Helminth eggs viability in sewage and biosolids sludge in Curitiba, Paraná, Brazil

RESUMO

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