Grass pulp has always been criticized for its high pollution as one of the raw materials in the papermaking industry. The pollution caused by straw pulp and papermaking has brought many disasters to the ecological environment in China. In order to control pollution, as early as the 1990s, the country forced the closure of paper mills using straw pulp as the main raw material. Under high-pressure environmental policies, straw pulp once withdrew from the historical stage.

    In 2021, China will completely stop importing waste paper. Faced with such a large shortage of raw materials, high cost-effective grass fiber papermaking such as non wood fibers and agricultural and forestry processing residues has returned to people's sight. How to solve the problem of high pollution? Recently, Professor Dai Hongqi from Nanjing Forestry University gave a detailed answer to the environmental protection issues of straw pulp papermaking in an interview with China Paper Industry Network.

    Dai Hongqi first analyzed the reasons for the high pollution caused by straw pulp papermaking. In the past, the production of chemical pulp from straw pulp had low black liquor extraction and alkali recovery rates, and the pulp was bleached with elemental chlorine. The wastewater generated was not only difficult to treat, but also had a high AOX content, causing huge damage to the ecological environment and posing a threat to human health. Therefore, the country has implemented a policy of mandatory closure of all straw pulp chemical pulp production lines, including the production of semi chemical pulp (high yield straw pulp) for packaging paper. However, although the production of grass based pulp has been completely banned, research on the utilization technology of abundant and inexpensive grass based fibers has not stopped as a result. In recent years, research on biomass refining technology and enzyme assisted thermal milling and pulping technology in the comprehensive development and utilization of resources has received attention from the industry. Biomass refining technology can not only obtain papermaking fiber raw materials, but also prepare high value-added platform products from its by-products lignin and hemicellulose;          The biological enzyme pre-treatment technology for hot grinding pulp production generally does not use chemicals. In addition to obtaining papermaking fiber raw materials, the organic matter in wastewater is concentrated and processed through certain compounding techniques to generate organic fertilizer. These technological methods greatly reduce the generation and treatment load of pollutants, and significantly reduce environmental protection costs. Especially the straw pulp produced by biological enzyme pretreatment and thermal milling technology is very suitable for packaging paper products.

The return of straw pulp and paper to the stage of the papermaking industry is not only due to the progress of clean pulp making technology and environmental protection technology, but also due to the high cost-effectiveness of straw fibers. Grass fiber, as a leftover agricultural product often burned by farmers, has obvious cost advantages. Therefore, enterprises voluntarily invest more funds in environmental protection, achieving a win-win situation between economy and environmental protection.

Since straw pulp has a high cost-effectiveness and environmental protection issues can be solved, can it be developed on a large scale in the future? Although the country has not yet issued a clear policy on straw pulp, Dai Hongqi revealed that the paper industry has started many scientific research projects and has conducted straw pulp pilot projects in some enterprises, such as Century Sunshine, which has received strong support from the government. There is also Yangzhou Yongfengyu Group, which uses wheat straw bio pulp for household paper, packaging paper, etc. Many companies are silently conducting scientific research. He believes that the country will also have a more objective view of straw pulp and make appropriate planning and layout, especially in the production of straw mechanical pulp, which can alleviate the shortage of packaging paper raw materials caused by restrictions on imported OCC waste paper and papermaking raw materials. When asked about the future proportion trend of straw pulp, Dai Hongqi believes that the proportion of straw pulp will gradually increase in the future, but the possibility of a large proportion is relatively small. On the one hand, compared to the past, combine harvesters only harvest the upper half of the straw, resulting in the high-quality fiber of the straw not being harvested, which is a great pity. In addition to wheat straw pulp, China also produces a certain amount of bamboo pulp in non wood fibers. Such as Sichuan, Guizhou, Fujian and other places. Therefore, straw pulp can only serve as a supplementary resource and will not dominate.

Professor Dai Hongqi is not only dedicated to the research of clean production technology for straw pulp and paper, but also collaborated with Fang Guigan, Director of the Pulp and Paper Research and Development Center of the Chinese Academy of Forestry, on the project of "Key Technologies and Industrialization of High Yield Clean Pulping with Mixed Materials". As a result, he won the second prize of the 2019 National Science and Technology Progress Award, vigorously promoting the development of clean papermaking technology.