As the preliminary tests show, not all stocks are suitable for processing sewage sludge: chemical reaction, moisture content, microbiological properties, gas generation, pollution are all factors that have to be considered. Although the composition of sewage sludge is, as a rule, characteristic for a given community, it is considered a substance the quality of which varies over the time. This is again a fact that justifies the necessity of performing comparative analyses on the available redworm stocks. We test sample stocks from stocks available in Hungary and the neighbouring countries in parallel tests, under identical conditions. We establish the surviving capability and the fertility of the various populations by measurements. We place the offspring of the various sample stocks on media (experimental plants) corresponding to the various sewage sludge types, and perform additional tests to establish the degree of their adaptability.
At the end of the tests we shall have all the data at our disposal by the help of which the stock necessary for the planned biotechnological process can be selected.