Evaluation of sequencing batch reactors performance in removal of NMP from aqueous solutions

Regarding high stability, polarity and solvent power, the increasing usage of N-methyl-2-pyrrolidone (NMP) as an alternative solvent in various industries such as petrochemical industry has been unavoidable. Consequently, NMP content of the industrial wastewater is being increased; therefore, appropriate environmental efforts should be made in order to prevent the organic pollutant from having hazardous effects on the environment. There are several wastewater treatment methods amongst which biological ones especially Sequencing Batch Reactors (SBRs) have high priority since they are compatible with the environment and show proper performance in term of pollutant removal. Due to its unique features namely better settling properties, cost and energy saving, simplicity and flexibility of the method in comparison with other biological wastewater treatment methods, SBR has attracted lots of attentions recently. The present study has investigated the performance of four laboratory-scale SBRs treating synthetic petrochemical NMP-containing wastewater at four influent NMP concentrations of 0 (blank), 100, 400 and 800 mg/L. In addition, the influent synthetic wastewater contained carbon sources (Glucose), nitrogen and phosphorous sources, and some needed trace compounds. The SBRs were operated with one cycle per day, temperature 28±2ÚC, and pH 6.5-7.5. The sludge retention time (SRT) was set at 10 days, and the hydraulic retention time (HRT) was adjusted at 2 days. Under steady state in all reactors, following parameters were monitored and measured; mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), and sludge volume index (SVI), NMP concentration in effluent, and Turbidity. The results of approximately 100 days of experiment demonstrated the total NMP removal of more than 96%. All reactors followed a relatively stable trend which reflected reaching steady-state conditions. However, the reactor with initial NMP concentration of 400 mg/L presented the best sludge adaptation and the most steady-state in terms of MLSS, MLVSS, SVI, and turbidity

کلیدواژه ها:

Biodegradation ، N-methyl-2-pyrrolidone (NMP) ، Sequencing Batch Reactor (SBR)