造紙廢水處理 
    造紙廢水主要來自造紙工業生產中的制漿和抄紙兩個生產過程。制漿是把植物原料中的纖維分離出來，制成漿料，再經漂白；抄紙是把漿料稀釋、成型、壓榨、烘干，制成紙張。
    這兩項工藝都排出大量廢水。制漿產生的廢水，污染最為嚴重。洗漿時排出廢水呈黑褐色，稱為黑水，黑水中污染物濃度很高，BOD高達5-40g/L，含有大量纖維、無機鹽和色素。漂白工序排出的廢水也含有大量的酸堿物質。抄紙機排出的廢水，稱為白水，其中含有大量纖維和在生產過程中添加的填料和膠料。
造紙工業廢水的處理應著重于提高循環用水率，減少用水量和廢水排放量，同時也應積極探索各種可靠、經濟和能夠充分利用廢水中有用資源的處理方法。例如浮選法可回收白水中纖維性固體物質，回收率可達95%，澄清水可回用；燃燒法可回收黑水中氫氧化納、硫化鈉、硫酸鈉以及同有機物結合的其他鈉鹽。
   中和法調節廢水pH值；混凝沉淀或浮選法可去除廢水中懸浮固體；化學沉淀法可脫色；生物處理法可去除BOD，對牛皮紙廢水較有效；濕式氧化法處理亞硫酸紙漿廢水較為成功。此外，國內外也有采用反滲透、超過濾、電滲析等處理方法。
    聚丙烯酰胺絮凝劑應用于造紙廢水處理和纖維回收，有利于達到排放標準。氣浮，沉降用陰離子絮凝劑，壓泥用陽離子絮凝劑。 Papermaking Wastewater Treatment
Paper wastewater mainly comes from pulping and papermaking processes in paper industry. Pulping is the separation of fibers from plant raw materials, making pulp, and then bleaching; Paper making is the dilution, forming, pressing, drying of pulp into paper.
Both processes discharge a large amount of wastewater. Wastewater from pulping is the most polluted. Wastewater discharged during pulp washing is black-brown, which is called black water. The concentration of pollutants in black water is very high. BOD is as high as 5-40g/L. It contains a lot of fibers, inorganic salts and pigments. The waste water from bleaching process also contains a lot of acid-base substances. The waste water discharged from paper machine is called white water, which contains a lot of fibers and fillers and adhesives added in the production process.
Paper industry wastewater treatment should focus on improving the recycling water rate, reducing water consumption and wastewater discharge. Meanwhile, various reliable, economical and effective treatment methods should be actively explored to make full use of the useful resources in wastewater. For example, flotation method can recover fibrous solid substances in white water, the recovery rate can reach 95%, clarified water can be reused; combustion method can recover sodium hydroxide, sodium sulfide, sodium sulfate and other sodium salts combined with organic matter in black water.
Neutralization adjusts the pH value of wastewater; coagulation sedimentation or flotation can remove suspended solids in wastewater; chemical precipitation can decolorize; biological treatment can remove BOD, which is more effective for kraft paper wastewater; wet oxidation process is more successful in treating sulfite pulp wastewater. In addition, reverse osmosis, ultrafiltration and electrodialysis are also used at home and abroad.
The application of polyacrylamide flocculant in papermaking wastewater treatment and fiber recovery is conducive to meeting the discharge standards. Anionic flocculant for air flotation, settling and cationic flocculant for mud compaction