Priprava pjenostakla uporabom pepela otpadnoga mulja nastaloga pročišćavanjem komunalnih otpadnih voda

doctoral thesis

• Title (english): Preparation of foamed glass using ash of sewage sludge obtained from municipial wastewater treatment
• Author: Marin Ganjto
• Mentor: Hrvoje Ivanković (mentor)
• Committee member: Nevenka Vrbos (predsjednik povjerenstva)
• Committee member: Marija Vuković Domanovac (član povjerenstva)
• Committee member: Zdravko Schauperl (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-11-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Basic Technical Sciences; Materials
• Universal decimal classification (UDC): 666 - Glass industry. Ceramics. Cement and concrete

Abstract

U disertaciji je istražena mogućnost priprave visokokvalitetnog pjenostaklenog materijala iz pepela dobivenog spaljivanjem mulja nastalog pročišćavanjem komunalnih otpadnih voda, koji zbog rastućih količina i nepovoljnog kemijskog sastava predstavlja opasnost za okoliš.
Uz pepeo za pripravu pjenostakla korišteni su otpadno ambalažno staklo i otpadni vapnenac kao agens za pjenjenje. Utvrđeno je da se pjenostaklo ujednačene poroznosti i volumne stabilnosti te poboljšane tlačne čvrstoće (≈ 30 MPa) u odnosu na komercijalne pjenostaklene proizvode može pripraviti brzinom zagrijavanja od 5 °C/min do temperature od 850 °C uz zadršku od 15 min na vršnoj temperaturi. U pjenostaklu može se zbrinuti visoki maseni udio pepela (do 28 %) s niskim masenim udjelom vapnenca (1–2 %). Izluživanjem teških metala iz uzoraka pjenostakla utvrđeno je da su koncentracije teških metala u eluatima unutar zakonskih dopuštenih granica za neopasne otpade te da pjenostakla pokazuju antibakterijsku aktivnost prema klinički relevantnoj bakteriji Acinetobacter baumannii. Poboljšana mehanička svojstva dobivenog pjenostakla posljedica su stvaranja novih mineralnih faza tijekom toplinske obrade. Dodatkom pepela dolazi do pojačane kristalizacije natrijevog-kalcijevog silikata, α-kvarca, diopsida i volastonita. Kristalizacija ovih faza osim što doprinosi poboljšanju tlačne čvrstoće materijala istovremeno smanjuje izluživanje teških metala iz pjenostaklene matrice. Antibakterijska aktivnost posljedica je visoke pH-vrijednosti eluata uzrokovane otapanjem nevezanog kalcijevog oksida čije su čestice utvrđene elektronskom mikroskopijom na stijenkama pora.

Abstract (english)

In this PhD thesis thepossibility of high quality foam glass material production from sewage sludge ash prepared by incineration of sewage sludge from waste water treatment plants, that due to its increasing quantities and adverse chemical composition represent an environmental hazard was investigated. Besides ash as starting materials,waste container glass culet and waste limestone as a foaming agent were used. It has been found that foam glass with uniform porosity and volume stability with improved compressive strength
(≈ 30 MPa) in relation to commercial foam glass products, can be prepared through heating by 5 °C/min to 850 °C with holding time of 15 min at final temperature. Prepared foam glass can utilize a high content of ash (up to 28 wt.%) with small share of foaming agent
(1 – 2 wt.%). Leaching of heavy metals from foam glass samples showed that heavy metal concentrations in eluates are within the legislative limits for non-hazardous wastes and that they show antibacterial activity against a clinically relevant bacterium Acinetobacter baumannii. Improved mechanical properties of prepared foam glass resulted from enhanced crystallization of sodium calcium silicate, α-quartz, diopside and wollastonite. Crystallization of these phases apart from contributing to the improvement of the compressive strength of the material simultaneously reduces the leaching of heavy metals from foam glass matrix.
The antibacterial activity was the result of high pH value of eluates, which were the consequence of alkaline reaction of unreacted calcium oxide adhered to walls of pores, particles of which were detected by electron microscopy.

• Keywords: antibakterijska aktivnost; karbonati; otpadni mulj; pepeo; pjenostaklo; teški metali
• Keywords (english): antibacterial activity; carbonates; sewage sludge; ash; foam glass; heavy metals
• Language: croatian
• URN:NBN: urn:nbn:hr:149:317933
• Promotion: 2017
• Study programme: Title: Engineering Chemistry - Doctoral Course; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 127 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-12-06 12:53:03