Operation of Moving Bed Biofilm Reactor in Terms of Organic Matter and Triethylene Glycol from Simulated Petrochemical Wastewater

Abstract

Background: Triethylene glycol (TEG) is an organic compound of the two-factor or di-alcohol alcohols and is used as a vinyl plasticizer. TEG has high toxicity and is classified in the chemical and polymer production group of petrochemical industry. Methods: The current experimental study was conducted on a pilot scale. The total volume of the pilot study was 35.1 liters and its useful volume considering freeboard was 30 liters. The range of variables in the current study was input COD (chemical oxygen demand) (1000 - 3000 mg/L), pH (6, 7, and 8), C6H14O4 (600, 800, 1200, and 1800 mg/L), and hydraulic retention time (6, 8, 10, and 10 hours). Results: The results of the study showed that by increasing the compatibility time within 30 days, the COD input to the system also increased, as the input organic loading of the system in the 10 days was 769 mg/L, and then this amount after 20 days, the time spent for 30 days was 941 mg/L, during which high concentrations of sewage could be significant. On the other hand, output organic loading also increased with the overtime and increase of the input organic loading. By increasing the moving bed biofilm reactor (MBBR) hydraulic retention time after 5 hours, residual COD level of input to the amount of 1165.2 mg/L reached 40.5 mg/L. Conclusion: The obtained results showed that the MBBR system had the highest efficiency after 5 hours and optimized pH 8 for concentrations of TEG entering the system about 600 and 800 mg/L were 96.5% and 92.87%, respectively; and in the hydraulic time of 1 hour reached the efficiency of about 70% at 600 mg/L concentration, and no removal was observed in 800 mg/L, which can be concluded that in 1 hour or less and at concentrations of 800 mg/L and above, it can be used as pretreatment.