Study On Cultivation Of Aerobic Granule And Treatment To HMX Production Wastewater

The study cultivated aerobic granules with synthetic wastewater, analysed the characteristics, and applied to the treatment of HMX production wastewater using a gradual domestication method. The removal efficiency of HMX production wastewater with aerobic granular sludge and biofilm were compared. This paper also systematic researched the impact factors of HMX production wastewater treatment using aerobic granules.Aerobic granules were successfully cultivated after 35 days with glucose and sodium acetate synthetic wastewater in a SBR (sequencing batch reactor). During the culture process, the MLSS of the reactor increased gradually from 3.46g/L to 7.76g/L, SVI (sludge volume index) increased at first and then decreased, the total polysaccharide/total protein ratios of EPS(extracellular polymeric substances) increased from 1.16 to 3.38, the removal rate of COD and ammonia nitrogen increased, too. The mature aerobic granules were regular, dense and had rich biological phase, high mechanical strength and hydrophobicity. The removal efficiency of COD and ammonia nitrogen were up to 95.03% and 100% respectively and the denitrification rate in anoxic condition were higher than that in aerobic condition. The aerobic granular sludge had the ability of SND(simultaneous nitrification and denitrification) and the SND rate were 87.22%, the SND reaction followed with the equationThis study investigated short-term storage and the subsequent reactivation of aerobic granules. After one month anaerobic storage in 4℃, some granules disintegrated, the Pr content of EPS decreased and the removal rate of COD and TN reduced. The reactivation process last 25 days, the physical characteristics and the removal rate to COD of granules were recovered, however the removal efficiency of TN were lower than that before storage.The paper compared the HMX production wastewater treatment efficiency with aerobic granular sludge and biofilm, the results showed aerobic granules had higher ability to withstand shock and adapt to new organic loading. Cycle profiles indicated when the pollutant concentration of the two reactors were identical, the loading rate in the aerobic granular reactor was higher, however the removal rates of COD and TN in biofilm reactor were lower. The biofilm reactor was beneficial to remove organic nitrogen of the HMX production wastewater while the aerobic granular reactor with higher concentration of DO was favorable to treat inorgnic nitrogen.The experiments investigated the impact factors of HMX production wastewater treatment using aerobic granules, the optimal operational parameters were COD/TN ratio of 4/1, sodium acetate as external carbon addition, initial pH of 7.5, reaction temperature of 30℃, aeration rate of 100L/h and preposing 60 min of standing stage before aeration. When the reactor operated on optimum conditions, the effluent could accord with national standard GB8978-1996.