活性污泥法动力学模型应用中的参数校核

对国际水协的活性污泥法动力学模型在应用中遇到的参数校核问题进行研究 ,总结了目前常用的三种方法 :专家法、灵敏度分析法和过程工程 (ProcessEngineering)法。分析了每种方法的原理、优点和不足之处 ,列举了实际应用的例子。     

Hydrothermal fabrication and visible-light-driven photocatalytic properties of bismuth vanadate with multiple morphologies and/or porous structures for Methyl Orange degradation

Monoclinic BiVO₄ with multiple morphologies and/or porous structures were fabricated using the hydrothermal strategy. The materials were characterized by means of the XRD, Raman, TGA/DSC, SEM, XPS, and UV-Vis techniques. The photocatalytic activities of the BiVO₄ materials were evaluated for the degradation of Methyl Orange under visible-light irradiation. It is observed that pH value and surfactant exerted a great effect on the morphology and pore structure of the BiVO₄ product. Spherical BiVO₄ with porous structures, flower-cluster-like BiVO₄, and flower-bundle-like BiVO₄ were generated hydrothermally at 100℃ with poly(vinyl pyrrolidone) (PVP) and urea (pH = 2) and at 160℃ with NaHCO₃ (pH = 7 and 8), respectively. The PVP-derived BiVO₄ showed much higher surface areas (5.0-8.4 m²/g) and narrower bandgap energies (2.45-2.49 eV). The best photocatalytic performance of the spherical BiVO₄ material with a surface area of 8.4 m²/g was associated with its higher surface area, narrower bandgap energy, higher surface oxygen vacancy density, and unique porous architecture.     

钙对紫外辐射B胁迫下小麦幼苗若干生物学特性的影响

采用模拟紫外辐射(UV-B,280～320nm)的盆栽实验法,研究钙离子对紫外B辐射胁迫下小麦幼苗若干生物学特性的影响.结果显示,在紫外辐射胁迫下(0.35W/m²,每日照射6h,连续照射7d),2mmol/L钙离子处理的小麦,地下与地上部生长指标均明显低于对照植株(降幅为8.1%～36.1%).而6mmol/L钙离子处理的小麦幼苗,各种生长指标的降幅(3.2%～28.6%)低于2mmol/L钙离子处理的小麦幼苗.表明钙离子具有缓解紫外辐射伤害小麦幼苗的效应,这同钙离子对小麦幼苗部分生理生化指标的影响有关.     

序批式膜生物反应器同时脱氮除磷的比较研究

对比了厌氧-好氧(AO)及厌氧-缺氧-好氧(A²O)2种运行模式序批式膜生物反应器(SBMBR)对模拟生活污水同时脱氮除磷的性能.结果表明,2种运行模式的SBMBR对有机物及氨氮的去除率分别可保持在90%和95%以上.A²O MBR具有更强的释磷能力,其SPRR₃₀(前30min比释磷速率)比AO MBR高出47.5%;但SPUR₃₀(前30min比吸磷速率)却比AO MBR低,这是导致前者膜出水中TP值较后者高的原因之一.2个系统内污泥均有反硝化除磷能力,A²O MBR中DPAO(反硝化聚磷菌)的比例比AO MBR提高了57%;硝酸盐为电子受体时单位电子转移所吸收的磷,前者比后者高30%.这2个因素双重作用的结果导致了A²O MBR反硝化除磷能力的提高.A²O MBR系统曝气时间减半并没有加重膜污染,反而该系统的膜污染相对较轻.膜对有机物有较好的过滤截留作用,污泥沉降性能对SBMBR出水水质影响很小.     

“活性甲醛”与甲醛远距离毒性的初步研究

甲醛是否具备远距离毒性(distant-site toxicity)是揭示甲醛与白血病关系的关键问题.本研究采用DPC、MTT实验方法检测甲醛的远距离毒性,结果发现当把等剂量的甲醛与GSH联合作用对细胞进行染毒后细胞内产生的DPC系数比单独同剂量的甲醛组要高很多,在MTT实验中发现在单独甲醛组中加入等量的GSH后细胞活性也出现了显著下降;在动物实验中,当对小鼠肝染毒后脑组织中也同样出现了损伤.说明甲醛在机体内与GSH形成了结合物,这种结合物可能协助甲醛完成跨膜并进入到局部组织再次释放出游离态甲醛,实现了甲醛的远距离毒性,这种结合态的甲醛称之为"活性甲醛".     

化学预处理对微塑料Pb吸附潜力的影响及机理研究

污水和污泥是土壤等生态环境中微塑料的重要来源,受到人们的广泛关注.由于污水和污泥中含有大量的有机质,化学预处理通常被用于提高其中微塑料的提取及分析效率,然而至今关于化学预处理对微塑料的吸附潜力及表面理化特性的影响研究较少.本研究探讨了5种预处理条件,即1 mol·L~(-1) HCl、1 mol·L~(-1) HNO_3、30%H_2O_2、1 mol·L~(-1) NaOH和5 mol·L~(-1) NaOH,对6种微塑料类型(PA、PE、PP、PS、PET和PMMA)Pb吸附潜力的影响,同时通过微塑料表面理化特性的分析,探讨了预处理影响微塑料Pb吸附的机理.结果表明6种微塑料对Pb吸附等温式符合Langmuir模型,Pb吸附能力大小顺序分别为:PAPMMAPETPEPPPS,最大吸附量分别为2922.9、699.3、584.8、549.5、510.2和277.8μg·g~(-1).与此同时,不同预处理条件对微塑料Pb吸附特性的影响不同,总体而言,碱预处理会导致微塑料Pb吸附量增加,且随着碱处理浓度的增加而增加,而酸预处理会引起Pb吸附量减小,其中硝酸预处理作用更加显著.进一步分析预处理前后微塑料质量、尺寸、表面官能团及表面形态等的变化情况,发现碱预处理对微塑料的腐蚀作用最大,其次为硝酸预处理组,最后为盐酸和过氧化氢预处理组.此外,与玻璃型(如PS)微塑料相比,预处理对橡胶型微塑料(如PE)的影响更大.     

上海市郊4种地表径流污染负荷调查与评价

地表径流属于非点源污染，地表径流的产生取决于复杂的降雨过程，径流中污染物浓度，径流深度，产流面积是地表径流污染负荷的３大要素，该文对上海郊的４种地表径流进行了调查，并在污染源评价的基础上与市郊非点源污染总量进行了比较。结果表明，上海市郊进入水全的污染负荷，ＣＯＤｃｒ约为６２６３４．７ｔ／ａ，总氮为６２８８．２ｔ／ａ，总磷为１２４４．６ｔ／ａ，此结果说明地表径流是上海市郊仅次于畜禽类尿的重要非点污染     

Distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface water and sediments from Baiyangdian Lake in North China

Persistent organochlorine compounds, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs) were analyzed in surface water and sediments from Baiyangdian Lake, North China. Total concentrations of HCHs, DDTs and PCBs in surface water were in the range of 3.13-10.60, 4.05-20.59 and 19.46-131.62 ng/L, respectively, and total concentrations of HCHs, DDTs and PCBs in sediments were 1.75-5.70, 0.91-6.48 and 5.96-29.61 ng/g dry weight, respectively. Among the groups of HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) and DDTs (sum of DDT, DDD and DDE), the predominance of β-HCH, DDE and DDD in water and sediment samples was clearly observed. This observation suggested that β-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD. For PCBs, penta-, hexa- and hepta-chlorinated congeners were the most abundant compounds in the both phases. Furthermore, the partitioning of chlorinated compounds between sediment and water was investigated to understand their transport and fates in aquatic ecosystems. The results indicated that average logs of organic carbon-normalized sediment-water partition coefficients (logK_oc') for OCPs varied between 3.20 and 5.53, and for PCBs, logK_oc' values ranged from 3.19 to 5.57. The observed logK_oc' was lower than their equilibrium logK_oc predicted from linear model, which may be attributed to the solubility enhancement effect of colloidal matter in water phase and the disequilibrium between sediment and water.     

Mechanism of Cu(Ⅱ) adsorption inhibition on biochar by its aging process

Biochar exposed in the environment may experience a series of surface changes, which is called biochar aging. In order to study the effects of biochar aging on Cu（Ⅱ） adsorption, we analyzed the surface properties before and after biochar aging with scanning electron microscopy（SEM） coupled to an energy-dispersive X-ray spectrometer（EDX） and diffuse reflectance infrared Fourier transform spectroscopy（DRIFTS）, and then explored the influence of the aging process on Cu（Ⅱ） adsorption by batch experiments. After the aging process, the oxygen concentration, phenolic hydroxyl groups, aromatic ethers and other oxygen-containing functional groups on the biochar surface increased, while carboxyl groups slightly decreased. Thus, over a range of pH, the cation exchange capacity（CEC） and adsorption capacity of Cu（Ⅱ） on the aged biochar were smaller than those of new biochar,indicating that when biochar is incubated at constant temperature and water holding capacity in the dark, the aging process may inhibit Cu（Ⅱ） adsorption. Meanwhile, the dissociation characteristics of oxygen-containing functional groups changed through the aging process, which may be the mechanism by which the biochar aging process inhibits the Cu（Ⅱ） adsorption. Carboxyl groups became more easily dissociated at low pH（3.3–5.0）,and the variation of maximum adsorption capability（qm） of Cu（Ⅱ） on the old biochar was enlarged. Phenolic hydroxyl groups increased after the aging, making them and carboxyl groups more difficult to dissociate at high pH（5.0–6.8）, and the variation of qmof Cu（Ⅱ） on the aged biochar was reduced.     

Impact factors of the degradation of bisphenol A by nitrocellulose membrane under illumination

Nitrocellulose membrane (NCM) can produce hydroxyl radicals under illumination, which promotes the oxidative degradation of organic pollutants. In this paper, NCM was used to oxidize bisphenol A (BPA) under simulated sunlight. The effects of pH, temperature, light intensity, anion and cation on the degradation of BPA were analyzed. The photodegradation process of BPA was discussed. The optimal photolysis rate was 0.031 min^?1 when the temperature was 30°C, the light intensity was 2.67 × 10⁴ Lux, and the pH value was 9.0. The alkaline environment, temperature and light intensity can promote the photodegradation of BPA. Except for nitrate ions, anions and cations can inhibit the photodegradation of BPA. Compared with cations, anions have a greater inhibitory effect on BPA degradation. The degradation products of BPA by NCM were analyzed by gas chromatographic/mass. This study may provide useful information for the BPA degradation by NCM in complex water samples.