順酐是順丁烯二酸酐的簡稱，又稱馬來酸酐或者失水蘋果酸酐，是一種重要的有機化工原料或精細化學(xué)品，主要用于不飽和聚酯樹脂、醇酸樹脂、1,4-丁二醇(BDO)、四氫苯酐等化工產(chǎn)品，開發(fā)應(yīng)用前景十分廣闊。目前國內(nèi)外在正丁烷為原料的順酐工藝中，多采用有機溶劑為吸收劑，有機溶劑一般為六氫化鄰苯二甲酸二異丁酯(DIBE)和鄰苯二甲酸二丁酯(DBP)。有機溶劑吸收順酐后通過氣提工段提純順酐，吸收劑經(jīng)分離機處理之后循環(huán)使用。以正丁烷為原料順酐產(chǎn)生的廢水來源于三部分，即解析真空泵排出的廢水、精制真空泵排出的廢水和離心機輕相排出的廢水，其中混合有機酸及醋成分包括丙烯酸、馬來酸、富馬酸、鄰苯二甲酸、六氫化鄰苯二甲酸二異丁酯(DIBE)或者鄰苯二甲酸二丁醋(DBP) 、丙烯酸二聚體，廢水pH=0.5-1.5，總有機物含量在1.0%-1.4% ，幾乎不含氮、磷和無機鹽類，屬于高濃度化工廢水。有機酸及DIBE等溶劑是增加水體COD的源頭，還含有一定量的氨(胺)基化合物、雜環(huán)化合物、酚類、苯類，屬生物不易降解高濃度有機廢水成分，對微生物生長具有抑制作用。此類廢水中間產(chǎn)物均對微生物有較強的抑制作用，我們常稱為生物毒性，并具有很強的腐蝕性。
Maleic anhydride, also known as maleic anhydride or dehydrated malic anhydride, is an important organic chemical raw material or fine chemical used in the production of unsaturated polyester resin, alkyd resin, 1,4-butanediol (BDO), tetrahydrophthalic anhydride and other chemical products. Its development and application prospects are very broad. At present, in the production process of maleic anhydride using n-butane as raw material both domestically and internationally, organic solvents are mostly used as absorbers. The organic solvents are generally diisobutyl hexahydrophthalate (DIBE) and dibutyl phthalate (DBP). After the organic solvent absorbs maleic anhydride, it is purified through the gas extraction section, and the absorbent is treated by a separator before recycling. The wastewater generated from the production of maleic anhydride using n-butane as raw material comes from three parts, namely the wastewater discharged from the analytical vacuum pump, the wastewater discharged from the refining vacuum pump, and the wastewater discharged from the centrifuge light phase. The mixed organic acid and vinegar components include acrylic acid, maleic acid, fumaric acid, phthalic acid, diisobutyl hexahydrophthalate (DIBE) or dibutyl phthalate (DBP), and acrylic acid dimer, with a pH of 0.5-1.5, The total organic matter content is between 1.0% -1.4%, almost free of nitrogen, phosphorus, and inorganic salts, belonging to high concentration chemical wastewater. Organic acids and solvents such as DIBE are the sources of increasing COD in water bodies. They also contain a certain amount of ammonia (amine) based compounds, heterocyclic compounds, phenols, and benzenes, which are not easily degraded by organisms as high concentration organic wastewater components and have inhibitory effects on microbial growth. The intermediate products of this type of wastewater have a strong inhibitory effect on microorganisms, commonly referred to as biological toxicity, and have strong corrosiveness.
目前的順酐廢水處理工藝一般是：順酐工藝廢水-集水井-隔油調(diào)節(jié)池-EBR反應(yīng)器(鐵碳微電解)-破乳反應(yīng)池-氣浮系統(tǒng)-緩沖水池-混凝沉淀池-配水池-IC反應(yīng)器-一階氧化-中間沉淀池-二階氧化池-二級沉淀池-臭氧氧化池-生物濾池-清水池，由于其中含有較多的難降解有機物，經(jīng)過現(xiàn)有技術(shù)進行生物降解后仍很難達到排放標(biāo)準(zhǔn)，并且造成廢水處理費用高。
The current treatment processes for maleic anhydride wastewater generally include: maleic anhydride process wastewater - collection well - oil separation regulation tank - EBR reactor (iron carbon micro electrolysis) - demulsification reaction tank - air flotation system - buffer tank - coagulation sedimentation tank - distribution tank - IC reactor - first order oxidation - intermediate sedimentation tank - second order oxidation tank - second order sedimentation tank - ozone oxidation tank - biofilter - clean water tank. Due to the high content of difficult to degrade organic matter, After biodegradation with existing technologies, it is still difficult to meet the discharge standards and result in high wastewater treatment costs.
現(xiàn)有技術(shù)中處理順酐廢水時，把順酐廢水中的馬來酸異構(gòu)為富馬酸，然后降溫結(jié)晶得到富馬酸，同時降低廢水中有機物含量，但是此方法僅適用于水吸收法順酐工藝，而不適用普遍使用的有機溶劑吸收法。
In the existing technology, when treating maleic anhydride wastewater, the maleic acid in the wastewater is isomerized into fumaric acid, which is then cooled and crystallized to obtain fumaric acid, while reducing the organic content in the wastewater. However, this method is only applicable to the water absorption method of maleic anhydride process, and is not applicable to the commonly used organic solvent absorption method.
另外，有人提出一種順酐廢水處理的新工藝，即使用堿性萃取劑回收其中的馬來酸和富馬酸，降低廢水中的有機物，然后再去生化處理廢水，但是廢水中六氫化鄰苯二甲酸二異丁酯(DIBE)或者鄰苯二甲酸二丁醋(DBP)的可生化降解性比富馬酸、馬來酸等要低很多，其主要是針對廢水中的有機酸性物質(zhì)的回收處理，但該方法對于廢水中的難降解有機物如DIBE或者DBP沒有考慮，廢水難降解有機物含量依然較高，亦難以進行生化處理，主要依靠其他水稀釋處理達標(biāo)排放。可見，順酐廢水處理工藝需要進行改進。
In addition, some people have proposed a new process for treating maleic anhydride wastewater, which uses alkaline extractants to recover maleic acid and fumaric acid, reduce organic matter in the wastewater, and then biochemical treatment of the wastewater. However, the biodegradability of diisobutyl hexahydrophthalate (DIBE) or dibutyl phthalate vinegar (DBP) in the wastewater is much lower than that of fumaric acid, maleic acid, etc, It mainly focuses on the recovery and treatment of organic acidic substances in wastewater, but this method does not consider the difficult to degrade organic substances such as DIBE or DBP in wastewater. The content of difficult to degrade organic substances in wastewater is still high, and it is also difficult to carry out biochemical treatment. It mainly relies on other water dilution treatments to meet the discharge standards. It can be seen that the treatment process of maleic anhydride wastewater needs to be improved.
