Treatment Of Domestic Wastewater By ESROTAE

ESROTAE is developed from common rotating biological contactors(RBC), it has the advantages of larger specific surface area, higher oxygen delivery capacity, water distribution is more uniform and so on. This thesis, which combined pilot study and small-scale test, the effect of ESROTAE on the removal of pollutants in domestic sewage was analyzed.Through the small-scale test of the aerobic ESROTAE, the following conclusions be made:1) Under the condition of 1.3 hours of hydraulic retention time, and the COD loadings ranging from 6.55~25.97g/m2?d and NH4+-N loadings 0.75~1.79 g/m2?d, the ESROTAE Ⅱhas a good performance of organic matter, ammonia nitrogen and SS removal. It turned out that ESROTAE has a very good adaptability to the fluctuation of water quality and water quantity. 2)The COD loading increased cause the ESROTAE Ⅱ removal efficiency increase within a certain COD loading range. But when the COD loading is too high, the removal efficiency will decrease and may cause lots of beggiatoa bacteria growth. 3)Ammonia nitrogen removal efficiency are very high in a wide range of temperature. Even at low temperatures(below 15 degrees Celsius) which inhibits the growth of nitrifying bacteria, the removal ratio of ammonia nitrogen is still very high, the reduction in ammonia nitrogen averaged 87.77%. 4)ESROTAE has a good effect of ammonia efficiency obviously improved by the increase of rotational speed. 5)In order to avoid the heterotrophic bacteria inhibit the growth of autotrophic nitrifies, the aerobic RBC should be according to the actual water situation, paying attention to the ratio of length to diameter during the design so that make it be similar to plug-flow-reactor. Or using multi-stage biological, the advantages of doing this is allow two different types of bacteria growth, then promoting the ammonia nitrogen removal efficiency.The two-stage RBC anoxic–aerobic system was operated under COD concentration 250mg/L and ammonia nitrogen concentration 50mg/L, Changing reflux ratios from 50% to 150% under the 2.48 h hydraulic retention time(HRT) based on the total working volume of the whole system. 1)The system has a best overall performance under 100% reflux ratios, The final effluent COD and ammonia nitrogen and TN were satisfactory with the first grade criteria of “Chinese Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”(GB 18918-2002). Oxygen-deficient environment in denitrification reactor would be broken at the recycle ratio of 150%.2)When the recycle ratio increased, the COD removal rate would be decreased in anaerobic RBC, but the nitrate nitrogen would be less affected. 3)When the NH4+-N loadings ranging from 1.12~1.86 g/m2?d, the ammonia nitrogen removal rate would be increased by the higher NH4+-N loadings. 4)To the whole system, the removal effect of ammonia nitrogen and TN and TP will be promoted by a higher recycle ratio, but the effect of organic removal was negligible.Biofilm development and characteristics:1)The thickness and growth of biofilm both increased in aerobic RBC by improving the organic loadings, and biofilm gradually turns from dark brown to light yellow. But if the organic loadings were too high would be make lots of beggiatoa bacteria growth. 2)The thickness of biofilm would be decreased by the increasing rotational speed. Under similar test condition, a higher rotational speed can suppress beggiatoa bacteria grow abundantly. 3)Biofilm development in the anoxic unit was more uniform and thinner, it is a slightly yellow transparent biofilm.The internal biofilm has a dark color.