[Treatment of sludge from purification stations with the purpose of ameliorating soils intended for agriculture: parasitic contamination and model development with a view to managing the sanitation risk].
Helminth eggs (Ascaris, Taenia...) present in urban sludge constitute a sanitary risk when used for the enrichment of agricultural soil. These eggs are very resistant in the environment and their survival could reach 6 months to one year in soils. To control the risks for the public health, we have to determine parameters leading to the eggs destruction in soils. Then the aim of the work is to study several conditions (humidity, temperature, texture,...) that could influence the survival of intestinal nematode eggs in various types of soil. Survival experiments were carried out in clayey soil, silty-loam soil and sandy soils with humidity levels corresponding to: field capacities, wilting point and variation between this 2 limit point (storage temperatures 4 degrees C, 19 degrees C and 30 degrees C). The result of this study has shown that the temperature conditioned for a great part the survival of the eggs in all types of soils with survival times superior at two year with a temperature of 4 degrees C. Between survivals at 20 degrees C and 30 degrees C, no difference has been observed. The humidity is the second parameter that condition the egg survival with a good viability preservation at the wilting point. This study also shows better survival in the conditions of deep soil with the protection of the egg from drying. With these data and with the simulation of continental temperate conditions, a contamination rate of 0.35% could be found on the surface soil after one year and a more important rate in the deep soil with 10.6%. The last step is the validation of this model and calculated values seem to be a good evaluation of the results found on fields. All these data must be take into account for the establishment of the regulation about the urban sludge reused for agricultural purpose.
Gaspard
P
P
Faculté de Pharmacie, laboratoire de parasitologie, centre collaborateur OMS, Nancy.
Ambolet
Y
Y
Schwartzbrod
J
J
D000383:Agriculture; D018570:Risk Assessment; D012499:Sanitation; D012987:Soil / Q000469:parasitology*; D014865:Waste Disposal, Fluid / Q000379:methods*
D012987:Soil
Valorisation des boues de stations d'épuration en vue de l'amélioration des sols destinés à l'agriculture: contamination parasitaire et modélisation en vue de la gestion du risque sanitaire.