江苏携德节能科技有限公司

Brief Introduction

Wastewater discharged from the production process of the paper industry. Paper industry wastewater can be divided into two types: sulfate pulp wastewater and sulfite pulp wastewater. Among them, the wastewater discharged from the pulp process is the most polluted. The dark brown wastewater discharged during pulp washing is called black liquor; the wastewater discharged from the bleaching process contains acids, alkalis and BOD (100-300 mg/L); in the papermaking process, the wastewater discharged from the paper machine is called White water. Black liquor and white water are the main waste water in the paper industry. Papermaking wastewater contains a large amount of organic matter and suspended matter, as well as a large amount of chemicals and impurities. It is one of the main sources of water pollution in my country.

Source

1、Stripping wastewater mainly contains a large amount of suspended solids, resin and cellulose.

2、Pulping wastewater contains cellulose, lignin and hemicellulose, in addition to pectin, tannin, resin, wax, and ash. Caustic soda and kraft pulping wastewater is also called "black liquor", which contains 10-20% impurities, of which about 35% are inorganic substances and 65% are organic substances. The waste liquid contains a large amount of caustic soda, and the BOD is as high as 9000-30000mg/L. Ammonium pulping wastewater is brownish-red, also known as "red liquor". Impurities account for 8-15%, of which 20% are calcium and magnesium salts and residual sulfurous acid; 80% are organic matter, mainly lignosulfonic acid Salt, sugars, fatty acids and a small amount of alcohols, ketones, aldehydes, resins, tannins, proteins, etc., have high BOD in the waste liquid. Neutral sulfite pulping wastewater (semi-chemical pulp wastewater) contains sulfite lignin compounds, tannins and lower fatty acids.

3、The chemical composition of the beating wastewater is similar to that of the black liquid phase, but the concentration is slightly lower, the amount of wastewater is larger, and the suspended solids and BOD are high

4、Paper machine wastewater is called "white water", which contains fibers, fillers (kaolin, talc), rubber (rosin), etc. The BOD value is not too high .

The use of evaporation and concentration to treat papermaking black liquor is one of the more common treatment methods recently, and multi-effect evaporation equipment is generally used. Multi-effect evaporation equipment, the energy-saving effect is second only to the MVR evaporator, using the steam produced by the first effect as the second-effect heat source, and so on, so as to achieve the energy-saving effect. When treating papermaking black liquor wastewater, the papermaking black liquor wastewater enters each effect evaporator with the action of the material pump, and evaporates in each effect evaporator. This operation process has the advantages of less equipment and simple operation.