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In einer biologischen Bodensanierungsanlage wurden einfache Maßnahmen getestet, um den Mineralölkohlenwasserstoffabbau in Böden zu beschleunigen und damit die Sanierungsdauer zu verkürzen. Diese Maßnahmen bestanden in der Zumischung von 10 Vol.% Kompost mit dem Ziel einer internen Erwärmung und der Isolierung der Bodenoberfläche mit Luftpolsterfolie bzw. Holzhäcksel, um die Wärmeverluste zu reduzieren. Die Isolierung der Bodenoberfläche führte im Vergleich zum nichtisolierten Boden zu einer dreifach höheren Abbaugeschwindigkeit der Kohlenwasserstoffe, wobei die zwei eingesetzten Isolationsmaterialien zu ähnlich guten Ergebnissen führten. Der Kompostzusatz zum Boden hatte dagegen einen viel geringeren Effekt auf den Schadstoffabbau, weil die vom Kompost ausgehende Bodenerwärmung (bis auf 30°C) auf Grund seines hohen Rottegrades von IV nur kurze Zeit anhielt. Durch eine Kombination beider Maßnahmen wurde das angestrebte Sanierungsziel LAGA Z 1.1 (< 300 mg/kg) schon nach 63 Tagen Behandlung erreicht, während der Boden im Referenzsegment nach 105 Tagen noch fast 1000 mg/kg Kohlenwasserstoffe enthielt. Ein Vergleich der Bodentemperaturen und Schadstoffabbauraten in den individuell behandelten Segmenten ergab, daß neben der Temperatur noch weitere Faktoren existieren, die den Schadstoffabbau im oberflächenisolierten Boden begünstigen.

Studies of microbial purification of a model waste water containing 4-nitrophenol were carried out in a continuously working aerobic solid-bed reactor. The main emphasis was on the dynamic behaviour of the system after a sudden change in cultivation conditions and on the steady-state performance of the reactor as a function of the pollution load. A change from ammonium-free to ammonium-containing medium hardly influenced the nitrophenol degradation. The reactor responded differently to an increase in pollutant load, which was brought about by increasing either the 4-nitrophenol content or the flow of the waste water. Up to a load of 270 mg l−1 h−1 the pollutant was stably and almost completely degraded. At a higher load, only a partial 4-nitrophenol degradation took place. A mathematical model was derived to describe the processes that occurred in the reactor. By segregation into two compartments – the aqueous phase and the biofilm – account was taken of the fact that the pollutant is carried into the biofilm by diffusion and is degraded there. The observed relations between the pollutant load, the pollutant concentration in the outlet of the reactor and the reactor performance agreed with the simulated process behaviour. As the model simulation showed, the incomplete pollutant degradation at a higher reactor load was caused by oxygen limitation.

Aquatic sediments in industrial regions are often polluted by heavy metals. When removed by dredging, the sediments become an environmental risk. Because of the high costs and the deficient sustainability of landfill disposal, we intend to develop a remediation process for cleaning heavy metal-contaminated sediments by solid-bed bioleaching. Unfortunately, freshly dredged sediments are often impermeable to water. Therefore, they have to be conditioned to improve their hydrodynamic properties and make them suitable for solid-bed leaching. The treatment basin of 5.9 m × 7.5 m of a pilot-scale plant for sediment conditioning was filled with 0.5 m freshly dredged sediment, which originated from a trap in the Weisse Elster River near Leipzig, Germany, and was contaminated with Zn, Cr, Pb, Cu, Ni, and Cd. The sediment was planted with the helophytes Phragmites australis, Phalaris arundinacea, and Agrostis stolonifera. The vegetation evaporated large amounts of water and transported oxygen into the sediment. During conditioning the anoxic, black, muddy-pasty sediment changed to the oxic state and turned into a grayish brown, crumbly, soil-like material. Furthermore, the sediment turned acidic, its buffer capacity decreased, and, because of pore and particle enlargements, it became easily permeable to water. The plants on the sediment incorporated heavy metals in their biomass, especially Zn, Ni, Cd, and Co, but not enough for sediment remediation by phytoextraction.

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The addition of various nitrogen sources, such as liquid hog manure and mineral medium, to pine wood accelerated the composting process in Dewar vessels, which was obvious from the increased decomposition temperature and the more intensive oxygen consumption and carbon dioxide production. During composting in Dewar vessels of artificially PAH-contaminated pine wood soaked with liquid manure, the PAH degradation was influenced by the inoculum used. The fastest PAH degradation was achieved by compost addition, but the most intensive carbon dioxide evolution was measured with hydrocarbon-polluted soil as an additive. After 61 days, the PAH content of the wood was reduced from each 1000 mg/kg to 26 mg/kg of phenanthrene and 83 mg/kg of pyrene. The relation between the microbial wood decay and PAH degradation shows that the detoxification at least of artificially PAH-polluted wood demands only a partial wood decay.A pilot scale percolator was applied to composting of artificially contaminated pine wood and really polluted waste wood. After 27 days of remediation, the portion of residual PAHs was higher in the case of the really polluted material. The slower degradation in the real waste wood may be explained by the lower bioavailability of pollutants in comparison with the artificially contaminated wood. In really polluted wood, the degradation rate of PAHs depended on their degree of condensation (the higher the number of aromatic rings the smaller the degradation rate was).

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