U ovom radu opisana je niskotemperaturna sušara za sušenje mulja nastalog u postupcima pročišćavanja otpadnih voda. Mulj je nusproizvod koji nastaje pri tim postupcima, a problem stvara njegovo zbrinjavanje. U prvom dijelu rada opisani su postupci pročišćavanja kojima se podvrgava otpadna voda. Postupci su podijeljeni prema stupnju kakvoće vode koja se želi postići. Razlikuje se primarno, sekundarno i tercijarno pročišćavanje otpadne vode. Zatim je opisana niskotemperaturna sušara koja radi na principu odvlaživanja zraka preko modificirane toplinske pumpe. Opisan je način rada sušare uz prikazane sheme. Navedeni su dijelovi sušare i podjela prema tipu sušare. Karakteristike sušare su prikazane u tablicama i dodatno pojašnjene. U radu su zatim opisane toplinske pumpe i toplinska pumpa koja se nalazi u niskotemperaturnoj sušari. Navedeni su dijelovi toplinske pumpe niskotemperaturne sušare i cirkulacija freona unutar nje. Na kraju rada dan je uvid u zakonsku regulativu koja se odnosi na postupke zbrinjavanja mulja i plan gospodarenja otpadnim muljem u Republici Hrvatskoj. Prema navedenim i prikazanim podacima izveden je zaključak o procesima i načinu zbrinjavanja mulja.

This paper describes a low temperature dryer for drying sludge arising in waste water treatment processes. Sludge is a byproduct resulting from these processes, and the problem generates its disposal. The first part of the paper describes the purification processes that waste water is subject to. The processes are divided according to the degree of water quality that needs to be achieved. Primary, secondary and tertiary waste water purification is distinguish. Then a low temperature dryer is described which operates on the principle of air dehumidification through modified heat pump. The operating mode of the dryer is described along with the shown shemas. Parts of the dryer are listed and the difference according to the type of dryer. The characteristics of the dryer are shown in the tables and are further clarified. The paper after that describes heat pumps and a heat pump in a low temperature dryer. Parts of low temperature dryer heat pump are listed and a circulation of refrigerant inside it. At the end of the paper an overview of the legal regulation concerning the processes for sludge disposal and the waste sludge management plan in the Republic of Croatia is presented. According to the listed and shown data a conclusion has been made about the processes and disposal manner of the sludge.