Contrast Experimental Study On Domestic Wastewater Treatment With Hollow-fiber Membrane And Nylon-netting

Domestic wastewater was very available,but often brought huge pollution.As the separate treatment of domestic wastewater decreased the load of sewage plant and the pollution of environment,it became very important.Making use of the filtration of hollow-fiber membrane instead of the gravity deposition of secondary settling tank had lots of advantages,but the membrane was dear and the pollution of membrane was serious.To improve effluent quality by filtration cube which was made of inexpensive material became one of the popular wastewater treatment techniques in future.The experiment made use of two different aperture cubes which were made of big aperture,inexpensive nylon-netting and general plastic-pipe.The cubes looked like flat membrane and effused by hydraulic pressure.To contrast removal effect on domestic wastewater in the identic condition,two nylon-netting cubes and hollow-fiber membrane were placed in the A/O reactor and ran at the same time.The experiment made for exploitation of inexpensive filtration material.The results of experiment indicated that,the effluent of hollow-fiber membrane and nylon-netting took on good removal effect on turbidity,SS,COD_cr and NH₃-N.The average turbidity of membrane effluent was0.15NTU,the removal ratio of SS was 100%,the average removal ratio of COD_cr was 93.7%,and the average removal ratio of NH₃-N was 92.4%.The average turbidity of two nylon-netting effluent both were under3NTU, SS both were zero for the most of time,the average removal ratio of COD_cr both exceeded 91.0%,and the average removal ratio of NH₃-N both exceeded 92.0%.At the same time,the effluent of hollow-fiber membrane and two nylon-netting took on low removal effect on TN and TP because of low mixed rate and high nitrogen of wastewater.The average removal ratio of TN of membrane effluent was 49.0%,and the average removal ratio of TP was 41.6%.At the same time,the average removal ratio of TN of two nylon- netting effluent both exceeded 48.0%,and the average removal ratio of TP both exceeded 42.0%.Although the aperture of nylon-netting was wide,the self-forming dynamic membrane which was formed on the surface enhanced removal ratio and made up the deficiency of wide aperture.The effluent of nylon- netting took on good removal effect which was comparable with the effluent of hollow-fiber membrane.The results of experiment indicated that,the COD_cr removal ratio risen when HRT increased,but when HRT exceeded 6h,the COD_cr removal kept calm.The COD_cr removal ratio in the reactor risen when aeration intensity increased.But when aeration intensity was excess,the self-forming dynamic membrane which was formed on the surface was hard to form or easy to be destroyed,and the removal ratio of nylon-netting itself decreased.The COD_cr of effluent risen after high consistence impact,but effluent consistence was under 50mg/L all the same.The resistance to high consistence impact load of system was well.According to the degree of fouling,there were three steps of membrane cleaning: by water-by NaC1O-by HC1.The cleaning means of nylon-netting was high intensity and timing aeration.The intensity of aeration was 2m³/h,the time of aeration was 3min once time,and the frequency of aeration was once everyday.According to the results of espial,the status of microorganism were found out.In the cultivation period,the main types of microorganism appeared in activated sludge were amoeba,flagellate and so on.When the zoogloea was well cultivated,the main species were vorticella and so on.And the appearance of rotifera indicated that the system was run well,and the quality of effluence was steadily and well.