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2 2002

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Removal of heavy metals from excessive activated sludge

Gąsiorek J. A.

Polish Journal of Chemical Technology

2002

Vol. 4, nr 3

8-12

This paper presents the laboratory scale anaerobic treatment results from an acidic autolysis of a waste activated sludge and from a desulfiirication process of this sludge, too. The sludge with high contents of the heavy metals used in the study was derived from the treatment plant at Cze_stochowa. The anaerobic first-stage treatment system includes an acid reactor or a fermentation reactor with the population of the sulfate reducing bacteria e.g. Desulfovibrio desulfuricans respectively. The second stage was carried out on the aerated reactor, which was used to heavy metals extraction during bioleaching of the sludge from the first stage with Thiobacillus ferrooxidans bacteria. The removal yield of the heavy metals are given after each stages of the sludge treatment. The organic sludge after second stage operation can be application within agriculture as its heavy metals content is very low. The liquid product on separation phosphates and the metal hydroxides as the carbon source can be used to enhance the nitrogen and phosphorus removal at the waste water treatment plants. These investigations are part of the recycling project called 1TP (integrated treatment plant) process depending on the integration of the desulfurication to waste water treatment with an activated sludge technology at a treatment plant.

The effect of waste phosphogypsum on the denitrification and desulfurication processes

Seifert K., Moska A., Domka F.

Physicochemical Problems of Mineral Processing

2002

Vol. 36

209-216

The effect of waste phosphogypsum obtained after phosphoric acid production from apatites and phosphorites, on the processes of denitrification and desulfurication taking place with the use of bacteria from the genera Bacillus and Desulfotomaculum, have been investigated. It has been shown that the phosphogypsum concentrations used in the experiments were can serve as a sulphate source for the Desulfotomaculum bacteria. The phosphogypsum is not toxic towards the bacteria. The phosphogypsum has also been found to play the role of an electron acceptor in the processes of oxidation of simple organic substrates in the processes of bioreduction of nitrates or sulphates. In the optimum conditions of desulfurication in a medium containing the phosphogypsum, organic substrate and Desulfotomaculum ruminis bacteria, the degree of conversion is close to 90%, and a decrease of TOC reaches about 50%.

Badano wpływ odpadowego fosfogipsu, powstającego podczas produkcji kwasu fosforowego z apatytów i fosforytów, na procesy denitryfikacji oraz dysymilacyjnej redukcji siarczanów, zachodzące z wykorzystaniem bakterii z rodzaju Bacillus oraz Desulfotomaculum. Wykazano, że w określonym zakresie stężeń testowany fosfogips nie działa toksycznie na proces namnażania bakterii i stanowi źródło siarczanów dla bakterii Desulfotomaculum. Ponadto stwierdzono, że może on pełnić rolę akceptora elektronów w procesach utleniania prostych substratów organicznych w procesie bioredukcji azotanów lub siarczanów. W optymalnych warunkach dysymilacyjnej redukcji siarczanów, zachodzącej w podłożu zawierającym fosfogips, substrat organiczny oraz bakterie Desulfotomaculum ruminis, stopień przemiany kształtuje się na poziomie 90%, a ubytek ChZT wynosi około 50%.