[Optimization of propylene removal in a complete mixed activated sludge bioreactor by Taguchi method]

Exposure to propylene glycol can lead to many health risks on blood, skin and kidney. Biodegradation of synthetic wastewater containing propylene glycol was studied in a continuous conventional activated sludge bench scale reactor. Optimum conditions of microorganisms growth for biodegradation of propylene glycol were determined by Taguchi method. Primary microorganisms for start up of the bioreactor were obtained from sludge return line of a municipal wastewater treatment plant and adapted to different concentrations of propylene glycol in a conventional activated sludge reactor. Optimum growth conditions of microorganisms and also operational conditions of the system including pH, influent COD, source of nitrogen and salinity were determined in three levels by Taguchi method. COD removal efficiency in conventional activated sludge reactor for influent concentrations of 400, 700, 900, 1100 and 1300 mg/L were 98%, 95%, 95%, 90% and 85% respectively. Optimization of the process by Taguchi method showed that source of nitrogen urea, pH = 8, salinity of 8% and influent COD of 1300 mg/L with importance priority of 41%, 25%, 17.11% and 16.142% were as optimum growth conditions of microorganisms and also, operational conditions of the system for propylene glycol biodegradation respectively. According to the results obtained from this work, it can be concluded that optimum conditions of biological processes and improvement the efficiency of bioreactors can simply be done by the use of such experimental designs

[Optimization of moving bed bioflim reactor using taguchi method]

In recent years, mobile bed biological reactors have been used progressively for municipal and industrial wastewaters treatment. Dissented experiment is a trial that significant changes will accrue for influent variables in the process, and generally used for identification of the effective factors and optimization of the process. The scope of this study was determination of the optimized conditions for the MBBR process by using of Taguchi method. Reactor start up was done by using of the recycled activated sludge from Ahwaz wastewater treatment plant. After that and passing the acclimation period, with hydraulic residence time equal to 9 hours matched for 1000, 2000 and 3000 mg/1 based on COD respectively, for optimization determination of the acclimated microbial growth, the variables change [p[H], nitrogen source, chemical oxygen demand and salinity] were determined in 9 steps, and all of the results were analyzed by Qualitek -4 [w32b]. In this study, organic load removal based on COD was 97% and best optimized condition for MBBR were [inf. COD 1000 mg/1, pH= 8, salinity = 5% and the Nitrogen source= NH4CL]. Based on our finding, we may conclude that Taguchi method is on of the appropriate procedure in determination the optimized condition for increasing removal efficiency of MBBR