Abstract:

In order to screen efficient de-enzyme methods during dewatering process of Sedum plumbizincicola straw after harvesting, we investigated the dewatering of Sedum plumbizincicola straw with de-enzyme treatments of stir-fried, steam and microwave and directly dried in shadow. In this experiment, the differences of water-loss rate, water-loss ratio, moisture content and cadmium content of Sedum plumbizincicola straw with different treatments were analyzed. The results showed that the water-loss rate and water-loss ratio of the straw with de-enzyme process were higher than those of the straw directly dried in shadow, and the straw with de-enzyme process had lower moisture content at the end of treatment. At the beginning of drying in shadow after de-enzyme treatments, the water-loss rate, water-loss ratio and water-loss amount of the straw with stir-fried were significantly higher than those with steam and microwave de-enzyme treatments. During the drying process, it took the shortest time for the moisture content of the straw dropping below 70% with stir-fried de-enzyme treatment, which was only 120 h, while it took 180 h and 216 h for the moisture content of the straw dropping below 70% with steam and microwave de-enzyme respectively. At the end of drying in shadow, the straw with stir-fried and steam de-enzyme treatments had the most water-loss amount, 459.40 g and 459.80 g, respectively. And different de-enzyme treatments had no significant impact on the Cd content of straw. De-enzyme treatment can increase the drying rate of Sedum plumbizincicola straw after harvesting and will not have a significant impact on the Cd content of the straw. Stir-fried de-enzyme treatment can accelerate water dissipation and shorten the time for reducing the moisture content below 70%. The straw after stir-fried de-enzyme treatment is more in line with the requirements of transshipment, incineration or other disposal methods. This study provides a new idea and technical verification for the development of post-production disposal technology of hyperaccumulator engineering restoration application.

Key words: Sedum plumbizincicola, de-enzyme, drying in shadow, water-loss, Cd pollution