Wojciech Dąbrowski, Katarzyna Ignatowicz
Bialystok University of Technology, Poland
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In this work, there were shown the research results concerning anaerobic digestion in the mesophilic condition. There was done the assessment of content of chosen heavy metals and their fractions in dairy sewage sludge before and after diges-tion process. The research was conducted with the use of laboratory installation on the base of mixture of excessive and floatation sludge. The process parameters were adopted from the modernization project of dairy sewage treatment plant of Mlekovita cooperative in Wysokie Mazowieckie. The results showed that in case of agricultural use of sludge, the total amount of heavy metals in sludge after anaerobic digestion was sharply lower that the values demanded in regulation concerning municipal sewage sludge. The process of sludge digestion caused the increase of metals content in dry matter of sludge. Metals speciation was determined with the use of scheme in accordance with methodology worked by BRC, which meant indicating four fractions. In case of lead, copper and zinc, the researches of anaerobic digestion process of dairy sludge showed the little increase of immobile fraction. The decrease of metals fraction was observed in case of cadmium, nickel and the clearest – chromium.
heavy metals, fraction, sewage sludge treatment