Vpliv ozonacije na mikroplastiko v modelni odpadni vodi

Zupančič, Petra (avtor), Žgajnar Gotvajn, Andreja (mentor)

Zaradi visoke uporabe plastičnih izdelkov in nizke razgradljivosti postaja mikroplastika (MP) vseprisoten onesnaževalec okolja. To so majhni delci (1–1000 µm), ki nastajajo iz večjih plastik zaradi luščenja in razgradnje. Ker so delci MP majhne velikosti in gostote, se zlahka prenašajo med različnimi ekosistemi. Enega večjih virov MP predstavljajo komunalne čistilne naprave (KČN), kjer se večina MP ujame v aktivnem blatu, ostanek MP pa preide skozi postopke čiščenja. V zadnjem času so napredni oksidacijski procesi (NOP) najbolj obetavne metode za odstranjevanje obstojnih onesnaževal, ki temeljijo na tvorbi reaktivnih kisikovih spojin, s katerimi oksidiramo onesnaževala. Uporaba ozonacije v procesih čiščenja odpadnih vod lahko vpliva na razgradnjo MP ter izluževanje različnih snovi, ki zmanjšajo kvaliteto odpadne vode ter obenem vplivajo na nadaljnje možnosti obdelave odvečnega blata (kompostiranje, proizvodnjo bioplina). V okviru magistrskega dela smo ocenili potencial ozonacije odpadne vode za izluževanje organskih snovi iz MP. V ta namen smo primerjali polivinilkloridno (PVC), polietilentereftalatno (PET) in polipropilensko (PP) MP (< 1 mm), saj spadajo med najpogosteje zaznane vrste mikroplastike v vzorcih odpadne vode in odpadnega blata. Eksperimente smo izvajali v šaržnem reaktorju, t. i. koloni z mehurčki z začetno koncentracijo MP 1 g∙L−1, pri čemer smo spreminjali vrsto MP (PET, PP, PVC), dozo ozona (3,5–4,5 g∙h−1) in čas ozonacije (1, 2, 3, 4, 5, 6 ur) ob spremljanju vrednosti pH. Učinkovitost ozonacije smo določali z merjenjem totalnega organskega ogljika (TOC) in kemijske potrebe po kisiku (KPK). Za karakterizacijo MP je bila uporabljena Fourierjeva transformirana infrardeča spektroskopijo (FTIR) in vrstična elektronska mikroskopija (SEM). Ugotovili smo, da se razgradnja MP med ozonacijo povečuje, kjer je PET dosegla najvišje vrednosti TOC in KPK. Pri FTIR se je pojavil nov absorpcijski trak (1713 cm−1), ki je povezan s prisotnostjo karbonilnih skupin C=O na ozonirani PP. Na SEM slikah smo na površini ozonirane PET in PP opazili veliko skupkov delcev in novonastale mikrorazpoke, velikosti od 5 m do 15 m.

• Jezik: Slovenski jezik
• Ključne besede: čiščenje odpadne vode, mikroplastika, okoljsko onesnaženje, ozonacija, TOC
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2025
• PID: 20.500.12556/RUL-172603
• COBISS.SI-ID: 257114371
• Datum objave v RUL: 09.09.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: The impact of ozonation on microplastics in model wastewater

Izvleček

Due to the widespread use of plastic products and low biodegradability microplastics (MP) have become an ubiquitous environmental pollutant. These are small particles (1–1000 µm) formed from larger plastics through abrasion and degradation. Given their small size and density, MP particles are easily transported between different ecosystems. One of the major sources of MP are wastewater treatment plants (WWTPs), where the majority of MP is captured in activated sludge, while the remaining MP passes through treatment processes. Recently, advanced oxidation processes (AOPs) have emerged as promising methods for removing persistent pollutants, relying on the formation of reactive oxygen species to oxidize contaminants. The use of ozonation in wastewater treatment processes can contribute to the degradation of MP and the leaching of various substances, which reduce wastewater quality and simultaneously affect further treatment options for excess sludge (composting, biogas production). In this master's thesis, we assessed the potential of wastewater ozonation for the leaching of organic substances from MP. For this purpose, we compared polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polypropylene (PP) MP (< 1 mm), as these are among the most commonly detected types of microplastic in wastewater and sludge samples. The experiments were conducted in a batch reactor, specifically a bubble column, with an initial MP concentration of 1 g∙ L−1. We varied the type of MP (PET, PP, PVC), the ozone dose (3,5–4,5 g∙h−1), and the ozonation time (1, 2, 3, 4, 5, 6 hours) while monitoring pH levels. The effectiveness of ozonation was determined by measuring total organic carbon (TOC) and chemical oxygen demand (COD). For the characterization of MP, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. The results showed that MP degradation during ozonation increases, with PET reaching the highest TOC and COD values. FTIR analysis revealed a new absorption band (1713 cm−1), associated with the presence of carbonyl groups C=O on ozonated PP. On SEM images, we observed numerous particle agglomerates and newly formed microcracks on the surface of ozonated PET and PP, ranging in size from 5 m to 15 m.

• Ključne besede: environmental pollution, microplastics, ozonation, TOC, wastewater treatment