| Acrylic fiber wastewater is a kind of high density, complex component,poisonous and harmful wastewater, which does harmful to environment badly. Thewater quality and yield fluctuate greatly. Fushun acrylic fiber factory products fiberusing two-step process of dry acrylic, so the waste water from the factory,s acrylicpolymer plant, spinning and recovery devices and acrylonitrile device have flowedinto the wastewater treatment plant. The current technology ofanaerobic/oxic/active-carbon adsorption presents the high effluent chemical oxygendemand and poor biodegradation of ammonia nitrogen due to the low B/C of0.10.2,which belongs to the typical poisonous and harmful industrial wastewater. As a newtechnology of water treatment, membrane bioreactor has been widely used to thetreatment of high density domestic sewage and industrial waste. After a lot ofinvestigations of technology of fiber production and actual situation of sewagetreatment, based on the conventional membrane bioreactor, a new kind of hybridmembrane bioreactor with multiple tanks and high denitrification efficiency wasdesigned by using the new Biofringe （BF） filling combined with A/O system andbiofilm technology. Experiments of laboratory-scale were carried out to investigatethe performance characteristics of the hybrid membrane bioreactor and also thepilot-scale field operations were carried out to treat acrylic fiber sewage. Theseresults showed that:（1） Compared with the conventional membrane bioreactor（CMBR）, the hybridmembrane bioreactor can improve the TN removal efficiency, which is averagely8.2%higher than that of the CMBR but manifests almost the same efficacies for CODand NH4+-N removals. The biofilm surface of the BF has good nitrification abilityand dehydrogenase activity, thus enhancing the organics and nitrogen removal ability,showing better capabilities of shock loading resistance and recovery, shortening thestart-up period and slowing down the pace of membrane fouling of hybrid membranebioreactor. （2） Acrylic fiber wastewater mainly contains nitrile, phenol, nitrogenheterocyclic ring, amino-compound, ketone, ether, ester, alkane, organic acid, alcohol,sulfocompound, benzene and so on. And nitrogen heterocyclic ring, amino-compound,forked chain alkane, organic acid and alcohol are hard to be biodegradated. The BFbiofilm was cultivated with dynamically continuous water seepage, and thepilot-scale starting-up tests were carried out for35days with great variety ofmicroorganisms, different tanks played different roles in the removals of pollutants.（3） Under the conditions of no less than32h of HRT, recycle ratio of0.8, gaswater ratio of60:1and pH of7.27.8in aerobic tanks, the removal rates of chemicaloxygen demand, ammonia-nitrogen, total-nitrogen of hybrid membrane bioreactor are56.5%、86.6%、45.9%respectively in treatment of anaerobic tank effluent of theexisting unit. The deficiency of alkalinity and carbon sources limits the nitrogenremoval. The removal rates of SO32-, CN-, AN, DMF, BOD, TOC reach to99.34%,91.3%,100%,100%,92.53%,53.49%respectively. On account of efficiency and cost,the hybrid membrane bioreactor could replace the current unit.（4） Fifty percents of components of acrylic fiber wastewater are difficultbiodegradable materials. Pilot-scale on treating acrylic fiber wastewater fromreservoir with membrane bioreactor, ozonation, biological aerated filter have beenconducted. The effluent chemical oxygen demand and ammonia nitrogen of thiscombination method are below80mg/L and8mg/L, which meets the requirements ofGrade1of the National Standard of Acrylic Fiber Industry （GB8978-1996）. At thesame time, nitrile, amino-compound and nitrogen heterocyclic ring are well removed,but regretfully, alcohol concentration is still high. To make acrylic fiber wastewaterreach the discharge standard, aim to reduce investment and overcome theshortcuttings of the process, a new industrialization process flow was submitted forthe treatment of acrylic fiber wastewater. |
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