Rapping systems for collecting surfaces in an electrostatic precipitator

Dust build-up on adjacent surfaces is often an unwanted effect in industrial processes handling pulverized materials. In the case of electrostatic precipitation, build-up of dust on the collecting surface is the purpose of the process. Removal of this build-up is sometimes difficult, but necessary to maintain the continuity of the process. Dry-process methods for dust removal include rapping by impact.It is the intent of this paper to provide information on the general subject of dust removal from plates, on rapping systems used in electrostatic precipitators, and on measurements and order of magnitude of rapping forces.Rapping acceleration test results obtained in the laboratory are expanded to cover full-scale collecting surface plates.Effects of plate design, plate height and length, method of support, rapping, hammer weight, and lift are analyzed.     

Biotransformation rates of the butoxyethyl ester of 2,4-D by bottom and surface aufwuchs

An experiment was conducted to investigate the variability in biotransformation rate coefficients of a xenobiotic, the butoxyethyl ester of 2,4- , in natural waters between aufwuchs grown on Teflon strips located on the bottom and at the water surface of a pond and a river. The colonized strips and the natural waters were transported to the laboratory where the biotransformation studies were done under controlled conditions. Statistical analyses applied to the first-order rate coefficients showed a significant difference between bottom and surface aufwuchs for the river only. For both pond and river, a significant difference was shown when the aufwuchs was suspended, however. The aufwuchs mat thickness was significantly different between bottom and surface for the pond but not for the river and the biomass as ash-free dry weight was significantly different for both water bodies. The variability of biomass and first-order rate coefficients was higher with the bottom colonized aufwuchs than with the surface colonized aufwuchs.     

Elektrofilterasche aus Müllverbrennungsanlagen

The combustion of municipal solid waste leads to emissions containing high contents of heavy metals and organic pollutants. These residues, mainly collected by the electrostatic precipitator, have either to be deposited in special waste dumps or treated before being disposed in ordinary landfills. For the treatment or partial recycling of these residues the composition and the related variation are of primary importance. In this context a national inquiry for analysis data about fly ash composition was started. The results of this study, completed by own analytical results are presented in this paper.     

Eine neue,von einer Spezies der Streptomyces-reticuli-Gruppe gebildete Antibiotikakombination

The Science of Nature -     

Uptake of 203Hg++ and 115 mCd++ by Chlamydomonas reinhardi under various conditions

The uptake of radioactively labeled mercury and cadmium ions by living and dead cells of Chlamydomonas reinhardi WT⁺ was measured at 25 °C under minimal and optimal conditions (dark/nitrogen or light/air, respectively). In each case, incorporation was completely independent of external energy. Living and dead cells incorporated almost the same amount of the added heavy metal ions; after about 4 to 8 hours, saturation was obtained. Furthermore, the distribution of mercury in the system of algea/culture medium/gas phase and the amount of mercury and cadmium adsorbed by cells were studied.     

Seasonal patterns of ascorbate in the needles of Scots Pine (Pinus sylvestris L.) trees: correlation analyses with atmospheric O3 and NO2 gas mixing ratios and meteorological parameters

In the present field study the role of ascorbate in scavenging the harmful atmospheric trace gases O3 and NO2 was examined. For this purpose ascorbate contents were determined in needles of adult Scots pine trees (Pinus sylvestris L.) during three consecutive years. Ascorbate contents were correlated with ambient tropospheric O3 and NO2 concentrations and with meteorological parameters. The results showed a strong correlation of atmospheric O3 but not of atmospheric NO2 concentrations with the apoplastic content of ascorbate during the seasonal course. Ascorbate contents in needle extracts did not correlate with ambient trace gas concentrations. In the apoplastic space, but not in needle extracts ascorbate contents correlate highly significantly with global radiation. From these results it is assumed that apoplastic ascorbate in Scots pine needles is adapted to the actual atmospheric O3 concentration to mediate immediate detoxification of O3, while the atmospheric O3 concentration itself is largely dependent on light intensity.