【作者】 王广伟；

【导师】 邱立平；

【作者基本信息】 济南大学 ， 市政工程， 2011， 硕士

【摘要】 磷是造成水体富营养化的主要元素之一,又是不可再生且面临枯竭的重要自然资源,因此,研究高效除磷技术,开发新的磷资源迫在眉睫。利用结晶法去除并回收废水中的磷是目前公认的既能有效防治水体富营养化,又能实现磷资源可持续利用的有效途径,具有重要的研究价值。本文以模拟低浓度含磷废水为处理对象,对比考察了投加石英砂、陶粒、钢渣和矿渣材料对废水除磷的作用特性,筛选出了能够有效促进磷酸盐结晶反应的材料;探讨了不同活化改性方法对已筛选材料诱导结晶除磷效能的影响规律,在此基础上,利用机械活化后的粉末钢渣和矿渣分别制备了除磷晶种基质材料,进而通过水热改性获得了具有高效吸附和碱度及离子缓释效能的除磷晶种,总结提出了基于水热改性的新型除磷晶种制备方法;系统考察了除磷晶种处理低浓度含磷废水的结晶除磷特性,利用XRD和SEM-EDS等手段对除磷反应产物进行表征、分析,初步探讨了除磷晶种的结晶除磷机理。研究结果表明,在不调节原废水水质的条件下,投加石英砂、陶粒、钢渣和矿渣对模拟废水中磷的去除具有不同的作用效果。其中,钢渣的除磷能力显著优于矿渣,而陶粒和石英砂基本不具备除磷能力。提高模拟含磷废水的初始Ca/P、pH值、磷浓度和延长反应时间,可有效提高投加晶种材料的除磷效率。当Ca/P>2.0时,除磷效率缓慢增加;当溶液pH>9时,除磷效率显著提高;当初始磷浓度>10mg/L时,除磷效率显著高于低浓度时的除磷效率（<10mg/L）;当结晶反应时间>24h时,再延长反应时间对结晶除磷效率无显著影响。在本实验条件下,投加陶粒和石英砂对模拟废水除磷效能没有明显改善,而投加钢渣可有效去除模拟废水中的磷,说明具有释放碱度和钙离子能力的材料能够促进结晶除磷过程,是制备高效除磷晶种的良好基质材料。通过对比考察机械法、水热法和机械-水热联合法对钢渣和矿渣的除磷活化效果,发现改性处理可有效提高钢渣和矿渣的除磷效能,其中机械-水热法活化效果最佳。因此,首先利用机械活化法对钢渣和矿渣进行破碎、粗磨处理,经筛分后获得粒径为3-5mm颗粒钢渣和颗粒矿渣;利用进一步研磨所得的钢渣和矿渣粉末,通过造粒、成型和养护环节,制备钢渣基复合滤料和矿渣基复合滤料,并与颗粒钢渣和颗粒矿渣共同作为除磷晶种基质材料,进行进一步的水热改性活化处理。试验结果表明,水热改性活化处理可显著提高四种基质材料的除磷能力,改性温度、改性时间、NaOH浓度及液固比对活化效果具有重要影响。提高改性温度、NaOH浓度和液固比,延长改性时间,对钢渣、矿渣和矿渣基复合滤料的结晶除磷效能有明显促进作用,其最佳改性温度、改性时间、NaOH浓度和液固比分别为200℃、24h、6M和1;而钢渣基复合滤料的改性活化条件与其他三种有所差异,最佳改性温度、改性时间、NaOH浓度和液固比分别为105℃、6h、6M和1。综合考虑机械活化和水热改性的处理成本及基质材料结晶除磷效能,总结得出基于不同基质材料的除磷晶种制备方法,获得了四种除磷晶种材料,其水热改后的除磷能力分别为:颗粒钢渣6.88 mg/ cm³、颗粒矿渣4.67 mg/ cm³、钢渣基复合滤料5.63 mg/ cm³、矿渣基复合滤料4.19 mg/ cm³,较改性前分别提高了60.8%、45.2%、54.8%、39.9%。研究发现,除磷晶种的结晶除磷特性与其碱度及钙离子缓释能力密切相关,当溶液初始Ca/P=2,pH=8.0时,改性颗粒钢渣、颗粒矿渣及矿渣基复合滤料的碱度及钙离子释放速度较快,其结晶除磷效能衰减速度快于改性钢渣基复合滤料,后者具有更为持久的连续除磷能力。XRD和SEM-EDS表征结果表明,不同反应条件下晶种材料的结晶除磷产物为不同形式的磷酸钙;随着反应时间的延长,磷酸钙沉淀晶化程度逐渐加强,晶核数量逐渐增多同时晶体逐渐增大,转化为结晶度不高的球状羟基磷酸钙（Ca₅（PO₄）₃OH）晶体,其Ca/P=1.66,与理论值（1.67）基本一致。基于水热改性制备的钢渣基复合滤料含有大量的水化硅酸钙C-S-H和Ca（OH）₂,能够释放出结晶过程所需的碱度和钙离子,从而促进磷酸盐以磷酸钙的形式析出,并进一步转化成为羟基磷酸钙晶体。更多还原

【Abstract】 Phosphorus （P） is one of the major nutrient elements which could cause water eutrophication, however, it is also an important nonrenewable nature resource which is faced with exhaustion. So, it is extremely urgent to develop efficient phosphorus removal technology and new phosphorus resource facing the shortage of phosphate rock resources all over the world. Phosphorus removal by crystallization is of great research value which has been recognized as an effective way to prevent the water eutrophication and realize the sustainable utilization of phosphate rock resources.This study was investigated to recovery phosphorus from artificial low concentration phosphate wastewater. The character of phosphate removal with quartz sand, ceramsite, steel slag and blast furnace slag were compared and the favorable materials were screened out which could be in favor of phosphate crystallization. Different active methods for screened materials which could promote the phosphate crystallization were discussed. And the basis materials of crystal seeds were prepared by powdery steel slag and blast furnace slag. Then the crystal seeds could be obtained by the hydrothermal modification of basis materials, which have the ability of adsorption and release alkalinity and calcium. A method based hydrothermal modification to prepare an efficient crystal seeds for phosphate removal was extracted. The performances of crystal seeds for phosphate removal by crystallization were evaluated. The reaction products of phosphate crystallization with crystal seeds were analysed by XRD and SEM-EDS, and then the mechanism of crystal seeds in phosphate removal were also discussed preliminarily.The results showed that the performances of phosphater removal by quartz sand, ceramsite, steel slag and blast furnace slag were different, and steel slag was much better than blast furnace slag and that of quartz sand and ceramsite was very little.The phosphate remove efficiency of low P concentration wastewater by crystallization could be improved by increasing initial Ca/P、pH、P concentration and reaction time. When the Ca/P>2.0, the efficiency of phosphate removal increased slowly with increasing Ca/P. When the initial pH>9 or P concentration was higher than 10mg/L, the efficiency of phosphate removal was highly improved. When the crystallization was processed for more than 24 hours, the efficiency of phosphate removal was almost steady even if the reaction time was prolonged continually.In this experimental condition, the quartz sand and ceramsite could not promote the phosphate crystallization. But steel slag could remove the phosphate effectively. The results showed that the material which could release alkalinity and calcium can promote the phosphate crystallization and also the favorable basis material for prepare efficient crystal seed.The results showed that performances of phosphate removal by steel slag and blast furnace slag could improve by hydrothermal modification. So, the steel slag and blast furnace slag were crushed and grinded into smaller grain size firstly, and the granular steel slag and blast furnace slag with grain size at 3mm - 5mm could be obtained through sieveing. Then the powdery steel slag and blast furnace slag could be obtained through futher grinding, and the hybrid seed media with steel slag and hybrid seed media with blast furnace slag could be prepared by pelleting, molding and curing. The granular steel slag, granular blast furnace salg, hybrid seed media with steel slag and hybrid seed media with blast furnace slag as the basis material would be modified by hydrothermal method.The ability of phosphate removal by four basis materials could be improved by hydrothermal method, which was related to modification temperature, modicicaiton time, modification NaOH concentration and the ratio of liquid to solid. The efficiencies of phosphate removal by granular steel slag, granular blast furnace slag, hybrid seed media with steel slag and hybrid seed media with blast furnace slag were increased with increasing modification temperature, modicicaiton time, modification NaOH concentration and the ratio of liquid to solid. The optimum modification temperature, modicicaiton time, modification NaOH concentration and the ratio of liquid to solid of granular steel slag, granular blast furnace slag and hybrid seed media with blast furnace slag were 200℃, 24h, 6M, 1 and that of hybrid seed media with steel slag were 105℃, 6h, 6M, 1.A method based hydrothermal modification to prepare an efficient crystal seeds for phosphate removal was extracted. The ability to remove phosphate of modified granular steel slag, granular blast furnace slag, hybrid seed media with steel slag and hybrid seed media with blast furnace slag were 6.88mg/cm³, 4.67mg/cm³, 5.63mg/ cm3 and 4.19mg/cm³, and the phosphate remove rates were increased by 60.8%, 45.2%, 54.8%, 39.9%, respectively.The character of phosphate removal by crystal seeds were bound up with the ability to release alkalinity and calcium. When the initial solution Ca/P=2 and pH=8.0, the alkalinity and calcium release rate of modified granular steel slag, granular blast furnace slag and hybrid seed media with blast furnace slag was very fast. However, the modified hybrid seed media with steel slag could be reused for longer times for phosphate removal.XRD and SEM-EDS patterns of the recovered products which generated from the phosphate removal by crystal seeds showed that the degree of calcium phosphate crystallization enhanced, the amount of crystal nucleus increased and the crystal was growing up with the increasing reaction time. Then the calcium phosphate precipitation turn into global hydroxyapatite crystal with poor crystallization, the Ca/P of which was 1.66, which was very close to purified HAP crystal. The hybrid seed media with steel slag prepared based on hydrothermal modified had amounts of C-S-H and Ca（OH）₂, which could provide alkalinity and calcium to promote the phosphate crystallized as the form of calcium phosphate, and the hydroxyapatite could be obtained by a futher convertion.更多还原