Experimental Study On Remediation Of Groundwater/Soil Polluted By Petroleum Hydrocarbon In Dongying City

This study aims at groundwater/soil contamination caused by petroleum exploitationwhich widely existed in petroleum development region of Dongying City, the center city ofYellow River Delta. A typical and representative area is collected. Some groundwater and soilcontamination remedy tests are conducted in this area to acquire the best method of petroleumcontamination controlling, which will provide scientific basis to groundwater and soilcontamination controlling in petroleum development region.The study finds out the current situation of groundwater and soil contamination byground investigation, groundwater and soil sample test and field test. The technologicalcharacteristics of bioremediation process has been grasped through a series of small test andstudy which have been conducted in advance, including the bioremediation to residual sludgeand the microbial treatment to oily water in study site. In Hekou oil field and Xianhe oilfield, three different methods, aeration method, bioremediation method and replacementtechnique, are respectively applied to repair the contaminated groundwater and soil caused bypetroleum. Wanggang Water Injection Station and the contaminated areas around No.11-601well of Hekou oil field which locate in north-east of Hekou District are selected as the studysites.The main conclusions of this study are as follows:Three treatment methods are applied in this study. An area of 6552m2 contaminated bypetroleum around No.11-601 well in Hekou District was divided into two pieces, which weretreated separately with aeration method and bioremediation method. Apart from this, anotherpetroleum soil landfill area of 1610m2 around Wanggang Water Injection Station was treatedwith replacement technique, where 1210m3 of uncontaminated soil was backfilled in.The replacement technique was applied to the soil with high petroleum content. Thismethod is characterized by relatively simple techniques, convenient operations and a shortperiod to reach the treatment requirements. However, follow-up measures have to be carriedon the replaced oily soil to make it meet the standards of replaced soil. Large machinery isused during the whole process, which will result in a high cost. In addition, inadvertentoperation will likely cause secondary contamination which will cause damage to thesurrounding environment.To a certain extent, aeration method can decrease petroleum content in the contaminated soil with low petroleum content, but the effect is not ideal. With the help of environmentalfactors(such as UV and oxygen) and high temperature, aeration method can promote theoxidation, degradation and diffusion of contaminants, which will reduce the concentration ofcontaminants in soil. However, in this method the degradation ability of aboriginesmicroorganisms is weak and the natural degradation process of contaminants is slow. Theremediation effect of this method is not as effective as the method with additional applicationof high performance oil degradation microorganisms.In this study, with the application of oil degradation microorganisms, in two weeks thepetroleum content in target water has decreased from 349mg/L to 0.31mg/L and the CODvalue has decreased from 392 mg/L to 93.4mg/L. To contaminated soil with relatively low oilcontent, the oil content has reduced by 89.8% on average after four months and a halfbioremediation. Compared with aeration method, bioremediation makes the degradation ofpetroleum related contaminants to an even lower level. The petroleum content in soil can bereduced below 3000mg/kg, which reaches the standard of mineral oil content in agriculturalsludge. Wild plants grow in good condition in the restored soil, which proves that thepoisonous effect of the residual petroleum related contaminants has basically eliminated.To sum up, if the petroleum content in soil is not very high, the application ofbioremediation can dramatically decrease the petroleum content in soil and eventually reachthe discharging standard and recover the ecological feature of soil. Therefore, bioremediationtechnology is an economic and effective method on petroleum contaminated soil treatmentwith wide application prospects.