【作者】 张彦丽；

【导师】 李小明； 李善评；

【作者基本信息】 山东大学 ， 环境科学， 2015， 博士

【摘要】 高炉瓦斯灰是钢铁工业在生产过程中产生的固体废弃物,其主要组份为氧化铁(约占50%左右)、碳和少量难熔氧化物,如SiO2、CaO、MgO等。近年来,我国的钢铁产量跃居世界第一位,2012年,中国的粗钢产量已经超过了7亿吨,每年产生的高炉瓦斯灰超过1000万吨。味精废水主要是谷氨酸发酵液提取谷氨酸后产生的废液,以及生产过程中的洗涤废水。它是一种高浓度有机废水,具有酸性强、高COD、高BOD、高硫酸根、高菌体含量和低温等特点,其中含有大量的L-谷氨酸、还原糖与氨氮,如果任其排放不仅浪费了宝贵资源,而且造成严重的环境污染,破坏生态平衡。本文以高炉瓦斯灰为主要原料,制备了无机混凝剂PAFC,并研究了其铝铁形态分布、表面电荷特征、微观形貌、高效成份(Al+Fe)b的分离提取和混凝效果；利用味精废水为培养基合成了微生物絮凝剂和微生物油脂,优化了微生物絮凝剂的合成条件,考察了其混凝性能,并进一步合成了复合混凝剂PAFC-(γ-PGA)和PAFC-MBF,以发挥无机高分子混凝剂和生物絮凝剂的协同增效作用,提高混凝剂性能并降低混凝处理成本,同时为高炉瓦斯灰和味精废水的综合利用提供重要参考。主要结论如下(1)利用高炉瓦斯灰和铝材加工废渣合成PAFC的酸溶反应条件为：50g高炉瓦斯灰和l0g铝材加工废渣,分别在90℃和常温条件下与150mL盐酸(36%浓盐酸稀释一倍)反应3h和2.5 h,此时铁、铝的溶出率最高。而在铝铁水解聚合阶段,控制铝铁摩尔比为7：3、碱化度B=1.8,在60-70℃条件下铝离子预聚合1.0h、铝铁共聚合3.0h,所制备PAFC的除浊性能最好。PAFC的铝铁摩尔比和碱化度对其混凝性能有较大影响,PAFC(Al/Fe=7:3,B=1.8)具有最好的除浊效果,投加量为5mg/L时浊度去除率达到99%以上；PAFC(Al/Fe=8:2,B=1.8)具有最好的脱色效果,当投加缝为60mg/L时,脱色率为77.07%。通过对PAFC的表面电荷分析,在具有不同铝铁比和碱化度的PAFC中,Al/Fe=7:3,B=1.8时,Zeta电位达到最大值。说明PAFC在去除浊度过程中,电中和是非常重要的混凝机理,而在混凝脱色过程中,除了电中和作用外,还有其它混凝机理如压缩双电层、吸附架桥、卷扫絮凝等在起主要作用。对自制PAFC的混凝效果研究表明,其浊度去除效果、脱色效果、对原水pH的适应性以及絮体沉降性能等均优于市售PAC,证明以高炉瓦斯灰为主要原料合成的PAFC是一种高效无机混凝剂。(2)铝铁摩尔比和碱化度对PAFC中(Al+Fe)b的含量具有重要影响,并符合以下规律：当铝铁摩尔比较大,即PAFC中铝的含量较多、铁的含量较少时,碱化度B值较大时(Al+Fe)b的含量高；相反,当铝铁摩尔比较小时,碱化度B值较小时(Al+Fe)b的含量高。当B=1.8、Al/Fe=7:3时对应的PAFC中(Al+Fe)b的含量最高,为36.67%。以乙醇、丙二醇、丙酮混合溶液为溶剂对自制PAFC产品中的高效形态(Al+Fe)b进行了分离提纯。实验结果表明当有机溶剂乙醇、丙二醇、丙酮的体积比2：1：7、中段有机溶剂投加量V2=100mL (V1=V3=50mL)是较理想的分离提纯条件,此条件下所分离提纯的样品中(Al+Fe)b含量在75%以上,分离出的样品中铝铁含量占PAFC中铝铁总量的50%以上。通过透射电子显微镜(TEM)和扫描电子显微镜(SEM)对PAFC和(Al+Fe)b进行了微观形貌研究,结果表明(Al+Fe)b聚集体具有立体网状结构,网状结构除了互相联结的主链外,还有细小的二级乃至三级分枝,且各分枝表面较粗糙,有利于混凝时发挥吸附架桥和网捕卷扫作用。红外光谱对(Al+Fe)b和PAFC的分析结果表明,在(Al+Fe)b样品中通过羟基桥联的铝聚合物和铁聚合物较多,有利于形成立体网状结构。熟化时间与Zeta电位对应关系曲线显示,(Al+Fe)b的Zeta电位高于未经提纯的PAFC,其形态较稳定,Zeta电位受熟化时间的影响较小,进一步证明了(Al+Fe)b是PAFC中的高效形态,具有较强的电中和能力。混凝实验结果表明,(Al+Fe)b不仅具有比未经提纯的PAFC更好的除浊效果,而且其脱色性能也有大幅提高,进一步证明了(Al+Fe)b是PAFC中的高效混凝形态。(3)利用味精废水培养枯草芽孢杆菌168产γ-PGA时,味精废水浓度、初始pH、接种量和培养时间对枯草芽孢杆菌168生长和γ-PGA产量具有重要的影响,通过响应面分析中的Box-Behnken design (BBD)模型优化后的培养条件为：味精废水稀释倍数3.88,培养初始pH 5.84,50mL味精废水接种量10.55 mL,在37℃、180rpm条件下培养48h,γ-PGA的产量达到53.51±0.92g L-1。采用茚三酮比色法测定γ-PGA粗产品纯度为78.24%。紫外扫描光谱显示γ-PGA的聚合键与蛋白质的肽键结构有明显区别,γ-PGA是由y-酰胺键聚合而成。傅立叶红外光谱和核磁共振分析显示样品中含有酰胺基、羧基、羰基-CH、-CH2等基团,可确定为γ-PGA的结构。混凝实验结果表明,利用味精废水培养枯草芽孢杆菌所生产的γ-PGA粗品具有一定的除浊和脱色效果,其除浊和脱色效率分别为80%和55%左右。(4)利用味精废水混合培养枯草芽孢杆菌和斯氏油脂酵母菌,可以同时得到微生物絮凝剂和微生物油脂。在适宜的培养条件F,混合培养产生的生物量高于单菌种纯培养的生物量,说明在一定条件下枯草芽孢杆菌和斯氏油脂酵母菌的生长可以相互促进。味精废水浓度、初始pH、培养温度、接种量和培养时间对微生物絮凝剂和微生物油脂的产量以及味精废水中COD、NH3-N的去除率具有重要的影响。通过正交试验优化后的培养条件为：味精废水4倍稀释、初始pH 5.5、培养温度为30℃、枯草芽孢杆菌和斯氏油脂酵母菌接种总量为12mL(各6 mL),在此条件下微生物絮凝剂和微生物油脂的产量分别为78.25g/L和2.91g/L,味精废水中COD、NH3-N的去除率分别为83.67%和55.38%。气相色谱—质谱联用仪对微生物油脂分析结果：微生物油脂为C15-C18的中长链脂肪酸；对混合培养微生物絮凝剂中氨基酸的组成分析表明,混合培养微生物絮凝剂中谷氨酸相对含量为71.326%。利用味精废水混合培养枯草芽孢杆菌和斯氏油脂酵母菌所合成的微生物絮凝剂具有较好的除浊和脱色效果,其除浊和脱色效率分别为87%和58%左右,混凝性能较单菌种纯培养枯草芽孢杆菌合成的微生物絮凝剂有所提高。(5)将自制的无机混凝剂PAFC与味精废水培养枯草芽孢杆菌得到的丫-PGA粗品复合时,γ-PGA的加入对PAFC中铝铁形态的分布具有重要影响,当γ-PGA/(Al+Fe)贡量比P为10%时,复合混凝剂中(Al+Fe)b的含量较高,相应的混凝性能也较好。当Al/Fe为8：2或7：3、B＝1.8时,PAFC-(γ-PGA)的除浊和脱色性能均较高。当P＝5-10%时,PAFC-(γ-PGA)的脱色性能最好,50mg/L的投加量时脱色率达到80.15%,γ-PGA与PAFC复合后,不仅可以提高PAFC的脱色效果,而且可以降低混凝剂的投加量。将自制的无机混凝剂PAFC(Al/Fe=7:3,B=1.8)与味精废水培养枯草芽孢杆菌得到发酵上清液(γ-PGA浓度为41.86g/L)在超声搅拌下混合20min,得到的复合混凝剂当(Al+Fe)/(γ-PGA)=20%时,浊度去除率提高了15.59%；当(Al+Fe)/(γ-PGA)=15%时,脱色率提高了9.18%。将自制的无机混凝剂PAFC(Al/Fe=7:3,B=1.8)与利用味精废水混合培养枯草芽孢杆菌和斯氏油脂酵母菌得到的MBF在超声搅拌下混合20min制得复合混凝剂PAFC-MBF。当MBF/(Al+Fe)=5%时,PAFC-MBF的除浊、脱色性能比PAFC分别提高10.21%和10.29%。将自制的无机混凝剂PAFC(Al/Fe=7:3,B=1.8)与利用味精废水混合培养枯草芽孢杆菌和斯氏油脂酵母菌得到发酵上清液(MBF浓度为78.25g/L)在超声搅拌下混合20min制得复合混凝剂MBF-PAFC.与混合培养发酵上清液不加PAFC时相比,(Al+Fe)/MBF-10%时,MBF-PAFC的除浊、脱色效率分别提高17.55%和9.81%。当以PAFC与提纯的MBF(或γ-PGA)复合时,二者的用量以无机混凝剂pAFC为主,MBF的加入有利于提高其分子量,在混凝时更好的发挥卷扫絮凝作用,从而提高混凝效果；而当PAFC直接与发酵上清液复合时,则尽量发挥MBF无毒、易生物降解的优势,向发酵上清液中引入少量的阳离子无机混凝剂PAFC以改善其表面电荷特性,增加混凝过程中的电中和作用,从而提高混凝效果。更多还原

【Abstract】 Blast furnace dust (BFD) is a solid waste produced by the iron and steel industries with a general composition of iron oxides (approximately 50%) and small amounts of refractory oxides, e.g., aluminum, silicon, calcium and magnesium. In recent years, China’s steel output ranks first in the world, the crude steel production has exceeded 700 million tons by 2012. And the annual yield of BFD is more than 10 million tons.Monosodium glutamate (MSG), a sodium salt of L-glutamic acid, is used as flavor enhancer for foods. After the extraction of MSG, Monosodium glutamate wastewater (MSGW) has high levels of COD, BOD, sulfate, ammonium-N, and a low pH of 2-3. If discharged without treatment, it can cause severe environmental pollution and damage the ecological balance, which is a major obstacle for the development of MSG production.In this work, polyaluminum ferric chloride (PAFC) coagulant was produced using the BFD waste as the main raw material. We examined the impact of the molar ratio of aluminum to iron (Al/Fe) and basicity (B) of PAFC, which is [OH-]/[Al+Fe], on the content of (Al+Fe)b. Suitable conditions for separation and purification of (Al+Fe)b from PAFC by organic solvents precipitation method were explored, the structure characteristics of PAFC and (Al+Fe)b were investigated. The results of this study will promote the research progress of (Al+Fe) b species in PAFC, and then provide reference information for studies of PAFC coagulation effect on the removal of contaminants and its coagulating mechanism.The culture of Bacillus subtilis to produce y-PGA, mixed culture of Bacillus subtilis and Lipomyces starkeyi to produce microbial flocculant (MBF) and microbial lipid in MSGW were also studied in this paper. The purpose of this research was to determine the optimal cultivation conditions for Bacillus subtilis and Lipomyces starkeyi to produce MBF and microbial lipid using MSGW as a culture medium, which was to provide a method for economical production of y-PGA as well as a comprehensive utilization of MSGW. Moreover, the flocculation performances of culture supernatant and MBF were also investigated. The main conclusions were summarized as follows:(1) Fifty grams of blast furnace dust reacted with 150mL hydrochloric acid diluted solution for 3h at 90 ℃ and 10 grams of aluminum dross reacted with 150mL hydrochloric acid diluted solution for 2.5h under room temperature; In co-polymerization stage, the Al/Fe molar ratio=7:3, basicity B=1.8, polymerization temperature 60-70℃, and reaction time (pre-polymerization time of aluminum+ copolymerization time of aluminum and iron) 1.0h+3.0h.The coagulation tests indicated that self-made PAFC outperformed commercial PAC in turbidity and color removal. PAFC (Al/Fe=7:3, B=1.8) achieved above 99% for turbidity removal at dosage of 5mg/L (Al+Fe), and 77% for color removal at dosage of 60mg/L (Al+Fe). Self-made PAFC and flocs generated in water treating process were measured by Scanning Electron Microscopy. Surface charge characteristics of PAFC were measured by Zetasizer 3000HS. Charge neutralization was a very important coagulation mechanism of PAFC in turbidity removal process. And there were other coagulation mechanisms besides charge neutralization such as bridge connection and sweep flocculation, playing significant roles in decolorization process.(2) Both the Al/Fe molar ratio and basicity have significant influence on (Al+Fe)b content. The (Al+Fe)b content in PAFC peaked at 36.67% with Al/Fe=7:3, and basicity(B)=1.8. The optimal conditions for purifying (Al+Fe)b by organic solvents precipitation method were determined as follows:organic solvents (ethanol, propylene glycol and acetone mixed solution) volume ratio=2:1:7.50mL, 100mL and 50mL of organic mixed solution was added into lOmL of 0.3M PAFC solution to extract (Al+Fe)c, (Al+Fe)b and (Al+Fe)a, respectively.The (AI+Fe)b content in the separated samples reached over 75% with the yield higher than 50% of the total PAFC. Infrared spectrum of the extracted (Al+Fe)b, PAFC and commercial PAC showed that the content of hydroxyl bridge linked aluminum/iron in the extracted (Al+Fe)b sample was higher than that in PAC and PAFC. The transmission electron microscope images of the extracted (Al+Fe)b suggested 3D network structure of the (Al+Fe)b with rough surfaces, which benefits adsorption and sweep of contaminants.(3) The findings of the experiments suggested that the MSGW was an ideal medium for B. subtilis cultivation to produce γ-PGA. Single-factor experiments showed that B. subtilis growth and γ-PGA production were affected by cultivation conditions such as initial MSGW concentration, initial culture pH, inoculation concentration, and cultivation time. The maximum γ-PGA productivity (53.51 ±0.92 g L-1) was obtained by using Box-Behnken design (BBD) experiments to optimize the cultivation conditions. Simultaneously, results of coagulation tests showed that the turbidity and active red removal efficiency of crude y-PGA was about 80% and 55%, respectively.(4) Microbial flocculant (MBF) and microbial lipid were obtained through mixed cultivation of Bacillus subtilis and Lipomyces starkeyi using MSGW as culture medium. The biomass of mixed cultivation was higher than that of pure culture of single species, which indicated that the growth of Bacillus subtilis and Lipomyces starkeyi had mutual promoted effects. The initial MSGW concentration, initial culture pH, cultivation temperature, inoculation concentration, and cultivation time had significant influences to the MBF and microbial lipid production, as well as the COD, NH3-N removal efficiency of MSGW. The optimal conditions of mixed cultivation were as follows:4-fold diluted MSGW with pH 5.5, culture temperature 30℃, the inoculation volume of Bacillus subtilis and Lipomyces starkeyi was 12mL. The production of MBF and microbial lipid were 78.25g/L and 2.91 g/L, respectively. And the COD and NH3-N removal efficiencies of MSGW were 83.67% and 55.38%, respectively.The MBF produced by Bacillus sublilis and Lipomyces starkeyi had high removal efficiencies for turbidity and active red. The removal efficiencies for turbidity and active red were 87% and 58% approximately. MBF produced by mixed cultivation outperformed than that of pure culitivation in coagulation tests.(5) The γ-PGA content had significance influence to the species distribution in PAFC when compositing PAFC and γ-PGA. There was higher (Al+Fe)b content in PAFC and the coagulation performance was satisfied when y-PGA/(Al+Fe)=10%. The removal efficiencies of turbidity and active red reached peaks when y-PGA/(Al+Fe)=5-10%. The removal of active red was 80.15% treated by the compound coagulant PAFC-(y-PGA) with the coagulant doage of 50mg/L. PAFC (Al/Fe=7:3, B=1.8) produced using BFD was composited with the supernatant of Bacillus subtilis cultivation (concentration of γ-PGA was 41.86 g/L) under 20min of ultrasonic stirring. The turbidity removal efficiency improved 15.59% than that of the supernatant when (Al+Fe)/(γ-PGA)=20%, and active red removal efficiency improved 9.18% than that of the supernatant when (Al+Fe)/(y-PGA)= 15%.PAFC (Al/Fe=7:3, B=1.8) produced using BFD was composited with MBF produced in the mixed cultivation process of Bacillus subtilis and Lipomyces starkeyi under 20min of ultrasonic stirring. The turbidity and active red removal efficiencies of PAFC-MBF were 10.21% and 10.29% higer than that of PAFC, respectively. PAFC (Al/Fe=7:3, B=1.8) produced using BFD was composited with the mixed cultivation supernatant of Bacillus subtilis and Lipomyces starkeyi under 20min of ultrasonic stirring. The turbidity and active red removal efficiencies of PAFC-MBF were 17.55% and 9.81% higer than that of mixed cultivation supernatant.A small quantity addition of MBF or γ-PGA to PAFC could promote the molecular weight of the inorganic coagulant which enhanced the coagulation performance of PAFC. Meanwhile, less quantity of PAFC composited with the supernatant of cultivation impoved the surface charge of MBF, thus, the coagulation performance of the cultivation supernatant was promoted.更多还原