Characterisation and biological treatment of greywater.

Characterisation of greywater was conducted in two different greywater streams in the Netherlands (Groningen and Sneek). The concentrations of macropollutants and nutrients measured were very different in both streams; in particular the COD was 425 mg/L in Groningen's water whereas in Sneek it was 1,583 mg/L. The aerobic treatment of greywater in a fed-batch reactor led to a 90% removal of COD at different organic loading rates. Anaerobically, the removal reached 40% COD removal on average, the possible reason being the high amount of surfactants present in the influent.     

Thermal interactions between water and rock in an underground hot-water store

Storing solar or surplus heat in enormous unlined rock caverns has attracted considerable interest in Sweden. A comprehensive research programme on this subject has been running since 1982 in the city of Avesta, where a district-heating system has been completed with a hot water accumlator blasted in the rock. In the present paper it is shown that, if the cavity is assumed to be spherical, the complete mathematical formulation of the dynamic interaction between the temperatures of the stored water, of the rock mass and of the supply power can be solved. The results yield expressions for the rate of change of temperature, for time constants expressed in terms of the thermal properties of the rock and the water and linear dimensions of the cavity. For a relatively small store, like the one in Avesta (15 000 m³), the time for spontaneous cooling is extremely long (> 10 years). For big commercial stores it is even longer.     

Equilibrium distribution of water in the two-phase system supercritical carbon dioxide–textile

When natural fibres are dyed in supercritical carbon dioxide, the addition of a small amount of water increases coloration. For a process design it is important to know how much water has to be added to obtain a desired humidity of both textile and carbon dioxide. In this work a thermodynamic model is proposed to calculate the distribution of water over the textile phase and the supercritical phase as a function of pressure and temperature. The phase equilibrium is described with Raoult's law for non-ideal fluids. The absorbed water in the textile is a condensed phase and is modelled here as a non-ideal liquid, using the NRTL-equation. The non-ideality of the supercritical phase is described by a solubility enhancement factor, a new equation derived from statistical thermodynamics. Although the model is applied to cotton, viscose, silk and wool, it can be used for all water absorbing textiles.     

Countercurrent water-heating system with a heat exchanger in a solar energy collector loop

The counter current heat exchanger theory with periodic inlet temperatures has been applied to analyze the thermal performance of a water heating system. The theoretical results obtained are in agreement with the experimental data reported in the literature.     

Preserving poultry feeds in the humid tropics: A trial of calcium propionate under feed mill conditions

Calcium propionate was incorporated into a complete poultry feed and a feed concentrate at levels of 0, 0.3, 0.4 and 0.6%. The feeds were stored in 25 kg woven sacks in a feed mill. Air temperatures ranged from 22 to 34°C and relative humidity was in the range 67 to 93%. Mould growth was measured microbiologically and by measurement of feed temperature. Calcium propionate had a large effect on the microbiological measurements but only a small effect on heating in the feeds. As a preservative, it retained its activity for 6 weeks which extended the storage life by only 1 week in this case. The relative merits of the microbiological and temperature measurements are discussed.     

Einfluß der Trennverfahren auf das Ermüdungsverhalten von Stahlblechen

Influence of Cutting Method on the Fatigue Behaviour of Steel Sheets The present paper gives the fatigue behaviour of test specimens which have been obtained by laser cutting, plasma cutting or punching from steel sheets. The paper demonstrates the different damage to the surface introduced by the three techniques. For thin sheets (1.5 mm) laser cut specimens show advantages, for thicker sheets (6 mm) plasma cut sheets exhibit better fatigue properties.     

Detection and quantitation of aflatoxin B1 in orange juice by SOS-Chromotest

A new method for the detection and quantitation of aflatoxin B1 in liquids is described. The method is based on the SOS Chromotest, in which damage caused by aflatoxin B1 to the DNA of suitably engineered E. coli induces beta-galactosidase. Aflatoxin B1 developing in orange juice inoculated with spores of Aspergillus parasiticus is detectable equally well by TLC as by the SOS-Chromotest.