两性高分子水处理剂的研究进展

本文综述了近年来国内外两性高分子水处理剂的研究进展,并对今后的研究工作提出了一些建议.     

矿井火区可燃性混合气体爆炸三角形判断法及其爆炸危险性分析

矿井火区可燃性混合气体爆炸危险性的判断 ,目前常用单纯的瓦斯爆炸三角形判别法。此法对实际的判断往往未综合考虑火区温度的影响。为此 ,笔者论述了矿井火区多种可燃性气体同时存在时 ,其混合气体爆炸三角形各参数的工程计算方法 :爆炸界限可用 Le Chatelier法 ,但需根据火区实测温度进行修正 ;爆炸时的临界氧浓度 ,则需用另一种三角形图示法予以确定。由此画出的混合气体爆炸三角形分析图 ,可用于矿井火区 ,尤其是矿井大面积火区的密闭和启封过程中 ,作为可燃性混合气体爆炸危险性的综合判断及其防爆措施的制定 ,都具有实用价值和指导意义     

新型两性壳聚糖絮凝剂的合成及其絮凝效果的研究

该研究旨在通过化学修饰壳聚糖提高其污水处理的絮凝效果。通过壳聚糖的氨基与甲醛和酚类物质的曼尼希反应引入硫酸根基团,制备了3种具有不同取代度的两性壳聚糖衍生物。红外及核磁谱图分析结果证实,合成产物中具有苯并噁嗪环结构。经处理高岭土的水悬浮液进行模拟絮凝实验发现,这3种苯并噁嗪壳聚糖衍生物的絮凝效果随絮凝剂用量、污水pH和离子强度等条件变化而有较大变化,并均可在适当絮凝条件下获得最佳值。它们的絮凝效果全面优于未经处理的壳聚糖对比样品。取代度为80%左右的硫酸化壳聚糖絮凝剂处理污水可达近100%的浊度净化率。     

乳化油在汽车发动机上的应用及探讨

本文对乳化油的乳化性能和在汽车发动机上的发展现状进行了探讨,分析对比了混合燃料的优缺点。研究表明：汽车发动机燃用乳化油可提高热效率,有效降低NOx及碳烟排放,但动力性略差,CO排放有所增加。最后阐述了我国乳化油未来发展优势。     

Aeration optimization through operation at low dissolved oxygen concentrations: Evaluation of oxygen mass transfer dynamics in different activated sludge systems

In wastewater treatment plants(WWTPs)using the activated sludge process,two methods are widely used to improve aeration efficiency — use of high-efficiency aeration devices and optimizing the aeration control strategy. Aeration efficiency is closely linked to sludge characteristics(such as concentrations of mixed liquor suspended solids(MLSS)and microbial communities)and operating conditions(such as air flow rate and operational dissolved oxygen(DO)concentrations). Moreover,operational DO is closely linked to effluent quality. This study,which is in reference to WWTP discharge class A Chinese standard effluent criteria,determined the growth kinetics parameters of nitrifiers at different DO levels in small-scale tests. Results showed that the activated sludge system could meet effluent criteria when DO was as low as 0.3 mg/L,and that nitrifier communities cultivated under low DO conditions had higher oxygen affinity than those cultivated under high DO conditions,as indicated by the oxygen half-saturation constant and nitrification ability. Based on nitrifier growth kinetics and on the oxygen mass transfer dynamic model(determined using different air flow rate(Q′_(air))and mixed liquor volatile suspended solids(MLVSS)values),theoretical analysis indicated limited potential for energy saving by improving aeration diffuser performance when the activated sludge system had low oxygen consumption; however,operating at low DO and low MLVSS could significantly reduce energy consumption. Finally,a control strategy coupling sludge retention time and MLVSS to minimize the DO level was discussed,which is critical to appropriate setting of the oxygen point and to the operation of low DO treatment technology.     

Skew and attribute non-attendance within the Bayesian mixed logit model

We investigate non-attendance to choice set attributes and the accommodation of preference heterogeneity within the mixed logit model. We propose a generalisation of the mixed logit enabling the degree of skew of marginal utility distributions to be estimated. The implementation is Bayesian with the marginal likelihood used as an arbiter of model performance. We find strong evidence of skew in the distributions of marginal utilities for most attributes. Models incorporating skew are preferred in all cases. The irrelevance of an attribute to significant numbers of respondents is a possible cause of such skew. We test alternative empirical accommodations of self-reported attribute non-attendance (ANA) and continue to find strong evidence of skew in the distributions of marginal utilities even having accounted for ANA. We find that, contrary to some recent findings, respondents who report having ignored an attribute typically do indeed have a zero marginal utility for that attribute.     

新型高效微生物絮凝剂在废水处理中的应用

介绍了新型微生物絮凝剂的国内外研究进展和应用现状,并对今后的发展趋势作了展望。通过对微生物絮凝剂在废水处理中的分析,提出应加强对生物絮凝剂产生菌选育的研究,利用现代分子生物学技术和转基因技术构建基因工程菌株;寻找廉价的培养基,开发复合型生物絮凝剂。     

微生物絮凝剂A3的培养条件及处理啤酒废水条件研究

从土壤中筛选出一株产微生物絮凝剂的菌株A3,利用均匀设计安排试验,用曲线拟和方法创建数学模型的方法研究了其产絮凝培养基条件,结果表明:葡萄糖添加量2.2%、酵母膏添加量0.51%、pH7.6、温度30.3℃时A3产絮凝剂条件最佳,数学模型为Y=-486.2+60.5X1-13.7X12+61.9X2-60.7X22+56X3-3.7X32+18.2X4-0.3X42,培养的动力学模型为:(C0-C)t/C0×100%=96.03-338.15/t。同时利用A3菌产絮凝剂对啤酒废水进行COD去除处理,结果显示:pH值为8、100mL废水中絮凝剂的添加量为1.5mL和1%CaCl2用量为2mL时,COD去除效果最佳。在最佳工艺条件下的COD去除率可达60%。并构建了相应的数学模型为:y=40.8+22.4e-(x-8)2/4.5;y=66.4-58.9/(1+(x/0.67)6.5)和y=67.4-56.5/(1+(x/0.68)4.86)。     

复合微生物絮凝剂产生菌XL1的优化条件

从活性污泥中筛选出4株产微生物絮凝剂的菌株,将4株菌进行相互复合培养后,发现1号和2号菌株构建的复合菌群（XL1）所产MBF的絮凝率达到65．5％。优化XLI的培养条件及其所产MBF的絮凝条件后,发现XL1在培养温度为35℃、摇床转速为160rpm、培养基初始pH为8．0、菌液用量为15ml／L、种子液接种量为10ml／L、1％CaCl,溶液用量为40ml／L、高岭土悬浮液pH为4．5、静沉时间为12min等的条件下絮凝率可达到92．5％。16S rDNA测序鉴定1号菌属于沙雷菌属（Serratia）,2号菌属于芽孢杆菌菌属（Bacillus）。     

Cationic content effects of biodegradable amphoteric chitosan-based flocculants on the flocculation properties

A series of biodegradable amphoteric chitosan-based flocculants (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) modified carboxymethyl chitosan, denoted as CMC-CTA) with different substitution degrees of CTA were prepared successfully. The content of carboxymethyl groups in each CMC-CTA sample was kept almost constant. The solubility of the various flocculants showed that, higher cationic content of flocculants caused a better solubility. The flocculation experiments using kaolin suspension as synthetic water at the laboratory scale indicated that the substitution degree of CTA was one of the key factors for the flocculation properties. With the increase of cationic content, the flocculants were demonstrated better flocculation performance and lower dosage requirement. Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the cationic content of the flocculants on the flocculation properties from the viewpoint of flocculation mechanism in detail. Furthermore, flocculation performance using raw water from Zhenjiang part of Yangtze River at the pilot scale showed the similar effects to those at the laboratory scale.