The Experimental Research Of In-situ Bioremediation Control About Petroleum Polluted Sediments

Wang Yao Reservoir is the most important water supply source in Yan An.The reservoir is polluted by petroleum seriously in the long run.Some Of these pollutants consist in water in the form of floating oil,emulsive oil,soluble oil,and the others consist in sediments because of sorption of silts.Because the petroleum pollutant in the sediments will release and form secondary pollution to water,consequently bring a series of potential threatens to municipal water supply.The paper is about influence factors of Plesionmonas sp and Change of environmental factors.The main conclusions of the paper were as follows:(1)The influence on petroleum removal efficiency by the petroleum concentration,inoculum concentration,and dissolved oxygen concentration in the upper water is studied.The experimental results indicated that too high or too low petroleum concentration in the sediments went against petroleum biodegradation. When the Petroleum concentration in the sediments is low relatively,degradation rate of petroleum increases along with initial petroleum concentration.When the petroleum concentration in the sediments is 179.71mg/kg and 208.28mg/kg, petroleum removal rate per biomass is 0.91 mL/(d·10¹¹cfu)and 1.42mL/(kg·d·10¹¹cfu), higher than the other three groups obviously,which indicated that microorganism can grow healthily in the situation,therefore the degradation capability of petroleum can bring into play.Petroleum removal rate in the sediments is in proportion to biomass, when the biomass is 30mL,the peteoleum removal efficiency in the sediments is fast, that is 13.53mg/(kg·d).(2)After granular activated carbon is cultured bio-film,the petroleum removal rate in the upper water is 75.32%at last,and the petroleum removal efficiency is 0.207mg/(L·d),higher than granular activater carbon entirely.After zeolite is cultured bio-film,the petroleum removal rate in the upper water is 63.93%at last,and the petroleum removal efficiency is 0.1393mg/(L·d),higher than zeolite entirely,which indicated that after granular activated carbon and zeolite are cultured bio-film, adsorption and bio-degradation on the filler surface can control the release of petroleum in the sediments well.After macadam is cultured bio-film,the petroleum removal rate is not hightened obviously,the reason for which is that the interspace between macadam is big relatively,partial petroleum may release into the upper water through the interspace between macadam;in addition it can be concluded that as to granular activated carbon and zeolite,microorganism can grow well on which and the petroleum removal velocity is faster in early days,and the growth of microorganism and petroleum removal velocity is in stabilization in later days.(3)In the dissolved oxygen experiment,when the upper water is treated by hermetic aeration,petroleum removal velocity in the sediments is highest;when treated by open aeration,petroleum removal velocity take second place;when treated by no aeration,the velocity is lowest.The removal velocity are 18.61mg/(kg·d), 12.40 mg/(kg·d)and 8.33 mg/(kg·d)respectively.The removal rate are 64.51%, 48.95%and 37.11%respectively.It can be concluded that the dissolved oxygen is very important for the growth of microorganism.,otherwise temperature is also very important for petroleum degradation.(4)The petroleum removal rate and velocity are 58.06%and 22.50mg/(kg·d) respectively,higher than the other two,which indicated that bulking agents can increase gas permeability of sediments so as to accelerate petroleum biodegradation in the sediments.