Research On Degradation Of Refractory Organic Compounds In Coking Wastewater By Ultrasonic And Ozone Technology

Water pollution is one of the most urgent problems, which has to be soluted, specially the treatment of the difficult degradable organic pollutants, which is an important topic of potential environment research. Residual refractory organic in coking wastewater after biochemical treatment is a main issue to affect the depth reuse. In this article, the depth reuse of secondary biological treatment in coking wastewater is the main target of treatment, selecting the actual coking wastewater and typical refractory organics phenol as the main object of this study and exploring the effect and mechanism of ultrasonic and ozone technologies to refractory organics through experiments. By the experiments we find that:(1) Wastewater Initial pH value, initial concentration, ultrasonic time, ultrasonic power, ultrasonic frequency and the amount of fragmentation and other factors on the chemical oxygen demand CODCr degradation rate impact, ultrasonic treatment of different conditions on the phenol wastewater and secondary biological treatment of coking wastewater effluent difficult degradation of degradation of organic matter is different:in favor of increasing the time of ultrasound degradation of organic matter; the effect of low concentration organic wastewater by sonication than the high concentration of organic waste is good; the greater the degradation of ultrasound power value the better, but there is a critical optimum value; more conducive to ultrasonic frequency ultrasonic degradation; the smaller the amount of waste water broken in favor of ultrasound degradation; different organic matter corresponds to a good initial pH value. Under conditions of 45kHz ultrasonic frequency, the control ultrasonic time 120min, pH value of 7 to 8, ultrasonic power 200W, crushing volume lOOmL, ultrasonic treatment of coking wastewater treatment effluent has the best secondary biochemical degradation efficiency.(2) By means of molecular sieving before and after ultrasonic treatment of coking wastewater graded molecular weight distribution, the results showed that pretreatment of coking wastewater when CODCr indicators for the detection of organic compounds in water samples molecular weight organic content up to 5～10kDa, reaching 38.42% where in the organic matter content of less than 5kDa 21.91%; with UV254 as the characterization of water samples by molecular weight less than 5kDa organic content as high as 70.10%; coking waste water samples CODCr content after ultrasonic treatment with UV254 trends generally showed a uniform, when in CODCr organic matter detection index, water samples molecular weight less than maximum organic content 5kDa, reaching 40.73%, when the UV254 as the characterization of water samples by molecular weight less than 5kDa organic content is also the largest, accounting for 74.33%; sonication after the small organic molecules were significantly increased, which is coking wastewater sonication improve the theoretical basis of biodegradability.(3) Before sonication coking wastewater, BOD5/CODCr is 0.03, much less than 0.3, which is difficult to coking wastewater biodegradable lies; After sonication, BOD5/CODCr is 0.31, B/C 10.33 times improved, and B/C>0.3, biodegradability substantial increase, indicating that sonication benefit coking refractory organics in wastewater biodegradability improvement, and ultrasonic treatment significantly increased small molecule organic content.(4) Composition was analyzed by GC/MS before and after ultrasonic treatment of coking wastewater in water samples. Results show that, after the treatment of coking wastewater by ultrasonic, a part of the organic matter content decreased significantly, the ultrasonic degradation of organic matter for quinoline and pyridine containing nitrogen organic compounds and benzene, naphthalene, dimethyl benzene volatile organic compounds. Phenol, phenol and cresol organic compounds have not been fully degraded, but its concentration also decreased. This is the main reason for the improvement of B/C in coking wastewater after ultrasonic treatment.(5) Phenol wastewater and coking wastewater ozone treatment, the results showed that the initial pH value, initial concentration, reaction time and broken ozone and other factors had a significant effect on the rate of degradation of the chemical oxygen demand CODCr, different degradation law under different conditions:increased ozone action time help to improve the rate of degradation of organic matter; the same amount of ozone good condition, the effect of low concentration coking wastewater/phenol wastewater effluent concentration is high; the smaller the amount of waste water broken in favor of ozone on organic substances degradation; different organic corresponds to a preferred initial pH. When the control ozone through time 60min, pH value of 7, when the crushing volume of 100L, ultrasonic treatment of coking wastewater has the best degradation efficiency (55.45%).Experimental study results for coking wastewater pilot engineering research and design to provide effective reference data, and ultrasonic and ozone treatment on difficult degradation organic wastewater can biochemical improvement to provide reference, laying a theoretical basis for further study.