Study On Applications Of Continuous Membrane Filtration Technology

Within the developed and developing countries shortage of fresh water is now one of the main threats to sustainable development. Available water resources are under threat due to pollution or over-abstraction whilst domestic and industrial consumers demand an ever higher water quality and the right to an uninterrupted supply of water. In recognition of these problems, extensive use of poor quality water resources (such as contaminated/turbid waters and sewage) is rapidly becoming a necessity in order to secure resources for the future in China. So the membrane filtration technology especially the PVDF hollow fiber membrane and its Continuous Membrane Filtration (CMF) system made in China is more and more important in many fields. The "membrane software" is a key problem, for example how to secure the good quality and quantity of CMF's product and effective membrane cleaning under different influence and operating conditions.We studied the technical optimization of CMF manufactured by TMMETC such as the frequency of backwashing in line, air-cleaning technology and method of chemical cleaning lead to lower operating and maintenance cost and larger application field of CMF system in many full-scale study.At Tianjin Seawater Desalination Basement, the optimum operation parameters of CMF were 35 minutes of running time, 30 seconds of air-water cleaning time, 25 seconds of large flux backwash time and 15 seconds of drain. The cleaning with air-water was the most effective, when the pressure of compressed air tank was more than 0.5MPa.The clean agents prepared with NaClO, HC1 and influence of CMF was very effective for the membrane fouling of CMF used for seawater reverse osmosis pretreatment. The quality of CMF's product was consistent, regardless of upsets in the seawater quality. The turbidity was between 0.06⁰.07NTU.The SDI oscillated between 0².The recovery of CMF was more than 96%.The energy cost was 0.3kwh/m .At Beixiaohe wastewater treatment plant, the appropriate longest period of chemical cleaning was 60 days. Because PVDF hollow fiber membrane is characteristic of good chemical stability and anti-fouling, using acid, alkali and oxidative solution with multi-stage water cleaning process to clean membrane was very effective for removing organic fouling. There was a remarkable decrease of TMP in CMF system. In the course of running, CMF worked steadily. The mean turbidity was 0.07NTU and the removing of COD_cr was 35% . The energy cost was 0.28kwh/m³ and run cost was 0.19RMB/m³.At Shaying wastewater treatment plant of Shengli oil field, the optimum operation parameters of CMF were 20 minutes of running time, 30 seconds of air-water cleaning time with dosing NaCIO and HC1, 30 seconds of large flux backwash time and 10 seconds of drain. The most effective chemical cleaning was to use NaOH, NaCIO, HC1 prepared with tap-water in turn to remove membrane fouling for 40 minutes respectively. The mean turbidity of CMF's product was 0.06NTU.At Daqing oil field, the worse quality of CMF's influence was concerned, the the appropriate operating parameters of CMF were 10 minutes of running time, 40 seconds ofair-water cleaning time, 40 seconds of large flux backwash time and 40 seconds of drain. The most effective chemical cleaning was to use NaOH prepared with tap-water to clean membrane for 10 minutes, then wash membrane surface with tap-water. The content of oil was very effective and the removing was near 100%. The removing of polymer was form 80% to 90%.