| The drilling wastewater is a litter generated in Oil drilling process. It has the characteristics of high COD,high salinity,high color and low acidity,and it also has the characteristics of dispersing,complexity and changeability of component.Because of these it is so difficult and costly to treat that it has been a problem which need to be solved quickly by the oil exploration industry.In order to respond to the problem,the article choose three ways and combine them to deal with drilling wastewater by studying COD and color,and it would do the best to reduce the salt content in the wastewater.According to the study of effects of various factors on the process.the optimum operating conditions on each process have been determined and used to design a process to prove its feasibility.The results of the study are as follows.The sodium carbonate and sodium hydroxide were used as a group of precipitating agent during the chemical precipitation process,and it was mainly investigating the effect of initial pH,dosage and reaction time on the removing of calcium and magnesium ions.Through single factor experiments the optimum operating conditions have been determined,which are that the initial pH is in the range of 9 to 9.5,then the dosage of sodium carbonate and sodium hydroxide are 65 g and 32.5 g per liter, at last first reaction time is 10 minutes,the second is 15 minutes.Under the optimum conditions,Ca2+ and Mg2+ removal rate reached more than 99.9%, NH4+ degradation rate reached 51.56%.The electric flocculation have treatment effects on a variety of substances.When using four pure aluminum as the electrode plate,9mm as the plate spacing and 25 ℃ as the water temperature, we have gotten the optimum operating conditions on this process,which were that the initial pH was in the range of 4～6,the electrolysis time was 40min and the current density was 15mA · cm-2.At this point, COD removal rate reached 86.23% and color removal rate reached 89.88%, the water near colorless; Clremoval rate reached 32.38%, removal rate of Ca2+, Mg2+ and NH4+ were 42.31%,85.03% and 67.11%.The O3/H2O2/UV Oxide process was the depth of treatment,and the optimum operating conditions were that the initial pH was ll,the O3 dosage was 35L/h,and accordingly the the H2O2 dosage was 70mg/L, the oxidation time was 35min.At this point COD removal rate achieved 90.89%, color removal rate reached 91.67%,and the water was completely clear and transparent.After three drilling wastewater treatment process were combined,the total removal rate of COD and color were 98.9% and 99.3%, the total removal rate of Ca2+, Mg2+ and NH4+ were 99.99%,99.99% and 84.45% for each,and the total removal rate of Cl- was 32.55%. Slightly adjust the pH,the last of the water would be on full compliance with the third criteria in"integrated Wastewater Discharge Standard" (GB8978-1996).Finally a treatment process has been designed based on the result,and proved to be technically feasible with some economic benefits,yet the cost of desalination was high and the treatment of inorganic salts were not thorough. |
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