难降解有机物重金属选矿废水处理实验及中试研究

发布时间：2018-06-05 03:07

本文选题：选矿废水 + 三维电解　；参考：《湘潭大学》2017年硕士论文

【摘要】：选矿废水所含的污染物主要有持久性重金属离子、浮选药剂及油污、固体悬浮物等,若不经治理直接排放,将会对选矿厂厂区周边及下游地区的农田、河流、土壤、湿地等产生破坏性影响,并最终危害人类健康。因此,有必要在不引入二次污染的前提下,选择合适的工艺对选矿废水进行深度处理,并综合考虑投资费用、占地面积、运行成本等因素,最大程度去除选矿废水中的COD及重金属,改善选矿厂周边的环境,为我国选矿废水处理提供工艺选择和理论参考。混凝沉淀法是选矿废水处理最常用的方法,该工艺能有效去除选矿废水中的重金属,但对选矿废水中的COD去除效果甚微。研究拟先采用混凝沉淀法对选矿废水进行预处理,后采用物理吸附法或化学氧化法对选矿废水进行深度处理;三维电解法可同步去除选矿废水中的COD和重金属,可采用该方法直接处理选矿废水原水。在综合比较上述工艺对选矿废水的处理效果、运行成本及稳定性的条件下,选出最适合的处理工艺及工艺参数。研究表明:当采用混凝沉淀预处理-物理吸附法时,在废水初始pH值为10.0,混凝剂FeCl_3投加量为50 mg·L~(-1),絮凝剂PAM投加量为30 mg·L~(-1),混凝反应时间为15 min,活性炭投加量为3.0 g·L~(-1),搅拌时间为2.0 h的条件下,选矿废水中的COD浓度降至96.26 mg·L~(-1),重金属铅浓度降至0.38 mg·L~(-1),仍达不到排放标准。当采用混凝沉淀预处理-化学氧化法时,在混凝沉淀处理条件相同,曝气量为5.0 m3·h-1,臭氧浓度为10.0 mg·L~(-1),氧化时间为60 min的条件下,选矿废水中的COD浓度降至68.16 mg·L~(-1),重金属铅浓度降至0.38 mg·L~(-1),不能使选矿废水达标排放,且此时的运行成本高达7.08元·t-1,远高于企业承受能力,需进一步探究新的处理工艺。当采用三维电解法时,研究采用的装置为实验室自主研发的新型“回”形三维电解装置,在电解电压为20.0 V,电流密度为40 mA·cm-2,极板间距为4.0 cm,初始pH值为5.0,Fe~(2+)浓度为0.18 mmol·L~(-1),粉末活性炭投加量为20 g·L~(-1),曝气量为0.4 m3·h-1,电解时间为45 min的条件下,选矿废水中的COD浓度及重金属铅浓度分别降至32.67 mg·L~(-1)和0.18 mg·L~(-1),达到并优于排放标准,此时的运行成本为5.7元·t-1,相对于传统三维电解法其处理效率提升了25%,运行成本仅为传统三维电解处理工艺的75%。三维电解法能持续、稳定地同步去除矿废水中的COD及重金属,具有广阔的应用前景。
[Abstract]:The pollutants contained in the wastewater are mainly persistent heavy metal ions, flotation reagents and oil stains, solid suspended solids, etc. If discharged directly through treatment, it will affect the farmland, rivers, and soil around the factory area and downstream areas of the concentrator. Wetlands and other destructive effects, and ultimately endanger human health. Therefore, it is necessary to select a suitable process for advanced treatment of mineral processing wastewater without introducing secondary pollution, and consider the factors such as investment cost, occupation area, operation cost and so on. The COD and heavy metals in the wastewater can be removed to the greatest extent, and the environment around the concentrator can be improved to provide the process selection and theoretical reference for the treatment of mineral processing wastewater in China. Coagulation precipitation is the most commonly used method for the treatment of mineral processing wastewater. This process can effectively remove heavy metals from mineral processing wastewater, but has little effect on COD removal from mineral processing wastewater. In this study, coagulation and precipitation were used to pretreat the wastewater, and then the physical adsorption method or chemical oxidation method was used to treat the wastewater, and the COD and heavy metals in the wastewater could be removed simultaneously by three dimensional electrolysis. This method can be directly used to treat raw water from mineral processing wastewater. Under the conditions of comprehensive comparison of the treatment effect, operation cost and stability, the most suitable treatment process and process parameters are selected. The results show that when the coagulation precipitation pretreatment and physical adsorption method are used, When the initial pH value of wastewater is 10.0, the dosage of coagulant FeCl_3 is 50 mg / L, the dosage of flocculant PAM is 30 mg / L, the coagulating time is 15 min, the dosage of activated carbon is 3.0 g / L ~ (-1), the stirring time is 2.0 h. The concentration of COD and heavy metal lead decreased to 96.26 mg / L ~ (-1) and 0.38 mg / L ~ (-1) ~ (-1) respectively, which still can not reach the discharge standard. When the coagulation precipitation pretreatment and chemical oxidation process were used, under the same conditions, the aeration rate was 5.0 m ~ 3 ~ (-1), the ozone concentration was 10.0 mg / L ~ (-1) and the oxidation time was 60 min. The concentration of COD in the wastewater is reduced to 68.16 mg / L, and the concentration of heavy metal lead is reduced to 0.38 mg / L ~ (-1), which can not make the wastewater discharge up to the standard, and the operating cost is as high as 7.08 Yuan / t ~ (-1), which is much higher than the capacity of the enterprise. The new treatment process should be further explored. When three dimensional electrolysis method is adopted, the device used in the study is a new type of "return" three-dimensional electrolysis device independently developed by the laboratory. When the electrolytic voltage is 20.0 V, the current density is 40 Ma cm ~ (-2), the distance between electrodes is 4.0 cm, the initial pH value is 5.0 mmol / L ~ (-1) ~ (-1), the dosage of powder activated carbon is 20 g / L ~ (-1), the aeration rate is 0.4 m ~ (3) ~ (-1), the electrolysis time is 45 min. The concentration of COD and heavy metal lead in the wastewater decreased to 32.67 mg / L ~ (-1) and 0.18 mg / L ~ (-1) respectively, which reached and was superior to the discharge standard. The operating cost is 5.7 yuan / t ~ (-1), which increases the treatment efficiency by 25% compared with the traditional three dimensional electrolysis process, and the operating cost is only 75% of the traditional three dimensional electrolytic treatment process. Three-dimensional electrolysis method can remove COD and heavy metals from ore wastewater in a steady and steady manner, which has a broad application prospect.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X753

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