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Za područje povijesne jezgre grada Zagreba, Blok 19, proračunat je sustav daljinskog grijanja i hlađenje s dizalicom topline. Implementacija dizalice topline u sustavima daljinskog grijanja i hlađenja jedan je od obećavajućih načina povećanja učinkovitosti sustava te postizanja Europskih klimatskih i energetskih ciljeva 2050. godine. U sklopu rada analizirana su dva slučaja: postojeće stanje Bloka 19 bez energetske obnove te slučaj energetske obnove Bloka 19. U prvom slučaju pokriva se potreba samo za grijanjem prostora i pripremu PTV. Odabrane su četiri dizalice topline s dvostupanjskom kompresijom nazivne snage 1500 kW. Temperaturni režim vode je 80/65 °C. U drugom slučaju pokriveno je grijanje i hlađenje prostora te priprema PTV. Odabrane su dvije dizalice topline s jednostupanjskom kompresijom nazivne snage 1400 kW. Temperaturni režim ogrjevne vode je 65/55 °C, a rashladne vode 7/13 °C. Na kraju je priložena ekonomska i ekološka analiza za pojedini sustav. Jednostavan period povrata investicije za prvi sustav je 6,6 godina. Za drugi slučaj povrat je nakon 11,2 godine kada bi se gledao samo sustav grijanja, a 19,5 godina za sustav grijanja i hlađenja prostora. For the area of the historic core of the city of Zagreb, Block 19, a district heating and cooling system with a heat pump has been calculated. The implementation of heat pumps in district heating and cooling systems is one of the promising ways to increase the efficiency of the system and to achieve the European climate and energy goals by 2050. In this paper, two cases were analysed: the current state of Block 19 without energy renovation and the case of energy renovation. In the first case, only the need for space heating and DHW were provided. Four two-stage compression heat pumps with a rated power of 1500 kW were selected. The water temperature supply is 80 °C and return is 65 °C. In the second case, space heating, cooling and DHW were provided. Two single-stage compression heat pumps with a rated power of 1400 kW were selected. Supply temperature of heating water is 65 °C and return is 55 °C. Supply temperature of cooling water is 7 °C and return is 13 °C. Finally, an economic and environmental analysis for each system is given. The simple payback period for the first system is 6.6 years. For the second the return is after 11.2 years when only the heating system would be considered and 19.5 years for the space heating and cooling system.

Koncentracije nitrata u podzemnim i površinskim vodama su u porastu, a uzrok te pojave je u velikoj mjeri zbog ljudskog djelovanja. Suvišna gnojidba tla, nekontrolirano ispuštanje otpadnih voda i kemikalija jedni su od glavnih izvora zagađenja voda nitratima. Visoki sadržaj nitrata u pitkoj vodi može uzrokovati razne probleme za ljudsko zdravlje i zbog toga će biti sve veća potreba za njihovim uklanjanjem iz voda za piće. U ovom radu će se objasniti i proračunati postrojenje za uklanjanje nitrata u bunarskoj vodi koje se temelji na tehnologiji ionske izmjene jer se ona smatra jednom od najučinkovitih postupaka. Nitrate concentrations in groundwater and surface water are constantly being increased, and the cause is largely due to human activity. Excessive soil fertilization, uncontrolled discharge of wastewater and chemicals are one of the main sources of nitrate pollution in water. The high content of nitrate in drinking water can cause various problems for human health and therefore the need for eliminating them in drinking water will increase. In this thesis it will be explained and calculated the plant for nitrate removal in drinking water based on ion exchange technology because it is considered to be one of the most effective processes.