Research On The Remediation And Reducing Quantity Of Petroleum Contaminated Soils

The leaking petroleum contaminated soils is a heavy threat to the human health and environment.It has been a global environmental issue and the treatment of reducing quantity,harmless,reclamation also has become a trend.So the technology of extracting oil from petroleum contaminated soils by hot alkaline water and mechanical dewatering process is investigated to provide technical support and theoretical foundation.It was found that residual oil showed a trend of rising after decreasing with the increasing concentration of NaOH and alkaline water-oily sludge ratio and decreased drastically with temperature.The proper parameters were 0.2% NaOH,alkaline water-oily sludge ratio 4:1 and temperature 80℃.In the experiments of dewatering,it showed that the flocculation capability of AlCl₃,Fe₂（SO₄）3 and PAC was strongly influenced by p H.While Ca2+ ions turning into Ca（OH）+ and Ca（OH）2 boost the flocculation of tiny particles.Synthetically,taking the filtration ration,moisture content and residual oil ratio into account,we could draw a conclusion that 0.8% Ca Cl2 is proper.The effect of surfactant,particles,salts and p H on o/w emulsions was studied in this paper.With the increase concentration of surfactant,the diameter of droplets decreased and stabilized the emulsions.So the surfactant booted emulsification and it was significant to the separation of oil.The influence of particles was separate due to the different properties of clays and silica.The montmorillonite solution could form light flocks and 3D reticulation hindering the coalescence.But high concentration of silica had little effect on solution viscosity,and the heavy flacks struck the oil droplets breaking the interfacial film inducing coalescence.Therefore clays and little silica were important in the formation of particles stabilized emulsions.Salts always broke the emulsions especially the Mg2+,Ca2+ which inactivated surfactants,so it was necessary to monitor the concentration of salts.As the p H was beyond 11 the type of emulsion obtained varied,it had an adverse effect on o/w emulsions.According to the results,surfactant,the properties of sands,salinity in water and p H all had a significant effect on o/w emulsions which was the key in oil recovery efficiency.Based on the studies,a hot alkaline water and mechanical dewatering process was formed and it provided a reference for the treatment of petroleum contaminated soils.This work was financially supported by National Natural Science Foundation of China（NSFC,No.41471258）.