In July 2021 we were contacted by Mr Eric Jansen, business owner of “Mr Sprout”. As the name suggests, Mr Sprout is a supplier of salad sprouts to national chain stores.
As an environmentally conscious farmer, Eric was concerned that his company’s use of chlorine to control bacteria in their irrigation water was having an effect on both his product and the environment, and he was keen to explore the use of ozone as a disinfectant option.
The farm uses groundwater for irrigation, and all wastewater is treated before discharge using natural peat bed biofilters.
So the opportunity to use a powerful, natural disinfectant to treat his irrigation water, with no unwanted disinfection by-products, no residual chemicals and which would cause no harm to the environment, fitted Eric’s requirements perfectly.
The fact that ozone is generated onsite from oxygen in the surrounding air using only a little electricity, meant that there would be no monthly chemical costs, no handling or storage of hazardous chemicals, no chance of overdosing and no need to keep topping up chemical dosing tanks.
Ozone is created by splitting the oxygen molecule (O2) into two single oxygen atoms. Some of these oxygen atoms then recombine as ozone (O3), so ozone is purely a different form of oxygen, and returns back to the stable O2 form when its work is done. There are no harsh chemicals left behind. In fact, the additional leftover oxygen has many advantages for the farmer.
Eric was also interested in being able to monitor his water quality remotely, specifically the ORP (Oxidation/Reduction Potential) of his irrigation water, so that he could make sure that adequate disinfection was being applied.
So with EarthSmart’s water treatment and ozone experience, together with one of our remote monitoring systems, it was a perfect fit.
We installed the ozone generator and the results were obvious immediately. The ORP values showed that adequate disinfection was being applied in an extremely short time – under two minutes to treat the irrigation tank water.
Even though ozone is a natural disinfectant, it works very quickly – up to 3000 times faster in comparison to chlorine, and it has much more oxidation power than chlorine.
Eric immediately noticed that the growing area smelt fresher, which was no surprise as ozone gas is used extensively to treat odours – in cars, hotel rooms, fire damaged buildings etc.
The first samples for microbiology were submitted to the lab for testing, and came back with a 100% clean record:
Remote Monitoring
EarthSmart designed, built and implemented the remote monitoring solution, and the data it produced immediately gave us insight into what was happening inside the tank.
Remote monitoring allows Eric to monitor his water quality on his mobile phone from anywhere in the world, and it allows EarthSmart as a service provider to stay updated on the performance of installed equipment and possible maintenance needed.
The remote monitor is set up to send alert notifications automatically in the case of low ORP values, or the system going offline. The system also monitors the water pH, and will send an alert in the case of possible pump failure.
Using our remote monitoring system and plotting a chart of the data being sent, we could see that the ozone raised the oxidation (disinfection) power of the water very quickly, over a time of approximately 90 seconds, and then the ORP decreased slowly over a time period of between four and eight hours.
When the initial chemical dosing system was installed, the sensor probes had been positioned in part of the circulation loop, and they would only show the true readings when water was being passed over them during circulation.
This meant that the circulation pump needed to be running to get any meaningful information from the sensors. The remote monitoring data showed us that the circulation pump was running for hours on end while it was providing very little benefit in terms of disinfection.
Electricity Savings
At EarthSmart we always try to repurpose our customer’s existing equipment in the most economical way, so rather than just replacing the existing pump with a smaller unit, we looked at how to reduce the circulation time while using the existing 1.1 kW pump.
We hatched the plan to move the probes to the tank, where they would constantly give an indication of the state of the water. Eric’s existing chemical dosing controller, which would normally start and stop the disinfectant dosing, could also be used to start and stop the circulation pump.
This meant that instead of having to run the circulation pump 24 hours a day, the controller now runs the pump (and ozone generator) for around 90 seconds at a time, around 5 times a day.
Eight minutes a day versus 24 hours. That’s less than 0.6% of the original circulation time.
When a pump uses 1.1 kW of power, that’s a substantial electricity saving on a monthly basis and over the course of a year!
Benefits
- No more purchasing, handling and storage of chlorine
- Natural form of disinfection using a naturally occurring gas
- No harsh chemical by-products
- No chlorine residual allows wastewater biofilters to work more efficiently
- No overdosing of chlorine causing browning of sprout roots
- Oxygen left over after ozone use promotes root growth
- Ozone introduced during irrigation removes odours and leaves the growing area smelling fresh
- Improved water quality as ozone oxidises unwanted elements
- Ozone’s micro flocculant properties allow for more efficient filtration
- Significant electricity savings
- Remote monitoring constantly provides insight into water quality
- Automated notifications if water quality is out of spec
- The water quality monitoring provides information for food safety audits
The benefits to farmers and food processing companies of replacing chlorine with ozone and having the ability to monitor and control their water quality cannot be overstated.
From Eric: “Adrian and his team have managed to solve numerous water quality-related issues with one solution. It was great working with Adrian to tailor-make the best solution for our application”.
