基于双氨基粘土絮凝的嗜热微藻采收实验研究

文章将双氨基粘土([MgAC]和[CeAC]的混合物)作为絮凝剂,并研究了[MgAC]和[CeAC]的配用比例和絮凝时间对采收效果的影响。研究结果表明:当[MgAC]与[CeAC]的配比分别为8∶1,5∶1,2∶1和1∶2时,微藻的絮凝效率均可在20 min内达到75%以上;与单独使用[MgAC]或[CeAC]相比,双氨基粘土形成的紧凑网络可在微藻细胞之间进行有效桥接,从而提高微藻采收效率,综合考虑经济性及絮凝效果,确定[MgAC]与[CeAC]的最优配比为8∶1;微藻采收效率与藻液细胞密度有较大关系,过高的藻液细胞密度会使微藻采收效率大大降低;使用双氨基粘土絮凝微藻不会影响微藻培养液的pH值,且双氨基粘土絮凝剂不会影响微藻细胞的生理活性,以及后续的开发应用。     

阳离子絮凝剂对小球藻浓缩收集效果的研究

研究了3种代表性阳离子絮凝剂:聚合氯化铝(PAC)、聚合硅酸硫酸铝(PASS)和聚二甲基二烯丙基氯化铵(PDADMA)对小球藻(Chlorella vulgaris)的浓缩效果,并对其实际应用的经济性进行了评价。结果表明,3种絮凝剂均能高效浓缩小球藻,但浓缩成本相对较高,因此,亟需开展优化絮凝工艺过程和开发高效低成本的絮凝剂研究,解决限制能源微藻产业快速发展的收集瓶颈问题。     

微藻絮凝条件优化及絮体结构特征研究

以小球藻为原料,通过正交实验考察了藻液浓度、凝聚剂和絮凝剂用量、pH、搅拌强度对微藻絮凝效果和絮体结构的影响。结果表明,在实验范围内,浊度去除率可达96.43%;各因素中,随着藻液浓度增加,微藻絮凝效果和絮体强度、恢复率、分形维数也随之增加;适当增加凝聚剂用量,有利于提高絮凝效果和絮体强度、恢复率、分形维数;适当增加絮凝剂用量,可提高絮凝效果,但对絮体强度、恢复率、分形维数影响不明显;在酸性条件下,絮凝效果较高,在碱性条件下絮体强度、恢复率、分形维数较高;在保证药剂充分混合条件下,减小快速搅拌时间有利于提高微藻絮凝效果,但对絮体强度、恢复率、分形维数影响不明显。综合考虑絮凝效果和絮体结构两个指标,确认藻液浓度为192 mg/L、FeCl3为40 mg/L、PAM为20 mg/L、pH为5,快速搅拌为150 r/min,1 min和慢速搅拌为50 r/min,15 min时为最优组合。     

小球藻混凝条件优化与脉冲鼓泡压力溶气气浮采收研究

采用自制的脉冲鼓泡压力溶气气浮系统进行小球藻Chlorella sp.的连续采收试验,首先设计正交试验,用烧杯法确定合适的絮凝药剂条件,包括pH值、阳离子凝聚剂FeCl3用量和絮凝剂聚丙烯酰胺的用量;在最优药剂条件下,研究处理量、入料高度和循环溶气水量对分离柱流体流动和气浮采收效果的影响。试验结果表明:pH值在7~10时,对小球藻Chlorella sp.的促凝效果不明显,增加FeCl3的用量有助于絮凝;当pH达到11时,可显著促进小球藻的絮凝,絮凝率达96%以上,其他药剂的剂量对絮凝效果不再有明显作用;气浮处理量、入料高度和循环溶气水量一起决定了分离柱的流体环境,进而影响气泡与小球藻细胞絮凝体的碰撞粘附效率,对气浮采收效率产生影响。分析试验结果表明,适当增大分离柱的高度、控制合理的循环溶气水量能够有效提高微藻的气浮分离效率。     

基于泡沫浮选的能源微藻采收实验研究

文章以十二胺作为捕收剂,利用泡沫浮选法采收能源微藻——小球藻。利用正交实验研究了捕收剂用量、搅拌转速、藻液浓度、溶液p H和浮选时间对小球藻采收效率的影响。结果表明:捕收剂用量、搅拌转速、藻液浓度对采收效率影响显著,p H和浮选时间对采收率影响较小;十二胺能显著增加小球藻细胞的可浮性,较高的搅拌转速和藻液浓度有利于提高藻细胞与气泡的碰撞粘附效率。综合考虑采收率和采收成本,在不调节藻液浓度和p H的情况下,泡沫浮选法采收小球藻的最优条件为十二胺用量为30 mg/L、搅拌转速为1 200r/min、浮选时间为3 min,此时采收率可达到98.35%。     

聚合氯化铁-壳聚糖复合絮凝剂的制备及污泥高效调理研究

本文通过制备一种聚合氯化铁-壳聚糖(PFC-CTS)新型复合絮凝剂,并采用三步污泥调理法强化污泥脱水效率.实验结果表明,m(PFC)∶m(CTS)=1 ∶2,PFC-CTS投加量为40mg/L时絮凝效果最佳,为污泥高效减量化处理提供了理论依据.     

电絮凝法收集微藻

采用电絮凝法采收微藻,研究考察了电源电压、盐度、微藻初始密度、搅拌速率、电极板的宽度以及电极材料等因素对电絮凝采收微藻效果的影响。对不同因素影响下微藻采收率的变化趋势进行了较为详细的解释,并伴有试验数据作为佐证。研究表明:在电压为5 V,盐度为18.75 g/L(15 g氯化钠加入800 mL藻液中),搅拌速率为200 r/min,电极板宽度为3 cm,电极材料为铝电极时,眼点拟微绿球藻的采收率出现最大值,约为100%,微藻采收完全。     

生物质快速热裂解生物油对藻类的毒性效应

为明确生物质快速热裂解生物油的使用安全性能,以斜生栅藻和月牙藻为受试材料,设置5组不同生物油含量(分别为0、9.5、20.7、48.5和81.3 mg/L)的藻类培养液,测定生物油对藻类的毒性效应。结果表明:不同生物油含量的藻类培养液对两种藻的生长存在不同程度的抑制,对斜生栅藻的生长抑制率分别为0、(36.59%±5.94%)、(48.47%±2.53%)、(94.83%±2.50%)和(105.25%±1.39%);对月牙藻的生长抑制率分别为0、(45.14%±0.93%)、(55.45%±1.41%)、(64.07%±3.95%)和(92.58%±0.88%),藻类培养液中生物油含量越高,其抑制效应越强。对不同生物油含量下的藻类生长抑制率进行非线性回归分析(以生物量计),生物油对斜生栅藻和月牙藻生长的72 h半效应浓度分别为17.62和14.16 mg/L,说明月牙藻对生物油更敏感。     

颗粒粒径分布对泥浆絮凝效果的影响

为了探究颗粒粒径分布对泥浆絮凝效果的影响,通过室内絮凝试验,从絮凝剂添加量、泥面的沉降速率、底泥含水率、底泥渗透系数等方面分析了不同粒径分布下泥浆絮凝效果的变化。结果表明,随着泥浆中粉粒与粘粒含量比值的增大,APAM的最优添加量由400 g/t减至320 g/t, PAC的最优添加量由1 600 g/t增至3 600 g/t,经过两者絮凝后的泥面沉降速度和底泥渗透系数均随之提高;PAC对粘粒的沉降效果要优于APAM,经APAM处理后的底泥渗透性较好,相比无添加自然沉降的底泥渗透系数提高了约75%。     

微生物絮凝预处理养猪场废水研究

通过对养猪场废水水质的分析,使用无机絮凝荆与微生物絮凝剂对其进行预处理.结果表明,絮凝预处理可以有效降低水中有机负荷与SS,其中JW-2茵株对养猪场废水中COD与SS的去除效果优于其他无机絮凝剂,如果溶液中存在Ca2 JW-2絮凝效果更好,可达到89.1%.采用微生物絮凝剂预处理养猪场废水,可以缩短处理周期,提高处理效果,同时不产生二次污染,应用前景广阔.     

沉淀絮凝—吸附处理放射性废水的模拟实验

针对放射废水中三种典型核素去除开展了沉淀絮凝-吸附的实验研究。根据模拟放射性废水的核素的特点,对比不同沉淀剂、絮凝剂和吸附剂对三种核素的去除效果,并开展了铯离子的吸附动力学和竞争离子的影响实验。结果表明,以碳酸钠为沉淀剂可以去除93.2%的锶离子,以聚合硫酸铁为絮凝剂可去除98%以上的锶离子和钴离子,以自制的焦磷钒酸锆为吸附剂可去除99%的铯离子,并且自制的焦磷钒酸锆吸附剂对铯离子具有快速吸附和高效选择的特点。该沉淀絮凝-吸附工艺对钴、锶、铯三种模拟核素的去除率可接近100%,产生的二次废物少,可为核电站放射性废水处理的设计提供技术参考。     

Biomass harvesting and concentration of microalgae scenedesmus sp. cultivated in a pilot phobioreactor

Samples of a culture of Scenedesmus sp. grown in a pilot raceway photo bioreactor were processed in the laboratory by flocculation and centrifugation, to assess the efficiency of solid concentration of both methods. Three flocculation agents were tested, ferrous sulfate (FeSO₄), ferric chloride (FeCl₃) and aluminum sulfate Al₂(SO4)₃ using concentrations of 0.05, 0.2, 0.8, 1.5, 3.0 y 7.0 g L⁻¹ and pH range between 4.0 and 11.0 for the better concentration response of each flocculant. Additional flocculation tests were carried out to measure the sedimentation kinetics of the concentrated biomass. All these tests were performed with culture samples of 800 cm³ for 12 min of stirring and 10 min of sedimentation with three repetitions. In the case of centrifugation the testing was carried out using a laboratory centrifuge run at speeds of 1500, 1800 and 2200 rpm with culture samples of 300 cm³ for 15 min and three repetitions. In order to quantify the efficiency of the concentration, initial and final turbidity of the cleared water and concentrated portion were measured. The flocculation experiments showed that a limit of maximum concentration efficiency of 97.9% that was reached with 1.5 g L⁻¹ of Al₂(SO₄)₃ at pH of 8.5 and an average sedimentation velocity of about 2.7 cm min⁻¹. Testing also showed that FeSO₄ was the worst flocculant agent in the range tested. With respect to the centrifugation test, the solid concentration efficiency varied from 95.2% at speed of 1500 rpm up to 96.0% at speed of 2200 rpm.     

Influence of organic matter on flocculation of Chlorella vulgaris by calcium phosphate precipitation

Flocculation is a promising approach for reducing the cost of harvesting microalgae. Flocculation of microalgae can be induced by precipitation of calcium phosphate (Ca-phosphate) when pH increases above 8.5, a pH level that can be achieved by simple photosynthetic CO₂ depletion. Using the freshwater microalgae Chlorella vulgaris as a model, we identified the combinations of minimum pH and Ca and PO₄ concentrations to induce flocculation. Predicted concentrations of amorphous Ca₃(PO₄)₂ precipitation (chemical modelling) explained flocculation in these solutions. The efficiency of flocculation decreased with increasing microalgal biomass concentration. Solution renewal experiments suggest that flocculation is inhibited by algal organic matter in the medium, even when present at relatively low concentrations relative to concentrations in stationary phase medium. Addition of dissolved organic compounds showed that organic acids with a high molecular weight (e.g. humic acids, alginate) have a strong inhibitory effect on flocculation whereas glucose or acetate had no such effect. These effects may be related to complexation of Ca²⁺ or effects of organic matter on growth of the Ca-phosphate crystals. Precipitation of Ca-phosphate in media with high organic matter content requires a high water hardness (500 μmol L⁻¹ Ca) and high PO₄ concentrations (350 μmol L⁻¹ P). Flocculation can be facilitated by addition of surplus PO₄ to the medium. This surplus PO₄ may be recovered after flocculation by re-dissolution of the Ca-phosphate through mild acidification.     

Pre-reforming of liquefied petroleum gas on supported ruthenium catalyst

Cylindrical shaped CeO₂–Al₂O₃ support was prepared by calcining the pelletized powder mixture of cerium carbonate, aluminum hydroxide and poly-vinylalcohol. The specific surface area and porosity of the support were improved relative to those obtained by a conventional method. Ru was loaded on the porous carrier by using ruthenium trichloride and aqueous ammonia. The dispersion of Ru was improved 2.2 fold as much as that in the case using a conventional catalyst. The improved catalyst showed high activity for pre-reforming of liquefied petroleum gas (LPG) with low proportion of S/C as 0.8 at 450°C. Finally, 7000h of sustained run of the pre-reforming was successfully achieved on that catalyst.     

Pilot scale solids/liquid separation in hot geothermal discharge waters using dissolved air flotation

Hot geothermal discharge water, flowing through a pilot plant at 6 t/h, was continuously dosed with ferric sulphate, a flocculant and a surfactant; up to 89% of the resulting iron floc could be separated by dissolved air floation (DAF) in a total treatment time of six minutes. The aim was to coprecipitate arsenic (initial content 4.5 g/t) and inhibit silica scaling (by lowering the pH from 8 to 4), and provide a possible economic alternative treatment to re-injection. A commercial treatment plant would require an additional polishing filter for optimum operation. After filtration, 98% of the arsenic present in the water was removed by dosing with 17 g/t iron, and 93% of the arsenic was removed with 10 g/t iron. Several methods for recovering arsenic from the sludge and re-using the iron were examined; the most promising involves washing the sludge with dilute sodium hydroxide and precipitating calcium arsenate. The present pilot plant was also used for separating precipitated calcium silicate from geothermal waters. In hot water DAF appears to be a more successful solid/liquid separation system than settling (sedimentation). DAF operates faster, and produces sludges with higher solid contents, than settling.     

脱硫废水深度降氟机理及工艺优化的试验研究

在静态试验装置中,通过化学沉淀与混凝法相结合的二次除氟工艺处理电厂高浓度含氟脱硫废水,采用正交试验研究了多因素操作条件对脱硫废水除氟效率的综合影响．结果表明：氯化钙除氟性能优于氢氧化钙,最佳钙氟摩尔比n（Ca）／n（F）一l：1.3;添加硫酸铝、氯化铁等混凝剂可明显改善药剂的除氟性能,确定了最佳”（A1）／n（F）=1．5、最佳n（Fe）／n（F）=0．3;在PH=5～6的弱酸性条件、温度约为30℃、转速约为500r／min、添加聚丙烯酰胺（PAM）质量分数约为0．1％的情况下,除氟效率高达95％以上;影响脱硫废水除氟效率的因素由主到次依次为：CaCl2〉Al2（SO4）3〉PAM〉FeCl3〉PH〉温度〉搅拌转速．     

Synthesis of LiNi0.8Co0.2O2 cathode material through sintering in an air environment and electrochemical properties characterization

制备锂离子电池正极材料LiNi_0.8Co_0.2O₂通常需要在纯氧气气氛下进行烧结.本工作以硫酸镍,硫酸钴和氢氧化钠为原料,采用并流共沉淀法制备了高密度Ni_0.8Co_0.2(OH)₂前驱体,再采用高温固相反应法在空气中烧结制备了锂离子电池LiNi_0.8Co_0.2O₂正极材料.采用X射线衍射(XRD),扫描电镜(SEM),恒流充放电测试(ECT),循环伏安(CV)与比表面积(BET)测试等方法对目标样品进行了表征,详细考察了烧结条件对材料结构,微观形貌及电化学性能的影响.结果表明,锂/(钴+镍)摩尔比为1.13∶1时,在管式炉中和空气气氛下于第一段烧结温度700 ℃保温9 h,于第二段烧结温度750 ℃保温12 h,合成的材料比表面积适中(0.78 m²/g),具有规则的六边形α-NaFeO₂层状结构,晶粒分布均匀,电化学性能最优.在0.5 C充放电倍率下和2.7~4.3 V电压范围内,其首次放电比容量达到153.0 mA·h/g,循环20次后放电比容量仍为150.7 mA·h/g,容量保持率达到98.5%,显示了优异的循环稳定性能,可用做高能量密度动力电池正极材料.     

氮源和无机盐对酵母菌发酵酒精浓度的影响

在ypd培养基条件下,研究了尿素这种氮源对酒精发酵的影响,发现其对酵母菌发酵生成酒精的最佳浓度值为9.6g/L.并对5种发酵无机盐硫酸镁、硫酸锌、氯化镁、氯化铁、磷酸二氢钾的浓度与发酵酒精浓度之间的关系进行研究,初步找到了该株酵母所需无机盐的临界值,分别是硫酸镁为4.8g/L,磷酸二氢钾为4.8g/L,氯化镁为4.8g/L.添加硫酸锌、氯化铁的两组实验得到的乙醇产量明显比其他组要低,此酵母菌发酵随浓度的增大乙醇产量降低,由此推断硫酸锌、氯化铁对此种酵母菌发酵有着制约作用.     

Synergistic effect on hydrolytic sodium borohydride adding waste Al for hydrogen generation

Synergistic effect of sodium borohydride (NaBH₄) mixed with waste aluminum in hydrolytic system were investigated to improve the hydrogen generation (HG) efficiency. The alkaline aqueous originated from NaBH₄ hydrolysis impels the passive aluminum hydroxide film of Al surface to be dissolved, thus, mutual effect of HG amount increasing by 88% and 50% for Al powder and waste Al can, respectively. To add acid catalyst in the mutual mixture system prompts to significantly accelerate HG rate from 100 ml/min˙g to 400 ml/min˙g but raising temperature is not obviously found. It is speculated that exothermic effect dominates the NaBH₄ hydrolytic reaction and eliminates the temperature effect. In this study, the mutual hydrolyzed reaction of NaBH₄ and waste Al provides ecofriendly environment, low cost and enables to achieve higher HG rate and further uses for portable/mobile fields.     

Hydrogen recovery from the photovoltaic electroflocculation-flotation process for harvesting Chlorella pyrenoidosa microalgae

In this paper, an integrated process using photovoltaic power to harvest microalgae by electro-flocculation (EF) and hydrogen recovery is presented. It is mainly favorable in regions with high solar radiation. The electro-flocculation efficiency (EFE) of Chlorella pyrenoidosa microalgae was investigated using various types of electrodes (aluminum, iron, zinc, copper and a non-sacrificial electrode of carbon). The best results regarding the EFE, and biomass contamination were achieved with aluminum and carbon electrodes where the electrical energy demand of the process for harvesting 1 kg of algae biomass was 0.28 and 0.34 kWh, respectively, while the energy yield of harvested hydrogen was 0.052 and 0.005 kWh kg^?1, respectively. The highest harvesting efficiency of 95.83 ± 0.87% was obtained with the aluminum electrode.The experimental hydrogen yields obtained were comparable with those calculated from theory. With a low net energy demand, microalgae EF may be a useful and low-cost technology.