Experimental Study On The Pretreatment Technology Of Refining Alkaline Waste

Alkaline waste which has high concentration and toxicity was a special organic waste waterwith deep color, smell and strong corrosion. Alkaline waste is one of the main po11ution sourcesof oil refineries. The process of treating with alkaline waste also has some problems now, such asincomplete treatment of wastewater and complex process. The alkaline waste treatment hasalready been a great problem in the wastewater treatment fields of home and abroad. With theincreasing emphasis on environmental protection issues and the enhancement of environmentalprotection consciousness in mind, the research of new type, environmentally friendly and highlyeffective processing craft has been imminent.On the foundation of investigation the methods of advanced treatment for wastewater, themethods have been put forward to reduce its biotoxicity，such as ultrasound-Fenton reagentprocess, bioaugmentation technology. Factors influencing the ultrasound-Fenton combinedprocess for treating alkaline waste of refinery were investigated including the reaction time,n（H₂O₂）/n(Fe²⁺), H₂O₂concentration, initial system pH value and ultrasonic power on theremoval rates of phenol and COD. Bioaugmentation technology, adding highly effective bacteriainto the laboratory system was used to treat alkaline waste of refinery. The factors of hydraulicretention time（HRT），pH value，dissolved oxygen（DO） concentration，dilution multiple andtemperature，which affected the treatment efficiency of alkaline waste were investigated．The study results showed as follows:（1） At constant reaction temperature of30℃andultrasonic frequency of25kHz, under the optimum process conditions of a of n（H₂O₂）/n(Fe²⁺) of30, H₂O₂concentration of293.7mmol/L, initial system pH value of4.0, an ultrasonic power of900W and a reaction time of60min, the removal rate of phenol and COD by this combinedprocess reached87.4%and42.2%, respectively. Treatment by this combined process was muchbetter than that of by single ultrasound method or single Fenton oxidation. The B/C ofwastewater increased from0.10to0.24, and its biodegradabilties were improved greatly.（2）Adding highly effetive bacteria significantly enhanced the biodegradation capacity of the system,and improved the sludge settling characteristics while in the process of bioaugmentationtechnology. The optimum environment conditions of the biological system were HRT48h, waterdilution multiple12times, pH7.0⁸.5, DO3.0⁴.0mg/L, temperature27³2℃. The removalrates of CODCrand phenol could be over87%and95%under optimum conditions. After thehigher concentration of phenol shock, its ability of degradation recovered quickly. It indicatedthat the system possessed stronger resist impact load capability.