As an important chemical raw material, maleic anhydride has been in great demand in the market. The wastewater produced in the process of maleic anhydride production has brought great pressure to the surrounding environment. The application of maleic anhydride wastewater treatment process has alleviated some of the pressure to a certain extent.

顺酐生产过程中废水的来源有两个：

There are two sources of wastewater in maleic anhydride production:

(1) 苯在氧化过程中除生成顺酐外，同时有部分副产物反丁烯二酸(俗名富马酸)、饱和酸、焦油及其它碳化物等生成。因此，氧化工段部分冷凝器由于副产物聚集，而降低冷凝效果，间隔一定时间需用水清洗一次，产生部分废水。

(1) In addition to maleic anhydride, some by-products such as fumaric acid (commonly known as fumaric acid), saturated acid, tar and other carbides are generated during the oxidation of benzene. Therefore, some condensers in the oxidation section reduce the condensation effect due to the accumulation of by-products. They need to be cleaned with water at a certain interval, resulting in some wastewater.

(2) 该工艺恒沸脱水、减压精馏过程中有约5%顺酐异构化形成富马酸和精馏后期部分顺酐残余物出现，每批料结束，需用水清洗塔和釜，也产生一定量的废水，该废水属于高浓度有机污水，并有很强的腐蚀性，其COD在3000mg/L以上，直接排放会造成环境污染， 所以，须应用顺酐废水处理工艺将其处理好。

(2) In the process of azeotropic dehydration and vacuum distillation, about 5% of maleic anhydride is isomerized to form fumaric acid and some maleic anhydride residues appear in the later stage of distillation. At the end of each batch, water is required to clean the tower and kettle, and a certain amount of wastewater is also generated. The wastewater belongs to high concentration organic wastewater and has strong corrosivity. Its cod is more than 3000mg / L, and direct discharge will cause environmental pollution. Therefore, Maleic anhydride wastewater treatment process must be applied to treat it well.

先将待处理的含油及有机物的顺酐废水进入集中池，进行收集处理。将顺酐废水中的顺丁烯二酸在60℃下，经强酸和异构剂的作用异构化成富马酸，然后降温冷却，得到顺酐废水中的富马酸与顺丁烯二酸异构化的富马酸。

Firstly, maleic anhydride wastewater containing oil and organic matter to be treated shall be sent to the centralized tank for collection and treatment. Maleic acid in maleic anhydride wastewater is isomerized into fumaric acid under the action of strong acid and isomer at 60 ℃, and then cooled to obtain fumaric acid isomerized with maleic acid in maleic anhydride wastewater.

将得到的富马酸投入到下个反应釜中，加水升温到110℃，富马酸在热水中溶解。在反应釜中投入活性炭脱色精制，经过滤溶解，再投入活性炭反复脱色两次，然后， 降温结晶，离心分离，干燥，可得工业级富马酸，含量在98%以上。

Put the fumaric acid into the next reactor, add water and raise the temperature to 110 ℃, and the fumaric acid will be dissolved in hot water. Put activated carbon into the reactor for decolorization and refining, filter and dissolve it, and then put activated carbon into the reactor for repeated decolorization twice. Then, cool down, crystallize, centrifuge and dry to obtain industrial fumaric acid with a content of more than 98%.

从反应釜分出粗富马酸的母液，加入到超临界水氧化装置的储液罐，调节双柱塞泵泵头控制流量,进样。用温控仪设定砂浴加热温度在400～500℃,开始加热，调节空压机流量 4～10mL/min，向砂浴吹气，用手动泵加上所需反应压力20～40MPa，此条件下处理后顺酐废水的COD去除率为98%以上。

The mother liquor of crude fumaric acid is separated from the reactor and added to the liquid storage tank of supercritical water oxidation unit. The pump head of double plunger pump is adjusted to control the flow and inject samples. Use the temperature controller to set the heating temperature of the sand bath at 400 ~ 500 ℃, start heating, adjust the flow of the air compressor to 4 ~ 10ml / min, blow air to the sand bath, and use the manual pump to add the required reaction pressure of 20 ~ 40MPa. Under this condition, the COD removal rate of maleic anhydride wastewater after treatment is more than 98%.

采用这种顺酐生产厂家废水处理工艺将顺酐废水中的的顺丁烯二酸经过强酸与异化剂转换成富马酸，将富马酸提取，可以再次利用，同时有效降低废水COD。

Using this maleic anhydride manufacturer's wastewater treatment process, the maleic acid in maleic anhydride wastewater is converted into fumaric acid through strong acid and dissimilator. Fumaric acid is extracted, which can be reused and effectively reduce the COD of wastewater.