Repository logo

Browsing by Author "Alcivar, Adriana Rosaura Gonzalez"

Now showing 1 - 1 of 1
  • Effect of composting on biodegradation of compostable and conventional microplastic by bacterial communities from sewage sludge
    Publication . Alcivar, Adriana Rosaura Gonzalez; Beltrán, Isabel Marín; Costa, Maria Clara
    Microplastics (MP) threaten the aquatic and terrestrial ecosystems. Several studies have reported that wastewater treatment plants (WWTPs) are one of the main sources of MP to the ocean, even though they remove up to 98% of MPs from the influent (Carr et al., 2016; Murphy et al., 2016; Simon et al., 2018; Talvitie et al., 2017). Most of these MPs are not really eliminated but end up in the sewage sludge. This sludge is normally used as fertilizer in agricultural soils, after a composting process. However, current regulation does not consider the concentration of MP in sludge before their application on natural soils. This work focused on evaluating the effect of composting on MP particles. For this, we spiked sewage sludge from a European WWTP with MP films (2 mm-2 ) from a polyethylene terephthalate (PET) bottle and a compostable (according to the seller) bag of polyethylene (CPE). The experimental set-up consisted of: sludge spiked with 40 PET MP, sludge spiked with 40 CPE MP. These two treatments were repeated but inoculating a bacterial isolate from the genus Bacillus. Sludge with no added MP or bacterial inoculum was used as control. Samples were kept at 50ºC for 60 days, and organic matter content, pH, C:N ratio, the change in the functional groups of MP, and changes in the bacterial community were monitored monthly. Results showed that 40 MP had no effect on the composting process. There were differences among peaks indicating chemical changes and biodegradation for PET and CPE MP. After 60 days, scanning electron microscopy revealed adhering biofilms and a hole for CPE MP submitted to bioaugmentation treatment but did not decompose as expected. The concentration of MPs in the sludge after 60 days was 27 MP by g-1 , compared to 4 MP by g-1 at the beginning. Polyester (28%) was the most abundant polymer and fibers (84%) the most common shape.
    2023-09-21Master thesis Open access Show more