Current situation of pollution control technology

2022-09-22
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The research and application of key technologies for the resource utilization of waste paper and papermaking wastewater put forward a new model for the resource utilization of waste paper and papermaking wastewater. By developing new wastewater treatment equipment and processes with independent intellectual property rights and synthesizing new papermaking aids to treat sediment, the key technical problems of the resource utilization of waste paper and papermaking wastewater and sediment have been solved, It has realized the energy conservation, emission reduction and cleaner production of waste paper and papermaking, and created a new mode of waste paper and papermaking wastewater treatment in China. It has been popularized and applied in 56 paper mills across the country. A total of 760000 tons of papermaking wastewater are treated every day, 1140 tons of CODCr emissions are reduced, 456 tons of fiber are saved, 72000 kwh/day of energy consumption is saved, and the annual direct economic benefit is 202million yuan, which has achieved good environmental, economic and social benefits

the amount of waste paper is increasing year by year.

as the country with the largest amount of paper in the world, the paper industry is one of the pillar industries of sustainable development in China. With the shortage of plant resources and attention to environmental protection, in order to protect forest resources and reduce the pollution of the paper industry to the environment, waste paper papermaking has become an important development direction of the paper industry if there are time-varying values on the counter. Waste paper has accounted for more than 50% of the country's paper-making raw materials. Today, the annual output of waste paper papermaking in China exceeds 40million tons, and is increasing year by year

but what is worrying is that according to Professor Wan, the waste water produced by waste paper papermaking and the sediment produced in the waste water treatment process are large, with a water consumption of 3060 tons per ton of paper produced, a chemical oxygen demand (CODcr) load of 1500 2500mg/l, and 0.34 tons of sediment produced. At present, due to the large investment and high energy consumption in the treatment of waste paper and papermaking wastewater, the accumulation of pollutants in the process of wastewater recycling cannot be solved, and it is difficult to realize the long-term closed recycling of water; However, it is difficult to use sediment, which can only be landfilled and incinerated, causing environmental pollution

current situation of waste paper pollution control technology

at present, the general waste paper pollution control technology mainly includes physicochemical treatment technology and biochemical treatment technology, but they all have insurmountable defects

first of all, the sedimentation tank method in the physicochemical treatment technology has low pollutant removal rate, long flocculation and sedimentation time, and the sediment will be anaerobic fermentation; Shallow air flotation technology has low pollutant removal rate, high operation cost, sediment contains a large number of micro bubbles, and poor water filtration

in addition, biochemical treatment technologies include SBR method, Carrousel oxidation ditch, IC Anaerobic + aerobic method, etc., which are difficult to achieve effective degradation of refractory organic pollutants in wastewater, and pollutants will accumulate after wastewater recycling

Professor Wan said that these technologies make it difficult to use a large amount of wastewater and waste residue. The amount of waste water produced is large, with 3060 tons of water consumed for each ton of paper produced, and the CODcr load reaches 1500 2500mg/L. the amount of waste water produced by waste paper and paper making in China is about 1.98 billion tons every year, which is equivalent to the annual drinking water volume of 27million people; Because the sediment cannot be reused every year, 5million tons of plant fiber are wasted, which is equivalent to the loss of 60million adult trees

efficient integrated technology

Wan Jinquan said: the traditional paper industry wastewater treatment method usually adopts a single physicochemical or biochemical treatment method, which not only has large investment, but also has poor treatment effect and high operation cost. Our wastewater treatment is an efficient integrated technology

compared with other technologies, the R & D and application projects of key technologies for the resource utilization of waste paper and papermaking wastewater can not only protect the environment, but also create benefits. Professor wanjinquan said: compared with domestic and foreign technologies, the investment of this technology is reduced by about 20%, the operating cost is reduced by more than 30%, and the removal rate of refractory pollutants is increased by more than 20%, which can realize zero discharge of waste paper and papermaking wastewater

the overall process of the project can be described as follows: the papermaking wastewater is removed from the grid and enters the regulating tank. After the water quality and quantity of the wastewater are balanced in the regulating tank, it is pumped to the high-efficiency integrated treatment equipment (adding chemicals). About 80% of the effluent treated by the integrated equipment can be reused in the workshop, and the rest is gravity fed into the co metabolic bioreactor for treatment. The treated water can be recycled for a long time, Realize zero discharge of papermaking wastewater, and the sediment produced by physical and chemical treatment is reused for production after being treated by nhep-30

efficient first-class physicochemical treatment equipment and technology

Wan Jinquan explained that the main pollutants in waste paper and papermaking wastewater are fine fibers, resin acids, inks, dyes, etc. these pollutants exist in the form of insoluble fine fibers, rubber companies with advanced technical equipment and professional testing teams, dissolved organic substances and salts

by studying the coagulation process of wastewater, the project team proposed a new high-efficiency integrated physicochemical treatment equipment that integrates coagulation, sedimentation, adsorption and filtration of wastewater. Compared with the similar sedimentation or air flotation treatment of papermaking wastewater at home and abroad, the removal rate of SS, CODcr and BOD5 is increased by 20% 35%, the hydraulic retention time is shortened by 30% 40%, and the energy consumption is reduced by more than 30%. The treated effluent can be better reused for production, reducing the treatment capacity and load of subsequent biochemical treatment, as well as the energy consumption and operation cost of wastewater treatment

after long-term recycling of physicochemical treated effluent, soluble substances such as papermaking accessories and resin acids will accumulate, affecting production. If the physicochemical treated effluent is reused after biochemical treatment, the load and cost of biochemical treatment will be greatly increased

due to the efficient physicochemical treatment effect of this technology, the accumulated amount of wastewater treated by this technology is less after recycling. However, when the reuse rate of wastewater exceeds 80%, the accumulated amount of DCS in wastewater increases significantly, and the enrichment of anionic garbage will cause the paper machine to break and stick, which will affect the paper production. Biochemical treatment of 20% wastewater can not only solve the impact of DCS accumulated in water, but also reduce the investment scale and treatment cost of subsequent secondary biochemical treatment, and solve the contradiction between the economy of wastewater treatment and treatment effect

new technology of carbon source collaborative co metabolism biological treatment

Wan Jinquan said: through qualitative and quantitative analysis of the wastewater after physicochemical treatment, 90 kinds of main organic pollutants were detected, and the typical pollutants were dibutyl phthalate and xylene. Traditional biological methods can not achieve the effective degradation of such pollutants, which is one of the main reasons for the failure of zero discharge of waste paper and papermaking wastewater

in this case, only by artificially strengthening with additional carbon sources to induce microorganisms to produce key enzymes, and under the effect of key enzymes preparing the best lightweight solutions for energy conservation and emission reduction for potential customers in freight, logistics, urban environmental protection and other industries, can microorganisms use such substances, so as to be degraded or transformed, and finally removed

according to the characteristics of carbon source co metabolism technology, the project has developed anaerobic, facultative, aerobic biological processes and co metabolism bioreactors based on CO metabolism. The waste water enters the radial distribution pipe through the overflow weir to mix the organic matter and co metabolic carbon source in the waste water

because the water distribution pipes are evenly arranged in a radial shape, the uneven water distribution caused by the resistance along the way when water flows in a single pipe is overcome, the contact time between pollutants and co metabolizing microorganisms is increased, and the treatment efficiency is improved

new technology for sediment recycling of primary physicochemical treatment

project research shows that fiber accounts for about 72%, inorganic filler accounts for about 20% and other components account for 8% of the components of papermaking sediment. The fibers in the sediment and and Lilians Daron reg, which has excellent performance in these two aspects; Compared with fine fibers, the fibers in series resin waste pulp have a large proportion, high surface charge content and strong negative charge. The sediment fibers still have a certain tensile strength and are of reuse value. However, if they are directly reused in production, the retention rate is low and the paper strength is poor, which will cause problems such as broken ends and blockage of the paper machine, and seriously affect the normal production

therefore, it is necessary to add papermaking additives to realize the retention and reinforcement of fine fibers in order to realize the reuse of residues. Wan Jinquan said

the high content of fine fibers and inorganic fillers in the sediment will lead to difficult dispersion and reduced accessibility of papermaking additives. Therefore, the additives that can realize the recycling of papermaking residues should have the characteristics of high charge, small particle size, large specific surface area and so on, while the existing papermaking additives can not meet the above application needs

therefore, the project portfolio formed a nano-sized high charge amphoteric polyacrylamide (nhep-30). After being treated by nhep-30, the retention rate of fine fibers in sediment and the strength of paper can be increased by more than 30%. It can be used as papermaking raw material for production, realize resource utilization, and solve the secondary pollution caused by the relative environment of solids in papermaking wastewater

new mode of wastewater treatment

this technology has completely changed the traditional wastewater treatment methods in the paper industry. The paper mill has realized power saving, water saving, paper fiber saving, and achieved benefits from paper wastewater. Wan Jinquan said

compared with the current similar technologies, the investment of wastewater treatment project is saved by more than 30%, the operating cost is reduced by more than 40%, and the energy consumption is reduced by more than 30%, realizing the closed circulation of waste paper and papermaking wastewater and the cleaner production of paper mills

at present, it has been applied in 56 paper mills in Guangdong, Hunan, Hubei, Shandong, Heilongjiang, Jiangsu, Shanxi, Zhejiang, Guangxi, Hebei, Sichuan and other provinces. A total of 760000 tons of paper-making wastewater are treated every day, 1140 tons of CODCr emissions are reduced every day, and 456 tons of fiber are recovered every day. Through power saving, water saving, paper fiber saving and other direct annual economic benefits of 202 million yuan, the cumulative economic benefits in the past three years are about 560 million yuan, It has achieved good economic and social benefits

it is estimated that at present, the annual output of waste paper papermaking in China is more than 40million tons, and there are more than 1000 paper mills using waste paper as raw materials. These manufacturers basically do not realize the efficient resource utilization of waste water, which shows that this technology has a broad market prospect

based on the expectation that 400 paper-making enterprises will use this technology to treat about 4million tons of wastewater per day, the annual direct economic benefit will reach 1.2 billion yuan through cost saving, and the resulting environmental and social benefits will be greater

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