New Advanced Water Reclamation Demonstration Plant Commissioned

Padre Dam Municipal Water District (USA) opened its Advanced Water Purification Demonstration Facility in late April of this year. The demonstration facility will use advanced water purification technologies to purify and test approximately 100,000 gallons of recycled water each day.

The facility was designed to deal with California’s severe drought conditions by developing a new local water supply. The full scale system would have the potential to provide a water source that is up to 20 percent of Padre Dam’s current drinking water supply.

The new process has four treatment steps – free chlorine disinfection, membrane filtration, reverse osmosis and advanced oxidation (ultra violet light and hydrogen peroxide). Advanced oxidation is capable of killing difficult to eradicate pathogens and removing micro pollutants other processes can not treat.

If successful, the treated water would be injected into the ground water basin to be withdrawn at a later time for treatment prior to distribution as drinking water. Additionally, Padre Dam will study the possibility of expanding Padre Dam’s proposed Advanced Water Purification Project to accommodate and treat wastewater from the other agencies’ service areas in order to provide additional water supplies. This expanded program could produce up to 10 million gallons of water per day.

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Barriers to Water Reuse for Drinking Water in the US

It has been demonstrated that existing technologies for advanced water treatment can successfully upgrade wastewater to drinking water quality in large scale. There are installation for water reuse/water reclaim in California that are treating municipal wastewater to drinking water quality in volumes over 70 MGD.

These technologies employed include membrane filtration, RO, UV and ozone. Despite the technology there are a number of barriers from keeping this from happening. The first issue is that while water resources are being depleted and lower quality sources are increasingly being used, most of the US has ample supplies of water. Second, advanced treatment technologies cost more money that conventional treatment technologies. Simply put, treating dirtier water with higher technology costs more. It is difficult to justify diversifying the water resource given the higher costs.

However, even in areas where water is scarce and governments are interested in exploring new approaches, there are challenges. Schemes for water reuse up till now have used indirect water reuse for potable water. Wastewater is treated and then injected into the ground for later use. Direct reuse, connecting the sewage plant to the drinking water plant is creates the “yuck” factor. People are more comfortable with the water passing through the environment prior to going directly from wastewater treatment to drinking water treatment.

Even if the “yuck” factor is overcome, there is a regulatory gap that needs to be addressed. There are no federal regulations in place covering this area, thus no guidance to the states. California, the most advanced in this area, hopes to have regulations in place by 2016. Many states just have guidelines. Without clear rules, it is difficult for planners and governments to decide how to proceed.

Finally, there is no one solution for all locations. RO systems for example produce concentrated waste streams that need to be disposed of. Some location have the ability to do so economically and other do not. So, solutions have to be crafted for each location and water source. This involves engineering that adds to the cost and complexity of each project.

In all likelihood, it will take many years for direct reuse of reclaimed water for direct potable use to become a mainstream application. Nonetheless, many intermediate projects are moving forward to increase the overall supply of clean water.

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San Diego Moves Forward with IPR Demonstration Employing Advanced Oxidation

San Diego City Council members approved a Water Purification Demonstration project using a indirect potable reuse (IPR) program.

Implementation of an IPR would provide a significant new local water supply, while reducing the amount of primary effluent discharged to the ocean, helping the City avoid a $1.5 billion upgrade of the Point Loma Wastewater Treatment Plant.

IPR projects take tertiary treated municipal wastewater through an extensive filtration process using membranes followed by some form of advanced oxidation. Advanced oxidation methods used include ozone/peroxide and UV/peroxide. These methods can remove micro pollutants and kill any remaining micro organisms. The water is then normally injected into a well field for later recovery for drinking water use. A direct potable reuse project (DPR) would take the water directly to a drinking water treatment plant.

A two-year study of a 1 MGD (3,785 m3/d) demonstration project at the North City Water Reclamation Facility (WRF) demonstrated the robustness of the multi-barrier MF/RO and advanced oxidation arrangement to produce better-than-potable-quality water from tertiary effluent. The California Department of Public Health (CDPH) gave conditional approval to the proposed IPR concept.

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Jamaica Considers Water Reclamation

Whenever there is a drought, Jamaican households go without water and crops yields are affected. There is also an increase in water-borne illnesses such as gastroenteritis. One method for overcoming the problems associated with occasions of drought in Jamaica is reclaiming water.

Reclamation of water is the treatment or processing of wastewater to make it reusable. Treatment involves the physical separation of particles followed by the use of microorganisms to remove dissolved organic matter and finally chlorine, ultraviolet radiation or ozone to make water suitable for human consumption. In the United States, this practice began at the beginning of the 19th century in Arizona and California. The recycled water was utilized to irrigate lawns and gardens and was also used as cooling water. Currently, US installations in California and Florida mainly use ozone based reclamation processes because it provides superior disinfection and micro pollutant reduction.

The benefits of recycling water are of such that many countries have embraced it in some form. Israel began using recycled water in 1965 to irrigate crops; in 1984 Tokyo used recycled water to flush toilets and in 1999 in Australia wastewater reclaimed from a treatment plant was used to irrigate vegetable crops

The Monterey (California) Regional Water Pollution Control Agency did a study in 1987 which they updated in 1998 which showed that recycled water from a nearby waste water treatment plant was as safe as well water when used to irrigate food crops. In 2003 the Florida Department of Environmental Protection stated at the 19th Annual Water Reuse Symposium that there was no evidence or documentation of any disease associated with water reuse systems in the United States or in other countries that have reasonable standards for reuse.

The reuse of water has been done safely and has been beneficial for many countries and can be beneficial for Jamaica as well. Reclaiming water can serve as a protection against droughts for Jamaicans who are consistently without water during periods of little or no rainfall. Jamaican farmers consistently face challenges with the supply of water to irrigate crops. Reuse water could be beneficial in this regard and lead to economic stability.

The challenge of water reclamation is developing the infrastructure. While the process is well proven around the world, the safe production of reclaimed water requires significant capital investment. Given the potential to help countries such as Jamaica, organizations like the UN, World Bank and similar organizations may be able to make loans to support such development.

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Grey Water Reuse – A Low Cost Option for Sustainability

A recent paper published in the AWWA Journal (Olmos & Lodge, 105:2,February 2013, pp 41-42) discusses achieving zero water use and reasonable payback periods for a housing development in Davis California. Net zero water use as defined here is that annula water use equal annual rain fall. This would make the development sustainable from teh stand point of water.

The study concluded that such an objective can be obtained by increasing teh efficiency of indoor water use and landscape water conservation. principle savings came from reducing the need to heat water for indoor use. Simple residential greywater systems for landscape irrigation showed relatively short payback periods, about 1-3 years. Improving the efficient use of potable water for landscape irrigation has alonger payback period.

This February issue of the journal also discusses other water conservation and resue applications in San Francisco. The city published a guide to designing greywater water treatment systems. For a one or two unit residence directly using washing machine effluent, no permit is required for installing a grey water system if the water comes directly from the washing machine and does not require a change in the buildings plumbing.

Treatment of residential grey water, at least from the washing machine, seems to be a low cost and easy way to make an immediate impact on the sustainability of water resoruces

In larger greywater projects, for example large buildings, more extensive treatment may be required, especially if the water is going to be stored for some period of time since this could lead to biological growth. Ozone has been found to be effective in these types of water reuse situations.

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Water Reuse Requires Multiple Barrier Approach

In previous posts we have talked about reuse of wastewater for drinking purposes including the feelings of Americans towards the use of wastewater for their water supply. In reality, many American’s already use wastewater as their drinking water source. If your drinking water plant is down stream of another cities wastewater plant, you are in effect drinking their wastewater. This does not include the impact of farm run off and run off from animal waste. The standards for treating water downstream of the wastewater plant is not nearly as high as for direct reuse, but that is what is happening ecluding teh dilution effect.

One aspect of the issue of water reuse that we have not covered is the anlytical aspects for evaluating water quality in these situations. Obviously, utilities must be aware of the different contaminants present in the water and have clearly defined public health goals before deploying technologies to treat the water. Some of the contaminants associated with pharmaceutical or personal care producsts are in extrmely low concnetrations, e.g. nano gram per liter quantities. So, sophisticated analytical techniques are required to measure these contaminants before and after treatment. Additional analytical techniques are required for measuring the advanced oxidants that are sometimes applied in these applications.

In terms of treatment, the complexity of the chemistry of water contaminants at different stages of the water cycle results in no single technology being able to remove all the contaminants. Thus, a multiple barrier system is needed to ensure their reduction and removal. This is the same approach promoted by the US EPA to balance treatment of difficult to remove micro organisms while minimizing disinfection by products.

Advanced oxidation technologies effectively remove many pharmaceutical and personal care products and disinfect the water. Ultraviolet (UV) light can be effective in destroying some contaminants, such as N-nitrosodimethylamine, as well as killing a most micro organisms. Reverse osmosis can remove most contaminants, but creates a concentrated waste stream that contains the contaminants. Ozone, another strong oxidant, can also be used before or after water enters the reverse-osmosis membranes to remove contaminants.

Water reuse treatment often includes the use of UV or oxidation and membrane-based technologies as part of a multibarrier treatment scheme. Alternative schemes such as ozone and granular activated carbon filters are being explored to disinfect the water and remove contaminants, residual odours, discolouration and by-products created by other treatment processes.

Water reuse is slowly becoming a reality in the US out of necessity due to decling water source quality and increasingly stringent regulations. Ozone and advanced oxidation have an important role to play in this regard along with other advanced water treatment technlogies.

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Australian Floods May Have Been Prevented by Water Reuse Schemes

The long Australian drought increase interest in Australia for people to talk seriously about recycling our sewage to use as drinking water. It is possible that if recycling schemes had been in place, the massive floods that followed last year might not have happened.

There are two kinds of recycled water: ‘Indirect potable reuse’ or IPR uses advanced water treatment processes such as reverse osmosis and advanced oxidation, before discharging the recycled water back into a river, reservoir, or underground prior to re-harvesting it, retreating it and reusing it. ‘Direct potable reuse’or DPR would do away with the return to the environment and the water would be pumped directly back into the city’s water supply system.

By the worst stages of the drought around 2007, it had become clear that some of Australia’s largest cities would need to adopt varying approaches to IPR in order to make full use of available water supplies. Major IPR schemes have since been partially developed in Queensland and Western Australia.

The Western Corridor Recycled Water Project (WCRWP) was developed during 2007-2010 partially as a means to supplement drinking water supplies in Lake Wivenhoe, South East Queensland. This is the primary source of drinking water supply for Brisbane and much of the surrounding area. The WCRWP uses effluent from six wastewater treatment plants, which is then subjected to advanced water treatment at three new plants at Bundamba, Luggage Point and Gibson Island.

Some of this advanced-treated water is now used for industrial purposes, but the idea of drinking it has been postponed until storage supplies drop to below 40 per cent of capacity.

That public’s negative response to the idea of drinking treated effluent is one of the reasons why DPR is not being pushed. But the floods may change the attitude about recycling. Like many reservoirs, Lake Wivenhoe has two conflicting roles. On one hand, it must provide security of drinking water supply by storing as much water as possible. One the other, it must protect Brisbane from otherwise inevitable regular flooding by maintaining as much empty space as possible. To achieve these twin objectives, the reservoir is divided into two distinct components. The bottom 1,165 billion liters is kept as full as possible for drinking water supply and the top 1,450 billion liters is maintained empty for flood control.

When operating at full capacity, the WCRWP can produce around 35 per cent of the total water consumption of Brisbane and surrounding areas. If this water was used directly as part of Brisbane’s water supply, Lake Wivenhoe could be relied upon for 35 per cent less water supply. This means that the same security of water supply could be maintained while dropping the full supply capacity of Wivenhoe by 35 per cent and thereby freeing additional space for flood mitigation. The flood mitigation capacity would be increased by around 425 billion liters, which is an increase of around 30 per cent.

In terms of water storage capacity, this new-found 425 billion liters of flood mitigation space is the same as immediately constructing a new equivalent sized reservoir, without the cost of construction and without having to relocate a single home or farm. In addition to completely avoiding the environmental impacts of new dams, it would enable less water to be captured by the dam enhancing natural flow regimes in the Brisbane River. To put this extra storage capacity into some context, a new 425 billion liter reservoir would be the fourth largest reservoir to supply drinking water to a major city in Australia.

Using the existing infrastructure of the WCRWP, water would be available immediately and there would be negligible construction costs. But most importantly, the freed-up storage space will also be immediately available to help capture and control major flooding events when they occur. With careful management, this additional storage capacity would have been sufficient to capture and contain the entire peak flow into Wivenhoe Dam that occurred between 9th and 13th January 2011. There would have been no flood in Brisbane.

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MBR Ozone System for Water Reuse in Seafood Processing

Pescados Industrializados of Mazatlan, Mexico, a tuna cannery, has installed a new MBR system with down stream ozone treatment. The primary purpose of the MBR is to treat wastewater from the plant to comply with effluent regulations of the Mexican government. 30% of the effluent is further polished using ozone, AC, RO for reuse in the cannery. Ozone water treatment is used in this case to disinfect the water and provide partial oxidation of wastewater components. Removal of micro organisms protects the AC/RO units from biofouling. Ozone has been used extensively in wastewater disinfection because it does not form undesirable disinfection byproducts.

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Orange County Reclamation Project a Model for the World

Water Factory 21 (WF21), Orange County Sanitation District (OCSD), was dedicated in a 1977 and transforms secondary municipal wastewater into water that exceeds drinking water standards. In 1991, the Orange County Water District (OCWD) was granted a California Department of Health Services permit to inject 100 percent reclaimed wastewater into a potable water aquifer without blending.

In early 1997, Orange Country planned and constructed the world’s largest indirect potable reuse system which was completed in 2008. The 70 MGD facility will eventually produce 130 MGD. It employs micro filtration, reverse osmosis and advanced oxidation treatment.

The facility has won many awards and has demonstrated that municipal wastewater can be reclaimed for uses up to and including potable water supply. It has served as a model for other agencies and encouraged the development of water reclamation around the world.

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Tokyo Wastewater Reclamation Process uses Ozone and Microfiltration

The Japan ozone Association in conjunction with the Water Re-Use Promotion Center, the Japan Water Works Association and the Japan Industrial Water Association held a seminar cover various issues related to ozone in water treatment with a focus on water reuse.

A highlight of the meeting was a tour of a water reclamation projection where over 1 MGD of water is being produced from wastewater. The water is serving various districts of Tokyo for toilet flushing and other applications. this project employs both ozone and micro-filtration membranes to treat the water to a high standard.

While this is a relatively small project, it points to increasing use of wastewater for secondary applications and to the use of ozone water treatment as one of the main components in a water reclamation system.

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