Microbiological Stability of Post-fermentation Leachate

Wastewater is an environment very rich in a number of microorganisms, including many pathogens. The conducted research aimed to determine the microbiological quality of the post-fermentation leachates from municipal treatment plants and the parameters of their hygienization. Thermal treatment of liquid from mechanical dewatering of sewage sludge from sewage treatment plants results in complete hygienization, which leads to a fully sanitary-safe liquid fertilizer preparation. The preparation obtained does not contain pathogenic bacteria and intestinal parasite eggs. Compared to other natural fertilizers or waste fertilizing products, the use of a liquid form greatly facilitates its penetration into the soil, which does not pose a threat to the health and life of animals and people. Microbiological stability of leachate after hygienization was check and to indicate whether the hygienized leachate can be stored (e.g., in sales packages). The tests performed showed very rapid regrowth of the bacterial microflora of both raw and hygienized leachates. The number of microorganisms after 20 days of storing hygienized leachate at temperatures of 15 and 22℃ increases significantly. In the context of using such leachates as fertilizer, it is suggested to use them immediately after the hygienization process. No coliform bacteria were detected in the leachate stored for 20 days, but the total number of microorganisms increased so much that it may pose a sanitary threat.