Combined treatment of phenolic wastewater by wet air oxidation and activated sludge

Wet air oxidation (WAO) is employed in this work for treating high concentration chemical wastewater containing phenol and/or phenolic compounds. Experimental results indicate that over 90% removal of phenol or phenolic compounds can be efficiently achieved in the WAO process. Despite of the high treatment efficiency of the WAO process, the treated wastewater, however, still retains relatively high chemical oxygen demand (COD) concentration and does not meet the safe discharge standard. Hence further treatment of the WAO treated wastewater by an aerobic biological treatment using acclimatized activated sludge is necessary. It is found in the present studies that the combined process, if appropriately operated, is capable of drastically reducing the COD concentration of the high concentration chemical wastewater to meet the safe discharge requirement. The operating conditions of the combined process are investigated to determine their respective effects on the overall treatment efficiency. The experimental data also indicate that the oxidation reaction can be represented by a first order kinetics in terms of the component or COD concentration. For both single component and multicomponent wastewaters, the WAO process was found to have different activation energy for oxidation below and above 200°C, suggesting possibly different reaction mechanisms between these temperature ranges. The experimental results provided in the present work can provide significant and practical information for optimizing the combined treatment method.     

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Abstract

Three collectives of substances - plastics, plant nutrients, biotoxins - are candidates for monitoring programmes that could keep track of the quality of ocean waters for vital life processes. All three are not subject to systematic surveillance at present. They are each characterized by long residence times in the marine environment, by increasing influx, and by growing evidence of their deleterious impacts on living systems.     

环戊烯臭氧化反应瞬变物种产生机制

大气中烯烃臭氧化反应产物是二次有机气溶胶(SOA)形成的重要前体物. 运用自行组建的低温基质隔离系统研究环戊烯臭氧化反应的瞬变物种产生机制. 采用程序升温方法,将温度从6 K升至115 K,用傅里叶红外光谱仪检测不同温度下生成的活性中间体,并将试验值与理论计算值、文献报道值进行对比,以确定中间体构型. 结果表明:环戊烯臭氧化反应生成的中间体——POZ(初级臭氧化物)、SOZ(二次臭氧化物)和CI(一分子羰基氧化物和一分子醛或酮)被成功检测到. 其中,POZ的特征吸收峰在705和946 cm-1处,对应O—O—O反对称伸缩振动和环变形振动;SOZ特征吸收峰在939 cm-1处,对应C—O伸缩振动;CI的特征吸收峰在1 733和853 cm-1处,分别对应CO伸缩振动和O—O伸缩振动. 据此,环戊烯臭氧化反应遵循Criegee机制. 采用4种量子化学计算方法——B3LYP/6-311++G(d,2p)、B3LYP/6-311++G(3df,3pd)、MP2/aug-cc-pvdz和PW91PW91/6-311++G(3df,3pd),计算POZ、SOZ和CI特征吸收峰的振动频率,其中POZ在705 cm-1处吸收峰的振动频率计算值分别为725、698、703、680 cm-1;SOZ在1 030 cm-1处吸收峰的振动频率计算值分别为1 017、1 018、1 025和993 cm-1;CI在1 733 cm-1处吸收峰的振动频率计算值分别为1 796、1 803、1 732和1 745 cm-1.表明MP2/aug-cc-pvdz计算的特征振动频率与试验值最接近.      

鲍鱼对2种多环芳烃的富集动力学研究

为探究多环芳烃(PAHs)在海洋生物体内富集过程,选择皱纹盘鲍(Haliotis discus hannai)作为受试生物,应用半静态双箱动力学模型,分别考察了3-甲基菲和9,10-甲基蒽2种多环芳烃在皱纹盘鲍体内的富集动力学过程,通过非线性拟合获得鲍鱼对2种多环芳烃的吸收速率常数(K_1)、释放速率常数(K_2)、生物富集因子(BCF),以及平衡状态下鲍鱼体内2种多环芳烃的含量(Cmax)、生物学半衰期(t_(1/2))等动力学参数。结果表明,鲍鱼对9,10-甲基蒽富集动力学参数K_1、K_2、BCF、Cmax、t_(1/2)的平均值分别为4.9437、0.406、13.59、790.03μg·L~(-1)、3.78 d。鲍鱼对3-甲基菲富集动力学参数K_1、K_2、BCF、Cmax、t_(1/2)的平均值分别为2.3023、0.367、5.97、354.37μg·L~(-1)、3.13 d。鲍鱼在不同浓度下对3-甲基菲和9,10-甲基蒽的生物富集过程均符合双箱动力学模型。     

生物质气化发电厂灰渣中微量元素的赋存形态及其析出

分别用Tessier逐级提取形态分离法和模拟酸雨浸提实验,研究了生物质气化发电厂的气化器、淋洗器和旋风分离器底灰中微量元素的赋存形态及其析出规律,探讨了微量元素析出浓度和影响其析出的因素．结果表明,微量元素大部分存在于残渣态,其有机态、Fe-Mn氧化态和碳酸盐结合态的浓度依次减少,可交换态的赋存量极低;元素的析出受浸提液pH值、浸提温度和浸提时间的影响,元素在灰渣颗粒物中的赋存形态及含量的高低也影响元素的释放和析出程度．     

Effects of high ammonium level on biomass accumulation of common duckweed Lemna minor L.

Growing common duckweed Lemna minor L. in diluted livestock wastewater is an alternative option for pollutants removal and consequently the accumulated duckweed biomass can be used for bioenergy production. However, the biomass accumulation can be inhibited by high level of ammonium (NH₄ ⁺) in non-diluted livestock wastewater and the mechanism of ammonium inhibition is not fully understood. In this study, the effect of high concentration of NH₄ ⁺ on L. minor biomass accumulation was investigated using NH₄ ⁺ as sole source of nitrogen (N). NH₄ ⁺-induced toxicity symptoms were observed when L. minor was exposed to high concentrations of ammonium nitrogen (NH₄ ⁺-N) after a 7-day cultivation. L. minor exposed to the NH₄ ⁺-N concentration of 840 mg l^?1 exhibited reduced relative growth rate, contents of carbon (C) and photosynthetic pigments, and C/N ratio. Ammonium irons were inhibitory to the synthesis of photosynthetic pigments and caused C/N imbalance in L. minor. These symptoms could further cause premature senescence of the fronds, and restrain their reproduction, growth and biomass accumulation. L. minor could grow at NH₄ ⁺-N concentrations of 7–84 mg l^?1 and the optimal NH₄ ⁺-N concentration was 28 mg l^?1.     

Prenatal diagnosis of congenital mesoblastic nephroma in mid-second trimester by sonography and magnetic resonance imaging

Although congenital mesoblastic nephroma (CMN) is a rare benign congenital renal tumor, it is the most common solid renal tumor in the newborn period. The most common presentation of congenital mesoblastic nephroma is polyhydramnios, and only one case with prenatal fetal hydrops has been previously reported. Prenatal diagnosis of CMN has previously been made on the basis of the findings of sonography in the third trimester, and magnetic resonance imaging (MRI)–based diagnosis has been reported recently. Here we report a case of prenatally diagnosed classical type CMN diagnosed at 22 + 3 weeks of gestation based on the findings of sonography and magnetic resonance imaging. The characteristic imaging findings in this case were fetal hydrops and polyhydramnios. To our knowledge, this is the youngest reported gestational age for prenatal diagnosis of CMN and it is the second case of CMN associated with fetal hydrops detected prenatally. Copyright © 2003 John Wiley & Sons, Ltd.     

新一代地球观测信息在天然气水合物研究中的应用展望

地球上蕴藏着巨大的天然气水合物(GasHydrates)矿藏,它可作为一种新的烃类资源来开发利用。天然气水合物中CH4的释放影响全球气候变化。同时,天然气水合物是一种潜在的环境灾害诱发因素。天然气水合物的研究与开发目前在国内外成为研究热点。新一代地球观测信息,如已发射成功的TERRA中的MODIS、MOPITT信息以及即将发射的化学星CHEM为天然气水合物的研究与开发提供了新的技术方法。中国气候观测系统中观测台站观测信息的共享,加速了开发利用新一代地球观测信息的速度,也必将促进新一代地球观测信息在天然气水合物研究中发挥更大的作用。     

新一代地球观测信息在天然气水合物研究中的应用展望

地球上蕴藏着巨大的天然气水合物(GasHydrates)矿藏,它可作为一种新的烃类资源来开发利用。天然气水合物中CH4的释放影响全球气候变化。同时,天然气水合物是一种潜在的环境灾害诱发因素。天然气水合物的研究与开发目前在国内外成为研究热点。新一代地球观测信息,如已发射成功的TERRA中的MODIS、MOPITT信息以及即将发射的化学星CHEM为天然气水合物的研究与开发提供了新的技术方法。中国气候观测系统中观测台站观测信息的共享,加速了开发利用新一代地球观测信息的速度,也必将促进新一代地球观测信息在天然气水合物研究中发挥更大的作用。