污泥基生物炭固定化菌处理海洋溢油的研究

Treatment of Marine Oil Spill by Sludge-Based Biochar Immobilized Bacteria

以城市污水厂污泥作为原料,磷酸作为活化剂,通过热解法制备污泥基生物炭。并以生物炭作为载体固定化海洋石油烃降解菌Alcanivorax sp.ASW-2,探究活化剂浓度、活化时间、碳化温度与碳化时间对生物炭吸附效果的影响,优化获得微生物吸附固定的最优菌浓与吸附固定时间。在不同原油浓度、温度、pH、盐度等环境条件下考察生物炭固定化微生物对原油的去除效果。结果表明:当磷酸浓度55%、活化时间2 h、碳化温度500℃、碳化时间1 h时生物炭的吸附效果最佳,对石油烃降解菌的吸附量为1.77×10^(11) CFU·g^(-1);在菌浓为5×10^(11)CFU·mL^(-1),吸附固定化时间为12 h时生物炭对微生物的吸附量达到最大;原油浓度对微生物降解效果影响较大,原油浓度为0.1 g·L^(-1)时固定化菌与游离菌对原油的降解效果最佳,7 d降解率分别为97.78%与90.24%,而随着浓度增加,原油的抑制效果逐渐增强,5 g·L^(-1)的高浓度原油条件下降解率分别降至50%和35%以下。原油浓度为1 g·L^(-1)时,游离菌对原油的降解在第9 d达到稳定,降解率为56.67%,固定化菌在第7天降解率达到最大并趋于稳定,其值为75.87%,固定化加快了微生物对原油的降解速率,提高了对原油的降解效果。固定化微生物降解原油的最优环境条件为:pH 8、盐度35、温度25℃。与游离菌相比,生物炭固定化提高了微生物对环境的耐受性,对原油的降解效果也有明显提高,在相同环境条件下,固定化后菌对原油的降解率最大可提升约28%。

In this paper,sludge-based biochar was prepared by pyrolysis with municipal sewage sludge as raw material and phosphoric acid as theactivator.The marine petroleum hydrocarbon-degrading bacterium Alcanivorax sp.ASW-2 was adsorption immobilized by the prepared biochar.The effects of activator concentration,activation time,carbonization temperature,and carbonization time on the adsorption capacity of the biochar were explored.The optimal concentration and the time of microbial immobilization were optimized.The efficiency of biochar immobilized microorganisms on spilled oil removal was investigated under different environmental conditions such as oil concentration,environmental temperature,pH,and salinity of seawater.The results showed that when the concentration of phosphoric acid was 55%,the activation time was 2 h,the carbonization temperature was 550℃and the carbonization time was 1 h,the adsorption effect of biochar was the best,and the adsorption capacity of Alcanivorax sp.ASW-2 was1.77×10^(11) CFU·g^(-1).When the bacterial concentration is 5×10^(11) CFU·mL^(-1) and the adsorption and immobilization time was 12 h,the adsorption capacity of biochar to microorganisms reached the maximum.Crude oil concentration has a great influence on microbial degradation,and high concentration crude oil will inhibit microorganisms′growth and degradation abilities.When the crude oil concentration is 0.1 g·L^(-1),the degradation effect of immobilized bacteria and free bacteria on crude oil is the best,and the 7-day degradation rates are 97.78%and 90.24%respectively.With the increase of concentration,the inhibition effect of crude oil gradually increases,and the degradation rate of high concentration crude oil of 5 g·L^(-1) decreases to less than 50%and 35%respectively.When the crude oil concentration is 1 g·L^(-1),the degradation rate of crude oil by free bacteria is stable on the 9th day,and the degradation rate is 56.67%.The degradation rate of immobilized bacteria reaches the maximum and tends to be stable on the 7th day,with a value of 75.87%.Immobilization accelerates the degradation rate of crude oil by microorganisms and improves the degradation effect of crude oil.The optimum environmental conditions for immobilized bacteria are pH of 8,35 of salinity,and 25℃of temperature.Biochar immobilization significantly improved the tolerance of microorganisms to the environment.Compared with the free bacteria,the degradation efficiency of immobilized bacteria on crude oil is significantly improved,and the increased degradation rate is up to 28%under the same environmental conditions.