Bohner H F, Bradley R L
Department of Food Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 1992 Mar;75(3):718-24. doi: 10.3168/jds.S0022-0302(92)77808-4.
Polysulfone UF membranes that were soiled by Cheddar cheese whey were successfully cleaned in place. This cleaning procedure was completed in about 1 h. Most cleaning chemicals used were common and inexpensive. The cleaning procedure consisted of rinsing the membrane system for 2 min with water initially and after each cleaning solution. Sodium hydroxide at pH 11.0, with .1% of a nonionic surfactant added, was circulated for 20 min. After a 2-min rinse with water, a 1:1 mixture of nitric and phosphoric acids at pH 2 was circulated for 20 min and rinsed again with water. Finally, sodium hydroxide at pH 11.0, with 200 ppm of sodium hypochlorite added, was circulated for 20 min and rinsed. All cleaning solutions and all rinse waters were at 54 degrees C. Membranes cleaned by this procedure were found to be free from whey residue under examination by scanning electron microscopy. The cleaning process did not damage the membranes even when it was used continuously for 300 h. Microbial populations on the membrane were estimated by incubating small (4-cm2) sections of membrane in screw-cap vials filled with trypticase soy broth. From the portion of vials showing growth after 72 h at 32 degrees C, a most probable microbial population was calculated. Santizing cleaned polysulfone UF membranes with 100 ppm of sodium hypochlorite or 100 ppm of dichloroisocyanurate at 54 degrees C resulted in membranes free from viable microorganisms. When dichloroisocyanurate was used at 10 degrees C and 200 ppm, a most probable microbial population of 290/m2 was found. No microbial growth was detected when cleaned and sanitized membranes were stored in tap water for 24 h. This technique for cleaning UF membranes does not require the use of a holding solution containing santizers to control the growth of residual microorganisms.
被切达干酪乳清污染的聚砜超滤膜成功地进行了原位清洗。该清洗过程在约1小时内完成。使用的大多数清洗化学品常见且价格低廉。清洗过程包括最初用水冲洗膜系统2分钟，每次清洗溶液后也用水冲洗2分钟。加入0.1%非离子表面活性剂、pH值为11.0的氢氧化钠溶液循环20分钟。用水冲洗2分钟后，pH值为2的硝酸和磷酸1:1混合溶液循环20分钟，然后再次用水冲洗。最后，加入200 ppm次氯酸钠、pH值为11.0的氢氧化钠溶液循环20分钟并冲洗。所有清洗溶液和所有冲洗水的温度均为54摄氏度。通过扫描电子显微镜检查发现，用该方法清洗后的膜没有乳清残留。即使连续使用300小时，清洗过程也未损坏膜。通过将小（4平方厘米）的膜片在装有胰蛋白酶大豆肉汤的螺口小瓶中培养来估计膜上的微生物数量。从在32摄氏度下培养72小时后显示生长的小瓶部分计算出最可能的微生物数量。在54摄氏度下用100 ppm次氯酸钠或100 ppm二氯异氰尿酸对清洗后的聚砜超滤膜进行消毒，得到的膜没有存活的微生物。当在10摄氏度下使用200 ppm二氯异氰尿酸时，发现最可能的微生物数量为290/平方米。当清洗和消毒后的膜在自来水中储存24小时时，未检测到微生物生长。这种超滤膜清洗技术不需要使用含有消毒剂的保存溶液来控制残留微生物的生长。
