Study On Treatment Technology Against Oil Spilling In Water

Oil spillings occur frequently,which make a serious threat to urban water supply.It is important to increase emergency response caparcity against oil spillg for water plant.In the past study,the oil removal was studied as a whole.In this study,oil composition was analyzed and oil in water was divided as floating,particle,emulsified(colloidal)and dissolved components.And then the removal technologies were conducted for different oil forms,especially dissolved compoent,so that the removal for oil pollutant could be studied in detail.Oil pollutants studied include diesel oil,crude oil,lubricating oil,vegetable cooking oil,such as soybean oil and canola oil.The main components of diesel oil and crude oil were paraffins,naphthenes and aromatic hydrocarbons.Lubricating oil contained firstly naphthenes,and secondly alkanes Edible vegetable oil mainly contained triglycerides.The fatty acids of soybean oil and canola oil mainly included palmitic acid,oleic acid,linoleic acid and stearic acid,and rapeseed oil contains erucic acid especially.After the oil had been stirred,the lower water sample was a water sample containing emulsified oil in the test.The dissolved oil could be obtained after coagulation sedimentation and filtration for emulsified oil sample.The components of diesel oil and crude oil were paraffins,naphthenes,aromatic hydrocarbons,and other components in order of percentage.The proportion of aromatic hydrocarbons increased significantly,the proportion of naphthenic hydrocarbons dropped significantly,and the content of naphthenes was extremely low in emulsified oil.Dissolved oil mainly contained aromatic hydrocarbons,including alkyl benzene,naphthalene,anthraquinone and tetrahydronaph thalene in order of percentage.Lubricating oil mainly contained paraffins and some naphthenes.The degree of lubricating oil emulsification was very low,and the main component was paraffin,and it was almost insoluble in water.The vegetable cooking oil mainly contained triglycerides,which had a low degree of emulsification and were almost insoluble in water.The emulsified oil concentration of diesel oil changed with the degree of emulsification.It’s value ranged from 2.73 to 23.08 mg/L in the test.Emulsified oil could be removed well by coagulation.The effects of air stripping and activated carbon directly on emulsified oil were both poor without coagulant.After adding coagulant,the effects of air stripping and active carbon both improved.However,naphthalene and 2-methylnaphthalene were still poor by air stripping.Therefore,coagulation is suitable to treat emulsified oil,and the process of coagulation and sedimentation or coagulation and air stripping are both feasible.The total dissolved compounds concentration of diesel oil ranged from 1-1.5mg/L in the test.With the more aromatic hydrocarbons contained in the oil,the oil dissolved in water would increase.Activated carbon could remove all kinds of aromatic hydrocarbons in the dissolved oil.When activated carbon was 15mg/L,the remaining concentrations of xylene were lower than 5μg/L and the concentrations of other Aromatic hydrocarbon were lower than 1μg/L separately.The different aromatic hydrocarbons were adsorpted parallel.Naphthalenes were moved poor by air stripping.Therefore,active carbon is appropriate to treat dissolved oil.Crude oil dissolved similarly to diesel oil,and removal techniques were same.In summary,for diesel oil and crude oil,coagulation and sedimentation could remove paticulateoil and emulsified oil;actived carbon could remove dissolved oil.In the operation,coagulant and powdered actived carbon could be added together.As for Lubricants and vegetable cooking oils,they could be treated by coagulation,sedimentation and filtration,due to their poor emulsification and solubility.