Tehnološka primjena sunčeva zračenja za razgradnju organskih tvari površinskih voda

Tema ovog rada je utvrđivanje mogućnosti primjene relativno nove skupine procesa u tehnologiji obrade voda – Unaprijeđenih Oksidacijskih Procesa (UOP), koji koriste ultraljubičasto zračenje kao izvor energije, za odvijanje procesa degradacije prirodnih organskih tvari (POT) u površinskoj vodi. Kako bi se postupak degradacije što više približio ekološkim načelima, pokušalo se kao izvor ultraljubičastog zračenja iskoristiti dio Sunčeva zračenja, koji iznosi svega 3-5% od njegovog ukupnog zračenja na površinu Zemlje, ali ipak predstavlja znatan potencijal za primjenu u praksi. Samo Sunčevo zračenje nema dovoljnu energiju za pokretanje reakcije degradacije POT-a, ali se u kombinaciji s heterogenim fotokatalizatorom titan(IV) oksidom (TiO2) degradacija započinje odvijati. U sklopu eksperimentalnog dijela rada proveden je niz pokusa s uzorcima jezerske vode izloženim Sunčevu zračenju i utvrđivanje kinetike fotodegradacije POT-a za različite kombinacije doza (od 0,05 g/L do 1,5 g/L) i kristalnih oblika TiO2 (anatas i rutil) s različitim dozama vodikovog peroksida (6-54 mg/L). Isto tako, provedena su mjerenja u sustavu zaklonjenom od Sunčeva zračenja kako bi se utvrdila razlika djelovanja TiO2 na POT sa i bez Sunčeva zračenja te stupanj adsorpcije POT-a na čestice TiO2. Istraživanja su pokazala da su najučinkovitije kombinacije za degradaciju POT-a u jezerskoj vodi oba kristalna oblika TiO2 - rutil i anatas u količini od cca 1 g/L + Sunčevo zračenje. Pokazano je da se samo u slučaju visoke doze vodikovog peroksida H2O2 od 54 mg/l i 1 g/L TiO2 kristalnog oblika rutil bilježi poboljšanje procesa degradacije organskih tvari, a u svim ostalim kombinacijama H2O2 usporava proces. Utvrđena je i činjenica da je kristalni oblik rutil TiO2 blago učinkovitiji u procesu degradacije organskih tvari od kristalnog oblika anatas, ali zbog boljih svojstava pokazanih pri pokušaju ponovnog korištenja u eksperimentu daje se prednost kristalnom obliku anatas TiO2 u preporuci za praktičnu primjenu ovakvog postupka obrade vode

EFFECTS OF CONCENTRATION AND UV RADIATION WAVELENGHTS ON PHOTOLYTIC AND PHOTOCATALYTIC DEGRADATION OF AZO DYES AQUEOUS SOLUTIONS BY SOL-GEL TiO2 FILMS

The photocatalytic and photolytic degradation of anionic azo dyes Methyl Orange and Congo Red dye aqueous solutions was investigated in glass reactors with/without TiO2 films that were irradiated with UV light. Two nanostructured sol-gel TiO2 films were prepared by means of the dip-coating technique with and without of polyethylene glycol (PEG) as a structure-directing agent. Experiments were carried out by varying the concentration of dyes, TiO2 films and sources of UV radiation. The concentrations of dyes were 0.0125 mmol L-1, 0.025 mmol L-1 and 0.05 mmol L-1; the wavelengths of the incident ultraviolet light were predominantly 254 (UV-C) and 365 nm (UV-A). In the presence of TiO2 film UV-C radiation showed higher degradation efficiency for both dyes than UV-A radiation. Also, UV-C radiation without TiO2 photocatalyst was capable of degrading both dyes, while UV-A radiation alone did not show a potential for dyes degradation. Higher photoactivity showed TiO2 film with addition of PEG

POSSIBILITIES OF ENVIRONMENTAL ASPECTS AND IMPACTS EVALUATION ACCORDING TO ISO 14001 STANDARD ON THE EXAMPLE OF AN ACADEMIC INSTITUTION

Environmental aspects and impacts are important components of the international standard ISO 14001:2004. This standard represents a possible way of introducing an environmental management system in an organization. Environmental management systems help in achieving ecologically sustainable development and environmental performance of the organization. This paper introduces a systematic approach for the determination of environmental aspects, possible ways of their evaluation and deals with potentially adverse environmental impacts of an academic institution on the example of the Faculty of Geotechnical Engineering, University of Zagreb. As the significant aspects for the Faculty, within the waste management process, the separation and storage of the waste electrical and electronic equipment (including the fluorescent lamps), toners and hazardous chemicals were determined. Additionally, the use of electricity and the use of natural gas for heating purposes of the Faculty were estimated to be normal, according to the European practice

Implementation of the Harmonised Model for Carbon Footprint Calculation on Example of the Energy Institute in Croatia

The effects of climate change on Earth already exist in different forms – as an increase in global average temperatures, as a sea level rise or as extreme weather events, and it is necessary to take significant measures to mitigate and adapt to the climate change. One of the tools that can help in attempts to mitigate climate change is the use of carbon footprint concept, as a measure of the greenhouse gas emissions. Since there are different approaches, it is necessary and possible to establish a harmonised approach for calculating the organisations’ carbon footprint, in order to obtain comparable results and benchmarks for different kinds of organisations. The Croatian version of the Bilan Carbone model, fully in accordance with appropriate international standards, with country-specific emission factors database, was tested on the case of the Energy Institute Hrvoje Požar for the period 2015-2017. The carbon footprint for 2017 was 650.6 tonnes or 7.31 tonnes per employee of carbon dioxide equivalent emissions, with dominant shares of people transport (59%) and energy sources (22%). This harmonised approach for carbon footprint calculation will lead to comparable results for the same kinds or groups of organisations and therewith, lighten the process of establishing the carbon footprint mitigation strategies

Influence of engine oils dilution by fuels on their viscosity, flash point and fire point

U sklopu ovog rada ispitivan je utjecaj razrjeđenja automobilskih sintetičkih i mineralnih motornih ulja dvjema vrstama komercijalnih goriva: motornim benzinom – Eurosuperom 95 i dizelskim gorivom – Eurodizelom. Time se simulirao slučaj koji se može dogoditi u motoru – prolazak neizgorena goriva u kućište motora te miješanje i otapanje u motornom ulju. Kao najvažniji parametri za praćenje promjena karakteristika ulja odabrani su viskoznost, plamište i gorište. Razrjeđenje ulja gorivom kretalo se u rasponu od 0% do 10% masenoga udjela (wt) goriva. Uzorci motornih ulja koji su korišteni u ispitivanjima nabavljeni su od dvaju proizvođača prisutnih na hrvatskom tržištu, po jedno čisto mineralno i jedno potpuno sintetičko multigradno motorno ulje gradacija viskoznosti prema SAE gradaciji: 15W-40 i 5W-30, bez dodatnih modifikacija. Promjene svojstava ulja premašile su pretpostavljene praktične vrijednosti potrebne za siguran rad motora u slučaju razrjeđenja ulja s benzinom u iznosu od 10 wt%. Razrjeđenje ulja sa 5 wt% benzina je maksimalni iznos uz koji se može očekivati mogućnost njegove praktične primjene za podmazivanje motora jer se plamište ispitivanih ulja snižava na temperature koje se već javljaju u primjeni – oko 150 °C ili niže. Kada se ulja razrijede dizelskim gorivom, tada se praćena svojstva ulja mijenjaju manje nego što je to slučaj s benzinom.In this project the influence of dilution of synthetic and mineral engine oils with two commercial fuels – gasoline (type Eurosuper 95) and diesel fuel (type eurodiesel) was studied. The situation that could really occur in the automotive engine was simulated – a breakthrough of unburned fuel to engine oil and its mixing and dissolution. Viscosity, fire point and flash point were chosen as the most important parameters to follow the changes in oil-fuel mixtures. The dilution range was between 0 and 10 wt% of fuel in the oil-fuel mixture. The samples used in this investigation were bought directly from the two producers present on the Croatian market, without further modification. The samples were multigrade mineral and synthetic oils – mineral oil with SAE gradation 15W-40 and synthetic oil with SAE gradation 5W-30. The changes of oil properties were too high for assumed safe use in engines in the case of oil dilution with 10 wt% of gasoline. The dilution of oil with 5 wt% of gasoline was maximal level of dilution that could be expected to be still adequate for use in engines, because the flash points of these mixtures were mostly near 150 °C, which is assumed as maximal allowed working temperature of engine oil. The properties of mixtures of the same oils with diesel fuel showed smaller changes than mixtures with gasoline

Tehničke mjere za sprječavanje razmnožavanja bakterija Legionella spp. u sustavima za opskrbu toplom vodom

Kontinuirano održavanje kvalitete tople i hladne pitke vode u stambenim građevinama, posebno naglašavajući mikrobiološke zahtjeve za kvalitetom vode, predstavlja veliki izazov za stručnjake iz različitih područja djelovanja. Istovremeno, svi oni dijele i odgovornost za zdravlje ljudi koji tu vodu koriste. Kroz ovaj rad dan je pregled pojave i razvoja patogenih bakterija Legionella spp. u sustavima opskrbe s pitkom vodom uz naglasak na podsustav potrošne tople vode. Patogene bakterije iz roda Legionella nalaze se u prirodnim vodotokovima i dospijevaju sustavom vodoopskrbe do kućanstava. Predstavljaju opasnost za ljudsko zdravlje izazivajući legionarsku bolest, teški oblik upale pluća, a infekcije najčešće uzrokuje L. pneumophila seroskupine O1. U dišni sustav čovjeka dospijevaju iz kontaminiranog okoliša u obliku vodenog aerosola. Prikazani su zakonski zahtjevi vezani uz kvalitetu pitke vode te navedeni primjeri ograničenja vezani uz prisutnost Legionella spp. koja postoje u nekim državama. Osim toga, prikazana su tehnička rješenja za uspješnu inaktivaciju Legionella spp