Biorazgradnja poli(vinil-klorida) primjenom Gram-pozitivne bakterije

master's thesis

• Title (english): Biodegradation of polyvinyl chloride using Gram-positive bacteria
• Author: Luka Očić
• Mentor: Dajana Kučić Grgić (mentor)
• Committee member: Dajana Kučić Grgić (predsjednik povjerenstva)
• Committee member: Vesna Ocelić Bulatović (član povjerenstva)
• Committee member: Lidija Furač (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-07-11, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Danas je život bez plastike i plastičnih proizvoda nezamisliv zbog njihove široke upotrebe i relativno lake proizvodnje, a među najkorištenijim plastikama su polietilen (PE), polipropilen (PP), poli(vinil-klorid) (PVC) i poli(etilen-tereftalat) (PET). Posljedica široke primjene plastika je njihova akumulacija u okolišu što može izazivati negativne utjecaje na okoliš, ali i na ljudsko zdravlje. Zbog toga se traže novi načini uklanjanja plastičnog otpada iz okoliša, a jedan način je i biorazgradnja. Biorazgradnja se odvija primjenom mikroorganizama koji su sposobni enzimima razgraditi polimerni lanac plastičnih materijala. U ovome radu istraživala se biorazgradnja PVC mikroplastike (MP) pomoću gram-pozitivne bakterijske kulture Bacillus subtilis. Cilj je bio odrediti optimalne uvjete biorazgradnje PVC MP. Pokus je proveden prema full factorial dizajnu ispitujući tri čimbenika na 3 razine: pH (6, 7 i 8), broj okretaja rotacijske tresilice (100, 150 i 200 o/min) i optička gustoća (OG) bakterijske suspenzije (0,1, 0,3 i 0,5). Pokus je trajao mjesec dana tijekom kojih se određivao ukupan broj živih stanica bakterija (CFU) te koncentracija ukupnog ugljika (TC), organskog ugljika (TOC) i anorganskog ugljika (TIC). Nakon provedenog pokusa biorazgradnje, iz vodene faze odvojene su čestice MP-a. Potom su čestice PVC MP okarakterizirane FTIR-ATR spektroskopijom, dok se LC-MS analiza primijenila za ispitivanje mogućih otpuštenih aditiva s PVC MP u vodenu fazu.
Na kraju je određena i ekotoksičnost vodene faze primjenom morske bakterije Vibrio fischeri, kako bi se utvrdilo nastaju li štetni razgradni produkti biorazgradnjom PVC-a. Dobiveni rezultati pokusa su obrađeni pomoću Design Expert programa uz statističku analizu (ANOVA). Određeni su sljedeći optimalni uvjeti biorazgradnje PVC MP primjenom Bacillus subtilis:
pH = 7,74, broj okretaja = 200 o/min te OG = 0,5.

Abstract (english)

Today life without plastic products is unimaginable because of its broad use and relatively easy manufacturing. The most common types of plastic are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). A result of its widespread use is the accumulation of plastic waste in the environment, which is not only a threat to the environment itself, but also the health of people and animals that live there. Because of that, new ways of removing plastic waste from the environment in an acceptable way are being researched, and one such method is biodegradation. Biodegradation occurs when microorganisms use their digestive enzymes to degrade the polymer chain of the plastic material. In this thesis the biodegradation of PVC microplastic (MP) using a
gram-positive bacteria Bacillus subtilis was investigated. The goal was to determine the optimal conditions of the biodegradation of PVC MP. The experiment design was the Full factorial design with 3 factors on 3 levels: pH (6, 7 and 8), speed of the rotary shaker
(100, 150 and 200 rpm) and the optical density (OD) of the suspension (0.1, 0.3 and 0.5). The experiment lasted 30 days during which the number of colony forming units (CFU), concentration of total carbon (TC), organic carbon (TOC) and inorganic carbon (TIC) were determined. After 30 days solid MPs were separated from the liquid phase using membrane filtration. After that the PVC MP was analysed using FTIR-ATR spectroscopy, while LC-MS was used to determine if any additives were released from the PVC MP into the liquid phase. Finally, the toxicity of the liquid phase was determined using the marine bacteria Vibrio fischeri, to determine if any harmful products of biodegradation of PVC were present.
The results were analysed using the program Design Expert with the analysis of variance (ANOVA). The optimal conditions for the biodegradation of PVC MP using Bacillus subtilis were: pH = 7,74, speed rotary shaker = 200 rpm and OD = 0,5.

• Keywords: mikroplastika; PVC; biorazgradnja; Bacillus subtilis; optimalni uvjeti biorazgradnje
• Keywords (english): microplastics; PVC; biodegradation; Bacillus subtilis; optimal conditions for biodegradation
• Language: croatian
• URN:NBN: urn:nbn:hr:149:902273
• Project: Number: IP-2019-04-9661; Title: Primjena naprednih tehnologija obrade voda za uklanjanje mikroplastike; Title: Advanced Water Treatment Technologies for Microplastics Removal; Acronym: AdWaTMiR; Leader: Tomislav Bolanča; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2024-01-01
• Created on: 2023-07-27 08:59:57