Dehidrirani mulj iz postrojenja za prečišćavanje gradskih otpadnih voda kao biočvrsto đubrivo (Dehydrated sludge from communal wastewater treatment plant as biosolid fertilizer)

Bosnia and Herzegovina is one of the few countries that disposes the entire amount of sludge generated in the communal wastewater treatment process at a communal waste landfill as it is categorized as non-hazardous waste. The treatment of sludge with WWTP and the possibility of its application in agriculture or for similar purposes such as: floriculture, forestry, pastures, rehabilitation of damaged parts of the land, all in accordance with the principles of sustainable development, is gaining more and more importance nowadays. Considering the above, we believe that dehydrated sludge from the communal wastewater treatment plant in Srebrenik has significant potential as a biosolid fertilizer. The paper presents the results of chemical and microbiological research aimed at defining the properties of this sludge and the possibility of its application in agriculture as a biosolid fertilizer. The research was carried out in two steps: the first one - defining chemical and microbiological properties of the sludge and the second one - "in situ" tests in an isolated greenhouse on seedlings of ornamental plant, marigold, (lat. Tagetes) and peppers (lat. Capsicum) in order to assess the effect of plant crop development in different mixtures of soil samples and dehydrated sludge. The research determined that the chemical and microbiological composition of the sludge has the potential for its application as a biosolid fertilizer in horticulture for growing flowers and ornamental plants. The use of dehydrated sludge in horticulture would reduce the amount and costs of disposing of dehydrated sludge in communal solid waste landfills while enriching the substrate for growing flower and ornamental plant crops at the same time. Keywords: Communal wastewater treatment plant, dehydrated sludge, biosolid fertilizer