Quecksilbergasfeinreinigung mittels metall- und salzpartikelbelegter Trägermaterialien (G/S-Reaktor) Ökotoxizität von Quecksilber und seiner Verbindungen

Waste and process gases from thermal power and metallurgical plants or such products from alkali-chloride industries contain metallic, inorganic and organic mercury. Widespread processes applied to remove the greatest amount of mercury are absorption and adsorption. Caused by the lowering of the emission limit from 200 to 50 μg/m³ [STP] by national and European legislators, considerable efforts have been made to enhance the efficiency of the main separation units of flue gas cleaning plants by applying the appropriate technological measures. This article is focused on the removal of mercury from waste gases. The state of engineering is described, especially with regard to enhancing the efficiency of separation in the raw gas, in wet, dry and quasi-dry processes as well as in tail-end process units. Specially impregnated ceramic carriers can be used for the selective separation of metallic, inorganic and organic mercury. Amalgamation has been investigated as a possible separation mechanism both experimentally and in theory. Using the ceramic reactor, removal rates for gaseous mercury and its compounds can be achieved which are even lower than 50 μg/m³ [STP]. The technology, the separation mechanisms and the ecological advantages through the use of ceramic reactors are presented in the article as well.     

A field study of triclosan loss rates in river water (Cibolo Creek, TX)

Triclosan (TCS) is an anti-microbial agent used in down-the-drain consumer products. Following sewage treatment some of the triclosan will enter receiving waters. This study was designed to determine the die-away rate of triclosan released into a river as part of the sewage treatment plant effluent matrix. The study was conducted in Cibolo Creek, a moderate sized stream (discharge approximately 0.1 m(3)s(-1)) located in South Central Texas. Triclosan was analyzed from samples collected upstream of the sewage treatment plant, the sewage treatment plant effluent, and the river downstream from the effluent discharge. The first-order loss rate of parent triclosan from the water column was calculated from measured data (0.06 h(-1)) and this rate corresponded to a 76% reduction in triclosan over an 8 km river reach below the discharge. Mathematical modeling indicated that sorption and settling accounted for approximately 19% of total triclosan loss over 8 km. When removing sorption and settling, the remaining amount of triclosan had an estimated first-order loss rate of 0.25 h(-1). This loss rate was presumably due to other processes such as biodegradation and photolysis. These data show that loss of parent triclosan from the water column is rapid. Additional data are needed to fully document loss mechanisms.     

Quecksilbergasfeinreinigung mittels metall- und salzpartikelbelegter Tr?germaterialien (G/S-Reaktor) ?kotoxizit?t von Quecksilber und seiner Verbindungen

Zusammenfassung  Bei einer genauen Kenntnis der vorliegenden Quecksilberverbindungen und ihrem Verhalten im Rauchgaspfad thermischer Anlagen k?nnen durch entsprechende technische Ma?nahmen die Abscheideeffizienzen in trockenen, quasitrockenen und nassen Rauchgasreinigungsanlagen erheblich gesteigert werden, so da? der derzeit gesetzlich vorgeschriebene Emissionsgrenzwert von 50 μg/m³ [i.N.tr.] eingehalten und unterschritten wird. Die in den letzten Jahren unternommenen Aktivit?ten und Fortschritte bei der Reduzierung des Quecksilberaussto?es von thermischen Anlagen werden zusammenfassend dargestellt. Am Beispiel von tr?gerimmobilisierten metall- und/oder metallsalzpartikelbelegten Tr?germaterialien (G/S-Reaktoren) wird die selektive Entfernung des Quecksilbers bzw. dessen Verbindungen experimentell und theoretisch im Rauchgaspfad verdeutlicht. Aus der selektiven Abtrennung von Quecksilber und seinen Verbindungen in der Gasphase resultieren auch entsprechende ?kologische und ?konomische Vorteile, die den allgemein erkennbaren Trend der artspezifischen Abtrennung von Schadstoffen mit einer m?glichen Rückführung des Wertstoffes Quecksilber in den Wirtschaftskreislauf unterstützen.