Characterization of the dissolved organic matter in sewage effluent of sequence batch reactor: the impact of carbon source

Dissolved organic matter (DOM) transformation in sequence batch reactor (SBR) fed with carbon sources of different biodegradability was investigated. During the biologic degradation process, the low molecular weight (MW) fraction (< 1 kDa) gradually decreased, while the refractory compounds with higher aromaticity were aggregated. Size exclusion chromatography (SEC) and fluorescence of excitation emission matrices (EEM) demonstrated that more biopolymers (polysaccharides or proteins) and humic-like substances were presented in the extracellular polymeric substance (EPS) extracted from the SBR fed with sodium acetate or glucose, while the EPS from SBR fed with slowly biodegradable dissolved organic carbon (DOC) substratestarch had relatively less biopolymers. Comparing the EfOM in sewage effluent of three SBRs, the effluent from SBR fed with starch is more aromatic. Organic carbon with MW>1 kDa as well as the hydrophobic fraction in DOM gradually increased with the carbon sources changing from sodium acetate to glucose and starch. The DOC fractionation and the EEM all demonstrated that EfOM from the effluent of the SBR fed with starch contained more fulvic acid-like substances comparing with the SBR fed with sodium acetate and glucose.     

Fe掺杂PTFE-PbO2/TiO2-NTs/Ti电极的制备、表征及电催化性能

采用电沉积法制备了Fe掺杂PTFE-PbO2/TiO2-NTs/Ti、PbO2/TiO2-NTs/Ti、PbO2/Ti 3种电极,运用扫描电镜、X射线衍射仪观察表面形貌与形态,通过线性扫描伏安法在0.1 mol·L-1的H2SO4中测定电极的析氧极化曲线.以对硝基酚(p-NP)为目标污染物,考察了电极的电催化活性,在20 mA.cm-2电流密度下降解100 mg·L-1 p-NP,120 min时表观速率常数分别为0.0370 min-1、0.0265 min-1和0.0180 min-1,COD去除率分别为77.38%、74.07%、66.18%,研究发现在相同的条件下Fe掺杂PTFE-PbO2/TiO2-NTs/Ti性能更佳,矿化更完全.     

滤料床在受污染新沂河水净化中的应用

采用滤料床工艺,对受污染的新沂河水进行了中试处理研究。结果表明:3种不同粒径的滤料床对NH3-N和CODMn的去除能力大小不同,依次为细滤料床>中滤料床>粗滤料床,对NH3-N的去除率分别为88%,70%和47%,对CODMn的去除能力较低,分别为22%,15%和12%,但均可以去除其中的可生化有机物。在25~35℃时,3种滤料床对NH3-H的去除效果最好,同时细滤料床抗温度的变化能力较强。     

由维尼纶厂废液合成乙酸乙酯

本文以维尼纶厂废液中提取的乙醛为原料,通过缩合反应合成乙酸乙酯,乙醛转化率达91.5%,选择性达93.0%,并对乙醛的提取、催化剂合成及缩合反应进行了探讨.     

水力帷幕防治海水入侵的数值模拟研究

为比较应用于防治海水入侵工程的水力帷幕效果,利用垂向二维非均质流体的对流-弥散模型,运用伽辽金有限元法求解,并用物理实验结果验证其有效性.将模型应用于模拟广西北海市海城区海水入侵过程及水力帷幕防治海水入侵效果,分别计算了超采地下水、抽水、注水和抽-注水情况下咸淡水界面随时间推移过程,并分析咸淡水界面推移与抽、注水流量及抽、注水孔位置之间关系,通过比较得出注水是北海市防治海水入侵较为理想的措施.     

Origin and assessment of groundwater pollution and associated health risk: a case study in an industrial park,northwest China

Groundwater quality which relates closely to human health has become as important as its quantity due to the demand for safe water. In the present study, an entropy-weighted fuzzy water quality index (WQI) has been proposed for performing groundwater quality assessment in and around an industrial park, northwest China, where domestic water requirements are solely met by groundwater. The human health risk was assessed with the model recommended by the United States Environmental Protection Agency. In addition, the sources of major ions and main contaminants were also analyzed. The study shows that groundwater in the study area has been contaminated conjunctively by natural processes and industrial and agricultural activities. Nitrate, manganese (Mn), fluoride, total dissolved solids, total hardness and sulfate are major contaminants influencing groundwater quality. Nitrate and heavy metals such as Mn are mainly affected by human agricultural activities and industrial production, while other contaminants are mainly originated from mineral weathering and water–rock interactions. The results of water quality assessment suggest that half of the groundwater samples collected are of medium quality thus require pretreatment before human consumption. The mean health risk caused by the consumption of contaminated groundwater in the area is 8.42 × 10^?5 per year which surpasses the maximum acceptable level (5 × 10^?5 per year) recommended by the International Commission on Radiologic Protection. The entropy-weighted fuzzy WQI proposed in this study can not only assign proper weights to parameters but also treat uncertainties associated with water quality classification. This study will be of interest to international environmentalists and hydrogeologists. It will also be useful in regional groundwater management and protection.     

Water use efficiency of a mixed cropping system of corn with grasses

A new cropping system of corn mixed with grasses was tried to make full and efficient use of water and to ease environmental problems such as soil erosion by water and wind in grain and forage feed production practices. Field experiments were conducted to investigate the water use efficiency under this mixture cropping system. Six treatments with two replicates were arranged as: bare field, corn only, rye only, alfalfa only, rye–corn mixture and alfalfa–corn mixture. Lysimeters were used to measure different components of water consumption in the crop fields for water use efficiency estimation. From the yields and water consumption of crops under different treatments, combined water use efficiency of corn and grasses were estimated. The results showed that WUEs in the mixed cropping fields of corn–grasses were much higher than those in the fields where only corn or grass were grown. Averaged WUE was 3.71 kg/m³ from the corn and rye mixture fields, 30% higher than that from the plots where only corn or rye were grown. Averaged WUE was 4.55 kg/m³ from the alfalfa and corn mixture fields, 60% higher than that from the fields where only corn or alfalfa were grown. Under the same conditions of irrigation, yields from the rye and corn mixture plots increased by 33%, as compared with those from fields where only corn or rye were grown. The yields from alfalfa and corn mixture fields were 61% higher than those from fields where only corn or alfalfa were grown. The experimental results also indicated that corn and alfalfa mixture cropping is better than a corn–rye mixture system.     

Numerical simulation on foam ceramic blasting block device under the action of explosion transform

The responsive behaviour of the action of under explosion blasting block damaging device structure was investigated based on quality equation, energy conservation equation and thermodynamics equation, using the ANSYS finite element simulation and Euler form of momentum equation. This paper analyzed the destructive situation of the inside and outside of the foam ceramic device. The research shows that the finite element simulation results and the numerical calculation results agree, which provides important reference basis in the anti-explosion design and improvement of cut off the device for blasting.     

Stability of workface using long-wall mining method in extremely thin and gently inclined iron mine

Long-wall mining method has its own advantages, such as small mining-cutting ratio, the simple technique of recovery and high level of mechanization, which is the optimal method used to mine gently inclined and extremely thin iron mine. How to ensure the safety of workers and equipment during mining is the key technical process. Based on elastic-plastic mechanics theory, the mechanic model of long-wall method mining gently inclined and extremely thin iron mine is established and the critical safety distance of workface is obtained. With the FLAC-2D simulation software, the rule of stress change, the deformation of workface and surrounding rock in different control-roof width are also summarized. The final results accord with the ones of theory test. We confirm the support-frame resistance of workface by analogy-statistic method. The results prove that hydraulic support-frame have the ability to provide enough pressure to assure the stability of working face within the 5-m of control-roof width.     

液化石油气容器受热下蒸气爆炸及影响因素的研究

液化石油气的生产、储运过程中,由火焰加热引发的蒸气爆炸事故屡有发生,并常相继导致其他类型的爆炸。分析了蒸气爆炸的危害特性,研究了影响蒸气爆炸的因素,对火灾的预防和扑救具有一定实用意义。