Biological enzymes or washing paper industry 'original sin'

In order to achieve China's "double carbon" goal, it is necessary to vigorously promote the energy conservation and emission reduction of key industries such as textiles, paper making, and pharmaceuticals, and the application of biotechnology will undoubtedly accelerate the pace of green transformation of these industries. To this end, this newspaper launched a series of reports on "green biological manufacturing", focusing on how biotechnology can help traditional industries out of high energy consumption and high pollution.

If you compare today's paper with the past, it's not hard to see that paper has gotten better and whiter over the years.

However, behind the bright paper, it hides the "original sin" of high pollution and high energy consumption that the paper industry is difficult to get rid of.

At the same time, China has more people and fewer trees, and there is an extreme shortage of wood raw pulp, and papermaking raw materials rely on imported raw pulp and waste paper for a long time. According to the announcement jointly issued by the Ministry of Ecology and Environment and other ministries, China has basically achieved zero solid waste imports by the end of 2020, and relying on imported waste paper is no longer feasible.

In recent years, under the dual pressure of environmental protection and cost, non-wood raw materials such as straw and high yield mechanical pulp assisted by biological enzymes are making subtle changes in the raw material structure of the paper industry, bringing a revolution to the industry, especially the wrapping paper industry.

Paper behind the industry's pain

Papermaking is one of the four great inventions of China, and the annual production and sales volume of China's paper industry rank first in the world, accounting for about a quarter of the global total.

In recent years, with the development of Internet technology, e-reading has become popular. However, in a short time, paper is still irreplaceable in many fields, such as teaching materials, advertising printing, household paper and so on.

No matter what type of paper, it is necessary to start from a wood fiber. "Paper is made mainly from wood fibers in plant materials." Dai Hongqi, a professor at Nanjing Forestry University, said that in order to obtain wood fibers, plant raw materials need to be sliced or cut short; After high temperature boiling in alkali water or mechanical grinding, the fibers are separated to obtain pulp. The pulp is mechanically ground and dehydrated at a certain concentration on the paper machine to form a wet paper sheet, and then further dehydrated by pressing and dried into paper.

In order to obtain the wood fiber for the manufacture of pulp, human beings must invest a large amount of water, electricity, alkali and other elements, while producing a large number of black, smelly, toxic wastewater, so that many papermaking enterprises have repeatedly boarded the environmental black list.

Although China is large and abundant, but the forest resources are very scarce, the per capita forest area is only 1/7 of the world per capita level, in order to reduce domestic wood resources consumption, reduce the environmental pressure brought by wastewater discharge, in recent years, China has imported a large number of foreign wood pulp and waste paper to meet the needs of our national economic development.

"Imported wood pulp can be directly used for paper making, the production of white cardboard, household paper, special paper, etc. The imported waste paper is mainly used for the production of cardboard, wrapping paper and newsprint, such as packaging boxes, corrugated paper and kraft paper, which are widely used in the e-commerce express delivery industry." Dai Hongqi said.

At present, the proportion of pulp imported for papermaking in China is as high as 40%. In order to alleviate the shortage of papermaking fiber raw materials and reduce production costs, papermaking enterprises began to turn to the reasonable application of cost-effective non-wood raw materials.

"Pulp raw materials are divided into wood and non-wood two categories, in addition to trees, straw, bamboo, reed, awn stalk, cotton stalk are non-wood raw materials." Dai Hongqi told the Science and Technology Daily reporter that in the past, limited by technology and process, non-wood raw materials production of chemical pulp black liquor extraction rate and alkali recovery rate is low, pulp using elemental chlorine bleaching, the wastewater generated is not only difficult to treat, but also can adsorb organic halide (AOX) content is extremely high, causing great damage to the ecological environment, and human health is also a threat.

With the rapid development of China's economy and the strengthening of ecological environmental protection and pollution control, after 1990, almost all non-wood fiber pulp and paper enterprises were shut down. So far, only a few areas such as Sichuan bamboo pulp and paper enterprises are still in operation.

New opportunities for non-wood fiber pulping

Although the production of non-wood pulp has been completely banned, the research of non-wood fiber utilization technology has not stopped. In recent years, biomass refining technology and high-yield chemical mechanical pulp technology have become hot topics and received attention from the industry, allowing non-wood pulp to return to the stage of the paper industry.