Study On On - Line Detection Method Of Hollow Fiber Membrane Integrity Based On Ohm 's Law

Hollow fiber membrane is widely used in the field of water treatment for its unique advantages. The integrity of the membrane module has a greater influence on the membrane effluent water quality. It is particularly important for life drinking water quality safety, the water treatment, sewage discharging standard, to effectively ensure the integrity of the membrane in the practical engineering. Based on the above, this study put forward a kind of hollow fiber membrane module integrity on-line detection device, according to the principle of electricity. The device identifies the integrity of the hollow fiber membrane module through the acquisition of fixed resistance voltage signal change. The experimental researched and optimized the sensitivity, detection range and applicable environment of the hollow fiber membrane module integrity test method.Firstly, the experimental studied the voltage signal change before and after the membrane module damage, filtering the lake water quality, and analyzed the influence on the change rule of the voltage signal of different bubble size. The experimental studied the influence of different breakage rate, different aeration intensity, different operating pressure on the voltage signal change rule. The results showed that voltage signal changes before and after the damage of the membrane module was relatively obvious, and the damage of membrane module could be identified by observing the voltage signal changes in a timely manner and clearly. Voltage reference signal has a fixed range of voltage 0.01 V. Bubble size had a greater influence on the value of the voltage signal, response voltage formed by big bubbles, Supercritical voltage formed by medium bubble was bigger than big bubbles, and probe voltage signal before and after the change were in turn. For the small bubbles, the formation of the response voltage is smaller, and a front voltage lower and rear probes voltage was constant, or the front voltage was constant and rear probe voltage values lower. The minimum air bubble diameter of the test method is 0.5 mm. The breakage of little effects on the sensitivity of the detection device is too small to detect through the probe. The minimum damage rate of the hollow fiber membrane module integrity online detection device is 0.5%. With the increase of aeration intensity, the response voltage frequency and the sensitivity was also increased. Aeration intensity of 5L/min can meet the requirements of the sensitivity. With the increase of the membrane effluent flux, the response voltage frequency and the sensitivity increased. Minimum detection effluent flux of the membrane is 28 mL/min.Secondly, the experimental studied the voltage change rule of seawater and six different filtering water distribution system. The results showed that the basic value voltage signal show increasing trend for different kinds of electrical conductivity of the water distribution, The voltage signal of fixed range was constant with 0.01 V. The change rule of voltage signal is relatively consistent, for different filtration system, but the change of detector sensitivity is not obvious with increase of the breakage rate, aeration intensity and the membrane effluent flux.Finally, a pilot scale submerged hollow fiber membrane module filtering device was adopted combined with hollow fiber membrane module integrity on-line detection device and the existing authority detection method-particle counter. The comparative study on the membrane integrity testing has been carried on to further determine the scientific nature, rigour and the applicability of the detection device.