Waternet covers the entire water cycle, from the treatment of waste water and provision of drinking water to cleaning and maintaining levels of surface water. These services are performed on behalf of the Regional Public Water Authority – Amstel, Gooi and Vecht – and the City of Amsterdam.

Amsterdam was one of the first cities to adopt the use of ozone for disinfection over a century ago.

Juice producing companies requires significant consumption of water and chemicals (detergents & disinfectants) for cleaning and disinfection of facilities, leading to a high volume of waste water.

AINIA technology center, Spain, has been investigating the development of cleaner post-harvest techniques applied to the citrus industry since 2010. This research has focused on three interrelated areas: hygiene equipment, product conservation and water treatment.

Laboratory and pilot work that has been completed concludes that the technical feasibility of developing systems for post-harvest treatment based on the use of ozone and ultraviolet light, is as effective as conventional systems,
and reduces the use of fungicides. Advanced oxidation of water discharged will regenerate the water that was used in treatments for possible reuse. Ozonated water used for cleaning juice tanks is as effective as the use of chemical disinfectants, but using a lower consumption of disinfectant and water.

Ozone is a powerful oxidant with a broad-spectrum bactericidal effect which does not generate chemical waste since it degrades rapidly to give oxygen, and ultraviolet light (UV) is a germicide that has no residual effect nor secondary.

Thus the use of advanced oxidation, has a high potential to become a useful tool for the citrus industry, mainly for its environmental benefits compared to traditional chemical fungicides used in post-harvest treatments or traditional disinfectants used in cleaning facilities.

The plant treats waste water to drinking-quality water. About 44% of the water is pumped into the Hueco Bolson aquifer which is a source of El Paso’s drinking water. About 54 percent of the reclaimed water produced at the plant is piped directly to two large customers: Painted Dunes Desert Golf Course, uses the water for irrigation, and El Paso Electric which uses the water to cool its Newman generating plant. The remaining 2 percent goes into an adjoining wetland.

The plant has increased its capacity from 10 million gallons a day to 12 million, but currently produces about 6 million gallons of water per day.

The project will allow the plant to discharge treated water into the adjacent wetland area that was created when the utility once used evaporative lagoons to get rid of waste water. When the utility needed to renew the plant’s permit several years ago, the Texas Commission on Environmental Quality decided to increase standards and require that a higher quality of water be discharged into the wetland.

The plant uses a multistep process to treat waste water:

1. It’s filtered for trash, then spun to remove sand and gravel.
2. Micro-organisms are then used to digest the solids in the waste water.
3. Powdered carbon is added to absorb pollutants
4. Waste water is then treated with chemicals like lime, ozone and carbon dioxide. Ozone is an important components of the treatment process because it is a broad spectrum biocide that can kill virtually all pathogens including viruses.
5. It goes through sand and granulated carbon filters and
6. Finally it is treated with chlorine.

Due to water shortages in various parts of the US and other parts of the world, water reclamation plants of this type will become more common.

While ozone has been successful use in water treatment for well over 100 years, it is not widely used in the food industry yet. This may be changing as the efficacy of ozone is proven out in commercial applications and alternative biocides fall out of favor.

To date, ozone treatment within the food processing industry has been carried out for decontamination of whole fruits and vegetables either by gaseous treatment or by washing with ozone containing water. Water containing ozone has been applied to the fresh cut vegetables for sanitation purposes reducing plate counts and extending the shelf-life. specific applications for ozone water treatment include reduced bacterial content in shredded lettuce, blackberries, grapes, black pepper, broccoli, carrots and tomatoes. A reduction of bacteria can result in a significant reduction in spoilage and potentially pathogenic species and most commonly associated with fruit and vegetable products.

Ozone treatment in the gas phase can be used to reduce the levels of either biological or chemical contaminants in grains. Applications include treating smoke damaged grain. Ozone has also been used in grain tower to drive away insects and other pests that can contaminate or damage the grain,

Despite success in a number of applications there is a lack of scientific and case studies on the use of ozone for food processing. This is likely to change as more food processors begin evaluating ozone for their specific applications.

During the shutdown the Metropolitan Water District’s Diemer Filtration Plant will undergo a series of operational upgrades and improvements related to a new ozone water treatment system.

Ozone water treatment for drinking water is increasingly being used to reduce contaminants in water, improve disinfection and improve the taste and appearance of drinking water.

Ozone, a form of oxygen, also works as an added barrier against viruses. A new building had to be erected to house ozone contact chambers, and half the cost of the total project went to the ozonation system. Switching to liquid chlorine will boost plant safety. Chlorine gas is an effective disinfectant, but also a highly dangerous chemical. The project also included new, Olympic swimming pool-sized filters that use granulated activated carbon and sand, replacing filters that used sand and anthracite.

The plant, which went online in 1985, produces about 5.5 million gallons of potable water daily and serves most of the town.

The panel included Shane Snyder of the U of Arizona, Chuck Graf of the Arizona DEQ and Guy Carpenter, a water reuse proponent and engineer. Dr. Snyder indicated that there is no litmus test to say for sure of the water is safe and that a risk analysis needs to be done. Mr. Graf felt that the risk was minimal. Mr Carpenter noted that there has been no evidence to date that reclaimed water is causing problems.

The application discussed at the meeting, snow making only creates casual human contact. Studies with mice and other mammals indicate that there is no apparent risk from this use.

Last year, Flagstaff got about 40 percent of its total water supply from Lake Mary, another 40 percent from underground wells and about 20 percent by treating waste water. That waste water is used for golf courses (the biggest consumer), manufacturing and construction, but the majority of this water is sent down the Rio de Flag in central Flagstaff and east Flagstaff, where it ultimately becomes part of the groundwater supply.

A University of Minnesota study finding one of the more advanced sewage treatment plants in the country was releasing material found in drug-resistant bacteria that can sometimes be fatal for people, including Methicillin Resistant Staphylococcus Aureus (MRSA). No live bacteria were found, however. Public health experts said the finding from Minnesota was noteworthy and that few facilities nationwide were subject to testing that would detect the so-called “superbugs.”

It seems likely that the use of reclaimed water will likely require additional testing and more sophisticated treatment in the future. New treatment will likely involve the use of advanced oxidation processes and ozone to insure that micro pollutants and super bugs do not reach people. Studies of these techniques indicate that they are indeed effectively in cleaning up the water.

In the spring, the city improved water quality by starting to use ozone at its largest treatment plant in Jameson Canyon, Costello said. Water treated with ozone has better taste and odor. The improved quality is expected to lead more people drinking tap water. Consuming tap water reduces the need for plastic water bottles. Other cities that have gone to ozone, as can be seen in past posts, have found consumer satisfaction rise. In fact, in blind tastings, the tap water often beats the bottle water.

While ozone offers many benefits for water treatment such as improved disinfection, reduction of disinfection byproducts, and improved clarification, taste and odor improvements are one of the main reasons why drinking water facilities adopt ozone. In fact, most bottled water is ozonated prior to bottling.

The criteria for a “living building” are determined by the International Living Future Institute, a Seattle-based organization dedicated to changing green building standards. The ILFI’s standards are considered to be the world’s hardest to meet. So far, only three buildings have been fully certified as Living, though about 100 other projects are in the works.

The building’s design aims to have net-zero emissions, meaning the building was designed to produce just as much energy as it uses. The roof of the building will be topped with photovoltaic panels that will produce enough energy in the summer to offset wintertime deficits and break even over the course of the year. The Bullitt center is expected to use less than one fourth of the energy of a normal building of its size.

The building also must supply and treat it’s own water, using a 50,000-gallon underground storm water cistern. One problem reported in the piece was regarding water treatment. Currently, the plans for the center show that it will collect rainwater for showers, sinks and drinking fountains, then filter the used water though a lower level green roof and landscaping. The raw sewage will be composted and sanitized before it’s shipped offsite to be converted into fertilizer. The problem, however, is that Washington State’s Department of Public Health requires public use buildings like this one that get water from anything other than the city, to chlorinate it.

Chlorine is on the prohibited list of the Living Building Challenge. The building’s designers are petitioning for ozone purification, which is a less toxic method. A number of green buildings have used or are considering the use of ozone as a green alternative to treating rain water or grey water in such applications. Ozone is made from oxygen in air and after use, ozone decomposes to back to oxygen leaving no disinfection by products. In addition, since it is made from air, there is no need to buy or store chemicals on site.

US drinking water systems are concerned about disinfection products that might contaminate the water either from contaminants that are in the chemicals used in the treatment or develop in the treatment process. Many of these contaminants have been identified by researchers and regulators and are regulated under the NSF/ANSI Standard 60. Changes to Standard 60 are always under consideration and new changes that can impact the disinfection process are anticipated to be effective in the year 2013.

Standard 60 covers the chemicals used in the treatment of water, including the disinfection chemicals, in general, and sodium hypochlorite and chlorine, in particular. Although there may be other changes to Standard 60, those effecting bleach are of importance to the industry. The changes relate to sodium hypochlorite and the contaminants in hypochlorite. These contaminants are bromate, perchlorate and chlorate.

Bromate

Bromate is a potent human carcinogen.. It can come from two separate sources in drinking water. The first is in the hypochlorite manufacturing process itself. Sodium hypochlorite is generally produced for bulk use by the reaction of chlorine gas with sodium hydroxide or can be produced on-site by the electrolysis of brine (salt) solutions. The compounds used in bulk production (chlorine gas and sodium hydroxide) can contain bromine (chlorine gas) or bromide (sodium hydroxide).

The bromine in the chlorine gas and bromide in sodium hydroxide are converted to bromate at the pH level of the sodium hypochlorite solution produced by the reaction. The addition of this hypochlorite to water in the disinfection process adds bromate to the finished water. Brine is used to feed on-site generation which also produces hypochlorite with bromate contamination.

Bromide ions can be present in the raw water supply, surface or ground water. When water containing bromide ions is exposed to disinfection using the ozonation process, the reaction of bromide with ozone will produce bromate ions. Most water system, however do not contain sufficient levels of bromide ions to make this a serious problem.

Perchlorate

Perchlorate affects the ability of the thyroid gland to take up iodine. This would affect the functions of the thyroid gland and its performance in the body. Perchlorate is a product of sodium hypochlorite decomposition. The longer hypochlorite is kept by the utility before use, the more likely the significant increase in perchlorate.

Chlorate Source

Chlorate can affect the health of certain population groups such as senior citizens, children, etc. Chlorate is included in the contaminant candidate list and will probably be included in the unregulated contaminant mandatory rule. Chlorate is formed when sodium hypochlorite decomposes in a bleach solution. Thermal decomposition of bleach is the primary source of chlorate.

Regulatory Considerations

The following are the current or proposed regulatory actions or regulations for each of the three contaminants or byproducts mentioned above:

1. Bromate – The maximum level of bromine allowed in sodium hypochlorite is expected to be reduced by January 2013 to around a level of 39 ppm. Currently, 69 ppm of bromate is the Maximum Contaminant Level (MCL) allowed in sodium hypochlorite.

2. Perchlorate – Several states have established regulatory limits for perchlorate in drinking water. Standard 60 is expected to have a perchlorate limit established by January 2013. The EPA has an advisory of 15 ppb of chlorate per liter of water but there is no deferral regulation for perchlorate in drinking water at this time. California has a maximum level of 6 ppb and in Massachusetts the maximum allowable is 2 ppb for perchlorate. New Jersey has a proposed MCL of 5 ppb.

3. Chlorate – Limits are being considered for addition to Standard 60 with a target date of January 2013. No current Federal regulations have been issues for chlorate. Currently Canada has guidelines established for drinking water for a MAC of 1 ppm.

The selection of a primary and secondary disinfectant is governed by both the requirements for pathogen inactivation and the production of disinfection byproducts. The choice between ozone and other agents such a hypochlorite with respect to bromate formation will depend on source water bromide levels. In areas where bromide levels are low and disinfection requirements are high, ozone will likely be the choice of more drinking water treatment facilities