Design Of The Treatment Process Of High Salinity Wastewater In The Oilfield

The oil field is located in the northwest edge of Zhungeer Basin,it is 20 km from Karamay.The wastewater treatment station is mainly used to deal with the wastewater produced in H operation area,Hong 003 well area and the four area of 2.The produced water of H oilfield is transported to the softening water treatment system of H oil field sewage treatment station for softening treatment,but in the softening process,due to the regeneration of sodium ion exchanger,a large amount of high salinity wastewater is produced.At present,the high salinity wastewater is discharged into the biological oxidation pond in the oilfield.It was found that the content of COD_cr and volatile phenol in waste-water with high salt content could not meet the requirements of GB8978-1996 wastewater comprehensive discharge standard.Moreover,because the biological oxidation pond in the oilfield without anti-seepage treatment,if the high salinity wastewater is discharged into the biological oxidation pond for a long time,it will pollute the natural resources such as water,air,soil and so on,which will bring difficulties to the rolling development of the oil field.Aiming at the above problems,according to the characteristics of high salinity wastewater in the oil field,the experiment of coagulation sedimentation and microbial treatment of high salinity wastewater in the oil field were conducted.After lab-scale experiment,some petroleum pollutants and refractory organic pollutants can be removed by adding flocculant.The removal rate of COD_cr was 39%⁵0%,the biochemical properties of wastewater were improved.The effective combination of the specific combination of bacteria has a certain effect on the degradation of COD_cr,after microbial treatment,COD_crr was reduced from 335 mg/L to 175 mg/L,the average removal rate was 48%.Through the cultivation,domestication and screening of microorganisms,the bacteria can survive in hypersalinity and high salinity waste water,and the growth and reproduction of bacteria were good,it can degrade organic matter in wastewater preferably.On the basis of the above experiment,the pilot scale test of"coagulation sedimentation+hydrolytic acidification+contact oxidation"and"advanced oxidation+contact oxidation"was carried out.It was found that the high salinity wastewater in the oilfield can meet the requirements of the"secondary standard of GB8978-1996",after the two treatment processes,and the treatment efficiency is preferabl.Combined with domestic high salt wastewater treatment experience,and the investigation of foreign oil field drainage treatment technology,two sets of high salinity wastewater treatment process in the oilfield were designed,one is"coagulation sedimentation+hydrolytic acidification+contact oxidation"and the other is"advanced oxidation+contact oxidatio".The two sets of process were compared with economic budget.Through cost analysis,the average annual cost of the former is 8.2588 million yuan/a,it saved 4.1518 million yuan/a than the average annual cost of the latter process?12.416 million yuan/a?.The total cost per unit of program one is 11.47 yuan/m³,it saved 5.77 yuan/m³ than scheme two units in total cost?17.24 yuan/m³?.Visiblly,the cost of"coagulation sedimentation+biological treatment"is lower and better economic benefits.After a comprehensive consideration,the final choice is the programme one of"coagulation sedimentation+hydrolytic acidification+contact oxidation"process to deal with high salinity wastewater in H oilfield.