Ispitivanje značajnih čimbenika za biorazgradnju polistirena i poli(vinil-klorida) primjenom bakterijske kulture Bacillus licheniformis

master's thesis

• Title (english): Investigation of significant factors for biodegradation of polystyrene and polyvinyl chloride using bacterial culture Bacillus licheniformis
• Author: Ornella Host
• 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: 2022-09-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Rastuća količina plastičnog otpada postala je ozbiljan okolišni i društveni problem. U skorije vrijeme pojavio se veliki problem malih dimenzija, mikroplastika (MP). MP su plastične čestice manje od 5 mm, a njihova je prisutnost danas zabilježena u svim sastavnicama okoliša. Bioakumulacijom u hranidbenom lancu vrlo brzo se mogu naći i u čovjekovom organizmu, gdje imaju visok potencijal štetnog djelovanja. Spomenute male dimenzije ovih čestica čine njihovo uklanjanje iz okoliša gotovo nemogućim zadatkom, stoga je bitno što prije razviti inovativni pristup zbrinjavanja ove vrste otpada. Kao jedno od ekološki prihvatljivih rješenja tog problema, javlja se biorazgradnja plastike koristeći mikroorganizme i njihov enzimski potencijal, čime se nudi mogućnost razvoja tehnologije biološke obrade plastičnog otpada. U ovom radu ispitali su se značajni čimbenici za proces biorazgradnje MP čestica, polistirena (PS) i poli(vinil-klorida) (PVC) primjenom bakterijske kulture Bacillus licheniformis. Eksperiment je osmišljen prema Taguchi dizajnu prema kojem je ispitano 7 čimbenika: temperatura, pH vrijednost, broj okretaja, veličina i koncentracija MP, optička gustoća i dodatak glukoze i to na 2 razine - minimalna i maksimalna vrijednost. Tijekom 30 dana praćena je promjena CFU vrijednosti, a u filtratu vodene faze određivane su vrijednosti ukupnog organskog ugljika (TOC) i anorganskog ugljika (IC). Nastali razgradni produkti i/ili otpušteni aditivi praćeni su LC-MS analizom, dok su strukturalne promjene okarakterizirane FTIR-ATR spektroskopijom. Nakon 30 dana provođenja procesa biorazgradnje ispitana je toksičnost filtrata na Vibrio fischeri. Značajni čimbenici određivani su statističkom analizom varijance (ANOVA) prema eksperimentalnim rezultatima. Rezultati ovog eksperimenta pokazali su prema CFU analizi da je B. licheniformis koristio PS i PVC kao izvor supstrata pri određenim uvjetima. LC-MS analizom potvrđena je prisutnost novih spojeva u vodenoj fazi, a FTIR-ATR spektroskopijom potvrđene su promjene u materijalu, što su potvrde uspješne biorazgradnje. Kao značajni čimbenik ovog procesa biorazgradnje pokazala se optička gustoća. Dakle, B. licheniformis ima sposobnost biorazgradnje PS i PVC čestica, ali je od velike važnosti odabrati optimalne uvjete za najveću učinkovitost.

Abstract (english)

The growing amount of plastic waste has become a serious environmental and social issue. Recently, a major problem of small dimensions has emerged, microplastics (MP). MP are plastic particles smaller than 5 mm, and their presence is now found in all components of the environment. Due to bioaccumulation in the food chain, they can very quickly enter the human body, where they can have negative influence on human health. The aforementioned small size of these particles makes their removal from the environment almost impossible, which is why it is urgent to develop an innovative approach to the disposal of this type of waste. One of the environmentally friendly solutions to this problem is the biodegradation of plastics using microorganisms and their enzymatic potential, and it offers the possibility of developing a biological treatment technology for plastic waste. In this work, the significant factors for the process of biodegradation of MP particles of polystyrene (PS) and polyvinyl chloride (PVC) were studied using the bacterial species Bacillus licheniformis. The experiment was designed according to Taguchi design in which 7 factors were tested: temperature, pH, rpm, size and concentration of MP, optical density and addition of glucose, at 2 levels - minimum and maximum. During 30 days, the change in CFU value was monitored, and the values of total organic carbon (TOC) and inorganic carbon (IC) were determined in the filtrate of the aqueous phase. The formed degradation products or released additives were monitored by LC-MS analysis, while the structural changes were characterized by FTIR-ATR spectroscopy. After 30 days of biodegradation, the toxicity of the filtrate to Vibrio fischeri was tested. Significant factors were determined by statistical analysis of variance (ANOVA) according to the experimental results. According to CFU analysis, the results of this experiment showed that B. licheniformis used PS and PVC as substrate sources under certain conditions. The LC-MS analysis confirmed the presence of new compounds in the aqueous phase, and the FTIR-ATR spectroscopy confirmed changes in the material, confirming successful biodegradation. Optical density was found to be a significant factor in this biodegradation process. Thus, B. licheniformis is able to biodegrade PS and PVC particles, but it is of great importance to choose optimal conditions for the highest efficiency.

• Keywords: mikroplastika; polistiren; poli(vinil-klorid); biorazgradnja; značajni čimbenik; B. licheniformis
• Keywords (english): microplastics; polystyrene; poly(vinyl-chloride); biodegradation; significant factor; B. licheniformis
• Language: croatian
• URN:NBN: urn:nbn:hr:149:061077
• 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: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2024-06-01
• Created on: 2023-03-10 16:10:26