Study On CSTR For Simultaneous Methanogcnesis Denitrincation-SBR For Shortcut Nitrification Combined Process For Treatment Livestock Wastewater

Manure wastewater is the emissions of all sorts of livestock, which contains many kinds of chemical constituents, volatile organic compounds (75%), protein (15.8%-23.5%), also contains lots of organic substances which have not been digested and absorpted. It has become one of the three water pollution sources associated with industrial wastewater and sewage, which is harmful to air, water and soil, but it is also rich in resources and has high recycling values, we can obtained the effective resources from it by adequate treatment properly, Both biomass methane can be recycled and nitrogen can be removed in the manure wastewater by using simultaneous denitrification and methanogenesis coupling with shortcut nitrification, and the methanogenesis reactor can avoid acidification. However, methanogenesis and nitrification coupling with shortcut nitrificationd needs high reflux ratio condition which has important influence to anaerobic and aerobic system.The author firstly studies the start-up of simultaneous methanogenesis and denitrification as well as shortcut nitrification reactor, identified the operation conditions suitable for the two reactor coupled in series, then researches carbon and nitrogen removal by the coupling system in different reflux ratio. Several main conclusions had obtained from the experiments:1) The suitable carbon source is ethanol and glucose by simultaneous denitrification and methanogenesis in CSTR, The best pH, maximum ammonia nitrogen concentration and COD/NO2--Nis7-8,1200mg/L and30:1respectively.2) The organic load and nitrite nitrogen load is3.0kgCOD·m-1and0.1kg NO2--N·m-3·d-1in the conditions of pH=6.8～7.6, T=35±1℃, COD/NO2--N=30:1, it can achieve starting-up simultaneous denitrification and methanogenesis and COD removal rate can reach about70%, the nitrite nitrogen removal rate reached over96%, the rate of gas production is stable in1.0L·L-1·d-1. The Alkalinity (ALK) in simultaneous denitrification and methanogenesis reactor is higher than simple anaerobic methanogenic reactor, which can effectively avoid acidification phenomenon in the anaerobic methanogenic.3) In the aerobic reactor, the pH, FA range for proper shortcut nitrification-denitrification iss8.0and18in high ammonia pig manure wastewater respectively, which is benefits to nitrite bacteria for competitive advantage and ammonia nitrogen removal. The removal rate of ammonia nitrogen and nitrite accumulation rate has little impact in the same period on the condition of constant aeration rate and constant DO. However, the removal of ammonia nitrogen and nitrite nitrogen accumulation occurred much later at constant aeration. In the shortcut nitrification reactor, the organic matter oxidate firstly, next ammonia, it can be appropriate to relax the restrictions on DO when the nitrite accumulation rate stability, DO will not affect the ammonia oxidizing bacteria growth as well as shortcut nitrification effect when the ammonia oxidation bacteria in dominant.4) There were better nitrogen removal carbon removal in the condition of pH=7.5～8, FA≈18mg/L, T=29±1℃and constant aeration (DO=0.1～2.1mg/L) respectively, the ammonia nitrogen removal rate reached94.25%, the nitrite accumulation rate was stable at90.25%, the removal rate of COD reaches63%～71%, the average removal rate of TN is73.8% when stable running to handle the effluent of CSTR. The sludge in SBR has higher activity with high ammonia oxidation rate, on average0.06161mgNH4+-N/mgCOD-h, not only has high effectively removed nitrogen and obtain high nitrite accumulation, but also can further remove COD in anaerobic digested.5) Using denitrification and methanogenesis (CSTR)-shortcut nitrification denitrification (SBR) combined process to treat manure wastewater, in the stage of simulated reflux, reflux ratio1:1and2:1, the removal rate of COD is95.8%,94.4%and94%respectively; the total ammonia removal rate is92%,94.5%and97.2%respectively. COD is removed mostly in anaerobic CSTR reactor, accounted for83.65%,76.5%and69.4%in total COD removal; whereas aerobic SBR reactor removes COD less, accounted for16.35%,23.5%and30.6%in total COD removal,respectively. In the condition of different reflux ratio, the total removal rate of COD and the contribution rate of CSTR anaerobic reactor for COD removal have the same trends: simulated reflux stage>1:1reflux ratio phase>2:1reflux ratio phase, but SBR on COD removal contribution rate is simulated reflux stage<1:1reflux ratio phase<2:1reflux ratio of phase.