利用改进的生物反应器研究不同通气条件下土壤中菲的降解

DEGRADATION OF PHENANTHRENE IN SOIL AT DIFFERENT AERATION RATES USING MODIFIED BIOLOGICAL REACTOR

摘要:

利用自行设计的生物反应器进行多环芳烃菲污染土壤的生物修复研究.在控制土壤水分、养分的情况下,设6个通气处理,分析测定各处理的土壤菲降解率、微生物量、多酚氧化酶以及土壤酸度的动态变化.为期60天的试验结果表明,通气量为0.08m³h^-1时,菲的降解率最高,达72.6%;与对照相比,微生物量最多,其中细菌、真菌都显著高于对照;多酚氧化酶活性也最高.通气量为0.08m³h^-1处理还可以控制土壤中酸度的变化,保持土壤中pH的稳定,从而更快地降解污染土壤中的菲.较高的菲降解率与通气改变土壤条件有关.在本实验的条件下,反应器中土壤细菌、真菌数量增加,多酚氧化酶活性提高,土壤保持稳定的pH值是土壤中菲降解率提高的主要原因.因而,改进的反应器具有较高的降解效果.本研究还表明,利用生物反应器能够快速、高效地消除土壤中的有机污染物,实现有机污染土壤的离位生物修复.

Abstract:

A new bioreactor was designed to study the effect of aeration on biodegradation of phenanthrene in soil. The phenanthrene mixed previously with a little soil sample was added to the paddy soil sample in the reactor to make a phenanthrene concentration of 200 mg kg^-1. The sample was stirred frequently and allowed to equilibrate for two weeks. Six aeration rates were used in this experiment: 0, 0.02, 0.04, 0.06, 0.08 and 0.10 ³h^-1. Bioreactors were incubated at 25 and water content was adjusted to 60% of the water holding capacity (WHC). Changes of phenanthrene degradation rate, number of soil microbes, act ivity of polyphenol oxidase and soil pH were measured during the 60 day incubation. Results showed that aeration at 0.08 ³h^-1 had the highest phenanthrene degradation rate (72.6%). Compared to the control, the number of bacteria and fungi were significantly higher than that of the control. Aeration at 0.08 ³h^-1 also had the highest activity of polyphenol oxidase in soil. At this aeration rate, accumulation of acidic matter in soil was avoided and consequently soil pH remained constant which favored biodegradation of phenanthrene in soil. The high phenanthrene degradation rate achieved in the present study (when soil was aer ated at 0.08 m³h^-1) can be attributed to the increase in the quantit ies of bacteria and fungi in soil, the rise in the activity of polyphenol oxidase and rather stable soil pH. The new bioreactor can be further developed and used ex situ for rapid and efficient removal of organic pollutants in solid phase of soil.