造纸废水处理 
    造纸废水主要来自造纸工业生产中的制浆和抄纸两个生产过程。制浆是把植物原料中的纤维分离出来，制成浆料，再经漂白；抄纸是把浆料稀释、成型、压榨、烘干，制成纸张。
    这两项工艺都排出大量废水。制浆产生的废水，污染最为严重。洗浆时排出废水呈黑褐色，称为黑水，黑水中污染物浓度很高，BOD高达5-40g/L，含有大量纤维、无机盐和色素。漂白工序排出的废水也含有大量的酸碱物质。抄纸机排出的废水，称为白水，其中含有大量纤维和在生产过程中添加的填料和胶料。
造纸工业废水的处理应着重于提高循环用水率，减少用水量和废水排放量，同时也应积极探索各种可靠、经济和能够充分利用废水中有用资源的处理方法。例如浮选法可回收白水中纤维性固体物质，回收率可达95%，澄清水可回用；燃烧法可回收黑水中氢氧化纳、硫化钠、硫酸钠以及同有机物结合的其他钠盐。
   中和法调节废水pH值；混凝沉淀或浮选法可去除废水中悬浮固体；化学沉淀法可脱色；生物处理法可去除BOD，对牛皮纸废水较有效；湿式氧化法处理亚硫酸纸浆废水较为成功。此外，国内外也有采用反渗透、超过滤、电渗析等处理方法。
    聚丙烯酰胺絮凝剂应用于造纸废水处理和纤维回收，有利于达到排放标准。气浮，沉降用阴离子絮凝剂，压泥用阳离子絮凝剂。 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