Fe(Ⅱ)投加时序对硫酸盐还原菌处理不同形态As或Sb的影响

Impact of Fe(Ⅱ)addition timing on the removal of different forms of As or Sb by sulfate reducing bacteria

在硫酸盐还原菌(SRB)基质中按照不同时序加入50 mg/L Fe(Ⅱ)及不同形态的As或Sb(初始质量浓度均为5 mg/L),设计4个处理(T1,同时加入As(Ⅴ)、Sb(Ⅴ)和Fe(Ⅱ);T2,提前2 d加入Fe(Ⅱ)后再加入As(Ⅴ)、Sb(Ⅴ);T3,同时加入As(Ⅲ)、Sb(Ⅲ)和Fe(Ⅱ);T4,提前2 d加入Fe(Ⅱ)后再加入As(Ⅲ)、Sb(Ⅲ)),分析实验过程中基质pH、氧化还原电位、光密度(OD_(600))、总碱度、SO_(4)^(2-)、硫化物、Fe、As或Sb含量等随时间的变化,以明确Fe(Ⅱ)对As、Sb的去除效率及机制的影响。结果表明,在硫化物较为充足的基质中(硫化物残余量>8 mg/L),各处理7 d时Sb的去除率均可达98%以上,As的去除率则为38.42%~87.36%,实验后期基质中As、Sb出现复溶,总体上Sb较As易固化;Fe(Ⅱ)提前加入有助于As、Sb的去除,但相较于Fe(Ⅱ)的投加时序,As、Sb自身形态对去除效果的影响更为显著,As(Ⅲ)、Sb(Ⅲ)比As(Ⅴ)、Sb(Ⅴ)具有更快的去除速率和更高的去除率,14 d后T3、T4的Sb残余量低于检出限,As的残余量则分别为1.94、0.62 mg/L。因而,通过硫还原作用处理含As、Sb废水时,除了通过添加适量Fe(Ⅱ)提高去除率,还需采取适当的措施促进As、Sb还原,以取得更为显著的固化效果。

In sulfate-reducing bacteria(SRB)matrices,50 mg/L Fe(Ⅱ)and various forms of As or Sb(with initial mass concentrations of 5 mg/L)were added at different time intervals to design four treatments:T1,simultaneous addition of As(Ⅴ),Sb(Ⅴ),and Fe(Ⅱ);T2,addition of Fe(Ⅱ)two days in advance followed by As(Ⅴ)and Sb(Ⅴ);T3,simultaneous addition of As(Ⅲ),Sb(Ⅲ)and Fe(Ⅱ);T4,addition of Fe(Ⅱ)two days in advance followed by As(Ⅲ)and Sb(Ⅲ).The changes in matrix pH,redox potential,optical density(OD_(600)),total alkalinity,SO_(4)^(2-),sulfide,Fe,As and Sb content over time were analyzed to clarify the impact of Fe(Ⅱ)on the efficiency and mechanism of As and Sb removal.The results showed that in matrices with sufficient sulfide(sulfide residual>8 mg/L),the removal rate of Sb in all treatments could reach over 98%after 7 days,while the removal rate of As ranged from 38.42%to 87.36%.Re-dissolution of As and Sb occurred in the later stages of the experiment,and Sb was generally easier to be solidified than As.The prior addition of Fe(Ⅱ)was conducive to the removal of As and Sb,but the form of As and Sb had a more significant impact on the removal effect than the timing of Fe(Ⅱ)addition.As(Ⅲ)and Sb(Ⅲ)exhibited faster removal rates and higher removal rates than As(Ⅴ)and Sb(Ⅴ).After 14 days of treatment,the residual Sb in T3 and T4 was below the detection limit,while the residual As was 1.94 and 0.62 mg/L,respectively.Therefore,when treating As and Sb containing wastewater through sulfur reduction,in addition to improving the removal rate by adding an appropriate amount of Fe(Ⅱ),appropriate measures should also be taken to promote the reduction of As and Sb to achieve more significant stabilization effects.