The Potential of Ozonation to Reduce Impact of Waste Sludge-Entrapped Microplastics to Biogas Production

Figures & data

Figure 1. Ozonation of PP- and PET-contaminated sludge.

Figure 2. Formed CH₄ ± SE and CO₂ in comparison to control sample, according to added concentration of a) PET and b) PP [%].* indicates statistically significant differences (p < 0.05) in comparison to control sample.

Table 1. Cumulative biogas production [hPa] ± SE of PP- and PET-contaminated anaerobic sludge in concentrations 0.1 10 g L⁻¹, compared to control sample. * indicates statistically significant differences (p < 0.05) in comparison with control sample.

Concentration of MPs	Control sample	0.1 g L^−1	0.5 g L^−1	1 g L^−1	1.5 g L^−1	10 g L^−1
Average total biogas production ± SD; PET [hPa]	172.9 ± 10.2	181.0 ± 1.2	210.5 ± 0.5*	185.0 ± 15.5	170.5 ± 2.5	182.8 ± 5.1
Average total biogas production ± SD; PP [hPa]	181.1 ± 7.3	176.8 ± 8.8	189.0 ± 9.0	171.0 ± 7.6	209.0 ± 1.0*	179.6 ± 0.6

Figure 3. Methane yields ± SE (a) and biogas inhibition ± SE (b) of contaminated (1 g L⁻¹) and ozonated sludge at dose 3.54 g h⁻¹ for 10 min compared to control sample for [%]. * indicates statistically significant differences (p < 0.05) in comparison with control sample.

Figure 4. Methane yields ± SE (a) and biogas inhibition ± SE (b) of contaminated (1 g L⁻¹) and ozonated sludge at dose 3.54 g h⁻¹ for 20 min, compared to control sample [%]. * indicates statistically significant differences (p < 0.05) in comparison with control sample.

Figure 5. Methane yields ± SE (a) and biogas inhibition ± SE (b) of contaminated (1 g L⁻¹) and ozonated sludge at dose 3.54 g h⁻¹ for 30 min, in comparison with control sample [%]. * indicates statistically significant differences (p < 0.05) in comparison with control sample.

Figure 6. Methane yield ± SE (a) and biogas inhibition ± SE (b) of PP-contaminated and ozonated sludge at 10, 20, and 30 minutes of ozonation. * indicates statistically significant differences (p < 0.05) in comparison with control sample.

Figure 7. FTIR spectra of (a) PP and (b) PET particles (non-treated, after anaerobic digestion and ozonation).

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.