RESUMO
This study evaluates the prevalence and viability of helminth eggs and protozoan cysts in sludge obtained by anaerobic treatment in four treatment stations in Curitiba, Parana State, Brazil. The parasites observed were helminths: Ascaris sp (85%), Toxocara sp (5.5%), Trichuris sp (4.5%), Hymenolepis diminuta (3.7%), H. nana (1%) and Taenia sp (0.4%), protozoan: Isospora sp, Entamoeba coli, Entamoeba histolytica, Giardia lamblia, Endolimax nana. In biological treatment based on the anaerobic digestion the effectiveness depends on the duration and temperature. The treatment showed efficiency for pathogen reduction of between 59.7 to 93%. However, the number of helminth eggs found in treatment stations was still high and new higher performance treatment is necessary for land application or for other objectives, seeking to reduce the risks for human and animal health.
Assuntos
Helmintos/crescimento & desenvolvimento , Contagem de Ovos de Parasitas , Esgotos/parasitologia , Anaerobiose , Animais , Técnicas de Laboratório Clínico/métodosRESUMO
Despite some benefits, municipal sludge poses hazards to human-kind and domestic animals because of the presence of some pathogenic agents in it. Bacteria, viruses, protozoan cysts, and helminth eggs may be present in the sludge. In Paraná State, SANEPAR, the responsible agency for collection and treatment of sewage sludge, is attempting to use the biosolids in agriculture. However, the risk to human and animal infection by the pathogenics should be considered before its use. An attempt was made to study the occurrence, viability and survival of helminth eggs and larva and protozoan cysts in the sludge. Parasitological analyses of twelve sludge biosolids and ten sewage sludge samples were collected and analyzed, from the treatment station ETE Belem (Curitiba, Brazil) for a period of one year. Four of the ten sewage sludge samples examined revealed the presence of helminth eggs as high as up to 20 eggs/l. In the biosolids sludge, the average number of helminth eggs, per 1 g of dry matter, was 4.85. However, the aerobic treatment reduced the viability of helminth egg to 56.67 per cent, and the total number of viable eggs was 1.85/g of dry matter. Ascaris sp. was the prevalent parasite (75.7 per cent), followed by H. diminuta (0.93 per cent), Trichuris sp. (7.4 per cent), Hymenolepis nana (3.6 per cent), Toxocara sp. (2.7 per cent), and Taenia sp. (1.3 per cent). Thus treatments will be necessary to hygienize the sludge for use in agriculture