Reseaerch On Microwave And Chemical Oxidation Technology Of Fracturing Wastewater

Oil and gas fracturing wastewater is diffcult to be degradation by conventional treatments for its high organic content(COD),complex composition and large viscosity.In this paper,combined treatment technology of microwave,advanced oxidation,flocculation,sedimentation and activated carbon adsorption on oil fracturing wastewater were carried to reduce the COD of the wastewater.The main conclusions were as follows:(1)Under the conditions of microwave power 800 w and 6min of radiation time,microwave as fracturing pretreatment process could lead to the increase of wastewater COD by promoting the degradation of refractory organics.(2)The COD removal efficiency was poor when the pretreated oil fracturing wastewater by microwave was oxided the single oxidant(such as hydrogen peroxide,sodium hypochlorite and potassium persulfate).It can be only as a pre-oxidant.(3)The conditions of different advanced oxidation technologies(UV/Fenton reagent,UV/H2O2/ferric oxalate system and UV/ H2O2/ferric citrate system)for the pretreated oil fracturing wastewater by microwave were carried by by the orthogonal test and response surface test.The results showed that UV / Fenton reagent had better degradation effect compared to other treatments,and the wastewater COD removal rate reached to 89.7% under the conditions that initial p H 2.6,the dosage of hydrogen peroxide was 1.9%,the mol rate of H2O2 and Fe2+was 6:1,UV illumination time was 30 min.(4)The conditions of the combined treatment technologies of different advanced oxidation technologies(UV/Fenton reagent,UV/H2O2/ferric oxalate system and UV/ H2O2/ferric citrate system),chemical flocculation and activated carbon adsorption on the pretreatedoil fracturing sit-wastewater by microwave were carried respectively.The results showed that:the process of "microwave-chemical oxidation-coagulation sedimentation-activated carbon adsorption" could make the COD of wastewater reduced from 3995.6mg/L to 398.2mg/L,its COD removal rate was 92.4%.In this process,the wastewater was oxided fristly undert he conditions that: the microwave power was control in 800 w for 6min,the initial p H was2.6,the dosage of hydrogen peroxide was 1.9%,the mol rate of H2O2 and Fe2+was 6:1,UV illumination time was 30 min.,Then chemical flocculation treatment on the pre-oxidation wastewater was carried under the conditions that the initial p H was 9.0,the PAC dosage was1600 mg/L,the PAM dosage was 300mg/L,the dosing gap between PAC and PAM was controled to be 20 s,.After settling 30 min,the treated wastewater was adsorpted by activated carbon for 1.5h under the dosage of 15g/L.In short,through this experiment,although the COD of fracturing wastewater does not meet the relevant national secondary effluent standards efflux,but the determined treatment process of organic pollutants in wastewater can be better removal.The wastewater treatment in this study may provide a more reasonable and feasible process method for fracturing wastewater...