Study On The Treatment Technology Of 6-Nitro-1,2-Azoxynaphthalene-4-Sulfonic Acid Wastewater

6-Nitro-1,2-azoxynaphthalene-4-sulfonic acid（i.e.6-Nitry） is an intermediate for producing acid medium dye. 6-nitry wastewater which comes from 6-nitry producttion, and the wastewater comprises two kinds of wastewater, 1,2,4-acid wastewater and 1,2-Naphthoxydiazole-4-sulfonic acid wastewater. COD, pH value, and treatment difficulty of the two kinds of wastewater are very similar . So the two kinds of wastewater can be mixed before wastewater treatment. This theses mainly studied on the treatment processes of 1,2,4-acid wastewater,and the wastewater composes of high concentration organics, has high toxicity and is difficult to be biochemical treated.This topic took the following methods to treat1,2,4-acid wastewater: （1） TOA-Octanol- Kerosene complex extraction process （2） organic bentonite adsorption process （3） Ferric-Carbon microelectrolysis combined with Fenton oxidation process （4） Flocculation Combined with complex extraction process （5） Flocculation combined with adsorption process.The experiment results indicated that:TOA-Octanol-Kerosene complex extraction process:under the optimum conditions that TOA:Octanol:Kerosene of 4:1:5, Wastewater pH value of 1.7, O/A of 1:5; the optimum parameters of back extraction are follow: NaOH concentration of 15%, phase volume ratio O/B of 2:1, and temperature of 40℃, stirred for 60min and standing for 6h to separate phase, the back extraction efficiency can reach for is 84%.In organic modification of bentonite and its application in 6-nitrate wastewater treatment, three kinds of organic bentonite system were studied: CTMAB modified bentonite （cationic surfactant system）, TOA modified bentonite （organic amine system）, cationic starch modification bentonite （organic polymer system）,by comparison, we got the following conclusions: the difficulty level of the three system from easy to difficult: cationic surfactant system > organic amine system>organic polymer system; the adsorption ability of organic bentonite: the cationic surfactant system （COD removal rate 75%） > organic amine system （COD removal rate 68%） > organic polymer system （COD removal rate 35%）; The cost of 1m³ wastewater treatment is RMB9.5, RMB65.7, RMB11 respectively. surfactants are as organic modifier or assist modifier, the corresponding adsorption ability of the organic bentonite is as follow: cationic surfactant > nonionic surfactant > anionic surfactant.In Ferric-Carbon microelectrolysis combined with fenton oxidation process, the optimum experiment conditions are as follows: adjusted wastewater pH value to 1, added activated carbon dosage of 1%, Fe/C = 3:1,microelectrolysis reacted for 3h at room temperature; adjusted the filtrate pH value to 3, added H₂O₂ for 2.5% dosage, then Fenton reaction for 1h.Flocculation combined with complexation extraction process:self-made dicyandiamide-formaldehyde polymer as flocculant, the main parameters are : adjusted wastewater pH value to 3, added flocculant of 1%, rapidly stirring at 70℃for 2 min, slow stirring for 10min, and then standing for 40min; TOA-Octanol extraction system at the following parameters: pH value is 1.5, phase ratio is 1:6, 40% extractants concentration , extracted at room temperature for two minutes, let it stand to layer for 15min. NaOH solution as back extractant, the main parameters of back extractant are:NaOH concentration is for 15%, phase ratio （B/O） is 1:2, reacted at 40℃.Treatment of 1,2,4-acid wastewater combined flocculation with adsorption process: In the flocculation experiments, use synthetic dicyandiamide-formalin polymer as flocculent, wastewater pH value is 3, flocculant dosage is 1%. In the adsorption experiments, employ synthetic organo modified bentonite as adsorbent, AEO-9 surfactant as modifier.the adsorption conditions are: The wastewater pH value is 8, adsorption time is for 30 min, adsorbent dosage is 5%, operated at room temperature. The process that adsorption after flocculation is more effective than the process flocculation after adsorption.Compared with the main technological and economic index, the treatment effect is as follows:From a technical viewpoint,the treatment effects are: Coagulation-Complex extraction process （COD dropped to 50 mg/L）> Flocculation-Adsorption process （COD dropped to 253 mg/L）> Ferric/Carbon microelectrolysis-Fenton oxidation process （ COD reduced to 860 mg/L）> TOA-octanol-kerosene complex extraction process （COD dropped to 1840 mg/L）> CTMAB bentonite adsorption process （COD dropped to 4300 mg/L）; From economic viewpoint, the treatment results are:Ferric-Carbon microelectrolysis -Fenton oxidation process （treatment costs RMB 5.4/m³） <CTMAB bentonite adsorption process （treatment costs RMB 9.5/m³） <flocculation-adsorption process （process cost of RMB 25/m³） <TOA-octanol-kerosene complex extraction process （treatment costs RMB 55.8/m³） <flocculation-complex extraction process （handling charges RMB 114.2/m³）.Technical and economic requirements in treatment of 6-Nitry wastewater were: COD dropped to 2000 mg/L below, processing costs reduced to less than RMB 50/m³, so flocculation-adsorption Process （preferred when technical factor is top priority）, Ferric/Carbon micro-electrolysis-Fenton oxidation process can meet the requirements （preferred when economic factor is priority ）.