Water is essential for all life on earth, but the availability and quality of water varies considerably in different parts of the world. Even in areas with access to good quality water, there may be situations that upset the lives of the population.One example is the outbreak in 2010 of the microorganism Cryptosporidium in the drinking water in Östersund, Sweden.

Approximately 27,000 people fell ill during the parasite’s ravages, which meant that more than half of the city’s inhabitants became sick with diarrhea. The outbreak is described as one of the largest ever in Europe.

When a large number of people fall ill in a limited geographical area, it is natural to suspect that drinking water is the source of the infection. However, it is relatively rare for the disease-causing organism to be detected in water samples. But in Östersund, the Cryptosporidium parasite was found in both lake water (water that is used for drinking after treatment) and in the outgoing sewage water.

The above case was widely reported in the media. As a result, many wondered if there are adequate water treatment methods to prevent similar outbreaks. Such methods are available and facilities for the treatment of sewage and drinking water have built up a barrier system to purify water from various types of pollution. The barriers are often a combination of mechanical, chemical and biological methods. One such barrier is the treatment of water with ozone gas. Ozone has proven to be effective against Cryptosporidium, but has many other applications for the purification of water.

Primozone is one such company that has developed an energy efficient method of generating ozone gas.

Ozone degrades rapidly

Ozone is formed from oxygen zapped at high voltages. The gas is unstable and therefore quickly reverts to oxygen. If ozone is to be used for water treatment it should be produced on site using an ozone generator.

“Traditionally, ozone generators were maintenance intensive and required a lot of energy,” says Anders Schening, CEO of Primozone.

“Our ozone generators are efficient. Our solution uses 70 percent less energy and less oxygen compared to conventional generators, which is a significant technological leap. We believe that the use of ozone has environmental advantages over the traditional chlorination of water. Chlorination produces dangerous by-products that pollute.”

Cold plasma method

Ozone can be generated using several industrial methods including corona discharge, cold plasma and UV light. Since ozone is a highly reactive substance, generators must be constructed with resilient materials such as stainless steel, aluminum or glass.

Producing ozone with the corona discharge method is very common in industrial applications and involves channeling air into a pipe with a strong electric field to create plasma. This method generates ozone at concentrations of between six and 12 percent.

Primozone’s generators use cold plasma technology. Cold plasma is a gas that is partially ionized and that can be created at room temperature or lower temperatures. The process is based on pure oxygen being ionized between two electrodes separated by an insulating barrier (dielectric barrier). This method consumes less energy than other methods and can produce higher concentrations of ozone, 14 to 20 percent concentrations.

The many uses of ozone

“It is a great advantage that our ozone generators are small, energy efficient and can generate high concentrations of ozone,” says Schening. “The water treatment market is big and there are numerous applications that are of interest to us. In addition to the purification of drinking water there is the purification of process water in manufacturing, and the re-circulating of water in fish farms.”

Some other examples of Primozone’s ozone generators include:

Disinfection of drinking water in Finland

Oulun Vesi WTP in Hintta, Finland replaced their old ozone generators with a Primozone system, including two low-energy Primozone ® GM12 ozone generators. Ozone is used for the disinfection of drinking water and to remove tastes and smells. The system purifies and distributes about 800 cubic meters of water per hour from a nearby river to Hintta residents.

Pilot plant for the control of bacteria in Helsingborg

The Öresundsverket in Helsingborg is one of the largest sewage treatment plants in Sweden that uses biological phosphorus removal. This means that no chemicals are added to purify water from phosphorus.

One problem is that during the late winter and spring a special type of bacteria emerges which causes major problems in water treatment processes. One way to control them is to treat the wastewater with ozone.

In this project, Primozone could examine and verify the ozone dose to achieve optimal results. This pilot project is part of a joint study between Lund University, NSVA (Northwest Skåne’s Water and Wastewater AB) and VA-South.

The article was published in January 2012