Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

Water-soluble polymer flocculants have been used to efficiently release entrapped water in oil sands tailings by bridging fine particles to create large heavier flocs which can then settle faster and release water more efficiently. Due to their initial interaction with the fine particles suspended in tailings, polymer nanofibres may perform better than their parent polymers because of the entire surface of the nanofibres being fully accessible to the fine particles. In this work, commercially available poly(acrylamide-co-diallyl dimethylammonium chloride) was chosen as a basis for this study. Initial settling rate, supernatant turbidity, water recovery, capillary suction time, and solids content were measured to determine the effect of polymer nanofibres on solid-liquid separation. The solid forms of the polymer (either as nanofibre or powder) perform better than the polymer solution in each test, with optimum dosages of 5 wt% mature fine tailings (MFT) loading. Nanofibres could achieve settling rates of 60 m/h, while the other forms were only able to achieve 42 m/h. Additionally, the turbidity of the supernatant obtained after flocculation with nanofibres was 15 nephelometric turbidity units (NTU), while the polymer solution and powder produced turbidites of 162 NTU and 70 NTU, respectively. In addition, polymer nanofibres and powders generated larger flocs compared to the polymer solution, which produced small, homogenized flocs.     

Impact of polymer flocculants on coagulation-microfiltration of surface water

Organic polymers are widely used as flocculants in pretreatment for microfiltration. However, their impact on microfiltration system performance was not well understood. In this study, the effects of three types of polymer flocculants on microfiltration permeate water quality and membrane fouling were evaluated using a hollow fiber membrane under two different operation modes, coagulation/flocculation-sedimentation-microfiltration (CFSM) and coagulation/flocculation-microfiltration (CFM). Interestingly, the effect of polymers on membrane fouling did not appear to reflect their impact on dissolved organic matter content or floc particle properties in the membrane feed water. The addition of polymer flocculants resulted in floc particles of larger size and smaller fractal dimension and slightly enhanced the removal of dissolved organic matter, both of which were expected to reduce membrane fouling. However, it significantly aggravated membrane fouling in all cases except when the positively charged poly(diallyldimethylammonium) chloride was used in the CFSM process. In particular, all polymers greatly increased hydraulically irreversible fouling in the CFM mode. The increased fouling in the CFSM mode is attributed to the residual polymer, while that in the CFM mode is attributed to the enhanced irreversible floc particle attachment on the membrane surface. Considering the potential severe membrane fouling and the small improvement in treated water quality when polymers are used, the application of polymers in microfiltration pretreatment needs to be carefully evaluated.     

多孔性交联淀粉絮凝剂的制备研究

以玉米淀粉为原料,先用a-耐高温淀粉酶处理,制备多孔玉米淀粉,然后以环氧氯丙烷(ECH)为交联剂,合成具有多孔结构的颗粒态交联淀粉絮凝剂,并对交联工艺进行了初步优化。制备多孔交联淀粉的最佳条件为:25 g多孔淀粉,碱性硫酸钠溶液用量50 mL,环氧氯丙烷用量0.75mL,反应温度25℃,反应时间18 h。     

丙烯酰胺-甲基丙烯酰氧乙基三甲基氯化铵共聚物的制备研究

用过硫酸铵(KPS)引发甲基丙烯酰氧乙基三甲基氯化铵(DMC)与丙烯酰胺(AM)单水相共聚,制备了阳离子聚丙烯酰胺类絮凝剂P(DMC-AM),并应用于废水。探讨了单体总量、引发剂用量、pH值、反应时间等因素对聚合物的特性粘数和粘均分子量的影响。结果表明,P(DMC-AM)粘均分子量可达1.72×107g/mol,对废水浊度的去除率达到80%以上,是一种性能优良的絮凝剂。     

无机有机复合高分子材料包覆纳米Fe_3O_4的制备及其性能研究

利用物理复合的方法制备出聚硅硫酸铁-壳聚糖(PFSS-CTS)复合高分子材料,并将其包覆在纳米Fe_3O_4的表面得到新型高效的磁絮凝剂PFSS-CTS@Fe_3O_4。通过扫描电子显微镜、傅立叶变换红外光谱仪、X射线衍射仪对其表面形态和结构进行表征,结果表明,PFSS与CTS在反应前后物质结构发生了变化,生成了一种新的聚合物,并成功包覆在了纳米Fe_3O_4的表面,得到了理想的产物。然后将其对工业废水进行絮凝试验得出该絮凝剂最佳合成及应用条件:m(PFSS)∶m(CTS)=5∶1,投加量为180 mg/L,沉降时间为20 min。PFSS-CTS@Fe_3O_4在最佳条件下COD、浊度、色度的去除率最高分别达到85.12%、93.54%,89.74%。     

Depressing effect of flocculants on molybdenite flotation

The quality of recycled process water is an important issue in the flotation of Cu–Mo ores. Processing of Cu–Mo ores includes two steps: a bulk flotation where molybdenite is recovered together with Cu sulfides, and a subsequent selective flotation step where molybdenite is separated from depressed copper sulfides. Flocculants are usually employed in the middling thickeners in the copper plant, and in the Cu–Mo bulk concentrate ahead of the molybdenite plant. However, the floatability of molybdenite, similarly to other naturally hydrophobic minerals, is highly sensitive to the presence of both natural and synthetic polymers. In this work flotation tests demonstrate that conventional flocculants, high-molecular weight anionic polyacrylamides (PAM), are strong molybdenite depressants. Low-molecular weight shear degraded polyacrylamides in spite of losing flocculation efficiency maintain depressing ability for molybdenite. Also a non-ionic flocculant, polyethylene oxide (PEO), has been studied in this project. Our results indicate that PEO is an efficient flocculant for molybdenite suspensions in a wide pH range. However, similarly to polyacrylamides, the PEO flocculant also depresses molybdenite flotation.     

紫金洗煤厂絮凝剂自动添加系统的研究

针对紫金洗煤厂煤泥水处理的实际情况,设计了絮凝剂自动添加控制系统。系统根据实时检测到的煤泥水浓度、流量以及溢流水浊度,通过前馈和反馈相结合的方法,自动控制絮凝剂添加量。工业试验表明:使用该系统降低了药耗,稳定了溢流水浊度,改善了循环水质量。     

绿色水处理化学品的研究进展

简单介绍了目前常用的几种绿色水处理化学品,包括天然化合物、聚天冬氨酸、聚环氧琥珀酸、γ-聚谷氨酸、烷基环氧羧酸盐、四羟基硫酸鏻和天然高分子絮凝剂等,指出了绿色水处理化学品及其清洁化生产是水处理化学品研究的必然发展趋势。     

辐照法制备秸秆絮凝剂的研究

通过辐照法制得秸秆改性阳离子絮凝剂,并探讨了该絮凝剂对高岭土悬浊液的絮凝作用,着重考察了单体(丙烯酰胺)与处理后秸秆的配比、LiCl/DMAc溶液浓度、辐照剂量对秸秆改性阳离子絮凝剂接枝率的影响。实验结果表明,水稻秸秆改性阳离子絮凝剂最佳的合成条件为:单体与处理后秸秆的质量比为3∶2,LiCl/DMAc溶液质量浓度为10 g/mL,辐照剂量为9 kGy。制得的秸秆改性阳离子絮凝剂的接枝率为50%,对高岭土悬浊液的去除率达到63%。     

微生物絮凝剂的研究及在废水处理中的应用

介绍了微生物絮凝剂的分类,絮凝机理以及微生物絮凝剂的提纯等,综述了微生物絮凝剂在废水处理中的实际应用。最后指出了在微生物絮剂研究中存在的问题,并对以后的研究提出了一些建议。