Klärschlammverbrennung in einer stationären Wirbelschicht mit integrierter Phosphor-Rückgewinnung

Currently, wet-chemical and thermochemical processes in particular are being discussed for the future obligatory recovery of phosphorus from sewage sludge. The coupling of phosphorus recovery with incineration in stationary fluidized bed incinerators, the dominant mono-incineration technology, offers potential advantages in terms of aftertreatment costs and economic efficiency. Tests have shown that by adjusting the incineration conditions and adding additives, an ash could be produced that corresponds to the fertilizer ordinance (DüMV) and can, therefore, potentially be used as phosphorus recyclate.     

Sauergasbasierte stoff- und energieautarke Trocknung von Klärschlamm und Gärresten

During the processing of biomass as well as during waste water treatment, residual materials with a high water content are produced. They must therefore be dried prior to thermal utilization. Classical drying processes often use fossil raw materials to generate the necessary energy. With sour gas-based drying based on carbon dioxide-air mixtures, an alternative is presented that considers CO₂ as a valuable raw material (second life) and uses it in the process for drying sewage sludge and fermentation residues. Especially in the drying of fermentation residues, significant differences in dry substance content (DS) were measured, which in individual cases amounted to up to 35 % DS with the same drying time. This is expressed, among other things, in a higher carbon content of 0.42 wt % (wf) in the dry material, accompanied by a heating and calorific value that is more than 1 MJ kg⁻¹ higher.     

Verfahren zur Eliminierung und Rückgewinnung von Phosphor aus Abwasser

Future challenges for the wastewater treatment will be the compliance with low discharge limits for phosphorus and the recovery of phosphorus from wastewater. Under favourable wastewater conditions and optimal process operation the conventional P‐elimination techniques can reliably and economically achieve phosphorus discharge values of approximately 0.5 mg L^–1 P_total. Lower phosphorus discharge values are reached by optimization of available or implementation of advanced P‐elimination technologies. The possibilities for the phosphorus recovery are indicated on the basis of several processes. The present P‐elimination technology influences strongly the choice of the P‐recovery technique and the P‐recovery degree. On the other hand, the P‐recovery techniques can influence the operation of the wastewater treatment plant.     

Jahreszeitliche Schwankungen in der Zusammensetzung von Klärschlamm bei der Betrachtung eines Klärwerks

By evaluating sewage sludge analysis data from a large German sewage treatment plant (>1 million population equivalents), seasonal fluctuations in the composition of the sewage sludge could be identified. These fluctuations include a periodic decrease in carbon content and an increase in ash content in the middle of the year. Various wastewater and sludge treatment processes as well as climatic influences could be identified as causes for this trend. The investigation of the contents of various heavy metals and trace elements in the sewage sludge also showed partly strong fluctuations in the course of the year, which can have an influence on the utilization possibilities of the sewage sludge.