| Organic nitrogen wastewater is mainly produced in pesticides, dyes, petroleum and chemical industries, etc. Since the wastewater generally contains a large amount of refractory organic matter, it is difficult to be degraded and the general biochemical treatment process is not effective. Meanwhile, the degradation of organic nitrogen will produce large amount of ammonia, which is difficult to remove by nitrification. This paper used anoxic/ two-stage aerobic biological contact oxidation and air-stripping process treating nitrogen wastewater.The results showed that: anoxic/ two-stage aerobic biological contact oxidation process could effectively remove acrylonitrile, nicotinamide, 3-cyanopyridine, COD and nitrate nitrogen in wastewater, the removal rates of which were 99.84%, 95.35%, 99.96%, 70.22%,88.63%, respectively. However, there was little removal of ammonia because of the inhibition of toxic substances, heterotrophic bacteria and high concentration ammonia nitrogen. After biochemical treatment,ammonia concentration was 400?500mg/L.The biodiversity of the three biochemical pools was, the second aerobic pool > the first aerobic pool > anoxic pool, and the bacteria structure of the first and second aerobic pools were similar. All three biochemical pools contained a lot of bacteria, which can degrade organic matter, organic and nitrate nitrogen, but only the second-stage aerobic had a small amount of nitrifying bacteria. The characteristic of the bacterial species in each pool was consistent with the pool's function.Under the condition of 30?, the pH, gas flow, stripping time affected ammonia removal rate significantly, the primary and secondary relationship of which is, pH >stripping time > gas-liquid ratio, and the interaction between any two of those three factors were significant. The best air-stripping conditions were: initial pH was 10.73, gas-liquid ratio was 4200, stripping time was 150.00min. Under the best conditions, the ammonia nitrogen removal rate was 90.53%. |
PDF Full Text Request