Microorganisms in AAO-biofilter after denitrification enhanced by composite carbon source
To reuse the agricultural wastes and develop the economic solid carbon source enhancing the nitrogen removal of domestic wastewater with low C/N ratio, the polyvinyl alcohol-sodium alginate (PVA-SA) is used as a carrier and combined with agricultural waste corncob powder to prepare a new composite carbon source in this study. The new composite carbon source filler should have the stronger mechanical strength compared to agricultural waste, and not be easily broken or microbial clogged when applied in the anoxic tanks of AAO process or in the denitrification filter. It has the characteristics of low cost, non-toxic and harmless, and easy dosage control.The new composite carbon source fillers are added into the anoxic tank of the traditional AAO lab-scale reactor and packed in the lab-scale denitrification biofilter to evaluate the enhanced nitrogen removal efficiency for treatment of the low C/N domestic wastewater. The result of the experiment is: the removal of nitrogen in domestic sewage was successfully strengthened, and the TN was reduced to below 2mg/L, provided that the effluent COD did not exceed 35mg/L. In order to clarify the effect of the addition of composite carbon sources on the microorganisms in AAO and denitrification filters, four different microbial samples were taken before and after the addition of composite carbon sources, namely: AAO anoxic tank activated sludge without carbon source filler : Q1, activated sludge of AAO anoxic tank after adding carbon source filler: Q2, biofilm attached to AAO carbon source filler: T, sludge in biofilter: L.