The hottest papermaking enterprises should avoid m

Papermaking enterprises should avoid the main pollution source

harmful waste liquid comes from the following three aspects:

(1) the waste liquid of the pulping section, namely the black liquid of alkali pulping (pulping) and the red liquid of acid pulping (pulping)

at present, only a few paper mills in China use acid pulping, and the vast majority of paper mills use alkali pulping. The black liquor discharged is mainly the degradation products of lignin and carbohydrates. For example, lignin sulfide, formic alcohol, dimethyl sulfide and dimethyl disulfide are the degradation products of lignin, which are odorous and even odorous compounds, and are the main pollutants causing high COD value in waste liquid; The degradation products of carbohydrates exist in the state of metaglycolic acid, which is the main pollutant causing the high BOD value in the waste liquid

the pollutants of acid cooking waste liquid are also the degradation products of lignin and carbohydrates, which are the main reasons for the high COD and BOD

(2) pollutants of chlorine containing bleaching waste liquid

the most serious pollution in paper mills is the discharge of chlorine containing bleaching waste liquid, which contains not only COD and BOD, but also other highly toxic substances

there are thousands of paper mills in China that produce bleached pulp. Except for a few, they all use chlorine containing bleaching technology, such as chlorination bleaching, hypochlorite bleaching, etc. Chloroform produced during hypochlorite bleaching contains about g of waste liquid per ton of bagasse pulp bleached and about 700g per ton of wood pulp bleached. In addition to chloroform, chlorination bleaching also contains more than 40 kinds of organic chlorides in the waste liquid, among which various chlorinated phenols are the most, such as dichlorophenols and trichlorophenols. Dioxins and furans are also produced, and more than 10 kinds of products are highly toxic

(3) pollution of wastewater in the middle of pulp and paper making process

compared with the pollution of black liquor from cooking and bleaching and chlorine containing bleaching waste liquid, the wastewater pollution in other sections of pulp and paper making process is not serious, and this part of wastewater is generally called middle section wastewater

due to technical and economic reasons, the current alkaline pulp production process cannot be completely closed and zero emission. There are also waste liquids and wastes discharged from other sections, which also contain various pollutants, such as dirty waste water generated in material preparation, white water of paper machine, dirty waste water caused by dripping, leakage, running and emitting of plant equipment pipelines, etc. If these waste water is not treated, it will also pollute the environment. However, these wastewater can generally reach the standard after proper physical treatment. In addition, a semi closed circulating system can be adopted, and the wastewater from the previous process shall be used as much as possible from the next process to reduce the discharge of wastewater

some suggestions on reducing environmental pollution in China's paper industry

(1) according to the above analysis, the size of pulp mills, as far as the current situation is concerned, pulp mills with a daily output of less than 30 tons of pulp (an annual output of 10000 tons of pulp) cannot carry out alkali recovery and medium and high concentration pollution-free bleaching, so the state must take tough measures to stop production, let alone build new ones

(2) pulping plants should realize two transformations, namely, to large and medium-sized scale transformation and to wood pulp plants, especially try not to use wheat straw as raw material. In terms of current technology, a lot of research work should be carried out in the near future on the pollution of wheat straw pulp mills and the quality of paper produced by wheat straw pulp. But we can't build a wood pulp plant with an annual output of nearly one million tons as in foreign countries. Even if we build a wood pulp plant with an annual output of 500000 tons, I think it will be very difficult, because it is limited by financial resources and forest resources (it will take hundreds of thousands of mu of forest to offer an investment of 9 billion yuan)

(3) the paper industry should have a unified management organization and management system according to the relevant staff of the sponsor, and strictly control the new plants and expansion plants. At present, the Light Industry Federation, the Ministry of forestry and the Ministry of agriculture all manage pulp and paper mills and should cooperate with each other to formulate unified regulations

(4) for pulp and paper mills with a daily output of more than 50 tons of chemical pulp, the government should support those with better products and economic benefits, establish alkali recovery and pollution-free bleaching systems and three waste treatment systems, and achieve up to standard discharge and civilized production

(5) for the pulp plant produced by the above less pollution pulping method, although the black liquor pollution is reduced, it is also necessary to adjust measures to local conditions, adopt medium and high concentration chlorine free bleaching technology, adopt effective comprehensive utilization methods and three waste treatment measures, and achieve the discharge standard. If the discharge standard cannot be reached temporarily, it should also be transformed 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 and loan from abroad to build new factories and expand factories, the practice of China's paper industry has proved that this road is not feasible

at present, China has some pulp and paper mills that rely on foreign loans to build new plants or expand plants are in trouble, because in the next two months: first, foreign loans are often replaced by foreign equipment; Second, foreign equipment is expensive (for example, the CIO2 generator in the chlorine dioxide bleaching section with a daily output of 150 tons of pulp costs US $6million, and a medium concentration pump costs US $150000); Third, the loan repayment period comes from the date of production, and the profit cannot reach the loan interest. Therefore, we must vigorously develop new equipment in the domestic paper industry, especially medium and high concentration chlorine free bleaching equipment, waste paper deinking equipment, alkali recovery equipment and chemical mechanical pulp equipment

(7) take effective measures to raise funds for environmental engineering in paper mills. A considerable proportion of the sewage charge collected from the paper mill should be used for the construction of the environmental engineering of the plant; Establish an environmental engineering fund to achieve mutual support among plants, centralize funds, and rectify by stages; In the enterprise profits, a certain proportion of the software part of the rib friction coefficient tester of Jinan experimental machine factory Jinan new era Gold Testing Instrument Co., Ltd. should also be taken to set up the environmental engineering construction cost

(8) improve the review and evaluation system of environmental engineering projects in the paper industry. The design, manufacturing and installation units of environmental engineering need to undergo strict examination and assessment, establish a qualification certificate system, and close those unqualified environmental engineering contractors

(9) in the pulp and paper mill, establish an environmental protection monitoring system, test the wastewater discharge load, ensure the normal operation of environmental engineering equipment, and timely report the wastewater discharge standard and environmental conditions of the plant