Research On Waste Activated Sludge Alkaline Fermentation To Abtain Carbon Source

Hydrolysis and acidification is a way to the resource utilization of waste activatedsludge （WAS）. There are several measures to improve the hydrolysis and acidification, andthe alkaline solution is one of them. Studies on alkaline hydrolysis mostly choose NaOH,and focus its dosage, temperature, retention time and the other influence factors. with thedissolution of COD being the discussed criterion. This study analyse the dissolution of C,N and P under different alkaline conditions （alkali type, dosage, temperature, sludgeconcentration, etc.）, obtaining the optimum alkaline hydrolysis condition, and then evalutethe supernatant recycling for denitrification.This study choose parallel batch experiment. The test time is48h, determined bypreliminary study, and choose NaOH and Ca（OH）₂to hydrolysis WAS. The results showthat: while TS=16g/L, the optimal conditions of NaOH hydrolysis WAS is35°C, thedosage of0.6/L, the reaction time of48h; the optimal conditions of Ca（OH）₂hydrolysisWAS is35°C, the dosage of0.9g/L, the reaction time of48h. The cost of the supernatantas denitrification carbon source is far lower than the external carbon source （sodiumacetate）.By the pretreatment of alkaline hydrolysis, ultrasound, alkaline hydrolysis+ultrasound, the effects of hydrolysis and acidification are: alkaline hydrolysis+ultrasound> alkaline hydrolysis> ultrasound> the original sludge. When Mg（OH）₂orCa（OH）₂is chosen to hydrolysis sludge，the precipitation of Ca²⁺, Mg²⁺and PO₄^3-willsignificantly reduce the amount of P in the supernatant.Good reaction conditions and sufficient substrate can make the dissolution rate oforganic nitrogen much higher than that of NH₄⁺-N, while the dissolution rates of organicphosphorus and PO₄^3--P are similar.Hydrolysis and acidification of the sludges from the anaerobic tank, the anoxic tank,the aerobic tank and the secondary sedimentation tank of A/A/O process shows that thedissolution rates of C, N and P have no significant difference. Under the same conditions,the dissolution rates of C, N and P nearly change in the same proportion with the sludgeconcentration.