Overview Pharmaceutical production process water can be divided into raw material medicinal water and preparation water. The preparation water is further divided into oral medicinal water and injectable medicinal water. In addition to tap water for the raw material ingredients, pure water must be used. Handmade Soap,Natural Soaps,Handcrafted Soap,Artisanal Soap Guangzhou Lingxue Cosmetics Co., Ltd , https://www.lxgj188.com
Reverse osmosis (RO) is a high-precision technology in water treatment. It has been widely used in China's pharmaceutical industry since the mid-1990s. Its use has greatly extended the regeneration cycle of traditional ion exchange equipment and reduced acid-base emissions. The ecological environment is advantageously protected. With the in-depth implementation and implementation of the "Good Manufacturing Practices" (GMP) technical standards, many pharmaceutical companies across the country have successively carried out technological transformations, and successively introduced advanced foreign technology and equipment. RO water treatment technology and equipment are gradually adopted by the pharmaceutical industry. .
1 Common reverse osmosis water treatment process plan
2 Problems in the application of reverse osmosis equipment
Reverse osmosis desalination has unique characteristics and advantages over other desalting devices, such as evaporators, electrodialysis, and beds. The work of reverse osmosis localization has also received increasing attention. With the increasing use of reverse osmosis technology, the problems have become more and more serious. In recent years, extensive research has been carried out on the application of reverse osmosis water treatment equipment. A total of 99 sets of RO water treatment equipment in various industries across the country have been collected, including a total of 76 sets imported from abroad, some of which are made up of domestically produced and partially imported equipment. 13 sets, the complete set of equipment is 10 sets made in China. After finishing research, it was found that the normal use rate of a full set of imports was 30%; the normal use rate of some domestically and partially imported equipment was 60%; the normal use rate of a full set of domestically produced was 10%. The above problems are mainly caused by the following reasons:
1 A full set of imported equipment due to the difference in raw water quality, lack of technical demonstration and process modification, copying and copying, is not suitable for China's actual situation. Therefore, the reverse osmosis water must be pretreated according to the difference of raw water quality to meet the requirements of the equipment for the influent water quality.
2 Some enterprises with poor technical ability do not understand the rational selection of the membrane components of the reverse osmosis device and the reasonable arrangement of the membrane components, which cause some membrane components to operate under abnormal conditions.
3 domestic film quality is not off. The quality of the membrane directly affects the removal rate of salt and other impurities. The Filmtec composite membrane produced by Dow Chemical Company of the United States can stabilize the rejection rate above 90%.
4 operation management is not strict. When the system is running, the pressure should be within the range of the working pressure of the membrane to prevent excessive strength and overload operation, causing mechanical damage to the membrane and causing leakage. When the reverse osmosis system runs for a period of time, when the water production decreases sharply, the water quality deteriorates or the pressure difference increases, the membrane needs to be cleaned. At this time, the machine should be converted into a cleaning state, so that the system can be cleaned by itself, and the membrane can be recovered. The function.
3 technical improvements
Mechanical filter design
The main reason for the low normal use rate of imported equipment is that the pretreatment equipment does not combine the characteristics of poor raw water quality in China. The mechanical filter backwash is not thorough, the upper layer of sand filter agglomerates, and the SDI (contamination index) rises, causing fouling of the membrane. , affecting system operation. RO devices generally require SDI<4 (each membrane component manufacturer has different requirements for SDI). To meet the above requirements, the following recommendations are made through research and practice:
(1) Selection of mechanical filters
Combined with the raw water quality and equipment materials and fillers in China, it is recommended to use a double-layer filter. From the mechanism of filtration, it should be large and small, but in fact the mechanical filter is intercepted by the finest sand layer in the upper layer, so the uppermost sand is easy to block and agglomerate, and the head loss increases rapidly. If the granular anthracite is added to the upper layer of the sand, the capacity of the raw material is increased, the operation period is long, and the loss of the head is slow, and the application effect is good in practice.
(2) Backwashing of mechanical filters
The mechanical filter has a large specific gravity due to the internal filling of quartz sand, and the recoil is not easy. Many systems are unstable in operation, neglecting the process of thorough and clean backwashing. The backflushing device installed on the system can not meet the requirements of backwashing strength. It is a problem for many water treatment equipment manufacturers and engineering companies. After the author and a certain processing equipment Co., Ltd. jointly research and practice, using the method of repeated flushing of gas and water, the backwashing effect of the mechanical filter after fouling is very obvious, the cleaning of the sand layer is very clean and the performance is well recovered. The specific measures are:
1 When designing the backwashing device, the recoil pump and pipeline must meet the requirements of backwashing quantity, and the backwashing strength is 12-15L/(s·m2);
2 The filter material is scrubbed with compressed air to remove sludge and the like on the surface of the filter material, and the strength thereof is 18-25 L/(s·m 2 ).
(3) Selection of fillers
Internal packing, quartz sand of different particle size may be selected according to the different drainage structure, but the particle size of the uppermost quartz sand should be 0.3MM. 0.5-1.0MM granular anthracite is filled at the top, and its height is not less than 200MM.
Application of activated carbon adsorption
The activated carbon adsorber has two main functions:
1 adsorbing some organic matter in water, the adsorption rate is about 60%;
2 adsorption of residual chlorine in water. For users who directly extract groundwater, activated carbon can be eliminated. If the hardness is large, the water softener should be used. For surface water, activated carbon must be used, because the residual chlorine in the water biocide has strong oxidizing property, which will damage the RO membrane. The system influent requires residual chlorine <0.1MG/L, so the activated carbon is used to adsorb residual chlorine. In addition, the removal of residual chlorine from activated carbon is not a simple adsorption, but a catalytic effect on the surface, so there is no problem of adsorption saturation of activated carbon, but only carbon loss.
Selection of coagulant
Add various coagulants and high-molecular flocculants before the mechanical filter to remove suspended solids, colloids and other impurities in the water. However, if it is not added according to the actual situation of the water source, it will not improve the water quality, but will be due to the drug itself or the drug. The impurities contained in the water bring the substances harmful to the RO membrane, and many domestic pharmaceutical water treatment systems have the above problems. Therefore, the choice of pharmaceuticals is very particular. According to the characteristics of the RO membrane:
1 Coagulants should avoid the use of aluminum salts. The aluminum salt coagulant makes it easy to produce aluminum glue during the coagulation process, and is difficult to clean after entering the RO surface;
2 Cationic polymer flocculants should not be used. The RO membrane is an anionic type, and the cationic polymer flocculant easily combines with the membrane to form a polymer membrane which is difficult to clean. If you do not pay attention to the above situation, the film life will be shortened, and some membrane elements will be scrapped. At the same time, the compatibility between the drugs can not be ignored. For example, the ST polymer flocculant should be used together with ArgoAF150uL.
Discussion on RO system
(1) The importance of security filters
The main purpose of the security filter is to ensure that the RO water does not damage the membrane module. Generally, the filter pore size is 5μm, and the filter element is determined according to the pressure difference between the front and the back. The pressure difference is controlled within 58.8kPa.
The filter filter should not be used too long, because the filter is easy to grow bacteria, it is recommended to use 14 ~ 15t / (h · m2) (m2 is the filter filter area.)
(2) Use of scale inhibitor
Reverse osmosis membrane pollution can be divided into: biological pollution, suspended solids pollution, chemical pollution, colloidal pollution, bacterial pollution and so on. At present, the most used scale inhibitor in the reverse osmosis system is sodium hexametaphosphate, but sodium hexametaphosphate is easily decomposed into phosphate, which is a nutrient source of bacteria, so improper use may cause biological pollution. In addition, sodium hexametaphosphate is not easily dissolved, and its own scaling also affects the operation of the system. The scale inhibitor has both:
1 can inhibit bacterial growth and prolong the cleaning cycle;
2 can prevent the dissolved and insoluble iron in the raw water from forming iron glue, which affects the operation of the system and causes irreversible pollution of the membrane;
3 Increase the saturation threshold (LSI value up to 2.5), can not add acid to most of the raw water, can also reduce the acid addition to a small part of the raw water, thereby reducing the CO2 in the reverse osmosis water;
4 The ingredients of the medicine are stable and can be stored for a long time and opened for use. In order to ensure the normal operation of the RO system, in addition to the selection of suitable scale inhibitors, the amount of dosing should be calculated according to the raw water quality.
(3) Configuration of large flow flushing
In the process of water separation, the surface of the membrane contains many pollutants. Since the direction of water separation is 90° with the direction of water flow, the surface of the membrane can be removed by a large amount of washing. In fact, the original domestic assembly equipment ignores the The device is cleaned and the inlet device is equipped with a cleaning device. At present, some water treatment equipment engineering companies that the author has contacted have developed a PLC self-control large-flow flushing system, which is beneficial to the prolongation of the service life of the RO membrane.
(4) Selection of chemical cleaning solution
In normal operation, the RO system only needs to be cleaned 3-4 times a year. Different pollutants should use different chemicals. In China, citric acid and EDTA are generally used as the main components, but the cleaning effect is often poor, and the cleaning effect of the imported cleaning solution is obvious.
(5) Design of reverse osmosis device
RO device design calculation has a complicated calculation method. At present, foreign membrane component manufacturers have developed special software. As long as the designer determines the scheme according to the raw water quality report and the performance of each membrane component, then the raw water quality is input into the computer, and the program software. To verify the feasibility of the initial plan, if not, issue a warning and tell which part of the design is unreasonable. In addition, the designer should pay attention to the various protective measures that should be provided according to the requirements in the manual of the membrane element.
Selection of mixed bed UV sterilizer and membrane filter
Mixed bed is the ultimate means to improve water quality. UV sterilizer can kill bacteria in water, and then remove the bacterial corpse through membrane filtration. These designs can be used in conventional products and will not be described here.
Problems in reverse osmosis water treatment technology and improvement measures