IRRIGATION WITH WASTE-WATER - PARASITOLOGICAL ANALYSIS OF SOIL

In third world countries, the agricultural use of treated wastewater r epresents an interesting solution. A recent report of W.H.O. shows the importance of strict parasitological criteria for such reuse. The aim of this paper is to study the conditions under which Ascaris eggs hav e been recovered from artificially contaminated soils (sandy, clay or loamy soil, mould garden). The eggs elution has been carried out from soil particles using various solutions (detergents, distilled water, f ormaldehyde, sodium hydroxide, sodium hypochlorite). The recovery perc entage analysis showed the superiority of the sodium hypochlorite solu tion titrating 10 chlorometric degrees, whatever the soil type. The eg gs concentration in the eluates has been carried out through the flota tion technique by testing various reagents with densities ranging from 1.16 to 1.44. The zinc sulphate solution at 50%, 55% and 66% prove to be flotation agents that are well adapted to this sampling type. By c arrying out the elution with a sodium hypochlorite solution titrating 10 chlorometric degrees and the concentration by flotation with a zinc sulphate solution at 55% the recovery percentages, which are independ ent of the parasitic load, vary from 66 to 78%.