Characteristics of MEG Removal from Industrial Wastewater by Sequencing Batch Reactor (SBR)

Background: MEG is extensively applied in the sour gas industry as a hydrate inhibitor. It is toxic in oral drinking and serious injury or death may result from swallowing of pure ethylene glycol and poses a potential hazard to the environment through impact soil. Glycols are harmful to aquatic life. There is little information about the digestion of MEG in the aerobic reactor. Therefore, the feasibility of MEG removal in the aerobic reactor was investigated. Materials and method: Biodegradation of MEG was done in an aerobic SBR reactor with the capacity of 2000 cc and sanitary wastewater as primarily required microorganisms. The experiments were done in the three stages. In stages 1 and 2, 500cc of reactor content was drawn-off and solutions contain 500 cc of 0.073 (wt %) of MEG (for the first stage) and 0.201 (wt %) of MEG (for the second stage) were added to the reactor. In stage 3, 500 cc of wastewater of MEG removal unit in the 2nd refinery of South Pars Gas Company, Iran with a concentration of 4.021 (wt %) of MEG was added to 1500 cc of reactor content. The feed of stage 1 was pure MEG that was diluted in demineralized water but Feed of stage 2 was a dilution of industrial feed of stage 3. Results: In stage 1, after four days, the removal efficiency of more than 80% was obtained. In stage 2 after six days, the efficiency of 20% was obtained. In stage 3, after seven days, more than 70 percent of MEG removal was obtained. Conclusion: by increasing residence time, the removal efficiency of the reactor could be increased acceptably. Therefore, the MEG solution of more than 4 (wt %) of MEG can be treated biologically.