Biological purification of exhaust air containing toluene vapor in a filter-bed reactor

Experiments during a period of 93 days are reported on the treatment of waste air containing toluene vapor using a laboratory scale biofilter system packed with peat inoculated with specific florae (Pseudomonas type) and intermittently humidified with a nutrient solution necessary for the survival of the micro-organisms. Design and operation parameters were regularly measured in order to check the performance of the biodegradation process. Under pseudo-steady state conditions, a maximum elimination capacity of 70 g/m³.h was obtained for an inlet load of 190 g/m³.h. Elimination capacity data obtained agreed well with the predictions of two recognized zero order kinetic models. Also, the biofilm thickness as predicted from the Ottengraf and van den Oever model (1983) was around lmm.     

海鲜食品中致病性微生物检测方法概述

为了适应海鲜食品中致病性微生物安全检测的需求,文章介绍了海鲜食品中病原微生物的检测方法与技术,包括传统培养基法、酶联免疫学技术、分子生物学技术,并概述这些检测技术对食品微生物安全的应用。     

The Microbiology of Lubricants and Oils for Water Supply Applications

Recent work in the US has shown that contact between lubricants and oils and drinking water can promote the growth of heterotrophic micro-organisms. It is unlikely that these species are pathogenic, and therefore harmful to man. However, the hygienic status of water distribution systems could be affected, leading to higher heterotrophic plate counts during routine sampling. Experimental work has been undertaken to study the microbiological impact of a range of lubricants and oils on drinking water. The methods have been based on an existing procedure for the assessment of the growth potential of drinking water, i.e. the 'assimilable organic carbon'test. The results of this work could serve as the basis of a future standard method for the rapid and inexpensive screening of oils and lubricants for their microbiological suitability in potable-water applications.     

Hydrodynamics of the double-wave structure of insect spermatozoa flagella

In addition to conventional planar and helical flagellar waves, insect sperm flagella have also been observed to display a double-wave structure characterized by the presence of two superimposed helical waves. In this paper, we present a hydrodynamic investigation of the locomotion of insect spermatozoa exhibiting the double-wave structure, idealized here as superhelical waves. Resolving the hydrodynamic interactions with a non-local slender body theory, we predict the swimming kinematics of these superhelical swimmers based on experimentally collected geometric and kinematic data. Our consideration provides insight into the relative contributions of the major and minor helical waves to swimming; namely, propulsion is owing primarily to the minor wave, with negligible contribution from the major wave. We also explore the dependence of the propulsion speed on geometric and kinematic parameters, revealing counterintuitive results, particularly for the case when the minor and major helical structures are of opposite chirality.     

微生物对酸性红B染料的脱色研究

研究了微生物的分离及在染料废水脱色中的应用．以细菌分离、驯化等方法从不同印染废水处理池中的活性污泥中筛选出对染料具有脱色作用的菌种，并对影响微生物生长的因素，如温度、菌种质量浓度、初始染料质量浓度以及pH值进行了研究．获得了微生物在染料脱色过程中所需的最佳条件．     

Polysaccharide exopolymer adhesives from periphytic marine bacteria

—Periphytic micro-organisms frequently adhere to marine surfaces via the synthesis of polysaccharide exopolymer. For one such polysaccharide adhesive viscous exopolymer (PAVE), synthesized by Alteromonas colwelliana LST, production and purification were optimized and properties characterized. Maximum PAVE yields and best adhesiveness were obtained from cells harvested during the late logarithmic phase of growth in rich brain-heart infusion medium. The polymer was optimally purified by isopropanol extraction. It retained bond strength in sea water, possibly because of integral L-dihydroxyphenylalanine (Dopa) residues, the hydroxyl groups of which can successfully compete with H-bonds from sea water. Based on a limited survey of carbohydrate polysaccharide exopolymers from related marine bacteria, it is proposed that these compounds are promising natural product adhesives and marine surface coatings.     

Control of activated sludge filamentous bulking—VI. Formulation of basic principles

Overgrowing of filamentous micro-organisms in activated sludge is affected by the following factors: (a) composition of treated waste water; (b) actual concentration of dissolved oxygen in an aeration tank; (c) actual concentration of soluble substrate under which micro-organisms grow; (d) technological parameters of the process (sludge loading and age). All these factors were analysed and discussed in the light of the formulated basic principles for control of filamentous bulking.     

Microbial aspects of health hazards from water based metal working fluids

Although known health hazards exist when microbial fouling and spoilage occurs in water systems, hay, cotton, grain and animal products, there is little good evidence that microbes are significant health factors in water based cutting fluids. Possible roles are as pathogens, as producers of toxins or as catalysts of chemical change. These possibilities are discussed and some evidence for a microbial involvement in health hazards is presented     

Effect of water hardness on the toxicity of cadmium to micro-organisms

A study was made of the effect of water hardness at different concentrations (viz. 0, 80, 120, 160, 240, 320, 400 and 480 mg l⁻¹ as CaCO₃) on the toxicity of cadmium metal (5 mg 1⁻¹) as sulphate to saprophytic and nitrifying bacteria, with respect to the rate constant (K) and ultimate biochemical oxygen demand (L) which were calculated from BOD data (15 days) using the Thomas Graphical Method. Glucose was used as a source of carbon for micro-organisms. It was observed that the toxicity of cadmium to micro-organisms (both saprophytic and nitrifying) decreased with increasing hardness and reached a maximum at 320 mg 1⁻¹ as CaCO₃ for nitrifying and 400 mg l⁻¹ as CaCO₃ for saprophytic bacteria. After these hardness levels, the ultimate BOD (L) and rate constant (K) showed a decrease. Nitrifying bacteria were found to be more sensitive to the metal as well as to its complexation with calcium or with other ions as they retained their normal activity at a lower hardness level as compared to saprophytic bacteria.     

Assessment of Microbial Populations in Activated Sludge Using an Organism Diversity Index

An organism diversity index for use with mixed liquor or wastewater samples was developed to assess the species richness and diversity of activated sludge. The index was used in several studies and was found to be fast and simple to perform using basic laboratory equipment. Two bench-scale and two pilot-scale studies found that the resulting 'organism diversity index'value was a good indicator of process performance and was not influenced by the total concentration of the mixed-liquor suspended solids but by their nature alone. The technique rapidly yielded pertinent information about the health of the sludge and could be used instead of genetic investigations to obtain population information quickly enough for wastewater-treatment plant process control.