JPS60216808A - Process for preventing reverse contamination - Google Patents

Abstract

PURPOSE:To prevent back flow of bacteria while reducing electric power consumption and load on the machineries by driving a small capacity pump provided in parallel to a main pressurizing pump during suspension of the main pressurizing pump so as not to stop the flow of liquid. CONSTITUTION:A main pressurizing pump 2-2 and a small capacity pump 4-4 are provided in parallel in a water treating system installed with a reverse osmotic device and an ultrafiltration device. During a stationary operation, water flows from a feed water feeding line 1-1, to a main pressurizing pump 2-2, check valve 3, membrane module 5 in order, but the water is passed in an order from a small capacity pump 4-4 to a check valve 3', and the membrane module 5 when the main pressurizing pump is suspended so as not to interrupt the liquid flow in the liquid feed piping and in the treating devices.

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 pylon-enfree 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 reality in the industry is that there is a shift to metal-combined equipment such as ion exchange resin equipment, ultraviolet sterilization equipment, and precision filtration equipment.

(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 sterilizing and cleaning is to pass an aqueous sterilizing solution through the entire stem, and after sterilizing and cleaning, flatten the stem over a long period of time.

If this sterilization/cleaning method is perfect, the number of viable bacteria will be 0/100m.
/! It is possible to maintain a sterile state for a long period of time, and it is possible to maintain a pyrogen-negative state.

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 still water in the pipes and multiplies within the system. It is considered.

To prevent this, there are five methods, including 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, bacterial backflow preventers are often incomplete no matter what method is used, and the reality is that it is difficult to maintain a highly sterile state of 0 cells/100 ml. It is much more effective to operate continuously without stopping.

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 present 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. Pressure bong.

This means switching to operation of only a small-capacity pump placed in parallel with the pipe 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 a relatively small-capacity pump with respect to the main pressurizing pump, and it is generally desirable that the motor output ratio used be in the range of 115 to 1/10.

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 7 seconds, the backflow prevention effect disappears.

It goes without saying that even if you switch from the main pressure pump to this pump, if the capacity is not much different from the main pressure pump electric motor, the energy saving effect will be small, and the negative impact of increased equipment costs will be greater. That's true.

(Effects of the present invention) The following effects can be obtained when the method of the present invention is applied to a system incorporating a reverse osmosis device or an ultrafiltration device, for example.

(b) Power consumption can be significantly reduced because a small-capacity electric motor is used.

(b) The load on the membrane module incorporated in a reverse osmosis device or ultrafiltration device is significantly reduced, and its lifespan is significantly extended.

(c) The load on the entire system equipment is reduced, reducing maintenance work.

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 it is temporarily stopped during operating hours. The effect of the case is strong.

Embodiment FIG. 1 is a flow sheet incorporating a reverse osmosis device showing one embodiment of the present invention, where -1 is a raw water supply line;
-2 is the main pressure pump, 3-3 TI check valve, 4-4 is the small capacity pump, 5-5 is the reverse membrane forming module, 6-6 is the concentrated water line, 7-7 is the ultra-slough overtreatment Water line, 8-8 is point-of-use circulation line, 9-9 is terminal precision filter, 10-10 is Stonob valve, 1l-11id sampling point.

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, and the number of bacteria was 1.
．． 5 x 10 cells/ml, pyrogen positive (+). In the case of raw water, the number of bacteria is measured by sampling 1 ml and using the direct method after culturing, and in the case of reverse osmosis equipment, the number of bacteria is measured using the direct method.
(Sampled 10ml, passed the entire volume through a 0.45μ membrane filter, and measured by the direct method after culturing.
Pyrogenic 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 (2 kg/dx1.sm/
hour, 0.75 kW), a smaller capacity pump (0.55 kl?/dX 1 m/hour, 01 kW)
The operation was carried out under the same conditions as in the example except that the following was used, and the analysis results are also listed in Table 1.

Table-1 Procedural amendment (method) Manabu Shiga, Commissioner of the Patent Office1, Indication of the case Patent Application No. 70023 of 19822 Name of the invention Method for preventing reverse contamination3 Person making the amendment Relationship with the case Patent applicant address Mail Number 590 1 Teppocho, Sakai City, Osaka Prefecture Name (
290) Daicel Chemical Industries, Ltd. July 31, 1982
Add a brief description of the sun's surface.

4. Brief Description of the 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 (3)

[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, the small capacity pump is operated when the main pressure pump is out of operation, and the liquid sending piping and treatment equipment are Back contamination prevention method that prevents contamination by not stopping the flow of liquid inside (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.