ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN

A review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready-to-eat crops.     

An experimental determination of combustibility

The author describes a laboratory method for determining ignitability, rate of heat release, and total heat release as a measure of the combustibility of materials. The results may be applied to building design and designation of contents with an eye towards reducing the possibility of a major fire. Note: Professor Smith is Director of Chemical Engineering Research, Engineering Experiment Station, The Ohio State University, Columbus, Ohio.     

Selective removal of gallium (III) from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate

Gallium was removed selectively from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate as a ligand (NaL). At low pH or low mole ratios, the gallium was removed by complexation with the ligand as GaL(3(S)), while the zinc or the aluminum remained in the solution. Nearly complete separation of gallium was obtained. By increasing the amount of ligand or by increasing the pH, the zinc or aluminum remaining in the solution was then removed as a solid complex: ZnL(2(S)) or AlL(3(S)), respectively. At a pH between 1.5 and 2 and a mole ratio ligand to total metals of 0.75 for zinc solutions and 1.0 for aluminum solutions, more than 98% of the gallium was selectively removed with a high molar selectivity, alpha(Ga/Zn) and alpha(Ga/Al), respectively. Over 95% of gallium was recovered from the solid GaL(3(S)) complex by treatment of the complex with a 3M NaOH solution and diethyl ether. The gallium was concentrated in the aqueous solution to 4 times its initial concentration and the ligand was extracted into the ether phase. After evaporation of the ether, 95% of the ligand was regenerated in its sodium form as a solid.     

Detection of enteric viruses, Giardia and Cryptosporidium in two different types of drinking water treatment facilities

In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity. Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants. Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size). Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR. Giardia and Cryptosporidium were detected by conventional staining methods and PCR. The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs. The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake. Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced. Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L. Virus count was reduced in sand of filters after washing. Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%). Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%). At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing. Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium. It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).     

Spatial competition and regulatory change in the grain handling and transportation system in western Canada

The grain handling and transportation system (GHTS) has been a defining component of the western Canadian economy since the early part of the last century. Only two major railways serve the grain handling industry, so the potential for the exercise of market power in transportation appears to be significant. In fact, spatially oriented regulations applicable to railways exist in Canada to mitigate this, but to date they have not often been used by shippers. While the reasons for this are not completely clear, we suggest that the regulations are now inadequate for the current state of the GHTS. Using a unique data set from the year 2000, we assess the effect on the grain handling industry of modifications to these regulations, and find that significant gains for shippers from these modifications are possible. These gains are computed to be on the order of C$10–15 million per year for grain shippers alone. We would like to thank conference and presentation participants (Transportation Research Board, Canadian Agricultural Economics Society, University of British Columbia, University of Leeds and California State University, Long Beach) as well as the anonymous reviewers who commented on the earlier versions of this paper. We would also like to acknowledge support from the Saskatchewan Department of Highways.     

社区环境管理取得成果的要素:美国酸性矿物废水治理的经验教训

1980年代,社区环境管理(CBEM:community-based environmental management)作为处理棘手环境问题的创新途径在美国开始出现.CBEM指的是地方团体采用与各类代理机构、地方政府或其他组织以合作方式处理环境问题.为更好地理解这一流行的环境管理手段,本文首先回顾环境管理制度的演变以及影响CBEM过程的资源变化,在此基础上,本文建构了关于CBEM过程的评估框架,并列举了两个通过发起CBEM来治理酸性矿物废水对流域污染的案例.     

Synthesis of ettringite: a way to deal with the acid wastewaters of aluminium anodising industry

Synthesis of ettringite from acid wastewaters of the aluminium anodising industry has been studied as a possible route of reducing the emissions to the environment, recovering at the same time resource materials as a useful marketable mineral. Wastewaters of different concentrations have been subjected to the process of synthesis suspending calcium oxide and calcium aluminate powders at different time and pH conditions. High caustic alkalinity (pH approximately 12) and low sulphate concentrations (<0.1 M) are the most suitable conditions to synthesise ettringite. The mineral characterisation has been performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA), proving the high purity of the pursued solid product when hydrated in the appropriate sodium hydroxide concentrations. In such conditions, around 90% of the aluminium initially present in the wastewater solutions is recovered in the form of ettringite.     

Finite element modelling of plate girders with web openings

This paper is concerned with a finite element model to predict the behaviour and ultimate load of plate girders with web openings. The finite element package is used to model the plate girders with web openings. Accuracy of the model is assessed by applying it to plate girders tested earlier by other researchers. Comparison of analytical results with the available experimental results for yielding patterns, ultimate load values and load–deflection relationships show good agreement between the finite element and experimental results thus validating the accuracy of the proposed model. The proposed finite element method was extended to carry out a parametric study. The study covered parameters such as web slenderness and flange stiffness.     

Observations on the changes in nitrate concentrations along streams in seven upland moorland catchments in Northeast Scotland

River water has been sampled under baseflow conditions in both summer and winter at c. 250-m intervals along the length of each of seven rivers in northeast Scotland, and the nitrate contents have been determined. The resultant data have been examined in the context of the nitrogen saturation hypothesis. Capacity of the catchment soils to retain nitrate was generally minimal in winter. Although biological uptake of nitrate was evident in summer, in the upper part of each catchment substantial nitrate leaching still occurred. The phenomenon was most marked in water draining from hill peats, except where these were conspicuously waterlogged. The results are discussed in the context of possible nitrogen saturation effects on upper catchment slopes.