JPH0351455B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Background) The present invention relates to a method for preventing back contamination of water treatment systems, and provides a system with excellent energy saving characteristics and quality maintenance characteristics by applying it to various liquid treatment systems. make it possible to produce. (Industrial Application Field) The present invention can be applied to a system for producing sterile pyrogen-free water, ultrapure water, etc. used in the water treatment field, particularly in the medical/pharmaceutical and electronic industries. Various effects can be obtained. Systems for producing sterile pyrogen-free water, ultrapure water, etc. include those that combine evaporation equipment, ion exchange resin equipment, activated carbon equipment, etc., and more recently, reverse osmosis equipment that uses semipermeable membranes, ultrafiltration equipment, etc. The current situation in the industry is that the industry is transitioning to systems that combine ion exchange resin equipment, ultraviolet sterilization equipment, precision filtration equipment, etc. (Prior art) A system incorporating a reverse osmosis device or an ultrafiltration device using this semipermeable membrane cannot apply heat to the entire system like an evaporator, so when the system is stopped and restarted, It is necessary to sterilize and clean the piping system and main parts of the system. A commonly used method for disinfection and cleaning is to pass an aqueous disinfectant solution through the entire system.
A method of brushing for a long time after sterilization and cleaning is known. If this sterilization/cleaning method is perfect, the number of viable bacteria will be 0/
It is possible to maintain 100 ml of sterile conditions for a long time, and it is also possible to maintain a pyrogen-negative condition. However, even if the system is in the perfect condition as described above, once the entire system is stopped, bacterial contamination will progress in a relatively short period of time, and the pyrogen will inevitably become positive. In this way, once the system is completely sterile, contamination occurs when the system is stopped because viable bacteria flows back from the end of the stationary water inside the pipes and multiplies within the system. It is considered. Methods to prevent this include installing a bacterial backflow prevention device at the end of the pipe to prevent backflow, and continuously operating the system without stopping the entire system. (Disadvantages of Prior Art) However, these methods have the following disadvantages. First of all, no matter what method is used to prevent bacterial backflow, it is often incomplete, and it is difficult to maintain a high degree of sterility with 0 bacteria per 100ml. It is much more effective to operate continuously without However, although this method achieves quality maintenance, it has the following drawbacks. (b) It consumes unnecessary power. (b) The wear and tear of the equipment is significantly accelerated, and maintenance costs and time are required. (Structure of the Invention) As a result of intensive studies to solve the above-mentioned drawbacks, the present invention was arrived at. The configuration of the present invention will be explained in detail. In other words, whereas the conventional technology maintains the quality by maintaining the flow direction and amount of liquid in the piping system in a state close to normal operation without stopping the entire system, the main part of the system is stopped and main processing is performed. This means switching to operation of only a small-capacity pump placed in parallel with the pressure pump to maintain the flow within the piping system, including the main parts, to the end of the use point so that it does not stagnate, even if only slightly. The small capacity pump used at this time means that the capacity is relatively small compared to the main pressure pump, and generally the motor output ratio used is 1/5 to 1/5.
Preferably in the 10 range. If you use a pump with too small a capacity, you will not be able to maintain the minimum necessary flow in the piping, which will be almost the same as stopping the system, and you will not be able to prevent the backflow of bacteria. Normally, when the flow velocity in the pipe at the end becomes smaller than several centimeters per second, the backflow prevention effect is lost. Furthermore, if the capacity is not much different from the main pressurizing pump motor, even if you switch from the main pressurizing pump to this pump, the energy saving effect will be small, and it goes without saying that the negative effect of increased equipment costs will be greater. . (Effects of the Invention) The following effects can be obtained when the method of the present invention is applied to, for example, a system incorporating a reverse osmosis device or an ultrafiltration device. (b) Power consumption can be significantly reduced because a small-capacity electric motor is used. (b) The load on the membrane module incorporated in the reverse osmosis device or ultrafiltration device is significantly reduced,
Lifespan is significantly extended. (c) The load on the entire system equipment is reduced,
Maintenance work is reduced. As described above, the method of the present invention can be applied not only when the factory is shut down at night or on holidays, but also when the factory is temporarily stopped during operating hours. The effect is large. Embodiment Figure 1 is a flow sheet incorporating a reverse osmosis device showing one embodiment of the present invention, where 1-1 is a raw water supply line, 2-2 is a main pressure pump, and 3-3' is a check valve. , 4-4 is a small capacity pump, 5-5 is a reverse osmosis membrane module, 6-6 is a concentrated water line, 7-7 is an ultrafiltered water line, 8-8 is a use point circulation line, 9-9 is a Terminal density filter, 10
-10 is a stop valve, and 11-11 is a sampling location. The arrows represent the flow of water in the system piping during steady operation, and the dotted arrows represent the flow of small volume water in the system piping when the small capacity pump is operated by the method of the present invention. Table 1 summarizes the specifications, operating conditions, and water quality analysis results of the main parts of the system used in this example and the comparative example described below. The raw water supplied was ion-exchanged water at room temperature.
The number of bacteria was 1.5 x 10 cells/ml, and it was positive (+) for pyrogenic substances. In the case of raw water, the number of bacteria is measured by sampling 1 ml of raw water and culturing it using the direct observation method, and in the case of reverse osmosis equipment, sampling 100 ml of water, passing the entire volume through a 0.45μ membrane filter, culturing it and measuring it by the direct observation method. Sexual substances were measured by the Limulus method. Table 1 shows the results of sampling and analysis once a day after the start of operation. Comparative example Small capacity pump used in the example (2Kg/cm ² ×1.8
Table 1 shows the results of the analysis conducted under the same conditions as in the example except that a smaller capacity pump (0.55Kg/cm ² × 1m/hour, 0.1Kw) was used instead of the pump (0.75Kw). Also listed. 【table】

[Brief explanation of drawings]

FIG. 1 shows a system flow to which the method of the present invention is applied, in which 2-2 is a main pressurizing pump and 4-4 is a small capacity pump.

Claims (1)

[Claims] 1. In a water treatment system equipped with a main pressure pump and a pump with a smaller capacity than the pressure pump in parallel,
A reverse contamination prevention method that prevents contamination by operating the small capacity pump when the main pressurizing pump is out of operation so as not to stop the flow of liquid in the liquid sending piping and processing equipment. 2. The method according to claim 1, wherein the water treatment system is a system using a reverse osmosis device. 3. The method according to claim 1, wherein the water treatment system is an ultrafiltration device.