尿素缩合法的影响 18

4.3初始 pH对尿素缩合法的影响 19

4.4反应温度对尿素缩合法的影响 20

4.5反应时间对尿素缩合法的影响 22

4.6 尿素缩合—石灰碱解法组合工艺 23

4.6.1石灰投加量对继续处理甲醛的影响 23

4.6.2反应温度对继续处理甲醛的影响 24

4.6.3反应时间对继续处理甲醛的影响 25

4.7小结 26

第五章 结论与展望 27

5.1结论 27

5.2展望 27

参考文献 29

致谢 31

第一章 绪论

1.1甲醛废水的来源和危害

甲醛常用的行业有化工行业、制药业、棉纺织业等，甲醛作为原材料用在涂料、油漆、杀虫剂等产品，除此之外，生产甲醛、聚甲醛和多聚甲醛的工厂是高浓度甲醛废水的主要来源^[1]。

人如果长期呼吸到甲醛气体可能会导致癌症，继而引发各种呼吸疾病、消化功能障碍，从而降低人体的免疫能力，最后导致各种皮肤病、呼吸困难等。女性长期呼吸到甲醛，会导致月经失调，孕妇可能会导致腹中的胎儿发育不正常；刚出生的婴儿长期吸入甲醛，会使婴儿体内的染色体发生改变，最后引发各种疾病；青少年长期生活在含有甲醛环境下，会降低其记忆力，严重的会降低智力^[1]。