The Treatment And Reuse Of Papermaking Wastewater

According to the summary of the techniques of the anaerobic water treatment and the reuse of the wastewater from papermaking, the Up-flow Anaerobic Sludge Bed (UASB) was used to treat the wastewater from pulp and paper making with recycled fiber in this research. The UASB was used as the central unit of the system, and the coal fly ash was settled to treat the effluent from the UASB. In addition to organic substance, many species of contaminants were removed by this system, such as group S042-, ions of alkaline earth metal and heavy metal, and total hardness et al. After the treatment, the wastewater could be recycled into the production of papermaking.Because the treatment system was operated in laboratory, simulated wastewater was confected according to the investigation of papermaking process in several companies. The COD of simulated wastewater was about 1100 mg/L, which was close the property of the wastewater of most paper mills using recycled fiber. The HRT of UASB reactor was about 4.43h, which was accord with most UASB plants.During the research, the starting up and operating process of the UASB reactor were observed. The temperature of the water, the VFA and alkalinity concentration of the UASB effluent was surveyed particularly. The UASB reactor was found can keep high treatment efficiency by adjusting the load of the UASB and supplying N, P elements and some other microelements. The process on average removed about 90% of COD, 50% of total hardness, and 80% of sulfate.The main factors affecting the treatment efficiency were temperature, nutriments and the sludge exposure level to substrate. Especially, the temperature had a close relationship with the methane yield rate. The relation could be given with the equation:V is the methane yield rate at the temperature T (K).According to the comparison between activated sludge process (AS) and absorption with coal fly ash, the coal fly ash absorption was decided as the reprocessing technique of the UASB effluent. After the process, the concentration of metal ions reduced obviously. The process of coal fly ash absorption wouldn't bring the dissolving of metal ions, and, withal, the concentration of metal ions could be controlled effectively. The removal of chromaticity meets the Freundlich isothermal equation:In q = 0.674 In C + 2.821...