Recently we ran successful pilot tests to evaluate phenol reduction with ozone in industrial wastewater. Our customer was a waste management company that offers wastewater treatment services to it’s customers. They will take wastewater from customers and process this water to safely discharge to the municipal wastewater system.
Limits on Phenol were lowered from 50 ppm to 1 ppm for an acceptable discharge limit to the municipal wastewater system. This presented a problem to our customer as phenol levels from various locations could range from very low, to well over 50 ppm. All of this water is mixed together in equalization tanks and processed with chemical processes, and ultra-filtration. None of these processes were able to lower the phenol level below 8-12 ppm on average.
What is Phenol?
Phenol is an organic compound - C6H5OH. Phenol is also known as carbolic acid. Phenol is found in petroleum products, detergents, herbicides, and pharmaceutical drugs. High levels of phenol are toxic and can cause permanent health issues.
Initial pilot test:
The first ozone pilot test consisted of a 300 g/hr ozone injection system recirculating water in the 5,000 gallon over a period of 12 hours of time. This did successfully lower phenol levels and prove that ozone was a viable solution. See chart below for data:
This data did confirm that ozone was a viable option. However, lower phenol levels were required, and a better process was required for process flow situations.
Final Pilot Test:
After initial processing the wastewater is stored in 5,000 gallon holding tanks prior to discharge. Overall water flow rate for the processing plant is an average of 10 GPM when averaged over a 24 hour time-frame. We decided to pull water from one holding tank treat that water with ozone at 10 GPM and pump that water to a second holding tank.
This new setup allowed for a 100 gallon contact tank to be used that could be operated under pressure up to 35 PSI to improve mass transfer of ozone into water. Also, the smaller 100 gallon tank allowed for very high dissolved ozone levels to be maintained for about 10 minute of contact time. See diagram below for details on this set-up:
Using the same 300 g/hr ozone injection system 300 g/hr of ozone was introduced into the water flow rate of 10 GPM for an effective ozone dosage rate of 132 mg/l. Despite this lower ozone dosage rate improved phenol reduction was achieved. This did achieve an acceptable phenol level of less than 1 ppm. Phenol levels up to 12 ppm were consistently reduced to less than 1 ppm at water flow rates up to even 12 GPM, an ozone dosage rate of 110 ppm.
Phenol removal prior to ozone was performed with carbon vessels. These did work well and achieve the necessary phenol reductions. Carbon replacement was necessary every 2-weeks at a total cost of $15,000/month. An ozone system to replace this carbon was rented at a cost of $3,900/month. With electric and all maintenance costs total costs were still less than $5,000.month for a total savings of $10,000/month.
This pilot test did show good results and proved two things.
First: Phenol reduction with ozone, in heavy industrial wastewater is possible and can be cost effective.
Second: using proper ozone mass transfer methods the efficiency of phenol reduction, and likely many other contaminates with ozone is much more efficient and offers large cost savings.
What is better than juicy red grapes sliced and sprinkled atop a leafy salad? Or what warms your heart more than seeing your child devour cluster after cluster of the succulent berries on a Saturday afternoon? After all, it’s not just a burst of sweetness that grapes offer with every bite–their flesh is saturated with vitamins C and K; their seeds, with antioxidants. So eating a lot of grapes is a good thing, right?
Yes and no. While it’s true that grapes ARE loaded with nutrients, it’s also a fact that they are exposed to chemicals–a LOT of chemicals. Grapes and their vines are fragile, and without the aid of modern agricultural pesticides and fungicides, those pretty grapes you feed to your children would have died and turned to compost long before making it to your kitchen table.
So how do we assist the survival of the grapes, and yet avoid ingesting those chemicals? This is where ozone steps in. A recent study shows that exposing grapes to ozone can reduce grapes’ fungicide residue.
In this study, a research team ran a trial to see if ozone exposure would increase the breakdown of fungicide residue on “Thompson Seedless” table grapes.
The grapes in the trial were treated with various fungicides. The grapes were then put into storage for 36 days. During the storage period, the control group was exposed to zero ozone. The trial group was exposed constantly to 0.3 PPM ozone.
While common grape fungicides do naturally break down over time, the study found that ozone helped several of the fungicides break down more rapidly. At the end of the 36 day trial period, the grapes in the control group still had 59.2% of the fungicide residue present. The grapes exposed to ozone, on the other hand, had only 35.5% of their fungicide residue remaining.
Further study is needed to determine if the chemicals resulting from the reaction between the fungicides and ozone cause negative health effects. In the meantime, though, ozone beckons as a hopeful assistant in keeping our grapes as clean and healthy as possible.
Link here to the original article, written by Emanuela Fontana. You can also purchase the complete study, published by the scholarly journal Postharvest Biology and Technology.
New treatment uses ozone and oxygen in hand-held device to treat herniated discs
By Pamela Fayerman, Vancouver Sun May 6, 2013
Patients and radiologists at Vancouver General Hospital are the first in North America to test an ozone/oxygen injection treatment to alleviate the pain from herniated discs in the lower back, a condition affecting at least five per cent of adults.
The treatment uses a combination of oxygen and ozone gas because its oxidating effect has been shown to shrink bulging discs, reducing compression by pulling the herniated part away from nerve roots.
The main objective of the clinical trial, now recruiting 25 participants, is to assess the safety of a new Canadian-engineered injection delivery system for the ozone-oxygen therapy. Discs are like the shock absorbers between the vertebrae; the experimental treatment requires radiologists to use CT imaging so they can guide the needle precisely into the centre of the herniated disc.
Ozone use for the degradation of aflatoxin in corn has become quite popular recently. There is a-lot of interest into the potential of ozone in this application. There is a great deal of data available that does prove that ozone will destroy aflatoxin.
With the rising prices of corn and other commodities the practical removal of unsafe levels of aflatoxin can be a necessary part of cost effective agriculture.
While there is a fair amount of lab data available, actual real-life data on the use of ozone to remove aflatoxin in corn, is not shared as much as other application. Recently we worked with a customer that did share the following information.
He used a 300 g/hr ozone generator on 6 bushels of corn for 2 hours of time. This reduced the aflatoxin levels from 58 ppb to 2 ppb. In further testing he was able to scale this to larger volumes of grain with lower ozone levels and longer periods of time. Thus, showing the potential of ozone use in a grain bin on a large scale over numerous days of ozone treatment. Also, he found that corn with higher levels of moisture showed improved results vs dry corn.
In addition to this data, we are currently in the process of building an ozone trailer with the capacity of 2,500 g/hr ozone generation for a customer in Indiana. This was secured after numerous on-site pilot tests with ozone were performed with ozone rental equipment.
On a large scale ozone gas can be introduced into the a grain bin aeration system. We have found that higher ozone concentrations have better results, and that the grain should be mixed or agitated during the process to ensure that all of the contaminated corn is contacted with ozone gas.
For additional information review the links below for technical papers on this topic:
Ever grab an apple out of the fruit bowl as you’re heading out the door, only to realize as the door clicks behind you that you forgot to wash it? If you’re like me, you don’t bother unlocking the door and going back inside to wash the apple. You quickly rub your sleeve over it and take the first bite, knowing even as you do so that you are leaving the bacteria alive and well on the apple’s skin.
What if you didn’t need to wash the apple, or even rub your sleeve over it? Kevin Keener, a food science professor at Purdue University, is doing a study on a method for ozonating fruit before it leaves its package. He has found that creating ozone inside a plastic bag of fruit kills food-borne bacteria. Even E. coli bacteria is killed after just 45 seconds of treatment.
It appears from the experiments so far that the quality of the food is not affected by the ozone treatment, although more studies will be performed in the future to ensure the quality of the food undergoing this treatment.
A recent Time news article, “Tipsy Fish: When Anti-Anxiety Meds Get Into Rivers”, discusses the effect that pharmaceutical-laden wastewater discharge may have on the behavior of aquatic life – even though these micropollutant discharges are not considered toxic by current testing standards.
The article cites a Swedish study where perch, a type of schooling fish, were pulled from rivers downstream of a wastewater treatment facility. These fish showed a bio-accumulation of Oxazepam, an anti-anxiety medication. Further lab testing showed that perch exposed to higher levels of Oxazepam became more agressive and willing to strike out on their own.
This sort of behavior is completely out of the ordinary for schooling fish. Indeed, a solitary schooling fish on its own in nature would almost certainly lead to its untimely demise. So while this particular drug is not toxic to the fish in a classic sense, it could have detrimental affects on fish populations due to changes in behavioral mechanisms.
How does this relate to the world of ozone? Current wastewater treatment technology fails to break down most micropollutants, including pharmaceuticals, which allows them to pass calmly into our rivers and lakes. One possible solution being tested by wastewater researchers is the use of ozone to combat these micropollutants. If the introduction of ozone does indeed prove successful at removing micropollutants from wastewater, it is one solution that may stem the ever-increasing tide of pharmaceuticals produced by our modern society.
If not, we can at least look forward to a future boom in wild-caught fish for the treatment of anxiety.
For more information about ozone research relating to micropollutants and pharmaceuticals, check out the IOA’s Ozone Engineering journal abstracts by searching the links here:
Several news stories have hit the headlines lately regarding ozone exposure incidents. For the most part, these have involved contractors or employees that were not directly involved with the use of ozone at these facilities. In other words, the individuals exposed were not familiar with the basics of ozone safety, but they were exposed to ozone nonetheless.
While these incidents can certainly become overblown by mainstream media (as media will do), that makes them no less significant to the ozone industry – it is public perception that counts. Where truth and media coverage collide, media coverage always has the upper hand. The matter is complicated further when ozone exposure incidents lead to civil suits – miring ozone-use facilities and ozone manufacturers in substantial legal expense and additional bad publicity.
Unfortunately, it is possible that these recent incidents could have been avoided if more care had been given to proper ozone detection equipment and proper ozone safety procedures. Whether you have a facility using ozone or are a manufacturer producing ozone systems, this is a lesson that needs to be taken to heart.
OSHA requirements dictate that ozone levels cannot exceed 0.1 ppm, so for the sake of expense many organizations implement a single monitor to satisfy the regulation. As applications for ozone increase, however, the number of individuals that work in the vicinity of ozone systems will also increase. While the increasing number of individuals does not increase the likelihood of an ozone leak, it does increase the likelihood of exposure if a leak does occur. For that reason, the extent of ozone safety equipment and training at a facility should instead be based on the likelihood of exposure – not just OSHA regulations.
What does this mean, exactly? Take these examples:
At a small company where all employees are familiar with ozone and fully trained in the use of their ozone system, a single or small number of monitors may be sufficient for employee safety. (As always, this also depends on proper maintenance, adherence to proper procedures, etc.)
At a large company, there may only be a handful of employees that use an ozone system and are familiar with its use. These organizations should implement additional ozone monitors and safety signage in any area where “non-ozone” employees may be present. This helps ensure that all employees in all areas can remain safe and act appropriately in the event of an ozone leak.
Public facilities need to take their safety measures one step further. In a facility where the general public could be exposed to an ozone leak, all areas need to be monitored (with redundancy where possible), proper maintenance should be observed, ventilation should be present, ozone equipment rooms should have limited access and staff should be trained in how to handle an ozone leak.
Regardless of how careful a company is, ozone leaks are a reality. As users of ozone equipment, please keep this in mind as you plan your ozone systems and then communicate your safety requirements to us as we help with the design process. As a manufacturer, Ozone Solutions will continue asking questions to ensure that the equipment we sell is being sold with proper detection equipment installed. Together we can help the ozone industry continue its stellar record of safety for another 100 years.
To sum up our ongoing series comparing ozone detection technologies, here is a full list that summarizes the advantages, disadvantages and common applications for various ozone monitor technologies. For further information, visit the Ozone Monitor Technology Comparison page on our website and then browse our product pages for details!
Electrochemical Ozone Sensors
An electrochemical ozone sensor uses a porous membrane that allows ozone gas to diffuse into a cell containing electrolyte and electrodes. When ozone comes into contact with the electrolyte, a change in electrochemical potential occurs between the electrodes causing electrons to flow.
In “zero air”, little or no electron flow occurs. As the presence of ozone increases, the electrical signal increases proportionally. The monitor interprets this signal and displays the ozone concentration in PPM (parts per million).
Good repeatability and accuracy
Very quick response time (1-2 seconds)
Long battery life
Can measure ozone accurately up to 20 ppm
Moderate resistance to interference
Humidity can affect sensor
Sensitive to EMF/RFI
Limited sensor life (12-18months), even if in storage.
Less accuracy at low ozone levels (below 0.1 ppm)
Personnel (portable) safety monitoring (esp. long shifts)
Ozone Leak Detection
Stationary ozone monitoring
Ozone Monitoring & Control
Semiconductor-Based Ozone Sensors
Heated Metal Oxide Sensor Cell (HMOS)
Gas Sensitive Semiconductor (GSS)
A heated metal oxide semiconductor (HMOS) sensor works by heating a small substrate to high temperature (around 300-deg F / 149-deg C). At this temperature, the substrate is very sensitive to ozone and exhibits a change in resistance that is proportional to to the amount of ozone which contacts its surface. The circuitry of the monitor interprets this change in resistance and displays the corresponding ozone level on the display as either PPM or PPB.
Very responsive to low levels of ozone ozone (below 0.1 ppm)
Slower response time to ozone (compared to electrochemical)
Very sensitive to interference
Shorter battery life due to heated sensor element
Not linear at ozone levels above 1 ppm
Ceiling Temperature threshold of 122F or less (depending on model)
The Ozone molecule has an absorption maximum at 254 nm. A UV lamp emmiting 254 nm wavelength of light is used to measure the absoption of ozone within a chamber. This is measured via a photodiode with a built in interference filter centered on 254 nm wavelength
Very accurate (within 1%)
Very linear at any ozone levels
Low ppb detection limits with accuracy
Minimal cross sensitivity to other gasses or interferences
Can read high concentrations (20% or higher)
Durable design with excellent longevity
Bench mount (no handheld)
Ozone badges are one time use cards that use a color change indicator. The indicator used is a small paper strip or circle that is oxidized in the presence of ozone.