Emerging disposal technologies of harmful phytoextraction biomass (HPB) containing heavy metals: A review.

Phytoextraction is an effective approach for remediation of heavy metal (HM) contaminated soil. After the enhancement of phytoextraction efficiency has been systematically investigated and illustrated, the harmless disposal and value-added use of harmful phytoextraction biomass (HPB) become the major issue to be addressed. Therefore, in recent years, a large number of studies have focused on the disposal technologies for HPB, such as composting, enzyme hydrolysis, hydrothermal conversion, phyto-mining, and pyrolysis. The present review introduces their operation process, reaction parameters, economic/ecological advantages, and especially the migration and transformation behavior of HMs/biomass. Since plenty of plants possess comparable extraction abilities for HMs but with discrepancy constitution of biomass, the phytoextraction process should be combined with the disposal of HPB after harvested in the future, and thus a grading handling strategy for HPB is also presented. Hence, this review is significative for disposing of HPB and popularizing phytoextraction technologies.