Experimental Research on the Reusing & Recycling Technology of Oil Extraction Wastewater Treatment in Oil Field

How to use water resource effectively is an important problem in developing industry. Three combined processes which are composed of oil separator＋de-emulsification flocculation＋sand filtration （SDF）, oil separator q-hydrolytic acidification＋SBR （SAS） and oil separator＋de emulsification flocculation ＋SBR （SDS） are conducted in laboratory-scale experiment to treat oil extraction wastewater for an oil field. The experimental results show that the removal rate of COD（chemistry oxygen demand） and oil treated by SDF process are 85 % and 95 % respectively, the residual oil in effluent can meet the discharge standard, but the residual COD can not. The removal rate of COD and BOD （biological oxygen demand） of the SAS effluent are 85% and 90% respectively, the BOD can meet but the COD can not meet discharge standard. So the further treatment is required in the process. The SDS effluent with removal rate of 95% and 90% are obtained for COD and BOD respectively, which can completely meet the national standards of oil wastewater discharge and refilling （China）. The experimental result shows that oil extraction wastewater has turned into water resource after being, treated by SDS.

Treatment of Chinese Traditional Medicine Wastewater by Photosynthetic Bacteria

The influence factors treating wastewater of Chinese traditional medicine extraction by photosynthetic bacteria are tested and discussed. The results indicate that the method of photosynthetic bacteria can eliminate COD and BOD from wastewater in high efficiency. And it also has high load shock resistance. On the conditions of slight aerobic and semi-darkness, treating wastewater of Chinese traditional medicine extraction, the method has better efficiency to eliminate COD and BOD from the wastewater than those by anaerobic illumination and aerobic darkness treatments. After pretreatment of hydrolytic acidization, the removal rate of COD in the wastewater reached more than 85 %, and that rate of BOD reached more than 90% in the treating system of photosynthetic bacteria. It may be more feasible and advantageous than traditional anaerobic biological process to treat organic wastewater using PSB system.

Enrichment of copper and recycling of cyanide from copper–cyanide waste by solvent extraction

The enrichment of copper from copper–cyanide wastewater by solvent extraction was investigated using a quaternary ammonium salt as an extractant. The influences of important parameters, e.g., organic-phase components, aqueous pH values, temperature, inorganic anion impurities, CN/Cu molar ratio, and stripping reagents, were examined systematically, and the optimal conditions were determined. The results indicated that copper was effectively concentrated from low-concentration solutions using Aliquat 336 and that the extraction efficiency increased linearly with increasing temperature. The aqueous pH value and concentrations of inorganic anion impurities only weakly affected the extraction process when varied in appropriate ranges. The CN/Cu molar ratio affected the extraction efficiency by changing the distribution of copper–cyanide complexes. The difference in gold leaching efficiency between using raffinate and fresh water was negligible.

Efficient removal of naphthalene-2-ol from aqueous solutions by solvent extraction

Naphthalene-2-ol is a typical biologically recalcitrant pollutant in dye wastewater.Solvent extraction of naphthalene-2-ol from aqueous solutions using mixed solvents was investigated.Various extractants and diluents were evaluated,and the effects of volume ratio of extractant to diluent,initial p H,initial concentration of naphthalene-2-ol in aqueous solution,extraction time,temperature,volume ratio of organic phase to aqueous phase（O/A）,stirring rate and extraction stages,on extraction efficiency were examined separately.Regeneration and reuse of the spent extractant were also investigated.Results showed that tributyl phosphate（TBP） achieved 98% extraction efficiency for naphthalene-2-ol in a single stage extraction,the highest among the 12 extractants evaluated.Extraction efficiency was optimized when cyclohexane and n-octane were used as diluents.The solvent combination of 20% TBP,20% n-octanol and 60% cyclohexane（V/V） obtained the maximum extraction efficiency for naphthalene-2-ol,99.3%,within 20 min using three cross-current extraction stages under the following extraction conditions：O/A ratio of 1：1,initial p H of 3,25°C and stirring rate of 150 r/min.Recovery of mixed solvents was achieved by using 15%（W/W） Na OH solution at an O：A ratio of 1：1 and a contact time of 15 min.The mixed solvents achieved an extraction capacity for naphthalene-2-ol stably higher than90% during five cycles after regeneration.