Discussion on Production and Recovery Technology of Green Packaging of Paper Products (II)

Second, the paper product packaging production and waste paper recycling green analysis

2.1 The main sources of pollution in paper production and the main links in cleaner production

The most important pollution in paper production is generated during the pulping process. Pulping can generally be divided into three methods: chemical pulping, mechanical pulping, and chemical mechanical pulping. China's papermaking industry mostly uses chemical pulping. There are three main types of processes: bleaching alkali wheat straw pulping, natural kraft wood pulp, and bleached kraft wood pulp. There are three main sources of pollution in the pulp and paper process.

(1) The black liquor from the pulping section (ie, pulping) and the red liquor from the acid-cooked pulp are used in the cooking section. At present, only some paper mills in China use alkaline pulping. The black liquor discharged is mainly lignin and Carbohydrate degradation products, while the degradation products of carbohydrates are in the state of meta-sugar acid, which is the main contaminant that causes high BOD value in the waste liquor. The contaminants in the acid-cooking waste liquor are also lignin and carbohydrates. Degradation products are the main reason for high COD and BOD.

(2) Chlorine-containing bleaching waste liquid The most serious pollution in paper mills is the discharge of chlorine-containing bleaching waste liquids. Thousands of bleached pulps are produced by paper mills in China. Chlorine-based bleaching technologies such as chlorinated bleaching are used in individual paper mills. Hypochlorite bleaching, etc., hypochlorite bleaching mainly produces chloroform, waste liquid also contains more than 40 kinds of organic chlorides, of which the most chlorinated phenols, such as dichlorophenol, trichlorophenol .

(3) Wastewater from the pulping and papermaking process Other wastes from the pulp and papermaking process, such as paper machine whitewater, are called mid-stream wastewater. They also contain various pollutants. If these wastewaters are not treated, they will also cause environmental pollution. However, these wastewaters are generally suitable. Physical processing can be achieved. In addition, a semi-closed circulation system can be used. The previous process can use the wastewater of the next process as much as possible to reduce the discharge of waste water.

The clean production of the paper industry includes three aspects: clean energy, clean production processes and clean products. To evaluate clean production, we must focus on the promotion, design, implementation, and improvement of the three links. The design and implementation process must follow five principles.

(1) Governance should be considered from the entire environmental system.

(2) The three waste treatment should be comprehensively used from the waste and set up for final treatment.

(3) Inorganic substances (heavy metals) must be thoroughly treated because they are harmful to the organism for a long time.

(4) The production of organic waste should be minimized, and hazardous organics should be incinerated.

(5) Solid waste should be treated centrally to reduce its environmental hazards.

2.2 Waste recycling technology

The general process used for pulp and paper in waste paper and cardboard is as follows:

Wastepaper - collection classification - smash - descrease - purification - screening - concentration - deinking - impurity removal - beating - fiber grading - pulp - paper stock. Since the reform and opening up, China has attached great importance to the introduction of advanced waste paper processing technology and advanced equipment, and has introduced more than 50 waste paper processing lines, including bleached kraft paper, corrugated paperboard waste paper, used newspapers, bleached printing paper waste paper and other wastes. Paper processing equipment, the largest daily production capacity of waste paper production line can reach 500T.

(to be continued)