Study On The Treatment Of Trace Naphthalene And Phenanthrene From The Discharged Wastewater Of Printing And Dyeing Plant By Electromagnetic Membrane Bioreactor System

Although wastewater discharged from printing and dyeing industrial plant treatedby biological system can satisfy the requirement of national comprehensivewastewater emission, trace naphthalene(Nap), phenanthrene(Phe) and otherpolycyclic aromatic hydrocarbons are still in it. Naphthalene and phenanthrene aretwo pollutants of the16polycyclic aromatic hydrocarbons, which belong to prioritypollutants controlled by the United States Environmental Protection Administration.As trace naphthalene and phenanthrene can be accumulated by organism, it causesgreat hazard for health and environment accumulation Therefore, most of researcherspay their attention on the treatment of naphthalene and phenanthrene. In this study,electricity-aerobic biological systems had been developed with aerobic activatedsludge, which taken from the printing and dyeing wastewater plant, and some inertelectrodes such as graphite and titanium. During the wastewater treatment includingtraceable concentration of naphthalene and phenanthrene, some effect factors such ascurrent strength, electrode materials, pH and operation mode have been discussed bybatch experiments. The optimal operation parameters have been obtained based on theresults of those experiments. Moreover, a novel electromagnetic-membrane biologicalreactor (EMMBR) have been constructed. Compared with different aerobic MBRsystems, the treatment ability and effects of the EMMBR system for the dischargedwastewater from a dyeing and printing industry were investigated under thecontinuous operating condition. By means of GC/MS analysis, possible degradationpathway of naphthalene and phenanthrene were investigated. The results are follows:(1) Under the room temperature,when the initial pH is7.0and the initialconcentration of Nap is1ppm, the degradation of nap can reach59%by Electricaerobic biological system developed with the graphite electrode,which is20%and27%higher than the Aerobic microbial system and Electrolysis system.At the samelaboratory conditions excepting the Reactive substances is Phe, the degradation of Phecome to77.3%,which is which is26.3%and21.0%higher than the Aerobic microbialsystem and Electrolysis system.(2)At room temperature when the initial concentration of phenanthrene is12ppb,the proper operating conditions for the Electric aerobic biological system developedwith the graphite electrode: pH=8, I=20mA, sludge VSS=1.0gVss/L, power supplymode: supply1.5h, and then stop0.5h. Under these conditions, the concentration of phenanthrene will below2ppb after reaction4hours. The water quality can meetsdrinking water health standards（GB5749-2006）requirement about the total limitsconcentration of PAHs.(3)In process of continuous operation, the degradation of naphthalene andphenanthrene are14.2%and14%. Using the graphite electrode and the currentintensity is between10mA and20mA, the degradation of naphthalene andphenanthrene are increased to58.1%and56.1%. After adding magnetic biologicalcarrier, which the volume is5%of electromagnetic membrane bioreactor, the averagedegradation rate of naphthalene and phenanthrene are respectively75.8%and75.6%.(4)Speculated by GC/MS analysis, simple electrolysis system for degradation ofphenanthrene is mainly achieved by salicylic acid pathway; while electric aerobicbiological systems degradation of phenanthrene are both the salicylic acid and thephthalic acid pathway.