Effects of organic loading rate and DO on limited bulking and the study of its characteristics

Abstract:

In order to solve the problem of sludge bulking which happened in wastewater treatment plant frequently,a notion named low DO limited filamentous bulking was put forward.It is a new energy-saving and high-efficient method to treat wastewater with the characteristics of morphology and physiology of filamentous bacteria under low DO concentration condition.The impact of DO concentration and organic loading rate (OLR) on sludge settleability and the removal characteristics of nitrogen,phosphorus and COD under limited filamentous bulking were investigated by using sequencing batch reactor (SBR) through operation in aerobicanoxic pattern.The results show that OLR and DO concentration affect sludge settleability in special range respectively.When OLR is larger than 0.25 d-1,limited filamentous bulking state can not be maintained by low DO concentration alone.Nitrification will not be deteriorated under low DO limited filamentous bulking condition,and about 20% nitrogen is removed through simultaneous nitrification and denitrification (SND) based on the mass balance of nitrogen.Aerobic phosphorus release is found in the initial stage of low aeration rate,and the system can enrich phosphorus accumulating organisms (PAOs).