Study Of Hydrolysis-denitrification +A/O Process Of Wastewater With Low C/N Treatment And Sludge Reduction

The treatment of wastewater with low C/N has gradually become a hot issue.The effect of low C/N(BOD5/TN<4)sewage treatment is always poor by the general treatment process.The water taken from a wastewater treatment plant in Miyun District,the research point is the hydrolysis denitrification process of low C/N sewage in adding carbon source under the condition of nitrogen treatment effect,and the effect of sludge reduction.1.The experiment start to finish in a month.At the end of start-up,the effluent concentration of COD and ammonia nitrogen can achieve the national level A urban sewage discharge standards.The flora of nitrogen and phosphorus have been bred unwound in each pool system.2.During the operation,the removal rate of COD,ammonia nitrogen and total nitrogen was stable,and the removal rate was 83.4%,98.3%and 53.76%respectively.The average values of effluent COD and ammonia nitrogen achieve the national level A urban sewage discharge standards.In the operation stage five(dosing carbon source 145 g·h-1),the total nitrogen of influent was 83.9 mg/L,and the effluent was 14.3 mo1·L-1.The effluent total nitrogen concentration achieve the national level A urban sewage discharge standards,and the total nitrogen removal rate is 79.7%.3.Active sand filter showed good removal efficiency of the effluent,the total nitrogen removal efficiency of nearly 20%,the phosphorus removal efficiency was 26.5%,the effluent SS value is 5.8 mol·L-1,achieve the national level A urban sewage discharge standard.4.The sludge in hydrolysis reactor from second operational phase to(5%return sludge)accumulated gradually,in the third operational phase(nitrated liquid reflux 100%,5%sludge return,carbon dosage 20 g·h-1),showed the best effect of sludge reduction,sludge production decreased 43.2%.5.During the fifth operational phase,the sludge in the hydrolysis tank was increased evidently(nitrated liquid reflux 100%,5%sludge return,carbon dosage 145 g/h).At the fifth operational phase,the amount of sludge in hydrolysis reactor was 2.6 times of that in the non reflux stage.The amount of sludge in the secondary sedimentation tank is obviously reduced,at the end of the fifth operational phase,it is reduced 81%.The proportion of sludge in aerobic tank of the whole sludge decreased from 42%to 28%.The proportion of sludge in the hydrolysis tank increased gradually,and the proportion increased from 39%to 69%,and finally became the main accumulation area of sludge.According to the determination of oxygen consumption rate curve,when the sludge reduction is achieved,the treatment effect of pollutants will not be affected.6.The similarity of dominant bacteria species at different heights of hydrolysis denitrifying sludge was high,among which,Proteobacteria,Chloroflexi,Bacteroidetes and Nitrospira were the dominant groups of 3 samples.At the level of family,the proportion of Rhodocyclales in phosphorus removal was 6.31%-11.61%,close to the reported average.On the level of species,there are Thauera and a large number of denitrification genes of bacteria.The success of sludge reduction was proved through microbial function gene research.EggNOG database analysis showed that sludge reduction had some influence on the classification of KEGG metabolic pathway.