The storage of sewage sludge: influence of liming on the evolution of copper chemical fractions

Sewage sludge re-used in agriculture has to be stabilized and is often stored for several months before land spreading. Stabilization treatment may affect the behaviour of heavy metals such as Cu, which is an element potentially toxic to the environment. In the present study, the chemical forms of copper have been investigated in heaps of limed and unlimed sludge coming from the wastewater treatment plant of Roselies (Belgium). These limed and unlimed aerobically digested sludges were stored during 4 mo in controlled conditions close to field ones. The sequential extraction procedure developed by Tessier was used to determine the copper chemical forms of representative samples taken in the outer shell and in the depth of the heaps. The physico-chemical properties (pH, organic matter, dry matter and temperature) of these samples were also monitored. This study shows that liming transforms part of organically-bound copper into both exchangeable and residual copper. These changes mainly occur during the first 2 wk of storage. After several months of storage, copper passes from the residual fraction to the exchangeable and oxide fractions. During the whole experiment, changes occur faster in the outer shell than in the depth of the heaps. Thus, we demonstrate that the distribution of the copper forms depends on the storage time and it is different in the outer shell from that in the depth of the heaps.     

Survey of patterns,levels, and trends of perfluorinated compounds in aquatic organisms and bird eggs from representative German ecosystems

Purpose  

Samples from the German Environmental Specimen Bank (ESB) covering particularly the years 1994–1996, 2000–2002, and 2006–2009 were analyzed for perfluorinated compounds (PFC; mainly C4–C13 carboxylic and sulfonic acids) to gain an overview on current PFC levels and patterns in marine, limnetic, and terrestrial biota; to assess their concentrations in different trophic levels; and to investigate whether risk management measures for PFC are successful.     

Stackless Power Plant

When the 230-MW Volklingen power plant entered service in August 1982, it became the first power plant in Europe to desulfurize 100 percent of the flue gas without bypass. The FGD system forms an integral part of the cooling tower, and the flue gas is discharged through the tower. There is no stack. Mathematical models for the dispersal of the mixed emissions from the cooling tower have now been confirmed by readings of ground level concentrations. The dispersion pattern was recorded as part of exhaustive emission readings, which included measurements from powered gliders. It was shown that the dispersal of the desulfurized flue gas encounters more favorable atmospheric conditions than would be the case if it were discharged separately from a stack. One major element is the thermal thrust of the exhaust from the cooling tower. This approach to flue gas discharge reduces costs considerably, eliminating the need for reheating the gases to the 72° C required in West Germany for conventional FGD systems discharging through a stack.