THE OCCURRENCE OF MICROPLASTICS ON THE START-UP PROCESS OF AN ANOXIC BIOFILM BATCH REACTOR

Abstract

Seed sludge from several sources is often used to initiate bacterial growth at the start-up of the biological treatment system, and it contains microplastics contaminants. Currently, there is no information regarding the presence of microplastics in a biological reactor during the start-up process. This study aimed to investigate the occurrence of microplastics during the start-up process in an anoxic fixed-biofilm batch reactor. Three units of 42 Laboratory-scale reactor feed with synthetic biodegradable substrates were inoculated with fecal sludge residential areas were filled with PET media with three different specific surface areas (SSA). The results showed that the stable biofilm formation rates were associated with the removal of COD after 75 days of operation. The source of microplastics in the reactors during the start-up process comes from fecal sludge (x̅± SD, n = 3) 7.666,67 ± 513.16 MP/kg (w/w). Approximately 7.96 – 9.24% of microplastics were adsorbed on the biofilm. No PET as secondary microplastics was found during the start-up process. Two types of microplastics found in the reactor were fibers and fragments with the amount of 80.87 ± 44.8% and 19.13 ± 10,1%, respectively. The types of polymers detected by the Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy were PES, PE, PET, and PS. SSA affects the adhesion of microplastics on PET media. In a larger SSA, more microplastics are adsorbed on the biofilm.