Viscose Staple Fiber Sulfate Reuse Of Wastewater With Anaerobic Treatment Technology

Viscose staple fiber wastewater is high sulfate organic wastewater which sulfate was tens of thousands of milligrams per liter and was higher than industry standards of 600ppm. Entered ecosystem can cause water acidification, aquatic organisms deaths, soil acidification and hardening, and reduce SO42- to S2- which can transform H2S and metal sulfides causing harm to animals, plants and metal objects. When using anaerobic technology treats organic wastewater, sulfate in the wastewater can also reduce organics processing efficiency.In this paper, an integrated setup of physicochemical and biological process was constructed to treat viscose staple fiber wastewater. The three-step process was pretreatment by activated carbon, preparation of calcium sulfate whisker by atmospheric acidification technology and depth degradation by anaerobic technology, then effluent quality was analyzed after every step of the process. Influencing factors of preparation calcium sulfate whisker was systematically studied, then transformation and mechanism of calcium sulfate whisker was analyzed in the paper. After the preparation of calcium sulfate whisker, temperature and sulfate concentration of wastewater can be improved, and a good platform was provided for next step. Through determining the effluent water quality, removal efficiency was analyzed by anaerobic biological reactor.Pretreatment of viscose staple fiber wastewater using 5% activated carbon for 30 min can discolor the wastewater. This process has not obvious impacts to concentration of SO42- and COD.The best calcium sulfate whiskers with length range of 20～40μm and aspect ratios range of 15～20 can be prepared from wastewater with 300 r·min-1 stirring speed at 90℃ for 50 min reaction time in presence of calcium carbonate and mol(SO42-):mol(Ca2+) by 6:5. CaSO4·2H2O, CaSO4·1/2H2O and CaSO4 whiskers can be obtained by different thermal treatment temperature of 80,100 and 600℃. After this process, pH from below 2 risingto nearly 7, concentration of SO42- degrade from 30700ppm to 6200ppm, concentration of metal ion significantly reduced and temperature reduced to room temperature. After this process, a good platform was provided for the depth biotechnology processing.Anaerobic reactor was started with mesophilic condition 37±1℃ and applied mature granular sludge as sludge inoculation, with a loading of 9.6kgCOD·m-3d-1 and 4.8kgSO42-·m-3·d-1 when the reactor steadily running for 34 days. Effluent concentration of COD and SO4 can degrade from 4000ppm and 2000ppm to 200ppm and 150ppm, and the removal efficiency were 95% and 90%.The effluent concentration of SO42- reached discharge standards.Concludingly, viscose staple fiber wastewater can reuse the sulfate, and has a good treatment effect, and the effluent concentration of SO42-reached discharge standards.