Spontaneous imbibition of liquids in glass‐fiber wicks. Part I: Usefulness of a sharp‐front approach

Spontaneous imbibition of a liquid into glass‐fiber wicks is modeled using the single‐phase Darcy's law after assuming a sharp flow‐front marked by full saturation behind the front occurring in a transversely isotropic porous medium. An analytical expression for the height of the wicking flow‐front as a function of time is tested through comprehensive experiments involving using eight different wicks and one oil as the wicking liquid. A good fit with experimental data is obtained without using any fitting parameter. The contact‐angle is observed to be important for the success of the model—lower contact angle cases marked by higher capillary pressures were predicted the best. The proposed model provides a nice upper bound for all the wicks, thereby establishing its potential as a good tool to predict liquid absorption in glass‐fiber wicks. However, the sharp‐front model is unable to explain region of partial saturation, thereby necessitating the development of part II of this article series (Zarandi and Pillai, Spontaneous Imbibition of Liquid in Glass fiber wicks. Part II: Validation of a Diffuse‐Front Model. AIChE J, 64: 306–315, 2018) using Richard's equation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 294–305, 2018     

Contingent Valuation of First-Time Sewerage Provision in South-East England

Section 101A of the Water Industry Act 1991 requires that sewerage undertakers provide a public sewer to replace private wastewater systems if certain conditions are met. These include identification of pollution and amenity problems attributable to the private systems and economic justification of public sewer provision. Economic justification necessitates that the costs and the benefits of public sewer provision are compared. An environmental valuation study, using the contingent valuation method, has been carried out in three locations in south-east England to provide the average monetary value of the benefits accruing to households with unsatisfactory private systems. A statistical analysis of the survey-response data has yielded a monetary value which can be used in the assessment of the benefits of first-time public sewerage schemes.     

Studies on the dipping characteristics of RVNRL and NR latex compounds

The dipping characteristics of radiation-vulcanized natural rubber latex and natural rubber latex compounds were investigated with a lab-model semiautomatic dipping machine. The effect of the variation of the speed of immersion and withdrawal, dwell time, compound viscosity, and concentration of coagulant on the thickness of the latex deposit was investigated. The results of the study show that the deposit thickness depends on the withdrawal speed of the former, the concentration of the coagulant, dwell times, and the viscosity of the latex compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3141–3148, 2001     

Studies on promising cell performance with H2SO4 as the catholyte for electrogeneration of Ag2+ from Ag+ in HNO3 anolyte in mediated electrochemical oxidation process

Electrochemical performance of a divided cell with electrogeneration of Ag²⁺ from Ag⁺ in 6 M HNO₃ anolyte has been studied with 6 M HNO₃ or 3 M H₂SO₄ as the catholyte. This work arose because in mediated electrochemical oxidation (MEO) processes with Ag(II)/Ag(I) redox mediator, HNO₃ is generally used as catholyte, which, however, produces NO _x gases in the cathode compartment. The performance of the cell with 6 M HNO₃ or 3 M H₂SO₄ as the catholyte has been compared in terms of (i) the acid concentration in the cathode compartment, (ii) the Ag⁺ to Ag²⁺ conversion efficiency in the anolyte, (iii) the migration of Ag⁺ from anolyte to catholyte across the membrane separator, and (iv) the cell voltage. Studies with various concentrations of H₂SO₄ catholyte have been carried-out, and the cathode surfaces have been analyzed by SEM and EDXA; similarly, the precipitated material collected in the cathode compartment at higher H₂SO₄ concentrations has been analyzed by XRD to understand the underlying processes. The various beneficial effects in using H₂SO₄ as catholyte have been presented. A simple cathode surface renewal method relatively free from Ag deposit has been suggested.     

Gasification As An Innovative Method of Sewage-Sludge Disposal

There is a significant amount of energy in the carbonaceous component of sewage sludge. Effective use can be made of this energy through conversion to the gaseous state followed by gas cleaning and subsequent firing of a gas turbine.
This paper (a) compares the technology for the gasification of dried sewage sludge, noting the advantages in favour of fuelling a gas turbine, (b) reviews the significance of the individual components in sewage sludge, and (c) provides a brief introduction to a demonstration project which was embarked upon by Northumbrian Water in conjunction with Lurgi, with the financial support of an ECU Thermie Grant.     

Agriculture: Sustainable Business – Sustainable Environment?

Irrigation is a small but important part of UK agriculture, accounting for about 150 000 ha of land and 160 000 Ml of water in a 'dry'year. By the year 2021, the irrigated area is predicted to increase by 14% and the volume applied by 50%. Irrigation is of significant economic importance to (a) farmers, (b) growers, (c) the food industry – improving crop yields, quality, consistency and reliability.
The environmental impacts of irrigation on river flows and wetland biodiversity are now receiving more attention. Irrigators are given advice on environmental impacts, voluntary agreements are secured between groups of irrigators and the Environment Agency, and on-farm reservoirs are constructed to reduce summer abstraction and provide more secure and flexible supplies. Better long-term planning and short-term management are essential.     

A 'Standard Industrial Classification'Coded Strategic Planning Model of Industrial and Commercial Water Demand for UK Regions

Knowledge of future demand is essential for promoting sustainability in water resources, informing decisions over the allocation of water between people and the environment. Improved econometric models of non-household water demand are presented, which have been developed for the Yorkshire Water region, providing annual demand forecasts to the year 2010 disaggregated with reference to the Standard Industrial Classification. Increases of 0.44–1.0% per annum are forecast, mainly driven by service sector demand. Water companies and regulators cannot influence economic activity, but have the ability to manage demand using price controls. Waste minimisation also offers the potential to offset forecast increases, if widely adopted. Current application of price controls act to increase demand, counter to the goal of environmental sustainability; therefore it is concluded that, within the UK water industry, competition should be focused on levels of service and environmental-impact measures, rather than on price.     

Flood Forecasting and Warning on the River Rhine

The River Rhine has its source in the glaciers of the Swiss mountains and eventually flows to the flat-lands of The Netherlands. The course of the river can be split into six major morphological sections within different climatological regions. This heterogeneity (in the hydrological sense) is reflected in twenty-five flood-warning centres along the Rhine and its tributaries. There is one flood-warning centre in Switzerland, one in France, three in Germany and one in The Netherlands. This paper describes the organisation and responsibilities of the German flood-warning centres.
The Federal Institute of Hydrology provides the German centres at Mainz and Duisburg with forecast results. These results were obtained by a statistical multichannel filtering model between 1980 and 1997. Commencing in 1998, a new forecasting system has been in use, which is built up by hydrodynamic models for the most important river reaches, coupled with statistical approaches for some input gauges. The implementation and data usage of this new system is discussed and forecast results for the 1993, 1995 and the 1998 floods are presented. Finally, the paper provides an outlook on the linking with precipitation-runoff models.     

The Role of Coal Recovery in the Reclamation of the Merthyr Vale Colliery Site, South Wales, UK

This paper describes the reclamation of the Merthyr Vale colliery site and shows that the incorporation of coal recovery produced economic, as well as environmental, benefits. The optimum plant throughput for a 2.1 m dia. barrel washer was 120 t/h at an operating density of 1200 kg/m³. Coal and discard qualities were acceptable, and the final landform was suitable for development with few restrictions.     

Potential Endocrine Disrupting Substances from Materials in Contact with Drinking Water

At present, there is much interest in the potential effects of chemicals on the endocrine systems in animals and man. Chemicals with endocrine-disrupting potential include (a) various phthalates, (b) compounds based on bisphenol A and F, (c) compounds based on alkyl phenols, and (d) the antioxidant butylated hydroxyanisole. However, the potency of these chemicals in comparison with natural hormones appears to be very low. Although there is some evidence for activity in animals, high doses are usually necessary, and there is controversy and uncertainty in the interpretation of some positive findings. In addition to consideration of potential hazards, the level of exposure through leaching of these chemicals into drinking water is an important component of risk assessment. The present approval processes ensure that such exposure is very low. The paper suggests a strategy for the future continued assurance of an adequate safety margin for human exposure to such substances through drinking water.