SEPA
- About SEPA
- The issue of waters
- What SEPA guarantees?
- Device description
- Conditions of installation
- Technical details
- Certificates
- Legionella Pneumophylis
- SEPA and waste water
- SEPA and pools
1.About SEPA
SEPA electrolytic unit for the treatment of water serves for the treatment of cooling or warm water for industrial purposes.
The treatment eliminates all forms of iron from the treated water and the treated water is clear and colorless. It also leads to a considerable limitation of the formation of varnish of the so-called water scale on the inner walls of heaters or coolers of water and connecting pipeline.
Due to these physical and chemical processes the environment of germs is eliminated, which form usual columns right under these deposits. For the additional disinfection of the treated water free chlorine is used, which is formed in an electrolytic decomposition of chlorine ions present in water.
For the perfect security of water against the formation of undesirable microorganisms copper ions are periodically released in the water in a controlled way by decomposing copper anodes. This way the so-called oligodynamic copper effects are used.
The result of the aforementioned processes is that the treated water is in a calcium-carbonate balance, i.e. there is no corrosion of metal materials or varnish and the water is sanitarily secured against the increase in noxious germs. The treated water considerably prolongs the life of technological apparatuses, pipeline distribution and other devices in the system.
The calcium-carbonate balance is strongly dependant on the temperature of water therefore the treatment plant is installed principally on heated cooling water or warm water for industrial purposes.
The treatment plant is always installed in the circulation pipeline, where the possible loss of water pressure is eliminated with a tonic pump, which is a possible part of the device.
The treatment plant is installed parallelly with the existing pipeline, which in case of defects or regular maintenance serves as its bypass.
WWT 05
2.What are the main problems in the pipeline of cooling and warm water for industrial purposes?
The main problem in the distribution system of cooling and warm water for industrial purposes is the quality of water with regard to the tendency of formation of varnish or corrosion. Varnish or corrosion are caused by the pollution of the system, decrease in the efficiency of the transfer of heat energy, considerable decline in the life of the whole system, and create optimum conditions for the formation of water microbiological pollution. It is therefore necessary for the cooling or warm water for industrial purposes to be in the so-called calcium-carbonate balance.
Besides these chemical and physical parameters another important problem is the microbiological pollution of water. This pollution is caused by three fundamental sources:
- Actual quality of crude input water in the system
- Cultivation of germs due to an increased temperature in the system and their growth on the impurities caused by varnish or corrosion
- Transfer from ambient atmosphere in open cooling systems
It can generally be defined that in case that the quality of circulation water is secured so that it is in the calcium-carbonate balance, the probability of microbiological contamination of the water in question is considerably lowered.
3. Why SEPA and what are its guaranties?
One of the fundamental functions of the SEPA water treatment plant is the function of reaching the maximum value of the water stability Ryznar index.
During the electrolysis of water with direct current the hydroxyl ions in the vicinity of cathodes are in excess, which results in the elimination of calcium carbonate on the surface of cathodes in the concurrent formation of free carbonic-acid gas. This reaction is controlled by the quantity of the direct current brought in the electrode system. The turning of polarity of the direct current in pre-defined time intervals leads to the release of varnish of calcium carbonate from cathodes. This varnish is subsequently eliminated from the water in hydrocyclone and the loading filter.
This process leads to the elimination of “excessive” calcium carbonate and with the formation of free carbonic-acid gas to the gaining of calcium-carbonate balance.
In case of water with a tendency to form corrosion the water is deaerated in hydrocyclone and gradually saturated with the eliminated calcium carbonate on cathodes. The effect of the elimination of corrosive products from the treated water is higher than 90%.
Since the balance is strongly dependant on the temperature, the “SEPA” water treatment plant must be installed on the heated cooling water or warm water for industrial purposes.
Another important function of the SEPA water treatment plant is the security of the microbiological compatibility of the treated water. This function uses the synergic effect of three independent SEPA processes.
One of them is the formation of compounds of chlorine and oxygen in the stage of nascent by an oxidation reaction on titanic electrodes. The formation of free chlorine is influenced and limited by the presence of free chlorides in the treated water. This process is ideal for the security of long-term microbiological compatibility, but in case of a strongly polluted system or massive contamination of water from outside it is not efficient enough.
For the security of shock and preventative disinfection of the treated water another stage of the process is the emitting of copper ions. The efficiency of the disinfection by means of copper ions and “oligodynamic effects of heavy metals” is generally known. The SEPA water treatment plant, due to the fully controlled system of electrolysis control with the help of digitally controlled sources, safely secures the controlled emitting of copper ions.
The third independent process is the use of natural filtration material Carbonsilic, which as biocide qualities and is approved as filtration material.
The efficiency of water treatment plant is more than 90% in the security of microbiological compatibility of treated water.
A very important function, especially for the cooling circuits, is the security of the automatic surface blowdown - decantation of the system. Due to the on line installation conduction measuring secures automatic operation on the basis of pre-set and calculated units.
4.Description of the device
The technological process is described by the enclosed technological scheme.
Treated water is taken back for the sucking of the tonic pump of pressure of the treated water. The delivery of the pump is placed an impulse water meter, which measures the flow of water in the treatment plant.
The first stage of the treatment is the electrolysis of water with direct electric current. Anodes oxidize all forms of iron to a filtered trivalent form and oxidize other inorganic and organic substances causing increased coloring and mist. Cathodes precipitate water scale in form of calcium carbonate and in higher temperatures of magnesium hydroxide.
Created varnish is periodically eliminated from the electrodes by short-term turning of the direct current polarity. This process is controlled with a controlling computer, which continuously evaluates physical, chemical and electrical units and controls the amount of the current and voltage accordingly to the electrode system, as well as the quantity of reversal of voltage on the electrodes.
Undissolved substances formed in electrochemical reactions in the first stage of the treatment plant are partially eliminated from the treated water in the second stage of the treatment plant. The stage is formed of hydrocyclone (tangential separator), which is constructed for the elimination of the most of solid suspended substances with the particle size larger than 0.2 mm.
Under the concurrent increase in the speed of water flow with a suitable construction of container, tangential inflow in the vertical container leads to the elimination of mechanical impurities in the water. These are accumulated in form of sludge in the lower feeder of the sludge, which in pre-selected time intervals is elutriated in the waste. After the elimination of mechanical impurities, water is transferred in the upper part of the container, where gases present in the water are eliminated.
The remaining part of undissolved substances is eliminated in the third stage of the treatment in a filtration through close-grained silicic sand. The filtration is processed downwards in a press single-chamber filer, equipped in the upper part with a water separator along the filter surface and in the lower part with a jet bottom provided with jets with slits of 0.2 mm. After using the so-called mist capacity of the filtration bed the filter pressure loss is increased and the load of silicic sand needs to be washed. The process is happening in the backwards water flow downwards, whereas the jet bottom serves as a separator of washing water along the whole surface of the filter and the upper.
The output of the treated water filter is installed a “Y” filter of 0.2 mm selectivity, which serves for the capturing of the filtration load in case of a defect of some of the filtration jets.
Treated water is taken from the treatment plant back to the circulation circuit of the heated cooling water of warm water for industrial purposes.
During night time, there is a minimum or no intake of the cooling water for air conditioning or warm water for industrial purposes. In such a time period the water treatment plant can be bypassed and the technology of water treatment plant can perform some special operations.
In the increase of pressure loss on the operation electrolyzer due to the growth of varnish in the interelectrode space, the voltage on electrodes is reversed for so long, until the surface of electrodes is completely clear. To eliminate the separated varnish from the electrolyzer its lower part is short-term elutriated in the waste. The success of this regeneration of the surface of electrodes is indicated both by gaining the right relation between the electric units and by the decrease in the pressure loss in the operation to the original value.
Another special operation, which can be performed as needed either during night unavailability of the treatment plant or during the common operation of the device, is the shock periodical dosing of copper ions in the treated water for the purpose of securing its microbiological compatibility. For this purpose the second electrolyzer is used with an automatic valve on the output of the water from the electrolyzer. Depending on the volume of the circulation circuit of the cooling or warm water for industrial purposes the relevant electric values are set for the controlled dissolving of the copper ions, which are enough to kill the present microorganisms.
5. Conditions of installation
5.1 Principals of the installation of SEPA units in the system of the cooling circuits
We install always two and only in the circulation of the cooling circuit and in the following variants:
- By means of a separate feed pump from/in an accumulation well
- In full-flow with a branch from the circulation circuit to the heat source
For a correctly designed size of the unit the following information is needed
- Overall flow of water in the circulations of cooling water (by the performance of circular pump)
- Overall volume of additional water per day
- Overall volume of cooling water in the system
- Maximum pressure and temperature drop in the system
- Chemical analysis of additional water and cooling water - pH, Fe, Ca, alkalinity, CO2 total, CO2 aggressive conduction
- Process a basic scheme of connecting the cooling circuit – type of cooling including of the lightness of individual pipes, types and power of pumps, types and volumes of accumulation tanks, cooling types and temperature drop maps
The optimum size of the unit is for the full-flow of the circulation flow in case of the variant of the actual feed pump; in this type of installation it is possible to secure the washing of the filter with the right function on the principle of pressure loss. For the cooling water the capacity of the treatment plant is designed on the basis of the overall circulation volume of the water and its chemical and physical parameters. It is though necessary to maintain the minimum flow for the sufficient washing of the filter of the minimum speed of 20 m/h.
In case that the flow through the unit is distributed as a branch from the whole circulation, it is possible to install the unit as the so-called “side filtration” in the relation of 80% - 95% of the circulation with the so-called “by-pass” and of a 5% - 20% through the unit; in this type of installation it is not possible to control the emergency on the principle of a pressure loss, but it is needed to follow the time.
The connecting pipeline including of fittings on the choking gallery must be fully functional and this needs to be secure before the actual installation!
Never install treatment plants on cool additional water, since their efficiency is minimized. In case that the additional cool water is polluted, the additional sieve needs to be installed behind the water meter.
In case of no guaranty that the pressure in the system is not higher than 0.6 MPa reduction and a safety valve must be installed.
5.2 Principles of installation of SEPA units in the system of cooling circuits of water for industrial purposes (TUV)
Always install only in the TUV circulation and in these variants.
- For the so-called reverse run
- For the output from the heater/flat, countercurrent, boiler
- Between the flat exchangers and accumulation tank
For the correctly designed size of the unit the following information is necessary:
- Overall flow of water in the circulation (by the power of the circular pump)
- TUV withdrawal tips
- Maximum pressure and temperature in the system
- Chemical analysis of the additional water - pH, Fe, Ca, alkalinity, CO2 total, CO2 aggressive conduction
- Process the basic scheme of the connection of transferring – exchanging station including of the lightness of individual pipes, types and power of pumps, types and power of heaters, types and volumes of accumulation tanks, type of primary heat.
Optimum size of the unit is for the full-flow of the circulation circuit; in this type of installation it is possible to secure with the function of filter washing on the principle of pressure loss. It is though needed to maintain the minimum flow for sufficient filter washing.
Connecting pipeline including of fittings on the choking gallery must be fully functional and this needs to be secured before the actual installation!
Never install treatment plants on cool water, since their efficiency is decreased to minimum. In case that the additional cool water is polluted, an additional sieve can be installed.
In case of no guaranty that the system pressure is higher than 0.6 MPa reduction and a safety valve need to be installed.
6. Technical data
| PARAMETR/MODEL | Unit | SEPA 300 | SEPA 500 | SEPA 800 | SEPA 1200 |
|---|---|---|---|---|---|
| Flow | m3/hour | 3 | 10 | 15 | 30 |
| Electrolyzer diameter Hydrocyclone diameter DN |
DN DN |
150 100 |
200 150 |
300 200 |
500 300 |
| Filter diameter | DN | 300 | 500 | 800 | 1200 |
| Pipe diameter | DN | 40 | 50 | 80 | 100 |
| Electrolysis feeding max | V/A | 12/1,5 | 12/5 | 12/7,5 | 12/15 |
| Operating pressure max | kPa | 600 | 600 | 600 | 600 |
| Operating temperature max | 0C | 60 | 60 | 60 | 60 |
| Weight total | Kg | ||||
| Nominal voltage Nominal input max |
V/Hz W |
240/50 40 |
240/50 130 |
240/50 200 |
240/50 400 |
7. Certificates
8. SEPA and Legionella Pneumophylis
Legionella Pneumophylis is a germ, which lives and reproduces in the water environment under the optimum temperature 25-50°C. Usually it lives in the so-called dead edges of pipelines or under the varnish on the inner walls of the pipeline or feeders, created of iron oxides and water scale.
Dangerous for a man is to inhale the aerosol of the contaminated water e.g. during showering. If a person has a weakened immunity system (elderly and ill people, after-operation state etc.), the entering of the germ in organism leads to a speedy development of pneumonia, which can even result in death.
Precautions against the development of germs of the Legionella type in the TUV system can be divided in primary and secondary.
Primary precautions:
- Sufficient heat insulation of the cool water pipeline especially when it is distributed along with the TUV pipeline or positioned in the vicinity of the heat source
- Sufficient heat insulation of the TUV pipeline against cooling and thermal radiation towards the cool water pipeline
- Sufficient circulation of TUV by eliminating the so-called dead edges of the pipeline, where the discharge fittings are in the distance of the maximum of 1.5 m to 3 m from the ascending pipe.
- Regular decantation of TUV feeders and ascending pipes including of the recommendation for the relief of the first water ratio (to reach constant temperature) at users after longer overcharging of water intake
- Regular cleaning of sieves before water meters
Secondary precautions:
- Periodical disinfection of the TUV pipeline with a high dose of chlorine (up to 15 mg/l)
- Periodic disinfection of TUV pipeline by dosing chlorodioxide (ClO2), produced in the place out of relevant chemicals
- Periodical overheat of TUV to the temperature of 70-80°C
- Periodical chemical cleaning and disinfection of faucet aerator at shower heads at users
- Installation of the treatment plant of warm water for industrial purposes
SEPA lowers the danger of occurrence and amount of germs Legionella Pneumophylis in several ways:
- Brings water to the so-called calcium-carbonate balance, which defends from the formation of varnish
- Older varnish on inner walls of pipelines and feeders is gradually dissolved
- Eliminates all iron and colloid undissolved substances from water, which cause increased mist and water color
- Due to the electrolytic oxidation of chlorides present in water to free chlorine it additionally disinfects the water
- Due to the electrolytic oxidation of free chlorine present in the water to chlorodioxide (Cl O2) it additionally disinfects the water with chemicals, which disrupt the cell structure of the germs and thus multiplies the disinfection with chlorine
To control the occurrence of Legionella it is needed in approximately 3-month intervals to take samples of the water at least for the input of cool water in VS, TUV output from VS and recurrent circulation water in VS.
The analysis is carried out by the local sanitary laboratory, which will also lend samplers for the take of samples.
9. SEPA and waste water
The use of SEPA for additional cleaning of cleaned soil water from communities up to 5,000 inhabitants.
Problem:
These small communities either have no waste water treatment plant or have an old one, which does not fulfill the required parameters of cleaned waste water (BSK5 – biological consumption of oxide per 5 days, CHSKCr – chemical consumption of oxide in a double-chromane method, NL - undissolved substances filtered by a filter of 2-4 microns and dried under 105 °C).
Use of “SEPA”:
The installation of the SEPA unit to the discharge of the cleaned waste water in the recipient (creek, river etc.) leads to the decrease in the above-stated parameters as follows:
NL = O (70 - 80%)
BSK5 = O (60 - 80%)
CHSKCr = O (40 - 60%)
The SEPA unit can be favorably used for the re-circulation of waste water to a back use (even for large water treatment plants over 5,000 inhabitants) as technological water, water for irrigation and the spraying of greenery, waster for the cleaning of technological devices, washing of floors etc.
10. SEPA and pools
The use of SEPA in the filtration and treatment of pool water
Problem:
The fulfillment of the ČSN-EN requirements requires the filtration of pool water and dosing of chemicals – chlorine, pH plus or minus, algicide or corrosion-proof preparations. These chemicals have to be produced, transported and stored, which generally harms the environment. In the pool the stock, preparation and dosing of chemicals create a potential danger not only for the service of the equipment, but also for the visitors.
The use of SEPA:
Installation of the SEPA unit on flow corresponding to the filtration of pool water (according to ČSN-EN) leads to the same effect without transport, storing, preparation and dosing of the above-state chemicals.
SEPTA unit secures the following:
- By the filtration of pool water while saving the work of water given by a pre-controlled hydrocyclone and washing of the load in reaching the pre-set pressure loss.
- By the chlorination of the pool water due to the dissolution of common salt (NaCl) to sodium hypochlorite – to gain the concentration of the free chlorine of 0.3 to 0.5 mg/l it will be needed to add common salt in the pool in the concentration of 0.5 to 1.5 g/l (expert estimation).
- Substitution of the algicide chemical with a shock dosing of the solution of copper ions prepared in the electrolysis from anodes produced of nutritional copper.
- By shock dosing of copper ions the quality of the pool water from the viewpoint of Legionella, which the classical chemicals in common doses cannot do.
- Substitution of chemicals, treatment of pH and anti-corrosion preparations, whereas on cathodes produced of nutritional stainless steel it eliminates excessive water hardness in the electrolysis and the pool water is brought to the so-called calcium-carbonate balance.