Wastewater recycling and reuse: How far will we go?

Current water shortage and the high cost of water, especially considering the drought conditions that have afflicted the United States in the last year, have made water reuse and recycling critical.

By Linda Chaloux, Environmental Health & Safety Research Analyst, U.S., Frost & Sullivan

The dwindling supply of natural resources, which is definitely more severe in states such as California and Florida, is an increasing cause for concern. The past few years have resulted in numerous companies and municipalities developing water reuse and recycling programs, involving a greater level of treatment at these facilities. However, what this reused or recycled water is now being used for, and the potential reuse applications are quite different, and is driving a decision that will inevitably reveal itself in the form of total water reuse, i.e. the 'toilet to tap water' concept.

Current water shortage and the high cost of water, especially considering the drought conditions that have afflicted the United States in the last year, have made water reuse and recycling critical. Water reclamation and reuse treats wastewater to a level that is safe for industrial, agricultural, and residential uses. As much as 50 to 70 percent of residential water use is spent watering lawns and gardens, while an average 39,000 gallons of water is used to produce the average automobile. Both of these, as well as numerous other applications can use non-potable, or non-consumable water. To get this water, treatment plants, municipally and industrially, must develop ways to reuse or recycle their water. That means additional treatment must be applied to the dirty water.

Recycling or reuse of wastewater is a significant trend in the water and wastewater communities. Recycled water is typically used for nonpotable purposes such as agriculture, landscape, public parks, and golf course irrigation, but also in cooling water for power plants and oil refineries, industrial process water, and water for toilet flushing, and construction activities such as concrete mixing. Recycling has many benefits to include protection of ecosystems, reduction and prevention of pollution. Though often times costly initially, water reuse and recycling measures are quite cost-effective in the long term. Implementing advanced wastewater treatment at wastewater treatment facilities enables the purification of a natural resource that is dwindling due to population increases. Water recycling and reuse is also beneficial because it reduces the demands on available surface and ground water sources. Additionally, recycling at wastewater treatment facilities delays the impending need to expand the potable water supply by building more drinking water treatment plants.

Industrial and municipal facilities are interested in recycling or reusing water as often as possible rather than immediately discharging into surface waters. Industrial facilities reuse their water to decrease the amount of wastewater being discharged to the municipal sewer, thereby decreasing costs for the industrial facility. The gray water, for example, from power plants, if treated to the secondary level, can be reused as cooling water. Additionally, advanced wastewater treatment will allow the gray water to be used as process water for paper mills and carpet dyers, construction activities, concrete mixing, and even artificial lakes.

Municipalities are also seeing wastewater reuse and recycling as a new avenue for revenues, and are therefore expanding their efforts in this area. For instance, if municipal facilities treat to the secondary level, that water can be used for surface irrigation of orchards and vineyards, non-food crop irrigation, groundwater recharge of non-potable aquifer sources, and wetlands and wildlife habitat augmentation. Tertiary or advanced treatment of gray water provides several additional uses such as home gardening, lawn maintenance, landscaping, food crop irrigation and toilet flushing.

Water reclamation is partly driven by the Pollution Prevention Act (PPA) of 1990 which indicates that pollution should be prevented or reduced at the source whenever feasible. Any pollution that can not be prevented should be recycled. Water recycling requires that effluent be treated to the maximum possible extent to reduce BODs, TSS, and other constituents in wastewater that could be potentially harmful to human health. Several technologies, such as membrane filtration, chemical precipitation, biological nutrient removal (BNR), and ion exchange systems, are being used currently to achieve water qualities that are acceptable for the previously mentioned reuse opportunities.

Water reuse and recycling doesn't necessarily end at irrigation, however, with areas of northern Virginia already implementing indirect water reuse (IWR) for drinking water purposes. Many populations across the country are adamantly opposed to reusing wastewater for drinking water purposes, not because it isn't clean enough, but because it is 'gross.' What these communities need to remember is that wastewater is already inadvertently ingested by consumers through the 'natural' water recycling process. Simply, wastewater is discharged into a river, and a community downstream withdraws that water supply to use for its drinking water. The IWR concept simply replaces some of the natural steps, utilizing chemical treatment and membrane filtration to achieve high water quality levels. Reverse Osmosis is one of the principal membrane technologies

used for this purpose.

Inevitably, water recycling and reuse will be necessary across the United States as populations continue to grow, while our water resources continue to deplete. Water reclamation for drinking water purposes is not readily accepted at this point, but as treatment facilities continue to expand to accommodate for more stringent regulatory requirements, the feasible next step is to use that highly refined wastewater again. This is a trend that should be watched for, as the likelihood of reusing wastewater for drinking water grows through the next several years.

For more information visit www.water.frost.com, or contact Kimberly Howard at 210.247.2488.

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