چكيده به لاتين
Abstract:
To overcome the problems of settling tanks in wastewater treatment by conventional activated sludge, application of aerobic granulation has attracted the attention of researchers. In this study, the effects of various factors on granulation and performance of aerobic granules in treatment of phenolic wastewater have been studied and comparisons were made to conventional activated sludge. Microbial granulation and performance of granules in five parallel systems with different conditions at initial phenol concentration of 400 to 2000 ppm were investigated. The results showed granulation after one week, stable and dense granules after the fifth week with the sludge volume index below 20 ml per gram and beginning of the breaking of the granules after the eighth week. Effects of shear stress, substrate composition and addition of iron ions were also examined. It was shown that addition of iron expedites granules formation by twofold with larger size of granules at about 5 mm in diameter compared to other systems. Use of mineral salt medium with industrial sources was in favor of granulation with respect to speed and stability. Suitable shear stress by creating multiple back and forth pathways lead to formation of dense granules with suitable particle distribution and sludge volume index about 10 ml per gram. Comparison with the conventional activated sludge capable of phenol removal at 5.56 mg per hour per gram of activated sludge, granulation resulted in higher phenol removal of 20 mg phenol per hour per gram of granules. Results confirm the superiority of aerobic granulation in wastewater treatment with regards to both phenol removal and cell removal provided that formation of granules are carried out under suitable conditions.
Keywords: Water Treatment, Removing Phenol, Activated Sludge, Granulaion.
