| Aerobic rotating biological contactor(RBC) can treat artificial domestic wastewater and organic industrial wastewater efficiently, and has been paid more attention to by wastewater treatment technology.[9]Like other biological treatment process, the purified reaction of RBC includes: oxidation and decomposed of organic substances, nitration, denitrification and so on. RBC doesn't need aeration, and returned sludge, so it can economize energy sources, simultaneously reaches good effect of purification in short contact time, including removal of BOD and nitrogen.Through experiments on removal of carbon and nitrogen from artificial domestic wastewater in an aerobic RBC, we reach the conclusions as following:1. Decomposed of organic substances: 1)Experiments on the condition of serious organic loads 8.33, 15.72 and 19.56gCOD/(m2 d),the average removal efficiency of COD were 88.63 %,94.37% and 95.11 %. So the aerobic RBC can adapt to alteration of organic load.2) COD/NH4+ in the influent was from 150: 5, 125: 5 to 100: 5, the removal efficiency of organic substances in the aerobic RBC was from 95.4% to 97.16%. Simultaneously, the removal of organic substances in aerobic RBC was mostly in the first two plates, experiments showed that the influent COD was removed in a short contact time, and the removal efficiency of COD reached over 88.6%. 3)Under condition of various HRT 2~5hours, as various hydraulic loads 78.64 , 52.43, 39.3 5 31.45(L/(m2 d)), the removal efficiency of organic substances in the aerobic RBC were 94.51%, 89.2%. 86.35% and 87.68% separately. Experiments suggest that the aerobic RBC well adapts to alteration of hydraulic load.2. Removal of nitrogen:1) Experiments on the condition of serious nitrogen loads 0.59. 0.79 and 0.98mgNH4+-N/(m2 d),the average removal efficiency of NH4+-N were 100%. 95.28% and 90.95 %, the average efficiency of transformation from NH4+-N to NO3--N were 55.77 % . 49.9% and 56.12%. Therefore the nitration in the aerobic RBC well adapts to alteration of NH4+-N load.2) When COD/NH4+=100:5 in the influent, without or with recycle, the NO3--N concentration was 14.3mg/L or 16.19mg/L separately.In this condition, denitrification was not affected. Because the removal efficiency of COD in RBC is well, so in the effluent the NO3-3~-N concentration is high, but COD is low. 3 ) Under serious C/N condition-5 , 3 and 1.5, the datum of experiments showed that, on the condition of C/N=5, the removal efficiency of total nitrogen was upwards of 87%. But on the condition of C/N= 1.5, the removal efficiency of total nitrogen was under 50%. Thus it can be seen that if we want to realize well effect of denitrification, we must control the C/N at 3~5. So in the practice it is important to adjust the C/N to reach the expected effect of denitrification.4) The nitration and denitrification in the aerobic RBC were also mostly in the first two plates, experiments showed that ammonia and nitrate in the influent were removed in a short time period. Because in this stage organic substances is enriched,biofilm is thick enough to present nitrobacteria and denitrification bacteria 5) Salfate promotes denitrification.The datum of experiments showed that when C/N=3, namely NO3-= 100mg/L, the effect of denitrification as the SO4 2-concentration of 200mg/L was better than other serious SO42- concentration, in this condition the NO3--N concentration in the effluent was about lmg/L(Fig.5.16), but without SO42-, the average of the NO3--N concentration in the effluent was about 37.63mg/L.3. The microorganism of RBC:1) There were much filamentous bacteria on the first plate of RBC, but the last plate of RBC had little filamentous bacteria2) The distribution of microorganism on the RBC is as following: On the first several plates, because of enriched nutrient, hererotrophic bacteria is eugonic, and hererotrophic bacteria propagates fast, so biofilm is thick, and mainly in removal of COD; On the last several plates, due to COD is removed fast by the first several plates, now nutrient is less, bi...
|
PDF Full Text Request