1. technical name

Remediation of reed bamboo in heavy metal-contaminated soil and manufacturing technology of ecological panels.

2. scope of application

Remediation of heavy metal-contaminated soil.
3. technical content
3.1 technical principle

Phytoremediation technology uses the mechanism of plant absorption, fixation, volatilization, and degradation to remove or decompose and transform pollutants, so that the function of the soil system can be restored or improved. It belongs to a low-cost, non-destructive type of in-situ contaminated soil remediation and soil resource protection. In order to promote the practical application of phytoremediation technology, Arundo, which grows rapidly and has large biomass, is used to repair contaminated soil, and the harvested plants are utilized as resources, so that owners of contaminated land can continue to obtain good benefits during the restoration period. benefits.

Arundo has high biological yield and no obvious pests and diseases throughout its growth period. It can not only be used as a remediation plant for soil contaminated by heavy metals, but also a pioneer plant for restoring wasteland vegetation and sand prevention and soil consolidation. It has important ecological value. This technology uses Arundo bamboo to repair heavy metal-contaminated soil, and uses Arundo bamboo straw enriched in heavy metals as raw material. According to its component characteristics, it uses formaldehyde free modified isocyanate (MDI) as an adhesive to form the straw fibers into a solid whole., made into artificial board.

3.2 main innovations
(1) The technology of making artificial panels from straw after soil remediation provides a technical route for the safe utilization of plant resources after remediation of heavy metal-contaminated soil. It can not only solve the problem of green and sustainable remediation of contaminated soil in my country, but also solve the problem of shortage of artificial panel raw materials., to achieve a closed loop of the plant remediation industry chain.
(2) Vacuum fiber separation technology is used to peel off the "strong and tough fibers" of plant stems and combined with MDI ecological adhesives that do not contain formaldehyde. The resulting board is stronger than ordinary boards.
4. Pollution control or environmental restoration effects
Taking the restoration project of severely polluted soil (average Hg content of 21.44± 19.94 mg/kg) in the Tongren mercury mining area of Guizhou as an example, the yield per mu of planted Arundo is about 4t (dry weight)/a, and the Hg content and total accumulation of the plants are 4.46± 1.40 mg/kg and 11.63~ 18.47 g/mu respectively. The mercury content in the prepared straw artificial board is 17.01±0.82mg/kg, which meets the limit requirement of soluble mercury ≤ 60mg/kg in the "Limits for Hazardous Substances in Interior Decoration Materials and Wood Furniture"(GB 18584-2001).
5. Technology demonstration
This technology has completed two demonstration projects for farmland soil remediation in different regions and different levels of mercury pollution. Through field application demonstrations, Arundo, as a remediation plant for mercury-contaminated soil, can adapt to different regions, climates and soil types, and has good remediation effects on soils with different degrees of mercury-contaminated soil. The artificial panels made of reed bamboo straw harvested after restoration realize a profitable plant restoration model of "utilizing while repairing" farmland contaminated by heavy metals.
In the polluted farmland of Zhonghuashan Village, Wanshan District, Tongren City, the mercury content is 8.61 mg/kg to 36.10 mg/kg. The average mercury content in the planted Arundo plants is 4.46± 1.40 mg/kg. The yield per mu of Arundo is about 4t (dry weight)/a. The heavy metal Hg can be extracted from the soil every year as high as 11.63 - 18.47 g/mu, and it also absorbs the heavy metals Cd, Cr, As, and Pb. It has good remediation effect on soil contaminated by single or compound heavy metals. After the restoration, the artificial board is produced by the stems of Arunax japonica, and its performance indicators such as density, static bending strength, elastic modulus, nail holding force at the edge of the board, nail holding force at the board surface, and 2-hour water expansion rate all meet the indicator requirements of P2 type particleboard.
6. investment estimation
Take the investment and construction of a project with an annual output of 250,000 m3 of straw boards as an example, with a total investment of approximately 610.7 million yuan.
7. investment recovery period
Take the investment and construction of a project with an annual output of 250,000 m3 of straw boards as an example. The payback period is 4 years (after tax, excluding the construction period).
8. Prospects for transformation and promotion of technological achievements
Based on the annual growth rate of 18.57%, by 2025, the scale of wood-based panel production is expected to exceed 300 million m3. my country's Kuangqu has a large area of contaminated soil, and ecological restoration projects are urgently needed, which has good prospects for promotion. At the same time, since my country's comprehensive ban on natural forest logging, the artificial board industry has faced a serious shortage of wood raw materials. The market prospects for straw boards that replace wood with restored plant straw have broad prospects.