Study on the release of arsenic and permeability from arsenic-containing ferrihydrite by sulfate reducing bacteria and acidiphilium cryptum JF-5
Ferrihydrite is a common iron oxide mineral in soil and also the main arsenic carrying mineral.Releasing arsenic from ferrihydrite is a way to alleviate arsenic pollution in soil.In this paper,it is intended to promote the release of arsenic by biological reduction of arsenic-containing ferrihydrite(As-Fh)by sulfate reducing bacteria(SRB)and acidiphilium cryptum JF-5(JF-5),so as to achieve the purpose of soil remediation.To this end,two kinds of microbial shaker experiment and biological injection experiment were carried out by collecting typical arse-nic-containing ferrihydrite from Shimen mining area in Hunan Province,to explore the arsenic release and form of ferrihydrite,the change of suspended particulate matter in the process of biological dissolution,and the permeabili-ty of the system.The results showed that:① In two cycles,according to the total amount of arsenic released,JF-5+SRB operations＞JF-5+JF-5 operations＞SRB+JF-5 operations＞SRB+SRB operations,corresponding to these operations were able to release 16.4,16.2,7.3 and 3.3 mg per gram of ferrihydrite,respectively;② Hydrochemi-cal analysis also showed that SRB could provide stronger reducibility than JF-5 under the same operation;③ The biological column experiment showed that compared with SRB,JF-5 injection could produce iron suspended partic-ulate matter with an average concentration of 1 419 mg/L,7.25 times that of SRB;At the same time,the permea-bility of SRB column system(mean water pressure difference of 0.51 psi)was significantly better than that of JF-5(mean water pressure difference of 2.22 psi),and the dispersion of highly suspended particles was the main reason for the permeability change.These results demonstrate that continuous injection of SRB into the ferrihydrite system is an effective technique for reducing arsenic concentration in soil.
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