Sanitary analysis of crude and composted activated sludge
Loc, N.T.; Obertyńska, E.
Acta Microbiologica Polonica 50(2): 149-154
2001
ISSN/ISBN: 0137-1320 PMID: 11720309 Document Number: 529364
This paper presents a sanitary analysis of crude and composted activated sewage sludge from the sewage treatment plants in Sawa near Zielona Gora, Poland from September to December 1999. The composts were made from crude active sludge collected during 16 August 1999 with the addition of sawdust in a proportion of 15% with respect to dry sludge matter, and left in film bags with a capacity of 10 litres. Composting was carried out at a temperature of 20 degrees C for 8 weeks. Sanitary analysis of the activated sludge showed that the total quantity of bacteria, fungi, pathogenic bacteria (Salmonella sp., Escherichia coli, Clostridium perfringens) and parasite ova was higher in the summer period compared to the spring period. The quantity of pathogenic bacteria and parasite eggs exceeded the permitted level in activated sludge designated for agricultural use. Analysis of the suitability of composts made from crude activated sludge showed that the quantity of pathogenic bacteria and parasite ova had been reduced, but was still higher than the permitted value for sewage sludge designated for agricultural use.