Experimental Research On Purifying Raw Water Of Yangtse River In Chongqing Region With Tubular Micro-Filtration Membrane

The water treatment with micro-filtration is used widely as one of the membrane filtration technology in recent years. Raw water can be filtrated directly with micro-filtration membrane. Cryptosporidium , Giardia Lamblia and other bacteria can be get rid of with it. In additon, the micro-filtration process costs as much as the normal water treatment. Therefore, the micro-filtration technology has more advantages in water treatment compared with the normal water treatment technology. And that, the micro-filtration technology takes less than reverse osmosis and nanofiltration because it's pretreatment has less cost or it has no pretreatment and it has lower operation pressure. On the other hand, the micro-filtration process has more advantages as the pretreatment of advanced process than the traditional water pretreatment. For example, less land required, less investment of capital construction, more compact overall arrangement, more convinence in administration.Filtering the raw water of yangtse river in Chongqing region with tubular micro-filtration membrane is studied in the thesis. In the experiments of selecting more suitable membrane for water treatment, it is found that the turbidity of the outflow is under 3 NTU by means of micro-filtration when the turbidity of inflow is between 20-1500NTU. In this experiment, no any coagulate reagent and aid coagulate reagent was dosed, and no other pretreatment was done. In the experiments of how to recover the flux of the selected membrane by the physical means, it is found that the purpose to recover the flux of the selected membrane can't be obtained by backwashing the membrane with filtered water. However, the flux of the selected membrane can be kept within the reasonable range for some time by means that the compressed airflow sours the membrane reversely and raw water rinses the surface of the membrane at the same time. The flux of the membrane is related to the pressure and turbidity of the inflow, the frequency of the airflow souring, the proportion between filtering time and scouring time. Generally, the higher pressure and the lower turbidity of the inflow, the higher output. The higher frequency of the airflow scouring, the higher output. But, the output will reduce if the frequency of the airflow reaches the extremely high because backwashing water increases. The more the proportion between filtering time and scouring time is, the more output, whereas the more rapid the membrane pollution. Therefore, the proportion between filtering time and scouring time should fit for thewater treatment. In the experiments of rinsing polluted membrane with chemical solution, it is found that the chemical rinsing has perfect effect with sodium hydroxide solution and hydrochloric acid solution. And the chemical dose, the chemical solution and rinsing methods are decided,In the experiment of observering the operation stabilization of the micro-filtration membrane process, it is found that the filtered water quality is under 3NTU, the flux of micro-filtration membrane can be recovered and facilities work well for a long time.Finally, micro-filtration process is compared with the traditional water treatment process. It is found that the micro-filtration process has more advantages on technology and has economic feasibility.