Efficient dechlorination of chlorinated solvent pollutants under UV irradiation by using the synthesized TiO2 nano-sheets in aqueous phase

Titanium dioxide(TiO2), which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetrachloroethene(PCE), trichloroethene(TCE) and 1,1,1-trichloroethane(TCA). The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO2 system compared to UV/commercial P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene(NB) as a probe of hydroxyl radical(.OH), the degradation rate was better over UV/synthesized TiO2, suggesting the high concentration of.OH generated in UV/synthesized TiO2system. In addition,.OH concentration was confirmed by the strong peak displayed in EPR analysis over UV/synthesized TiO2system. The characterization result using XRD and TEM showed that the synthesized TiO2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 nm, side length of 50 nm and width of 33 nm and a surface 90.3 m2/g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO2. The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater.     

FBC-DPF在柴油机颗粒物控制中的应用研究

目前针对加装FBC-DPF(燃油添加剂-柴油机颗粒捕集器)后的柴油机放特性研究较少,并且缺乏FBC-DPF对颗粒物中PAHs排放量的影响效果研究.为全面评估加装FBC-DPF后柴油机颗粒物排放特性和FBC-DPF对柴油机尾气中的颗粒物排放污染控制效果,在发动机台架上对装有FBC-DPF的重型柴油机进行了颗粒物排放特性试验.利用电子低压撞击仪(ELPI)测量加装FBC-DPF前、后柴油机颗粒物的数浓度与粒径分布,用玻璃纤维滤膜采集加装FBC-DPF前、后尾气中的固相PAHs,利用色谱质谱联用仪对加装FBC-DPF前、后尾气中的固相PAHs进行定量分析.结果表明:①加装FBC-DPF后柴油机排放的颗粒物数浓度大幅降低,FBC-DPF对尾气中颗粒物的捕集效率平均值在95%左右;②加装FBC-DPF后柴油机固相PAHs总比排放量有所降低,在大负荷区域降幅在25.0%～88.0%之间;③加装FBC-DPF前的颗粒物中位直径为30～89 nm,而加装FBC-DPF后的颗粒物中位直径为41～98 nm,平均增幅为38.2%.对于国Ⅳ及未来国Ⅴ柴油机排放法规,FBC-DPF是解决柴油机颗粒物排放的有效手段;此外,FBC-DPF可以大幅降低柴油机尾气中的有毒成分,并且能够适应高含硫量的燃油环境.     

Aerobic granules cultivated and operated in continuous-flow bioreactor under particle-size selective pressure

A novel method based on the selective pressure of particle size （particle-size cultivation method, PSCM） was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and compared with the conventional method based on the selective pressure of settling velocity （settling-velocity cultivation method, SVCM）. Results indicated that aerobic granules could be cultivated in continuous operation mode by this developed method within 14 days. Although in the granulation process, under particle-size selective pressure, mixed liquor suspended solids （MLSS） in the reactor fluctuated greatly and filamentous bacteria dominated the sludge system during the initial operation days, no obvious difference in profile was found between the aerobic granules cultivated by PSCM and SVCM. Moreover, aerobic granules cultivated by PSCM presented larger diameter, lower water content and higher specific rates of nitrification, denitrifieation and phosphorus removal, but lower settling velocity. Under long term operation of more than 30 days, aerobic granules in the continuous-flow reactor could remain stable and obtain good chemical oxygen demand （COD）, NH4^＋-N, total nitrogen （TN） and total phosphorus （TP） removal. The results indicate that PSCM was dependent on the cultivation and maintenance of the stability of aerobic granules in continuous-flow bioreactors.     

盐酸小檗碱纳米乳的抑藻性能研究

选用处方为表面活性剂吐温-80、助表面活性剂甘油、油相大豆油及水,制备盐酸小檗碱纳米乳,并在对该纳米乳质量评价的基础上研究其对铜绿微囊藻的抑制效应。结果表明:在四相质量比为36∶9∶5∶10情况下制备出的水包油型盐酸小檗碱纳米乳澄清透明,分散均匀,平均粒径约为(14.2±3.8)nm,载药量为3 980 mg/L。该纳米乳能大幅提高盐酸小檗碱的抑藻性能,2 mg/L盐酸小檗碱纳米乳抑藻性能与8 mg/L未纳米化盐酸小檗碱抑藻性能相当,同时结果表明盐酸小檗碱纳米乳对无毒微囊藻的抑制效应强于有毒微囊藻。该研究将纳米药物技术应用于有害藻类的防控并取得较好效果,为纳米药物技术在水产养殖业应用提供科学参考。     

UASB处理酒精废水耐冲击特性与颗粒污泥分析

针对UASB耐冲击能力低的问题,采用短暂冲击负荷的方法进行52 d中试研究,并考察接种絮状污泥的UASB对以污冷凝水为主要成分的酒精废水的处理效果,结果表明,UASB呈现较强耐冲击负荷能力;第49天产气速率最高,可达3.03 L/(L·d),反应器内形成了粒径0.5~1.5 mm的颗粒,电镜扫描的颗粒污泥结构致密,由多个杆状细菌形成网状结构。在夏季无保温措施、负荷冲击条件下培养颗粒污泥是可行的。     

颗粒活性炭改性同步去除水中铅、铬的研究

为提高颗粒活性炭同步去除水中铅、铬污染物的能力,分别使用氧化铁、氧化锰、十六烷基三甲基溴化铵(HTMAB)和氯化十六烷基吡啶(CPC)制作改性活性炭(Fe Cl3-AC,Mn O2-AC,HTMAB-AC,CPC-AC)。通过测定4种改性活性炭表面的等电点p H、酸碱官能团和扫描电子显微镜图像,研究4种改性活性炭吸附效果优异并分析其中原因。结果表明:Fe Cl3-AC同步去除铅、铬效果最佳,HTMAB-AC、CPC-AC与原炭效果持平,Mn O2-AC效果还不及原炭。从等电点p H来看,Fe Cl3-AC拥有较低的等电点p H,有利于静电吸附铬酸根阴离子团;从酸性基团数目来看,Fe Cl3-AC表面拥有较多酸性官能团,有利于离子交换作用,保证了对铅离子较高的吸附效率;从SEM来看,Fe Cl3-AC上Fe Cl3负载均匀,有效改善了活性炭表面特性,有利于吸附。     

地下水中常见离子对纳米零价铁除Se（Ⅳ）动力学的影响

采用间歇实验对纳米零价铁(nZVI)除四价硒(Se(Ⅳ))进行实验性研究,考察了地下水中共存离子对nZVI除Se(Ⅳ)动力学的影响.结果表明,在厌氧条件下,当nZVI投加量为0.1 g·L-1,Se(Ⅳ)浓度为100μmol·L-1,NaCl浓度为0.01 mol·L-1,pH=7.0,T=25℃±1℃时,投加CO2-3或SO2-4浓度为1 mmol·L-1、腐殖酸(humic acid,HA)为5 mg·L-1时,明显抑制了Se(Ⅳ)的去除.投加0.5 mmol·L-1Ca2+或Mg2+时,对除Se(Ⅳ)影响不大;而Ca2+(3 mmol·L-1)、Mg2+(3 mmol·L-1)时,Se(Ⅳ)的去除效率明显下降.未加共存离子时,Se(Ⅳ)在20 min时基本去除完,共存离子存在的情况下,nZVI对Se(Ⅳ)的去除率在30 min时达到100%.反应过程中二价铁(Fe2+)随着Se(Ⅳ)的去除趋于平稳.ORP在反应过程中快速从正值下降至负值,由此说明nZVI除Se(Ⅳ)的过程发生了还原反应.     

SFBR中好氧颗粒污泥的培养及特性研究

接种自行培养的活性污泥,以模拟废水为基质,采用连续进水、间歇出水及厌氧/好氧交替的运行模式,尝试了在SFBR中进行好氧颗粒污泥的培养,并研究了好氧颗粒污泥的特性及反应器对污染物的去除效果.结果表明,通过逐步缩短沉降时间,28 d时成功培养出好氧颗粒污泥,所形成的好氧颗粒污泥呈黄色、形状不规则,且粒径较小(平均粒径0.56 mm),正常情况下的SVI保持在70 mL·g-1以下,EPS在59 d时达到最大值(以MLVSS计)373.24 mg·g-1,较培养初期增加了约2.5倍,运行后期由于颗粒出现解体,导致EPS急剧下降;反应器在运行过程中未能保持较高的污泥量,中后期MLSS始终在3 000mg·L-1以下;在63 d的运行时间里,除异常波动外,反应器对COD的去除率基本维持在90%左右,正常情况下出水COD小于100 mg·L-1,反应器对NH+4-N、TIN的去除效果波动较大,去除率分别为44.45%~94.72%及43.87%~93.13%,反应器对TP的去除率在44.50%~97.40%之间,正常情况下TP去除率可维持在60%以上;限于自动控制水平,夜间长时间的好氧饥饿期容易造成丝状菌过度生长,使得AGS在生长竞争中处于劣势,最终导致了AGS的解体.     

桂江主要离子及溶解无机碳的生物地球化学过程

河流水体的化学组成记录了流域内各种自然过程与人类活动的信息.对西江一级支流桂江化学径流的分析结果表明,桂江水体的离子组成主要受碳酸盐岩化学风化过程的控制,CO2是这一过程的主要侵蚀介质;H2SO4对碳酸盐岩的风化影响桂江河水的化学组成.大气沉降、人类活动、碳酸盐岩和硅酸盐岩化学风化对桂江水体贡献的溶解物质分别占总溶解物质的2.7%、6.3%、72.8%和18.2%.河流溶解无机碳(DIC)的稳定同位素组成(δ13CDIC)揭示桂江河水中的DIC明显被浮游植物的光合作用所利用.浮游植物初级生产力对桂江颗粒有机碳(POC)的贡献达22.3%~30.9%,这表明岩石风化来源的DIC经浮游植物的光合作用转化为有机碳,并在迁移过程中部分沉积水体底部,进而形成埋藏有机碳.     

颗粒直链藻水华生消对婆罗异剑水蚤（桡足类）种群动态的影响

近年来,国内外学者对湖库型水华的发生机理和生态效应都做了大量研究,但有关水华生消对浮游动物群落结构影响的研究还很少.因此,本研究利用两个室外水泥池在中等尺度上考察了颗粒直链藻水华生消过程对婆罗异剑水蚤(桡足类)种群动态的影响,以及后者摄食对水华生消的下行调控作用.结果发现,颗粒直链藻水华发展迅速,仅5 d时间叶绿素浓度就从(21.24±0.75)μg·L-1上升到(240.34±11.00)μg·L-1;随后水华进入快速消退期,3 d后叶绿素a浓度下降到(53.63±0.47)μg·L-1.婆罗异剑水蚤的摄食压力对颗粒直链藻水华具有明显的抑制作用,水华生消期间含有婆罗异剑水蚤的藻液叶绿素a浓度比对照组低20μg·L-1左右,最大差异为26.08μg·L-1.期间婆罗异剑水蚤的丰度也由接入时的(56.50±4.32)ind·L-1增加到(142.11±6.35)ind·L-1,增加了1.5倍.该研究结果表明,在无鱼类摄食压力情况下,颗粒直链水华的爆发和消亡对婆罗异剑水蚤的生长和繁殖没有负面影响,反而促进了其种群数量的增加,这可能是由于水华期间为其提供了充足的饵料供应.