How does presence of microplastics impact biogas production?

The aim of this study was to evaluate the inhibition on the biogas production caused by microplastics (MPs). Wastewater treatment plants (WWTPs) are receptors of MP. After wastewater treating, more than 90% of MP could be retained in the sludge. Anaerobic digestion of the excess sludge can help reduce its volume and operating costs of WWTPs, due to CH4 production. Analysis with OxiTop control system could help to follow anaerobic degradation process to evaluate impact of MP on biogas production with slightly modified standard procedure by adding MP. Comparison of pressures gain of samples with added MP to control sample could determine the impact of added MP on biogas production and give the ratio of methane and carbon dioxide in biogas. Presence of MP mainly negatively affected biogas and CH4 production. Polyamide (PA) had shown the most negative affect and reached even up to 19% less of total biogas produced, while its presence decreased CH4 yield for up to 10% at 2.38 g L-1. Polyacryl inhibited CH4 yield up to 15% at even the lowest added concentration 0.05 g L-1.