Effects of acid/alkali-pretreated peanut shells as a cheap carbon source for the bio-reduction of sulfate

Abstract

Sulfate reduction process is a promising approach for simultaneously removing sulfate, metals and metalloids from acid mine drainage (AMD). Abundant lignocellulose waste is an ideal energy source for sulfate bio-reduction (SO42−), but their low bioavailability is a limitation for actual application. In the present study, a representative lignocellulose waste, peanut shells (PS), was pretreated with a 4% H2SO4 and NaOH solution at 80 °C, respectively, and then applied for the bio-reduction of SO42−. The results showed that the carbohydrate proportion of the alkali-pretreated PS (55.45%) was higher than acid-pretreated PS (50.05%), and their specific surface area and pore volume also showed the same trends. The SO42− bio-reduction load of using alkali-pretreated PS (140.61 mg/g) was much higher than that of acid-pretreated PS (125.24 mg/g), which validated that alkali pretreatment can improve the utilization efficiency of PS by microorganisms. UV–vis and 3 DEEM analysis provided alkali pretreatment could improve the biodegradability of PS, which provided more electron donors to sulfate bio-reduction. Microbial community dynamic also indicated that alkali pretreatment increased the enrichment of microorganisms associated with carbohydrate utilization, thus increasing the overall energy supply of the community. This research provides a reference for realizing the simultaneous goals of SO42− bio-reduction and lignocellulose waste utilization.