Centrifugal extraction machine for treating phenol-containing wastewater in papermaking

Due to the large amount of water used in the paper industry, a large amount of wastewater generated in the papermaking process is also one of the important causes of water pollution. This is not only the primary problem of pollution prevention and control in China's paper industry, but also the primary problem in the treatment of industrial wastewater in China. The large amount of phenols and toxic substances produced in the papermaking process pose a serious threat to the ecological environment and human health. This paper mainly introduces the centrifugal extractor to treat phenol-containing wastewater in the paper industry in a closed environment.

Main ingredient

The composition of pulp and papermaking wastewater is complex, and its composition depends not only on the method of pulp, but also on various factors such as the type of product and the type of raw material. The suspended matter in the paper industry wastewater mainly comes from the bark of the preparation section, grass clippings, sediment and the ash, slag, fiber and filler lost in the process of pulping and papermaking; the BOD in the wastewater mainly comes from pulping. The cooking process, such as sugars, alcohols, organic acids, etc. produced by the decomposition of cellulose, the COD and coloring matter in the wastewater are mainly derived from the lignin and its derivatives in the pulping and cooking process; the toxic substances in the wastewater mainly include cooking waste. Crude sulphate soap in liquid, organic chloride in bleaching wastewater (such as dichlorophenol, chlorocatechol, etc.), as well as trace amounts of mercury, phenol, etc. In China, due to the large proportion of raw materials of grass fiber, the scale of enterprises Small, the production process and equipment are backward, raw materials, energy, and water consumption are large, which makes the pollution of China's pulp and paper industry particularly serious.

classification

Pulp and paper wastewater can be roughly divided into: pulping cooking liquor, washing wastewater, bleaching wastewater and paper machine white water. Alkali pulp cooking waste liquid, also known as "black liquor", is the main source of pollution in pulp mills.

The pollutants contained in the black liquor account for more than 90% of the total pollution discharge of the paper industry, and have high concentration and refractory characteristics. Its treatment has always been a major problem. There are three main components in the black liquor, namely lignin, polypentose and total alkali. Lignin is a kind of non-toxic natural high-molecular substance, which has a wide range of uses as chemical raw materials, and polypentose can be used as livestock feed.

Middle water

The mid-stage pulping wastewater refers to the wastewater discharged from the cooking slurry after black liquor extraction in the process of screening, washing and bleaching. The color is dark yellow. The most serious environmental pollution is the chlorine-containing wastewater generated during the bleaching process. Chlorinated bleaching wastewater, hypochlorite bleaching wastewater, etc. Hypochlorite bleaching wastewater mainly contains chloroform, and also contains more than 40 kinds of other organic chlorides, among which various chlorinated phenols are the most, such as dichlorophenol and trichlorophenol. In addition, the bleaching waste liquid contains toxic dioxins, which are extremely toxic, posing a serious threat to the ecological environment and human health.

White water

White water is the papermaking section wastewater, which comes from the papermaking process in the papermaking workshop. White water mainly contains fine fibers, fillers, coatings and dissolved wood components, as well as added rubber compounds, wet strength agents, preservatives, etc., mainly based on insoluble COD.

Centrifugal extractor for the treatment of phenolic substances in the paper industry

The centrifugal extraction machine removes phenol , which has the characteristics of small volume, high efficiency and small amount of extracting agent, which can save a lot of extractant cost, and the phenol removal rate is over 98%. At present, the annual discharge of industrial wastewater by domestic enterprises is about 40 billion tons, of which phenol industrial wastewater accounts for about 0.5%, about 2 billion tons. According to market research, it is estimated that about 30% of the total amount of phenol-containing industrial wastewater discharged in China can be removed by centrifugal extraction machine, and a total of more than one thousand centrifugal extraction machines are needed.

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