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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Drinking Water Utilities Treatment Practices Based On Recent Disinfection Rules

The Long Term 2 Enhanced Surface Water Treatment Rules, know as LT2ESWTR was promulgated in 2006 obligating large drinking water utilities to comply with the rules by 2012. The rule was designed to prevent cryptosporidium, a difficult to kill pathogen from entering the drinking water supply. An incident in Milwaukee resulted in thousands of people becoming ill and others to die. It was considered a serious threat that was not treated by the standard disinfection method of chlorination.

The AWWA has reported on both the monitoring results and treatment methodologies employed by these utilities in the August issue of the associations journal.

The LT2ESWTR required utilities to first monitor their water for the presence of cryptosporidium. Based on these results, utilities were placed in bins associated with the observation of cryptosporidium being in present in the source water. The more pathogen found, the more aggressively the utility had to treat its water. Reservoirs ad lakes showed the lowest occurrence with 3.2% of samples showing the organism while rivers and other flowing water sources showed up to 11% of samples with the pathogen. The average was about 6.4% of all surface water sources had the organism.

If utilities fell into the higher risk bins, i.e. they observed higher levels of cryptosporidium, they were required to use EPA methods referred to the microbial tool box. Utilities assigned in the higher risk bins used a variety of methods to treat the water. These methods begin at the water source where plans to control the watershed are intended to prevent the organisms from entering the source water. Various filtration methods were employed by the utilities to filter out the organisms. Finally, some utilities upgraded their disinfection processes to inactivate the organism. One of the more popular methods was ultraviolet light or UV.

Unfortunately, the AWWA survey only looked at 38 utilities with 24 actually reporting results. So the study did not provide good statistical information on how the various methods are being used. For example, the particular utilities contacted had not used ozone, although ozone is used to control cryptosporidium, especially were water temperature is higher and their are other reasons for using ozone. For example, in reservoirs and lakes, algae can create significant taste and odor challenges for a water utility while also having to deal with cryptosporidium. So employing ozone water treatment in these cases can provide both taste and odor removal as well as pathogen reduction.

The Milwaukee outbreak lead to a detailed study of the drinking water systems in this country that use surface water. A well designed plan involving considerable public comment resulted in an enhancement of the safety of drinking water. Although the process took over a decade, the results will be enjoyed for many years to come.

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Advanced Oxidation Facilitates Industrial Wastewater Reuse

Advanced wastewater treatment technologies can allow industrial enterprises to reuse water and thus decrease industries use of fresh water resources. Currently, these processes are expensive and are probably only suitable for developed economies. This is compatible with the nature of industrial water use which increases with per capita GDP.

Industries consuming the most water include textile, chemistry, paper and food industries. Studies done in the EU and the US have shown that advanced water treatment technologies can increase reuse of water, thereby reducing the demand on freshwater resources.

Advanced oxidation process (AOP) using ozone and hydrogen peroxide combined with various membrane separation technologies can make industrial wastewater suitable for reuse. AOP is able to break down organic materials that are not readily biodegradable, sometimes referred to as refractory, making them amenable to biological treatment processes. The ozone reacts with the peroxide to form hydroxyl radicals. The hydroxyl radicals are a non specific oxidizing agent that breaks down organic materials into smaller molecules. Water quality is improved in other ways, for example reduction in odor and color.

The produced water can be used for different applications within the industrial complex such as cooling water make-up, water for back washing filters and other applications where the water quality is not as important. Even if the water is discharged, it is much less toxic and the environment can absorb it much more easily.

A further advantage of AOP, unlike membrane processes, is that there is no stream of concentrated waste formed. The entire water stream is treated to an higher level of quality. This offers the potential of zero liquid emissions.

Water reuse with AOP is a proven alternative, but its application is strongly dependent on economics. These technologies are both capital and energy intensive. the application of AOP will thus depend on water availability, quality and price, as well as regulatory requirements for zero emissions of polluted water.

Given the increasing limits on water resources and increasing regulations, AOP technologies such as ozone peroxide are likely to find ever increasing application.

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Santa Barbara Brings Ozone Drinking Water Plant On Line

Santa Barbara brings an advanced ozone water treatment plant on line to improve water quality after two years of development. Water for the City of Santa Barbara comes from Lake Cachuma and the Gibraltar Reservoir, both located on the Santa Ynez River. The water is treated at the William B. Cater Water Treatment Plant (Cater Plant). For the last two years, the City has been constructing new facilities to improve the water treatment process. Prior to the improvements, chlorine was used in the pre oxidation step prior to further treatment. An evaluation indicated that ozone is more effective than chlorine. Ozone reacts with organic material in the water, making it easier to removal in the subsequent treatment processes which include clarification and filtration. The recent upgrades in the process substitute ozone water treatment for chlorine in the pre oxidation step.

The Project was constructed to comply with new federal water treatment rules, which required lowering the allowable concentration of disinfection byproducts in the water. Disinfection byproducts are produced when chlorine combines
with naturally occurring organic material in the water, forming new compounds which are suspected to cause cancer. Ozone does not form these compounds. It also improves the removal of organic materials while improving the taste of the water. Over 1.6 billion gallons of drinking water per day are treated with ozone due to its superior treatment capabilities and the reduced risk associated with disinfection products. 9DVFG2NWT3Z4

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Sappi Fine Paper’s Cloquet Mill Installs the Largest Single Ozone Generator in the World

After $170 million in expenditures and a one-year construction period, Sappi Fine Paper’s capital conversion project was completed. The new production line is designed to produce specialized cellulose. The mill employs the largest single ozone generator of its kind in the world.

In the first two weeks of the new facility’s start-up curve, average production went from 500-600 tons to over 1,000 tons produced per day as ramp-up continued into July making it the largest manufacturer of the multi-faceted product in the world, with capacity totaling some 1.3 million metric tons per year.

Specialised cellulose, also known as dissolving wood pulp, is a versatile raw material used by manufacturers to produce a wide range of products including textile fibers and pharmaceutical, beauty and household products.

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