Effect of Biochar and Acidithiobacillus ferrooxidans on Heavy Metal Content in Soil and Lettuce

ABSTRACT The mechanism of biochar remediation of heavy metal contamination in soils has been studied quite a lot, but there are still many uncertainties about the effect of interaction between biochar and functional bacteria that adsorb and leach heavy metals. In this paper, we conducted a pot experiment to investigate in depth the effects of biochar, Acidithiobacillus ferrooxidans, and their combined treatment on heavy metal contents (Cr, As, Cd, and Pb) in soil and lettuce by using biochar and A. ferrooxidans. The results showed that biochar, A. ferrooxidans, and combined treatment increased soil pH by 42.55 ~ 51.06% and decreased the content of heavy metals in soil (0.07 ~ 60.80%). The average decrease was as follows: combined treatment (28.42%) > biochar (22.35%) > A. ferrooxidans (18.94%). All three treatments reduced the content of heavy metals in lettuce (26.19–84.42%), and the average size was combined treatment (60.82%) > biochar (52.55%) > A. ferrooxidans (44.00%). Biochar and A. ferrooxidans inhibited the enrichment of heavy metals in lettuce and promoted the growth of lettuce and the increase of nutrients. The combination of biochar and A. ferrooxidans can effectively control soil heavy metal pollution. The combined treatment can reduce the heavy metal content of lettuce and promote its growth, which is an excellent material for soil heavy metal deterrent control and has distinguished application prospects.