Papermaking companies to avoid major sources of pollution

Harmful waste rate liquid comes from the following three aspects:
(1) The black liquor from the alkali cooking pulp (pulp) and the red liquor from the acid cooking pulp (pulp) in the cooking section.
At present, only some paper mills in China use acid pulping, and most paper mills use alkaline pulping. The black liquor discharged is mainly the degradation products of lignin and carbohydrates. For example, sulfide lignin, formic acid alcohol, dimethyl sulfide, and dimethyl disulfide are degradation products of lignin. They are all odor- and even malodorous compounds, and are major pollutants causing high COD in waste liquids. The degradation products of carbohydrates are in the state of meta-sugar acid, which is the main contaminant causing high BOD value in the waste liquid.
Acidic cooking contaminants, also degradation products of lignin and carbohydrates, are the main reasons for high COD and BOD formation.
(2) Contaminants containing chlorine bleaching waste liquid The most serious pollution in paper mills is the discharge of chlorine bleaching waste liquids. The waste liquid contains not only COD and BOD but also other highly toxic substances.
Thousands of original paper mills producing bleached pulp in China have adopted chlorine-based bleaching technologies, such as chlorinated bleaching and hypochlorite bleaching, in addition to individual plants. Chloromethane produced by bleaching of hypochlorite contains about 150-250 g of waste liquid per ton of bagasse slurry bleached, and about 700 g of wood pulp per ton of bleach. Chlorination bleaching In addition to the production of chloroform, the waste liquid also contains more than 40 organic chlorides, of which the most is a variety of chlorinated phenols, such as dichlorophenols, trichlorophenols, also produces dioxins. ) And furan products, more than 10 species are highly toxic.
(3) Compared with the pollution of retort pulping black liquor and chlorine bleaching waste liquor in the middle section of the pulping and papermaking process, the waste water pollution in the other sections of the pulping and papermaking process is not serious. This part of the waste water is generally called the middle section waste water.
Due to technical and economic reasons, the current alkaline pulp production process cannot be fully closed and zero emissions. There are wastes discharged from other sections, as well as various pollutants, such as waste water generated from stock preparations, white water from paper machines, and waste water caused by drip, leakage, running, and running of pipelines in plant equipment. If these wastewaters are not treated, they will also cause environmental pollution. However, these waste waters can generally meet the standard through proper physical treatment. In another place, a semi-closed circulation system can be used. The previous process uses the waste water of the next process as much as possible to reduce the discharge of waste water.
Some Suggestions for Reducing Environmental Pollution in Papermaking Industry in China (1) According to the above analysis, the size of pulp mills, according to the current situation, the pulp mills with a daily output of 30 tons of pulp (an annual output of 10,000 tons of pulp) are unable to For alkali recovery and high-concentration non-pollution bleaching, the state must take tough measures to stop production, and it must not be newly constructed.
(2) The pulp mill needs to achieve two conversions, that is, conversion to large and medium-scale scales, and conversion to pulp mills, especially wheat straw as raw materials. As far as the current technology is concerned, a lot of research work has been conducted in the near future against the pollution problems of wheat straw mills and the quality of paper produced by wheat straw pulp. However, it is not possible to establish a wood pulp mill with an annual output of nearly 1 million tons as in other countries. Even if a pulp mill with an annual output of 500,000 tons is established, I think the difficulties are also great because of the constraints of financial resources and forest resources ( To invest approximately RMB 9 billion, hundreds of thousands of mu of forest will be needed.
(3) The paper industry should have a unified management structure and management system, and strictly control the construction of new plants and expansion of plants. The current light industry associations, the Forestry Department, and the Ministry of Agriculture all control pulp and paper mills and should work together to formulate unified regulations.
(4) For the pulp and paper mills with a daily output of more than 50 tons of Nissan Chemical Pulp, the government should support the establishment of an alkali recovery and non-polluting bleaching system and a "three wastes" treatment system to achieve the target discharge and civilization. produce.
(5) For the pulp mills produced by the above-mentioned low-pollution pulping method, although the black liquor pollution is reduced, it is also necessary to adjust the conditions to local conditions. The medium-high concentrated chlorine-free bleaching technology is adopted, and effective comprehensive utilization methods and “three wastes” treatment measures are adopted. If the emission reaches the standard, and it cannot be discharged for the time being, it shall be renewed within a time limit.
(6) Strengthen scientific and technological investment and vigorously develop new technologies and equipment that can control and eliminate pollution. If we simply rely on the introduction of foreign loans and foreign loans to build new plants or expand factories, the practice of China's paper industry proves that this road does not work.
At present, there are already some pulp and paper mills in China that rely on foreign loans to build new plants or expand their plants. The reasons are as follows: First, foreign loans are often replaced by foreign equipment; second, foreign equipment is expensive (eg, the oxidation of 150 tons of pulp per day The CIO2 generator in the chlorine bleaching stage will cost 6 million U.S. dollars, and 1 medium-density pump will have 150,000 U.S. dollars.) The third is that the date of repayment will come from the date of production and the profit will not reach the loan interest. Therefore, we must vigorously develop new equipment for the domestic paper industry, especially medium-to-high concentration non-chlorine bleaching equipment, waste paper deinking equipment, alkali recovery equipment, and chemical pulp equipment.
(7) Take effective measures to raise funds for environmental engineering of paper mills. The sewage charges levied on the paper mills should be used in a substantial proportion for the construction of the factory's environmental projects; the environmental engineering funds should be established so that each factory can support each other, concentrate funds, and rectify in phases; in corporate profits, it is also necessary to A certain percentage of environmental engineering construction fees will be set up.
(8) Improve the review and evaluation system for paper industry environmental engineering projects. The design, manufacture, and installation of environmental engineering must undergo rigorous review and evaluation, establish a qualification certificate system, and close off those unqualified environmental engineering contractors.
(9) In the pulp and paper mill, establish an environmental protection monitoring system to test the discharge load of the waste water, ensure the normal operation of the environmental engineering equipment, and timely report the wastewater discharge standards and environmental conditions of the plant.