硫酸盐还原菌还原U(Ⅵ)的影响因素与机制

Efficiency and Mechanism on Reduction of U(Ⅵ) by Sulfate Reducing Bacteria

在厌氧环境下,改变温度、U(Ⅵ)的初始浓度、pH值、共存离子等因素,进行硫酸盐还原菌(SRB)还原U(Ⅵ)试验,以了解其特性.结果表明,SRB的最佳还原条件为温度35℃、pH值7.0、U(Ⅵ)初始浓度25mg·L-1.SRB的最大还原能力为179.1mg.g-1.共存离子Mo(Ⅵ)或Ca2+初始浓度小于或等于5g·L-1时,对SRB还原U(Ⅵ)影响不大;但当其浓度达到20g·L-1时,它们对SRB还原U(Ⅵ)均具有很强的抑制作用.Mo(Ⅵ)对SRB的抑制主要是生理抑制,Ca2+是通过和U(Ⅵ)形成稳定的Ca-UO2-CO3络合物竞争抑制.试验结果还表明,Ca2+浓度低于5g·L-1时未出现停滞期,但其浓度超过20g·L-1时出现了1d的停滞期.

Under anaerobic conditions, the characteristics of sulfate reducing bacteria（SRB） were applied to reduce U（Ⅵ ） under different temperature, pH values, U（Ⅵ） concentrations and coexisting ions. The results showed that the optimum reduction condition was the temperature 35 ℃, pH 7.0 and U （ Ⅵ ） concentration 25 mg· L^- 1 . The maximum reduction capacity of SRB was 179.1 mg· g^- 1 . Mo（ Ⅵ ） or Ca^2＋ did not affect SRB on the reduction process of U（ Ⅵ ） under the concentration less than 5 g· L^- 1, but they strongly inhibited the process under the concentration more than 20 g· L^-1. The main inhibition of Mo（ Ⅵ ） was physiological inhibition and the inhibition of Ca^2＋ was competitive inhibition through the stable complex formation, Ca-UO2-CO3. The results also showed that lag phase did not appear on the concentration of Ca^2＋ less than 5 g· L^-1 , but the lag phase of 24 hours appeared on the concentration of Ca^2＋ more than 20 g· L^-1 .