【作者】 晏全香；

【导师】 袁继祖； 张一敏；

【作者基本信息】 武汉理工大学 ， 矿物加工工程， 2009， 博士

【摘要】 我国湖泊和水库的富营养化程度已经相当严重,蓝藻水华暴发的面积、频度和强度及藻毒素的产生都呈现迅猛的增加趋势。铜绿微囊藻是我国富营养化水体中的主要水华蓝藻藻种,在富营养化水体中容易导致水华的暴发。絮凝去除藻类和富营养物质是处理水华的有效方法,但目前常用的传统絮凝剂聚合三氯化铝（PAC）和聚丙烯酰胺（PAM）等在水处理中均易产生二次污染,PAC水解后产生的铝离子通过饮用水进入人体会导致贫血、脱发和大脑痴呆等多种疾病,PAM水解后产生的丙烯酸和有机胺等有机污染物同样危害人体健康。因此,如何研制一种二次污染小、絮凝效果好的新型环保型水处理絮凝剂是当前水处理领域急待解决的重要课题。本文以资源丰富的层状硅酸盐粘土矿物及各种改性剂为主要原料,制备改性粘土絮凝材料,研究改性粘土对水华优势藻种铜绿微囊藻及富营养水体污染物质的絮凝去除效果,并进行了改性层状硅酸盐矿物/微生物复合新型絮凝材料试验,以及水环境中藻类及富营养物质的吸附絮凝行为与机理研究。本试验取得了较传统絮凝剂更加环保、价廉、高效的应用效果,主要研究内容和成果包括:1、采用新的制备工艺,将天然粘土制备成改性粘土絮凝材料,进行铜绿微囊藻絮凝效果对比试验。各种改性粘土投加量为50mg/L时,对于吸光度A_68nm=0.100的藻悬液,絮凝沉降4h后铜绿微囊藻的去除率比较:经过各种改性后,除藻能力提高,基本都可以除藻80%以上。改性剂聚硅酸铁改性粘土絮凝铜绿微囊藻效果优于聚硅酸铝、壳聚糖和聚丙烯酰胺改性粘土,其混凝能力强、絮体紧密、颗粒沉降速度快,除藻率都达90%以上,其中改性粘土矿物中累托石、海泡石、凹凸棒石除藻能力较强。因聚硅酸铁改性累托石絮体沉降体积较小,沉降时间短,沉降速度快。实验选择改性粘土累托石,改性材料聚硅酸铁,改性剂与粘土用量配比1:10,聚硅酸铁改性累托石投加量为50 mg/L左右,240min后,藻去除率达到95%以上,浊度由55.0NTU降到3.1 NTU,去除率达94.4%,絮凝效果显著。2、通过研究制备改性粘土的影响因素:矿浆浓度、改性剂与粘土配比、酸化pH值、聚硅酸熟化时间、Si/Fe摩尔比、老化时间、投药量等对铜绿微囊藻絮凝效果的影响,本试验确定试验条件为累托石矿浆浓度10%,pH为2,改性剂与累托石质量配比为1:10,聚硅酸熟化45min,硅铁摩尔比约为Si/Fe≈0.4,反应老化90min。充分反应后离心脱水形成改性泥备用,投加量在10mg/L左右,即可达到除藻率89.0%,浊度去除率90.4%。3、微生物制剂除藻试验,分别从除藻时间、微生物用量及对藻毒素的去除上进行研究,对比改性粘土,微生物处理所需时间较长、沉降效果较差,投加量5mg/L以上,10天后除藻率可达90%。微生物处理几乎不产生底泥,可分解藻类,将其与改性累托石复配使用,可减少底泥,去除水华危害。复合絮凝材料投加,先加微生物活化液,再添加改性粘土,即方案2效果较好,除藻率89.3%,除浊率90.8%。改性粘土和枯草芽孢杆菌活化液都对微囊藻毒素MC—LR有明显的去除作用。4、改性粘土复合微生物在富营养水体中应用研究,随着各种絮凝剂投加量的增加,处理汉江水、南湖水、生活污水的COD、TN、TP的去除率都随之增加,微生物与改性累托石复合絮凝剂效果明显较好,改性累托石处理汉江水效果也较传统絮凝剂PAC要好。处理后水体达到水质标准要求。经三种絮凝剂处理后,改性累托石和复合絮凝材料对自来水中铁离子有一定去除作用,PAC对于水样中的铁含量基本没有去除作用。投加量20mg/L时,改性累托石处理残余铁效果较好;投加量35mg/L时复合絮凝剂处理效果较好;投加量继续增加后,铁含量变化不大。由此可以看出,聚硅酸铁改性累托石及其复合材料在水溶液中溶出铁离子现象不明显,并且有一定继续吸附铁离子的能力,不会造成水体二次污染。5、重复利用研究中,煅烧除去吸附的挥发有机质后,二次使用改性累托石材料,除藻率、除浊率有所下降,投加量在50mg/L时,仍有除藻率89.2%、除浊率74.2%。三次使用改性累托石材料,除藻率80.1%、除浊率65.1%。因此,微生物降解后,改性累托石材料对水华优势藻种铜绿微囊藻,还是具有较好的去除效果,可以进行重复使用。处理效果相同的情况下,改性累托石复合微生物絮凝材料,处理水样单位成本较低,具有明显优势。6、复合絮凝材料处理水华主要是两个方面作用协同的效果,改性粘土迅速絮凝沉降水华藻类及其它悬浮物,微生物去除富营养物质和藻毒素。改性粘土絮凝剂在絮凝过程中主要是通过双电层压缩、吸附电中和、吸附架桥和沉淀物网捕等四种絮凝机理来对水中微粒或胶粒进行凝聚、聚沉;枯草芽孢杆菌主要通过微生物营养竞争、反硝化作用和聚磷作用进行脱氮降磷,快速分解水体中的有机质,分泌生物酶,降解藻毒素。因此,改性粘土矿物与微生物协同作用,粘土吸附架桥作用、聚硅铁电中和作用,聚合大分子与粘土共同网捕作用,最终脱稳沉降,不仅可使藻细胞和其它悬浮颗粒发生聚团絮凝沉降,另外微生物去除水体中富营养物质N、P、COD、以及藻毒素Microcystin等,较好的解决水体富营养问题。更多还原

【Abstract】 The eutrophic state of China’s lakes and reservoirs has been very serious. There have been emergencies in the rapid increase trend, with outbreak of algae bloom size, frequency and intensity of algal toxins. Microcystis aeruginosa is the main species of cyanobacteria bloom in the eutrophic water, and with the eutrophication of water bodies in our country easily lead to the outbreak of water bloom. Flocculation is an effective way to remove algae and eutrophic material on water treatment in China. But traditional flocculant commonly used in water treatment, such as polyaluminum chloride （PAC） and polyacrylamide （PAM）, etc. are prone to produce secondary pollution. Aluminum ions from hydrolysis of PAC enter human body through drinking water and it will lead to anemia, hair loss and dementia and other brain diseases. Organic pollutants are the same harm to human health by hydrolysis of PAM, such as acrylic acid and organic amine. Therefore, how to prepare a kind of novel environment-friendly water treatment flocculant, which is of less pollution and better flocculating performance, is a very important subject and an urgent task that need to be solved in water treatment field recently.In this paper, a kind of novel high-effect environment-friendly flocculant had been prepared by using the natural resources mineral. It used layered silicate clay minerals of sufficient source, microbe and various modifiers as the main raw materials, prepared modified clay flocculation. The flocculation effects were studied and the advantage of modified clay flocculation was analyzed. Algal bloom of Microcystis aeruginosa and the kinds of nutritious substances in water pollution were removed by the new modified layered silicate mineral / microbial flocculation materials. The adsorption behavior and mechanism of flocculation were also studied. Compares with the conventional flocculant, this new flocculant has more environmentally friendly function, lower price, higher effect and efficient application. The main research contents and results of this paper are included as following:1. By adopting the novel process, it took comparative test for the flocculating effect of Microcystis aeruginosa, on the preparation of natural clay material into modified clay flocculants. When modified clays dosage of 50 mg/L, the absorbance A_680nm = 0.100 of the algal suspension, flocculating 4h after the removal of microcystis aeruginosa comparison, the removal capacity of clay mineral after a variety of modification can be more than 80% basically. Polysilicate iron modified clay flocculant had better effect than polysilicate aluminum, chitosan or polyacrylamide modified clay, flocculating of microcystis aeruginosa together. It had stronger coagulation ability, more compact flocs, faster particle settling velocity, and removal rate of more than 90%. Modified clay minerals had better flocculating affect, of which ferric polysilicate modified rectorite, sepiolite, palygorskite had better removal ability of microcystis aeruginosa. Modified rectorite by ferric polysilicate, had stronger coagulation ability, more compact flocs, faster particle settling velocity, and excellent removal ability of microcystis aeruginosa. It chose modified rectorite clay to do next research in the experiment, using ferric polysilicate as modifying agent, dosage ratio 1:10 of modifier and clay, ferric polysilicate modified rectorite dosage 50 mg/L or so, keeping flocculating for 240min, the removel rate of algae up to more than 95%, turbidity value from 55.0 NTU down to 3.1 NTU, removal rate of turbidity reached 94.4%. The flocculating efficiency increased dramatically.2. The preparation of modified rectorite was studied by analysing the affect factors, such as slurry concentration, ratio of clay and modifier, acid pH, ripening time of polysilicate, molar ratio of Si/Fe, aging time, dosage and so on. The experimental condition was confirmed by studying flocculation efficiency of microcystis aeruginosa, the concentration of rectorite pulp 10%, pH value 2, modifier weight ratio of rectorite 0.1, polysilicate ripening 45min, the molar ratio of Ferric-polysilicate about Si/Fe≈0.4, the aging reaction 90min. After full reaction, the mixed pulp was prepared into modified slurry through centrifugal dehydration to form standby mud. With the dosage of 10mg/L or so, it could achieve the algae removal rate of 89.0%, turbidity value removal of 90.4%.3. Removing algae using microorganism were studied by means of removal time experiment, microbial dosage experiment, and mcrocystins removal experiment. Compared to modified clay, the time required for microorganisms was longer, and the removal behavior had less effective, the flocculation to deal with algae didn’t work. In the other side, microorganism had its own advantage of no organism left and complete catabolism. When the microorganism dosage was more than 5mg/L, the removal rate was up to 90% ten days later. Microorganism catabolism almost had no sediment, and modified rectorite compound had excellent flocculating efficiency, which were both required of water bloom removal. Flocculation composite material 2, adding microbial activation solution firstly, then adding the modified clay, algae removal rate of 89.3%, turbidity removal rate 90.8%. Modified clay and bacillus subtilis have a clear role in the removal microcystins MC-LR. 4. The new flocculant applied in the eutrophic water, with a variety of flocculant dosage to deal with the Han River, South Lake, and domestic wastewater. COD, TN, TP removal rates were significantly increased following the increasing dosage of composite flocculant. The removal rates are also better than the conventional flocculant PAC, treated water up to quality standards. Treated by three types of flocculants, Dosage of 20mg/L, the modified rectorite was better with the residual iron; when dosage was 35mg/L, the composite flocculant was better; dosage continue to increase, little change in the iron content. It can be seen, ferric polysilicate modified rectorite and composite materials in the dissolution of ions in aqueous solution are not obvious, and some continue to ion adsorption capacity of water bodies. It will not cause secondary pollution.5. The underside of sediment was calcined to remove the volatile organic matter adsorption for the secondary use of modified rectorite material. In dosage of 50mg/L, the removal rate was 89.2%, turbidity removal rate 74.2%; three times using modified rectorite material removal rate was 80.1%, turbidity removal rate 65.1%. Therefore, the modified rectorite has a good removal efficiency of the water bloom after microbial degradation, and it can be reused. The cost of new flocculant materials was lower than conventional flocculant, which have obvious advantages.6. The flocculatin of removal algae show mainly two aspects of synergistic effect, micro-organisms consumed nutritious substances and removed algal toxins, modified clay flocculated and adsorbted solid particle quickly. Modified clay flocculant in the flocculating process is mainly through the double-layer compression, electrochemistry adsorption, adsorption bridgework, netting capture sediment and so on. Bacillus subtilis consumed nutritious substances mainly through microbial competition, denitrification to get nitrogen off, polyphosphazenes to get phosphorus off, and the rapid decomposition of organic matter in water, enzyme secretion, and degradation of algal toxin. Therefore, the new flocculant not only enable the algal cells coagulation and other suspended particles agglomerate, but also consume and adsorb other nutritious substances in water to microbial remove N, P, COD, and Microcystin-LR, consequently solve the eutrophication problem of water bodies.更多还原