In the above image you can see an OXS-10 Ozone Water System. Ozone is an incredibly efficient component when it comes to aquaculture and hydroponics. In reference to hydroponics, the use of ozone can help in oxygenating root zones, as well as disinfecting and enhancing the hydroponic water quality. For aquaculture, ozone is used to improve water quality, reduce pathogens, and increase efficiency of the water treatment systems. We created a video going through the functions of the OXS-10, to see the video, Please Click Here! You can also Click Here to see more information, as well as purchasing options, for the OXS Ozone Water System.
Aquaculture is the breeding, rearing, and harvesting of fish, shellfish, algae, and other organisms in all types of water environments. 2 of the main applications we see ozone used in aquaculture is for fish farming and ozonated ice. Ozone works great for fish farming because it keeps the water cleaner, and therefore, the fish healthier. Healthier fish can eat more feed and grow bigger/faster. After fish are harvested, they are usually put on ice. By dissolving ozone into water and quickly freezing the water, ozone is essentially trapped within the ice. Locking ozone into the ice and setting the fish on top of the ice allows for the ozone to be slowly released and increases the shelf life for the fish.
One of the definitions of hydroponics is as follows, “Hydroponics is a technology for growing plants in nutrient solutions (water and fertilizers) with or without the use of artificial medium (ex., sand, gravel, vermiculite, rockwool) to provide mechanical support. Liquid hydroponic systems have no other supporting medium for the plant roots: aggregate systems have a solid medium of support.”
Produce Higher Yields
Less Labor Requirements
No Soil Needs
High Quality Foods
How Does Ozone Enhance Hydroponics?
Ozone allows us to disinfect water before it is used in a hydroponic system and gives us more control over the pathogens and algae that are present. Because of ozone’s efficiency in disinfection it is great for destroying bacteria, virus, and fungi, as well as eliminating microbes, algae and pathogens. It also gives us the ability to increase oxygen levels in the plants which can aid in increasing crop yields. Using ozone for disinfection saves money on chemical fertilizer, and can even get rid of unwanted smells inside of greenhouses.
While chlorine and ultraviolet light are the standard means of disinfecting water, ozone is equally effective in killing germs. To date, ozone has only been used as an oxidation agent for treating water in large plants. Now, however, a project consortium from Schleswig-Holstein is developing a miniaturized ozone generator for use in smaller applications such as water dispensers or small domestic appliances. The Fraunhofer Institute for Silicon Technology ISIT has provided the sensor chip and electrode substrates for the electrolysis cell.
Compared to conventional means of disinfection such as chlorine or ultraviolet, ozone dissolved in water has a number of advantages: it is environmentally friendly, remains active beyond its immediate place of origin, has only a short retention time in water and is subsequently tasteless. Due to its high oxidation potential, ozone is very effective at combating germs. It breaks down the cell membrane of common pathogens. In Germany, ozone is chiefly used to disinfect swimming pools and drinking water and to purify wastewater. Yet it is rarely used to disinfect water in domestic appliances such as ice machines and beverage dispensers or in other fixtures such as shower-toilets. MIKROOZON, a project funded by the State of Schleswig-Holstein and the EU, aims to change this. Researchers from Fraunhofer ISIT have teamed up with the Itzehoe-based company CONDIAS GmbH, which was founded in 2001 as a spin-off from the Fraunhofer Institute for Surface Engineering and Thin Films IST, and CONDIAS partner Go Systemelektronik GmbH, from Kiel. The three partners are developing a miniaturized ozone generator with integrated sensor technology and microprocessor control system.
Direct production of ozone via water electrolysis “The ozone generator is very compact and can be integrated in systems and appliances that require regular disinfection,” says Norman Laske, researcher at Fraunhofer ISIT. “You simply connect it up to the water line, and it will produce the right amount of ozonized water whenever required.” The ozone generator is only a couple of cubic centimeters in size and comprises an electrolysis cell, a sensor chip, control electronics to regulate current and voltage, and electronics to read the sensor signals. “The two electrodes are separated by an ion-conducting separator membrane,” Laske explains. “When a voltage is applied across the electrodes, the water is split by a process of electrolysis. Because of the diamond layer coating the electrodes, this process first forms hydroxyl radicals, which then react to form primarily ozone (O3) as well as oxygen (O2).”
The electrodes for the ozone generator are made of silicon wafers with precisely etched trenches. Credit: Fraunhofer-Gesellschaft
Diamond-coated silicon electrodes How the electrodes with their boron-doped diamond layer are made is the know-how that has given CONDIAS GmbH its name. The company already uses a chemical vapor deposition process to coat large-scale electrodes required to disinfect the ballast water of marine vessels. However, the electrodes required for the MIKROOZON generator are much smaller. They are made of silicon and have finely etched trenches that run through the electrodes to form narrow slits on the reverse side. In order to be able to etch these trenches with the required precision, the researchers from Fraunhofer ISIT had to have wafer material manufactured to their own specifications.
To build an ozone generator, pairs of these electrodes are mounted back to back, with a separator membrane between them. The gases are released at the interface to the separator membrane and then escape through the trenched structure to the other side of the electrode, where the turbulence of the water flow ensures that they are efficiently dissolved and dispersed.
The sensor chip from Fraunhofer ISIT is equipped with three sensors to measure conductivity, mass flow and temperature. These parameters need to be monitored in order to control the electrolytic process. The sensor chip provides the data that is required to control ozone production in line with the quality and the amount of water used. “In order to ensure that there is enough ozone available over the period required, the temperature has to be monitored,” Laske explains. “This is because ozone decomposes more quickly at higher temperatures.” Conductivity correlates to the degree of water hardness: the harder the water, the higher the conductivity—meaning that more current must flow in order to achieve the desired effect. When equipped with a system to monitor these parameters, the ozone generator should be capable of processing up to 6 liters of water per minute—without the sensor chip, it is currently specified for 0.5 to 1.5 liters.
CONDIAS is marketing the mini-generator under the brand name of MIKROZON. “Each partner has contributed years of experience from their own area of specialization,” says Volker Hollinder, CEO of CONDIAS GmbH. “This has created a product that can now be manufactured on an industrial scale. The spread of the coronavirus has underlined the importance of disinfection. The use of chemical disinfectants is often problematic, because they leave harmful residues. Our system uses electrolytically generated ozone to eliminate germs. It therefore does not produce any residues from disinfectants.”
Ozone has been used to disinfect water for over 100 years. Many water treatment plants throughout the world not only use ozone to disinfect water, but also remove organic compounds and improve taste and smell. Ozone is an attractive alternative to chemical treatment because it is very effective and does not introduce any new chemicals to the water you use. The drawback has been a high initial cost and equipment maintenance. Advances in technology have brought ozone within the reach of the average home owner, and small scale reliable ozone generating equipment has stood the test of time. Our ozone water treatment(WT) system is simple to operate and monitor to ensure that it is working properly to provide safe water. Here are five routine, simple, and quick checks of your ozone WT system to maintain your peace of mind.
You will know your water’s staying clean when …
1) The desiccant air dryer feels warm.
Put your hand near the top of the air dryer. Does it feel warm? If it is cold, something is not right. The air dryer contains two cylinders of desiccant material. It is the same stuff you find in little packets sometimes placed in the packaging of sensitive electronic equipment. This material absorbs moisture from the air. Eventually it becomes saturated with water and no longer absorbs moisture. The water is removed by heating the desiccant material. The desiccant air dryer is designed to cycle back and forth between two cylinders filled with desiccant material. When air is flowing through one to remove the moisture, the other is being heated to drive off the moisture. If the outside of the box feels warm, this is a good sign that all is well.
2) The moisture indicator is blue.
The moisture indicator provides additional assurance that your ozone equipment is getting dry air. This little viewer contains crystals that change color in the presence of moisture. When it is blue, you can be sure the air feeding your ozone generator is dry. If it is not blue, it could mean that the dryer is not working properly, the crystals have been contaminated in some way, or the crystals need to be replaced. Don’t become alarmed right away. The dryer requires a good six hours of uninterrupted operation to stabilize. If the location is excessively warm or humid, the dryer will not perform well.
If you continue to suspect that the air dryer is not performing as it should after a number of checks over the course of a few days, try to determine what has failed. If the dryer feels warm but the moisture indicator is not blue, it may be that the moisture indicator is contaminated. Newmoisture indicatorsare available from our store. It is also possible that the desiccant material has been contaminated or worn out. In that case, you will need one of ourdesiccant refill kits. If the air dryer feels cold, check the power connections. We also sell replacement heater tubesthat contain the desiccant. If you are unable to verify that the air dryer is working, it may be time for a new dryer.
The only part of the treatment system that is active 24/7 is the desiccant air dryer. All the other components wait until the well pump turns on.
3) The little silver ball in the flowmeter jumps up and hovers when the well pump turns on. (Newer models have a digital reading of air flow)
The flowmeter is a simple device telling us how much gas is flowing through the system. Air is pulled through the air dryer and ozone generator by suction produced by the black plastic venturi. Suction is created by the flow of water through the venturi. When the well pump turns on, water rushes through a narrow passage in the venturi. With sufficient flow, the water pressure differential between the input and output of the venturi creates air suction. Air flows through the tubing as it is pulled into the venturi. The little silver ball is lifted by this gas flow giving a visual indication that air is flowing through the system.
If no air flow is created when the water pump turns on, remove the ozone tube connected to the black venturi. Place your finger over the hole to see if suction is created. As long as the pump is running, the venturi should create air suction. If there is no suction, remove the check valve that is threaded directly to the venturi. Clear out any rust or mineral deposits. If the pump stops, water will squirt from this port, so try to open enough faucets to keep the pump running. If you are unsuccessful with getting air suction from the venturi, it could mean that the well pump is not pumping enough water through the venturi to create suction, or the venturi has worn out.
If you do have air suction at the venturi, but still no air flow indicated on your flowmeter, it may be that a check valve needs to be replaced or something else is blocking the flow. The source of blockage needs to be found and cleared before ozone generator will operate. The ozone generator turns on when it senses a sufficient flow of air. Most ozone generators will have a blue light indicating that the ozone generator is running.
4) You can smell ozone from the off-gas vent
But can you be sure that that sufficient ozone is being generated to disinfect your water? When your system is operating properly, left-over ozone that does not get dissolved into the water is vented from the top of your contact tank. If you remove the tubing from the off-gas vent, you should smell ozone when the system is running. It might take a little while for enough ozone gas to build up for venting, but when it accumulates at the top of the tank, it will be vented, often in short spurts.
5) Testing your water for dissolved ozone levels.
Ozone is a more powerful disinfectant than Chlorine. It destroys, inactivates, and prevents growth of bacteria and viruses with very low levels of dissolved ozone in water. As little as .3 ppm dissolved ozone for contact time of 5 minutes provides a 5 log (100,000 bacteria reduced to 1, 99.999% reduction) reduction of most bacteria and viruses. Contaminants are exposed to much higher levels of ozone when it passes through the venturi. By the time the water leaves the contact tank, any contaminants have been in contact with ozone long enough for most of them to be destroyed. The ozone has done its job and very little is left in the water that is distributed to your home. Enough will be left over to prevent growth. As little as 0.01 ppm will prevent growth. These low levels of ozone leaving your contact tank can be measured with our low costK-7404 dissolved ozone test kit. You don’t want much ozone left in your water. Too much ozone left over in the water can lead to irritating ozone off-gas at the point of use.
Ozone use for water main disinfection is possible, but has not caught on large scale here in the USA quite yet. Article below is a great example of an ozone trial that could grow the use of ozone use for water main disinfection in Australia, and hopefully more the world.
Reducing chlorine and chemical use worldwide is imperative for water quality and energy savings long term.
Unitywater first in Queensland to trial ozone water main disinfection
Unitywater is the first water utility in Queensland to trial ozone disinfection technology in water pipelines. Ozone disinfection sterilises water quickly and breaks down rapidly into harmless oxygen. The technique involves using ozone gas to inactivate bacteria and disinfect water mains. The ozone is pumped from a portable trailer unit, which can be placed on site where needed. Acting Executive Manager Infrastructure Services Division Michael O’Toole said Unitywater was partnering with Grenof Water Technologies to conduct the trial. “To ensure public health is protected, water utilities are required to disinfect new water mains before putting them into service,” Mr O’Toole said. “Traditionally Unitywater has used a process of chlorination to conduct this important disinfection. “Ozone is another option for us to consider as it is cost-effective, reliable, environmentally friendly and easy to use. “It also has the added benefit of sterilising mains quickly, thereby reducing delays for the development industry whenever new water main connections are required. “We are looking forward to the results of the trial.” Unitywater’s laboratory services staff will be testing water samples as part of the trial, while the ozone trailer itself also monitors water quality to ensure drinking water standards are met.
We connect with a lot of parents and clients who are doing great work eliminating toxic chemicals from their homes. They want to do even more, but they don’t know how – and that’s why they’re working with us. We advocate and implement ozone technology as a Toxic-Free Cleaning option.
The cornerstone of this system is using liquid (or aqueous) ozone to replace chemical disinfectants. Disinfectants are #1 on our list of 10 Most Toxic, so that’s a great place to start! Aqueous, or liquid ozone is perhaps the most misunderstood and maligned technology that we utilize, largely because of misunderstandings about ozone in general. Therefore, it has become the subject of undue concern.
To set the record straight, we’ve compiled a list of FAQs that we’ve received and answered for clients.
1. How safe is liquid ozone?
Liquid ozone is in fact a strong oxidizer. However, this does not mean that it is corrosive or combustible in the aqueous form (i.e. a solution of water). In residential and commercial cleaning applications it is completely safe and won’t harm bare skin. In fact, it may help to kill germs that your hands may have contacted during the cleaning process. Therefore, you don’t need to wear personal protective equipment like gloves as you would with harsh, chemical-based cleaning solutions.
The concern with liquid ozone tends to be around it off-gassing and becoming gaseous which dissolved at proper levels and sprayed at safe pressures won’t do (see #5 below). That being said, nobody has ever died of liquid ozone exposure, whereas every day someone dies from household chemical exposure. In fact, cleaning staff with asthma using our product say their breathing is perfect after working with it for 8 hours, contrary to the effect chemicals had on their breathing by the end of a shift.
2. Is liquid ozone bad for asthma suffers?
No. There is much confusion between liquid ozone and atmospheric ozone. However, high-atmospheric (gaseous) ozone concentrations are bad for asthma and allergy suffers. It can contribute to those Code Red days which the weatherman warns us about. Atmospheric ozone is created by Mother Nature to try to break down air pollutants like NOX, VOCs, dust and allergens. So on those Code Red days, more ozone is being produced naturally because there are more VOCs in the air. Ozone gas is an indicator that there are other atmospheric contaminants that also affect asthma and allergy sufferers like VOCs, nitrogen oxides, dust and pollen. Being quicker and easier to measure than the thousands of air pollutants, ozone gets a bad rap.
Man-made atmospheric ozone an also be produced by air purifying generators and filters to deodorize and disinfect rooms like operating rooms, hotel rooms, and even weather-damaged homes. Allergy and asthma sufferers should indeed be wary of such high concentration applications.
Liquid ozone cleaners, are different than atmospheric ozone generators. They create ozone gas infused into a watermedia, as opposed to the air. Since ozone is an unstable molecule, it reverts to oxygen faster than the water evaporates without off-gassing. In this way liquid ozone is a safe and preferential alternative to chemical disinfectants, many of which are themselves asthma triggers.
3. How does liquid ozone work?
Ozone is a molecule of three oxygen atoms (O3) that is not stable and will breakdown quickly and form radicals that have a high oxidation potential, or redox. This is what makes it a strong oxidizer and disinfectant. During the oxidation, only one oxygen atom is used for the chemical reaction forming with hydrogen into OH-radicals. Harmless to people, the ozone quickly attacks and eliminates contaminants it comes in which it contacts. The oxidization reacts with the cell walls of bacteria and viruses the same way hydrogen peroxide and iodine do, causing cell poration of the microbe, which leads to its death. The oxidation also removes electrons of molecules, eventually rendering them inert. In this way O3 kills the bacteria that cause odors, viruses that cause illness, as well as breaks down bio matter on surfaces that provide the food for microbes.
4. How much ozone do liquid ozone cleaning solutions contain?
It varies from application and manufacturer. It can be is as high as 5ppm or more for high-volume industrial settings but is normally around 2-3 ppm for most cleaning and sanitation applications. We keep ozone levels in water to reasonable levels to prevent off-gassing as ozone in air is regulated by OSHA.
5. How long does ozone last?
Ozone in aqueous form has a roughly 15 minute half-life (dependent upon temperature and water quality). While is is obviously NOT radioactive as “half-life” may seem to imply, it is used because of ozone’s rapid degradation. In 15 minutes half its solution has lost potency, at which point it is a better cleaning solution than disinfectant for the next few hours.
6. What residues will liquid ozone leave after it dries?
Contrary to chlorine, which always leaves an oxidation or disinfection byproduct, ozone simply will revert back to oxygen.
7. How strong is liquid ozone?
O3 is is often compared to bleach and other chlorinated products as they are used in many of the same disinfection applications. When used as such ozone has proven to be 50% stronger and 3000x faster than bleach.
In regulated cleaning applications, EPA guidelines direct us toward disinfection with chlorine and ozone. For example, disinfecting with 1 ppm chlorine at a water temperature of 59°F and a pH of 7 requires a dwell time of 75 minutes. The disinfection efficiency achieved will be 99.9 percent. Assuming the same temperature and pH, a concentration of 1 mg/l of liquid ozone water achieves a disinfection efficiency of 99.9% in only 57 seconds. For this example giardia is the parasite used in the water sample because it is one of the most difficult microorganisms to kill.
Ozone has many applications on the home and commercially. We covered cleaning using liquid ozone quite thoroughly by now. Ozone generators can be made for water treatment plants and are in use all over the world. There are applications for it in laundry and dish washing, but mostly in commercial or industrial settings.
Ozone generators have been used on both public and private pools as a means of disinfecting pool water. Similarly, some aquariums use it to keep water fresh and germ-free. Another important application is air purification. As an oxidizer it attacks the bacteria at the cell level, killing them and their aerobic activity, which is what causes odors and areas of potential for infection.
SB-100 Ozone Spray Bottle
The SB100 Ozone Spray bottle uses an electrolytic ozone generating cell to produce ozone in water as the bottle is used. No chance of low ozone levels as ozone is produced real-time while used. Great for small scale cleaning applications
Ozone Injection Systems
For larger scale applications an ozone water system can be used. Ozone levels in water of 3-5 ppm can be created easily at water flow-rates from 3 – 300 GPM.
Ozone can be very effective at treating well water for residential, commercial, or agricultural applications. Ozone is also commonly used for municipal water treatment, click here for information on ozone used for municipal water treatment.
Ozone implementation can be very simple, reliable and efficient. Ozone equipment is a one time cost with no salt, or other chemicals to buy. Only minor long term maintenance and electrical costs are incurred. Long term, ozone can be a more cost effective solution, while minimizing lugging of salt bags and chemicals!
When considering ozone for well water treatment keep in mind total water consumption in a day, but also peak water demand. Remember, ozone cannot be stored and must be produced as it is used. Therefore, the ozone generator must be sized based on peak water demand, not average water flow.
Also consider when sizing an ozone system for one application, like iron removal from water, that TOC in the water, while potentially not a primary concern, will need to be considered, as this TOC will also consume ozone and create ozone demand. Be ready to provide complete water quality data when trying to determine the size of ozone system for water treatment.
Every water is different. Also, each contaminate will require different ozone demand, and may require excess contact time, or filtration to remote contaminate. Below we outline considerations when trying to determine the right ozone system for your application. This is by no means a comprehensive list, for specific recommendations for your water, contact our ozone experts today!
Hydrogen Sulfide is found in well water where organics have broken down over time to form sulfides and hydrogen sulfides. H2S produces a foul odor and taste to the water. Some describe the odor as a “rotten egg” odor. Ozone can be used to efficiently, and safely remove H2S from water without the addition of any chemicals or salt.
Hydrogen Sulfide is oxidized easily by ozone into soluble Sulfite and Sulfate. Extra contact time of ozone with water will be required to ensure complete oxidation of H2S in water, however no filtration is required for H2S removal alone.
To oxidize H2S with ozone a working dosage rate of 4 ppm of ozone for every 1 ppm of H2S has been proven effective. A contact time with water up to 10 ppm may also be required for complete removal of H2S from water. This will be dependent upon incoming H2S levels in your water.
High levels of H2S in water will also foul resin beds of a water softener. Therefore, while the softener may remove some H2S from water for a while, this will not be along term solution. Another consideration is aeration of water to remove low levels of H2S. While a low cost solution, may increase the bacteria that formed sulfide to begin with and increase overall bacteria levels in the water system. Consider using ozone prior to a water softener to reduce H2S in water safely and provide water disinfection at the same time.
Well water and surface water may have taste and odor issues beyond the common H2S contamination. Iron, manganese, and other elemental metals in high levels can also cause taste and odor issues. Most commonly organics that are decomposing in the water source cause high bacteria, and other organics that will cause off odor or taste to your water.
Ozone will efficiently oxidize organics from water much the same as it will oxidize H2S from water. It will be helpful to ensure you have accurate water quality data to ensure ozone is an effective and complete solution to your taste and odor issues.
Coliform bacteria or other pathogens maybe found in well water, especially when the well is shallow. These pathogens commonly cause the well to be unused, or used for non potable applications. Ozone can be used to kill bacteria and pathogens efficiently.
As ozone is an efficient disinfectant minimal contact time is required, therefore minimal equipment beyond the ozone generator, and ozone mixing equipment is required.
Ozone is non-selective and will destroy all pathogens in water. Unlike other chemical based solutions bacteria cannot become immune to the oxidation action of ozone. Also, using ozone will ensure residual chemicals are not added into your water supply.
Commonly when using ozone for water disinfection other benefits are realized. Ozone will enhance particulate removal and coagulation of minerals from your water, reducing the salt used in a water softener, or enhancing overall taste and odor of your water.
Total Organic Carbon (TOC) is any compound containing the carbon atom that is not already fully oxidized. For example, CO2 would not be considered TOC.
TOC is found in most water sources in small amounts. High levels of TOC may be found in water containing microorganisms or other organic matter. Commonly TOC levels in surface water or shallow wells will change with the seasons, there may be spikes of high TOC levels during the spring or summer season.
Ozone can efficiently oxidize TOC into CO2 or other volatile or soluble carbonates. Only ozone in water and sufficient contact time is necessary for complete TOC removal from water. Ozone is a safe option, and a cost effective vs ongoing chemicals that are added to the water, or Activated Carbon (GAC) that will require replacement and maintenance.
The John J Carroll Water Treatment Plant in Massachusetts recently was declared to have the best tasting public drinking water by the AWWA (American Water Works Association). Water is evaluated much like wine would be to see who has the best tasting water.
A the John J Carroll Water Treatment Plant the water is treated with ozone for disinfection and water quality, but not filtered. The aquifer the water is pulled from does a great job of filtration. This provides water quality from the tap water in the area served on par with bottled water.
Tap water flowing in Framingham, Newton, Southborough, Waltham and Weston has been declared the best tasting public water in the country, according to a national water association.
To determine which area had the best tasting water, national water specialists from the American Water Works Association (AWWA) conducted blindfolded taste tests.
“It’s kind of like a wine tasting,” said Ria Convery, spokesperson for the Massachusetts Water Resources Authority (MWRA).
In the end, the MWRA water won the “Best of the Best” Tap Water Tasting Test. MWRA water originates from the Quabbin and Wachusett reservoirs in central Massachusetts and then flows via underground aqueducts to a filtration plant in Southborough.
The water filtration plant in Southborough delivers 200 million gallons of water to 51 communities, serving a total population of 2.5 million people – including people in Boston.
“The reservoir is designed for natural filtration,” said Convery. “We don’t filter, the source is well protected, and most of it is delivered by gravity.”
The John J. Carroll Water Treatment Plant in Southborough started using ozone to clean the water in 2005 and added the use of ultraviolet light in 2014. Ozone gas is bubbled through the water and is used as a disinfectant. UV light is also used as a disinfectant and can inactivate chemically-resistant parasites such as giardia and cryptosporidium.
“We are not adding chemicals or taking them out,” said Convery. “We don’t fool around with it a lot.”
The water that comes from the treatment plant has met every state and federal drinking water standard, according to the MWRA.
The water treatment plant provides great information on water quality and how the water is treated with ozone, uv and minimal chemicals.
It is completely possible to bring the same results achieved here to small municipal, industrial, and even residential well water. Contact us for more details on how we can achieve excellent water quality from your source water.
The city of Montreal is using ozone for waste water disinfection. This great article was put together to explain the use of ozone ozone. This is great PR as many times the use of ozone is misunderstood by the public. By educating the public there is buy-in for all parties. This is important as we all pay tax dollars for these systems.
Ozone consists of three oxygen atoms joined together into a single molecule of ozone. It is produced by the discharge of electricity in air. Ozone generators send an electric current through air or oxygen, which splits the molecules into separate oxygen atoms that combine with others to form ozone.
It is then injected into water in special tanks, where it breaks down bacteria by destroying cell walls. It also destroys 75 per cent of viruses, as well as the majority of pharmacological and cosmetic-based pathogens, considered important because Montreal is host to many of those industries.
Once the water has reached the end of the contact tanks, which in Montreal’s case are pipelines running 30 metres underground for kilometres before they spill into the St. Lawrence, disinfection is complete, and the ozone has converted back to oxygen.
Widely used in Europe, ozonation is much less popular in the United States because capital costs are high compared with other technologies like UV or chlorine, although disinfection rates are much higher. Maintenance expenditures, mainly for electricity, are also comparatively high, but this is less of a concern in Quebec because of it’s low cost hydro-electricity.
Montreal’s ozonation plant is expected to cost $9 million a year to run. Currently, Montreal’s waste water filtration plant spends $12 million a year to cover electricity costs.
Is ozonation the right solution to clean Montreal’s waste water?
In three years, Montreal plans to start operating the largest ozonation waste-water filtration system in the world. If all works as planned, the $285-million plant will inject ozone gas into the water to destroy the vast majority of bacteria, viruses and the more recent addition of pharmacological-based toxins before they’re flushed into the St. Lawrence River.
“This technological advance will soon elevate Montreal to be among the world leaders in waste-water purification,” Montreal Mayor Denis Coderre said in late March as the city announced the launch of the $100-million first phase of the project. An environmental boon to the health of downstream residents, be they plant, animal or human.
Except that being the first raises some troubling questions, especially when more than a quarter of a billion taxpayers’ dollars are at stake.
Being first is “foolhardy” in the opinion of McGill environmental engineering professor Ronald Gehr, who has specialized in waste-water treatment for over 25 years.
“Why are these technologies not more widely used? Because they don’t work,” Gehr said. “They are not efficient for waster water. They are efficient for drinking water.”
Waste-water plants in the United States abandoned ozonation because results were disappointing, Gehr said. Other municipalities typically use it as a secondary treatment process, after waste water has already been partly disinfected. Using it as a primary treatment method in Montreal, which has what is believed the third-largest waste treatment centre in the world, is unprecedented and risky, Gehr argued.
The fact only two companies bothered to bid on the $100-million portion of the contract that involves building the ozonation plant shows Montreal is going in a direction most companies find too risky, Gehr said. Degrémont Limité was ultimately chosen because it was the only bid that conformed to specifications. Gehr has been raising warning flags about the city’s intentions since public consultations were held in 2008.
“I felt at the time it was foolhardy to jump in and create the largest ozonation plant in the world for treating waste water whereas we just don’t have the expertise — we should rather build a smaller one somewhere and test it out like a pilot plant.” More consideration of ultraviolet radiation technology is warranted, and Gehr questioned whether the need justifies the expense.
Estimates for the total cost are already 40 per cent higher than the $200-million price tag given in 2005. Gehr predicts final cost overruns will be “huge.”
At Montreal’s Jean-R.-Marcotte waste-water plant on the eastern end of the island, everything is built on a scale designed for the gods. Four immense concrete wells plummet 17-storeys underground to collect water from the sewage receptor pipes running along the north and south sides of the island. Seventeen motors in the sub-basement, boasting 4,800 horsepower apiece, can each pump a backyard pool’s worth of water skyward in half a second.
The plant handles a volume of water that would fill Montreal’s Olympic Stadium every day. It handles 45 per cent of all the waste water produced in Quebec. When it was constructed nearly 30 years ago, it was the biggest in the world.
“When we built this plant, they said we were crazy,” Richard Fontaine, the man responsible for treating Montreal’s waste water, said during a tour of the bowels of a plant that is spotless and odourless despite its vocation. “Now they’re building them even bigger. If we can work this, I’m not worried about the new ozonation plant. I’m used to big stuff.”
Montreal’s plant collects the water that spews from toilets and storm drains, industrial plants and snow collection dumps, then filters out the solids, sands, and gravel, and treats it with chemicals to take out 70 per cent of the phosphorous, which promotes algae growth that clogs rivers and lakes. Leftover sludge is collected as a form of earthy mud that Fontaine delights in handing to gloved guests. (“I’ve had ministers hold this stuff, ” he chuckles “Even prime ministers.” ) The mud is incinerated.
While this is a step up from dumping untreated sewage into the river, it still does little to remove the bacteria borne mainly of human excrement dumped liberally into the St. Lawrence, as well as viruses and pharmacological pathogens emanating from medications dumped by patients, industries and users of illicit drugs.
“I don’t think the fish were expecting anti-depressants,” Fontaine said. Nor anti-inflammatories, hormones and anti-convulsant medication to temper the affects of Parkinson’s and epilepsy. Ozonation will remove 95 per cent of bacteria, most viruses and 75 per cent of pharmacological and cosmetic items, research studies show.
The province has been spared major environmental and health repercussions because of the huge amount of water flowing down the St. Lawrence that dilutes the effluent dumped into it, noted Viviane Yargeau, associate professor of chemical engineering at McGill University and specialist in waste-water treatment technologies. To this day, swimming is not recommended for several kilometres downstream of Montreal. Once the ozonation plant is installed, “indirect contact” with the water, meaning, for instance, water-skiers wearing wetsuits, will be possible within 300 metres of the city’s outflow pipes, and swimming allowed a kilometre downstream, Fontaine said.
A team of engineers, microbiologists, chemists and other experts mandated by the municipal and provincial governments have been researching the best solutions for over a decade, and decided on ozone in 2008. UV treatment for Montreal would be less efficient, almost equally costly and require the use of tens of thousands of glass tubes, which would have to be cleaned regularly, a prospect Fontaine said kept him awake many a night. Montreal’s plant has been testing ozonation for years, on a scale equivalent to that used by smaller municipalities, with excellent results. The only difference will be to increase the concentration of ozone used.
Fontaine said the capital costs of installing ozonation, most of which will be covered by provincial and federal grants, is not exorbitant when compared with the overall worth of Montreal’s plant, which Fontaine estimates at $3 billion, and the volume of water it treats. Cities like Toronto have at least seven waste-water treatment plants, whereas Montreal has just one to equip. There were only two bidders on the ozonation plant because there are few firms worldwide with the expertise to work at this level, Fontaine maintains. Initial cost estimates were low because there was nothing to compare with worldwide, and the city lowballed their estimate to keep bidders from charging too much. Final estimates will hold up, Fontaine promises.
“I don’t really see why the size is a concern,” Yargeau said. “It’s not just been tested, but implemented in many places in Europe, and even many cities in the United States. If it’s sufficient at a smaller scale, why shouldn’t it be effective on a large scale? … It’s great news.”
Montreal’s plant will be able to meet tightening environmental standards for decades to come and adapt to the new chemical toxins, Fontaine said.
While Fontaine said years of testing have gone into the decision, Gehr still feels the city is acting too hastily.
“The die has been cast, and you and I will be paying for it over the next I-don’t-know-how-many years,” he said. “I agree that ozone is more effective. But is it worth it?”
Fontaine said he’s convinced it is.
“We fight pollution, that is our mission,” Fontaine said. “I believe in that. If you’re asking me is it worth it, this kind of investment, my answer is for sure. This project is the best environmental news — this is not a line, this is what I think — probably the best environmental news touching our waste-water treatment and our waterways in 30 years. … It’s a good idea for my kids and your kids and their kids.”