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METHODOLOGICAL RECOMMENDATIONS for application of anolyte produced on the STEL-10Í-120-01 installations (modifications 20, 40, 80, 120, 120A, 250, 250A, 1000) for disinfecting water in swimming pools 1. General data
Swimming pools are facilities of mass communal usage which makes infective contamination of their water unavoidable. Therefore, for prophylactics of infectious diseases, the pools and water in them will be cleansed and disinfected irrespective of adopted system of filling them with water, intended usage of the pools, their type, the type of serviced community.
Prophylactics of infection spreading will be carried out using both the visitors' personal hygiene, maintenance of cleanness of the pool water and pool's facilities, and observance of sanitary-hygienic and sanitary-technological regimens of the pools operation.
These Methodological Recommendations establish rules for application of the anolyte preparation obtained on installations for electrochemical activation of water-salt solutions: STEL-40 and STEL-80. Anolyte is a substance containing chlorine and characterized by physical-chemical properties enabling to use it as a substitute of chlorine-containing preparations used for disinfecting water in the pools.
The Methodological Recommendations establish rules for obtaining anolyte, its quality control in respect to chlorine content, application of anolyte for disinfecting water in pools, and the control of the disinfecting efficacy.
These Methodological Recommendations are intended as guidelines for disinfecting water in pools, the pools either being put into service or operating pools, after thorough cleansing, washing and disinsecting of their facility rooms, pool's basin, filters, water-supply system.
"The Recommendations for Disinfecting Water, Disinfecting Facility Rooms, and for Sanitary Regimen of the Swimming Pool Operation"
#1229-75 of 19.03.1975 is the main document establishing rules for personal hygiene measures, sanitary-hygienic measures, measures against epidemics, and sanitary-technological measures.
Purification and disinfecting of water and facility rooms will be performed by the pool personnel under a systemic laboratory-industrial control on the basis of an industrial laboratory, and under a systemic supervision by the sanitary-epidemiological inspection.
The pool administration will be responsible for observance of sanitary-hygienic regimen of swimming pool operation and for application of anolyte as a disinfecting agent.
2. The operation mode of the STEL-type installation for obtaining the disinfecting anolyte solution
Preparing of the installation for putting it into operation will be done in accordance with the statements cited in the Installation Operation Passport which should be read prior to start of the operation. Below, a principle order of operating the STEL-type installations is quoted.
The principle of obtaining anolyte possessing disinfecting properties involves an electrochemical activation of the salt solution containing a complex of different form radicals of atomic oxygen, chlorine, perchloric acid, hypochlorous acid, etc.
Equipment, materials, reagents. To obtain the anolyte on the STEL installations, these items will be used: sodium chloride by the GOST
4233-77, GOST 13830-84, or a white salt by Technical Conditions (TU) 18-11-3-83, TU 10-04. 00966671-333-92, or their analogues, sweet water by the GOST 28248-82, containers made of an electric insulating material with tight covers for collecting, accumulation and storage of the obtained anolyte solution, volumetric flasks by the GOST 1770-74 of a one-litre volume, a stop-watch /watch with a second hand will be admissible/, 10% acetic acid by the GOST 61-65) or 5%-10% hydrochloric acid by the GOST 3118-77.
Prepare the initial solution of sodium chloride /white salt or technical salt) with the concentration of 15%, 150 g/dm3. To do this, dissolve the necessary weight charge of the salt in a tap water and filter the solution thus obtained through a 2-layer gauze. Pour the prepared solution into the container. Watch that the solution in the container do not run out during the operation. To obtain the needed large volume of the solution it is necessary to constantly add the water-salt solution of the same concentration into the container.
The order of switching the installation on. Before starting the operation, make sure that the water flowing from the tap is pure and make sure that there is no leakage from the installation. By controlling the water flow attain the needed total expenditure of anolyte and catolyte: 60 l/hour. Measuring will be performed by dosing 1 litre into the volumetric flask while observing the stop-watch time. The water flow velocity should be 1 l/minute. Before connecting to the mains, make sure that the salt solution tap is closed. Switch on the electric current: 16 V. With ampermeter adjust the current for 8 amperes to obtain the needed concentration of the active chlorine in the anolyte. This will be attained by means of a gradual opening of the salt solution leak-in tap.
The order of switching the installation off. Shutdown the salt solution leak-in tap. Switch off the current. Open the salt solution leak-in tap and the catolyte tap. Descend hoses of the catolyte, anolyte output and the salt solution leak-in into a single container and wash them for 5-7 minutes with pure running water.
Without fail make respective entries in the registry book concerning the volume of obtained disinfecting solution. After every 400 litres of the disinfecting solution have been obtained, the installation should be washed with 1-2 litres of 10% acetic acid or 5-10% hydrochloric acid. The washing will be performed by means of feeding the acid solution into the anolyte output pipe, and the output of the spent acid - through the catolyte output pipe. All other pipes of the installation at that will be shutdown.
When connecting the installation with the system of feeding the disinfecting solution via a dosing device to the pool's blender, allow for a system of the water head automatic control in the water-main, as well as an automatic current strength control, which should provide a feeding of the anolyte disinfecting solution with the adjustable established parameters of chlorine concentration. To attain this, a relay of the current strength automatic control will be established on the STEL's rectifying device to maintain an established current strength of 8 A after adjusting the installation operation regimen. To stabilize pressure of water fed to the installation and to control it, an electrical contact manometer with a reducer automatically regulating the pressure and, accordingly, the water feed, will be established at the reactor's input. These parameters /current strength and intensity of water flow/ must be rigidly controlled and checked in feeding the disinfecting agent anolyte, in order to obtain a constant established concentration of chlorine.
3. Method of the anolyte quality control.
The principle of the method. The method is based on oxidation of potassium iodide to iodine with active chlorine, the iodine being titrated with sodium thiosulfate. Ozone, nitrites, iron and permanganate oxides and other compounds do not drive out iodine from the potassium iodide in an acidic solution, therefore the neutral anolyte will be acidified with a hydrochloric acid solution. If the anolyte is acidic with the pH value 4.5 and less, its acidification is not necessary. The iodine-metric method is intended for testing samples with the active chlorine content 0.3 mg/dm3 and more.
Equipment, materials, reagents. Flasks will be volumetric intended for laboratories, made of glass by the GOST 1770-74 and GOST 20292-74: volumetric flasks of 100 and 1000 ml; pipettes 5, 10, and 25 ml; burette with a tap 25, 50 ml. Conic flasks with ground-in stoppers capable to contain 250 ml by the GOST 2533á-82. Potassium iodide by the GOST 4232-74, chemically pure (c.p.) in crystals. Distilled water by the GOST 6709-72. Chloroform (trichloromethane). Hydrochloric acid by the GOST 3118-77 with a 1.19 density. Soluble starch by the GOST 10163-76. Sodium thiosulfate in fixanals of the norm-dose for preparation of the 0.1 N sample solution. When using the sodium thiosulfate in crystals, after preparation of the 0.01 N sample solution, a correction factor will be determined by the GOST 18190-72. When using the thiosulfate in fixanals of the norm-dose, the correction factor will be 1. All the reagents used in the analysis must be qualified as pure compounds for analysis (p.c.a.).
Preparing for analysis. Preparation of 0.1 N sodium thiosulfate solution. According to the instruction, the fixanal of the norm-dose will be dissolved in recently boiled and cooled distilled water, its volume being then filled up to the mark. Preparation of 0.01 N sodium thiosulfate solution. 100 ml of 0.1 N sodium thiosulfate solution will be diluted with recently boiled and cooled distilled water, its volume being then filled up to the 1-litre mark. The solution may be used when the active chlorine content in the sample will be over 1 mg/dm3. Preparation of 0.5% starch solution. Mix 0.5 g of soluble starch with a small amount of cold distilled water, add it to 100 ml of boiling distilled water and boil for a few minutes. After cooling, it will be preserved by adding a few drops of chloroform to it.
Performing analysis. Weigh 0.5 g of sodium iodide in a conic flask, dissolve it in 1 or 2 ml of distilled water, add 5 ml of 1:4 hydrochloric acid, add the solution volume to 200 ml and add 10 ml of anolyte. Mix well and put it in a dark place. In 5 minutes, titrate the driven out iodine with 0.01 N solution of sodium thiosulfate until a stramineous colour, add 5 ml of starch and continue the titration until disappearance of the blue colour.
Analysis of results. Calculate the content of total residual chlorine (X) in mg/dm3 by the formula:
Õ= Ó*Ê*0.355*1000/10 mg/dm3,
where Ó - volume of 0.01 N thiosulfate solution spent for the titration, in ml;
Ê - correction factor of the thiosulfate solution normality equal to 1 when using the sample standard titer;
0.355 - the active chlorine content corresponding to 1 ml of 0.01 N sodium thiosulfate;
1000 - converting coefficient of the active chlorine content per dm3;
10 - the anolyte volume in ml taken for the analysis.
An example of using the method of determination of the active chlorine content in the anolyte. In titration of 10 ml anolyte taken for the analysis, 13 ml of 0.01 N thiosulfate solution was spent. The active chlorine content in the anolyte:
X = 13*1*0.355*1000/10 = 461.5 mg/dm3 of active chlorine in the anolyte.
4. Method of chlorination of the pool water with the anolyte.
The principle of the method. Chlorination of the pool water with anolyte or any other preparation containing chlorine must proceed from a preliminary identification of the water's chlorine-absorption, calculation of the operational dose of anolyte introduced in the pool water, determining of the residual chlorine in water which should not be lower than the sanitary norm for the pool (0.5-0.7 mg/dm3), and control of the residual chlorine in water in the course of the pool operation.
Equipment, materials, reagents. They are the same as in the anolyte quality control (see Section 5.2).
Determining of chlorine-absorption of the anolyte chlorine by water. Take three one-litre flasks and pour 1 litre of the pool under study's water into each of them. Introduce three sequential doses of anolyte in volumes containing 1, 2, 3 mg of active chlorine. The method will be explained on example as follows. Flask #1: 1 mg of chlorine will be introduced or, in other words, 2.2 ml of anolyte; flask #2: 2 mg of chlorine will be introduced or, in other words, 4.3 ml of anolyte; flask #3: 3 mg of chlorine will be introduced or, in other words, 6.5 ml of anolyte. Calculations will be taken from the above example of determining the active chlorine in anolyte. Contents of the flasks will be thoroughly mixed and kept for 30 minutes: the time established for water contact with chlorine yielding a disinfecting effect. In 30 minutes of the contact, amount of the residual, i.e. unbound chlorine, will be determined by means of the iodine-metric method. In our example: titration of residual chlorine in the first flask took 0.2 ml of thiosulfate, in the second flask - 1.3, and in third one - 3.9 which, when calculating the residual chlorine, yielded the values as follows: 0.07 mg/dm3, 0.462 mg/dm3, 1.385 mg/dm3. In the second flask, the result obtained was the nearest to the sanitary dose of the residual chlorine. The water chlorine-absorption is: 2 mg - 0.462 mg = 1.538 mg. The operational dose involves the water chlorine-absorption plus the sanitary dose of residual chlorine, i.e. 1.538 mg + 0.5 mg = 2.04 mg/dm3 of active chlorine or 4.42 ml, when converted for the anolyte volume containing 461.5 mg of active chlorine per 1 mg/dm3. Under condition of a known and established pool volume, the anolyte volume will be converted for the pool volume and a necessary amount of anolyte will be introduced with the aid of a dosing device or an automatic STEL dosing device.
5. Control of the efficacy of the anolyte disinfecting of the pool water. The residual chlorine will be checked every hour in the pool water. If necessary, a conversion will be calculated taking into account the water chlorine-absorption and introducing a necessary dose of anolyte for maintaining the sanitary standard of the residual chlorine. |
