Phytoremediation is the most environmental friendly and economical technology for restoring agricultural land contaminated by heavy metals. However, it is a slow process, requiring hundreds to thousands of years to reduce pollutant level to meet soil environmental quality standards for highly contaminated soils. Such a long period makes the practice of phytoremediation nearly impossible without economic revenue from crop production. Miscanthus floridulus (M. floridulus) is characterized by its high dry matter yield and strong vitality. This case study planted M. floridulus on fallow land that was contaminated by 6,000 mg/kg of lead to investigate the feasibility of phytoremediation. The case study results show that lead accumulated primarily in the roots of the M. floridulus. After one year of growing, the average lead content in the roots and shoots was 806.7 and 50.3 mg/kg, respectively. M. floridulus was effective for the phytostabilization of lead-contaminated soil and was a lead-tolerant plant. The cropping produced 22.4 ton/ha/year dry matter weight (shoot part) and removed 1.13 kg/ha/year of lead from the soil. The M. floridulus grown on contaminated fields could be used as biofuels, and each hectare of M. floridulus dry matter could generate 365.1 GJ of thermal energy per year, which is equivalent to the heat energy from combustion of 13.4 tons of hard coal. Furthermore, replacing hard coal with M. floridulus would reduce CO₂ emissions by 33.1 ton/ha per year. The yields, Pb-absorption concentrations, and carbon mitigation of M. floridulus may change in subsequent years for different environmental conditions; thus, it needs further planting trials for regionalization.

In order to improve the bioremediation efficiency of petroleum-contaminated soil, five test groups were selected in this study, including native bacteria, Acinetobacter venetianus, Vetiveria zizanioides L., and Vetiveria zizanioides L. combined with Acinetobacter venetianus and biochar to compare the degradation efficiency of petroleum-contaminated soil. The results of the study showed that after a six-month bioremediation, there was no significant difference between the native bacteria and the A.V. bacteria group in the removal efficiency of TPH, and the proportion of degradable TPH accounts for about 50~70%. The removal efficiency of TPH could be increased by 18.1–29% by increasing the phytoremediation of Vetiveria zizanioides L. The cultivation of Vetiveria zizanioides L. could not only stabilize the soil’s pH and conductivity but could also increase the soil’s bacterial abundance. It was suggested that bioremediation could be carried out through the combination of native bacteria and the planting of Vetiveria zizanioides L. Although the addition of biochar to the soil was able to improve the remediation effect of Vetiveria zizanioides L., it would increase the soil conductivity and reduce the abundance of soil bacteria. Therefore, it was recommended to reduce the conductivity of biochar before adding it, which may improve processing efficiency.

Metal contamination in groundwater often occurs in various industrial processes. Studies have confirmed that polysulfide could reduce hexavalent chromium to trivalent chromium, achieving the effect of in situ stabilization. For other metal contamination in groundwater, whether polysulfide also had a stabilizing ability to achieve in situ remediation. This research focused on metals in addition to chromium that often contaminated groundwater, including lead, nickel, zinc, copper, and cadmium, to explore the feasibility of using calcium polysulfide (CaS_x) as an in situ stabilization technology for these metals’ contamination of groundwater. Results showed that CaS_x had a great removal efficiency for metals lead, nickel, zinc, copper, and cadmium. However, for nickel, zinc, copper, and cadmium, when CaS_x was added excessively, complexes would be formed, causing the result of re-dissolution, in turn reducing the removal efficiency. As it is difficult to accurately control the dosage of agents for in situ groundwater remediation, the concentration of re-dissolved nickel, zinc, copper, and cadmium may not be able to meet the groundwater control standards. CaS_x had high lead removal efficiency and for a concentration of 100 mg/L, the dose of calcium polysulfide was more than the amount of 1/1200 (volume ratio of CaSx to groundwater). In addition, the removal rate was almost 100% and it would not cause re-dissolution due to excessive CaS_x dosing. CaS_x can be used as an in situ stabilization technique for lead-contaminated groundwater.

Once in soil and water, metals can enter the food chain, and the consumption of contaminated crops can pose a serious risk to human health. This study used pot experiments to evaluate the accumulation of metal elements and their influence on levels of antioxidants in vegetables. The current study clearly demonstrates that metals accumulated in the five vegetables that were planted in the contaminated soils, especially so for water spinach. Cd accumulation of all of the vegetables planted in the contaminated soils was greater Cu. The low accumulation rate that was seen in sweet potato leaf, potato, and tomato indicated their suitability for planting in suspected contaminated soil, such as at farms nearby metal industries, in replacement of high accumulators, such as leafy vegetables. The non-carcinogenic HI of Cd exposure from water spinach and sweet potato were >1, whereas those for Cu were <1. This study suggests that residents may experience health risks due to vegetable consumption, and that children are vulnerable to the adverse effects of heavy metal ingestion.