Water Reuse Potential for Expanding the Nation's Water Supply Through Reuse of Municipal Wastewater (2012) / Chapter Skim
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2 Current State of Water Reuse
2 Current State of Water Reuse
Pages 21-54
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From page 21... ...
. To understand the potential role of water reuse in the nation's water supply, it is important to consider Emergence of Sewer Collection Systems the infrastructure that has been developed to enable With the advent of pressurized potable water, per the collection, treatment, and disposal of municipal capita urban water use increased from approximately 5 wastewater because these systems serve as the source of gal/d (20 L/d)
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From page 22... ...
. As a result of these debates, downstream communities often took the responsibility for ensuring the safety of their own water supply by building drink ing water treatment plants or relocating their water supplies to protected watersheds.
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From page 23... ...
. Most of the sewage discharges increased during the postwar period, municipal wastewater treatment plants built in the with the passage of the Water Pollution Control Acts United States during the late 1960s and early 1970s of 1948 and 1956, which provided federal funding for were equipped with primary and secondary treatment wastewater treatment plant construction (Everts and (see Box 2-2 and Chapter 4)
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From page 24... ...
To protect downstream recreational users, waste Advanced treatment Nutrient removal, filtration, disinfec water effluent is often disinfected before discharge. tion, further removal of biodegradable organics and suspended solids, The most common means of disinfection in the United removal of dissolved solids and/ States is effluent chlorination, a process in which a or trace constituents as required for small amount of dissolved chlorine gas or hypochlorite specific water reuse applications.
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From page 25... ...
. In a recent study of drinking water supplies, one or more Increasing Importance of De Facto Water Reuse prescription drugs was detected in approximately 25 Irrespective of the treatment process employed, percent of samples collected at the intakes of drinking municipal wastewater effluent that is not directly re- water treatment plants in 25 states and Puerto Rico used is discharged to the aquatic environment where (Focazio et al., 2008)
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From page 26... ...
On an annual basis, about half of the water flowing into Lake Livingston is derived from precipitation. Therefore, water entering the drinking water treatment plant consists of approximately 50 percent wastewater effluent that has spent approximately 2 weeks in the Trinity River and up to a year in the reservoir before it becomes a potable water supply.
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From page 27... ...
Millions of Persons Served 12,000,000 10,000,000 8,000,000 Low Flow Avg Flow 6,000,000 4,000,000 2,000,000 Wastewater discharges upstream ÷ flow at point of withdrawal Persons served by a water supply with wastewater content according to EPA's 1980 survey of wastewater discharged upstream of drinking water intakes. SOURCE: Data from Swayne et al.
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From page 28... ...
Williams, CEH, personal communication, 2009. R02129systems currently provide reclaimed water for PLANNED NONPOTABLE WATER reuse Figure 2-5 irrigation, decorative water features, toilet REUSE APPLICATIONS landscape bitmapped flushing, fire protection, cooling water for and urinal As an alternative to releasing wastewater effluent air conditioners, commercial uses (e.g., car washes, into the environment, reclaimed wastewater can be laundries)
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From page 29... ...
uses • Potential ecological impacts depending on reclaimed water quality and sensitivity of species Groundwater Aquifer storage and recovery, seawater intrusion control, • Appropriate hydrogeological conditions needed recharge ground subsidence control • High level of treatment may be required • Potential for water quality degradation in subsurface Potable Water supply treatment • Very high level of treatment required water supply • Requires post-treatment storage augmentation • Can be energy intensive Miscellaneous Aquaculture, snow making, soil compaction, dust control, equipment washdown, livestock watering SOURCE: Adapted from Washington State Department of Health (2007)
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From page 30... ...
For example, calcium, magnesium, silica, and aluminum contribute to scale formation in boilers, while Dual Distribution and Distributed Systems for Urban excessive alkalinity and high concentrations of potas Water Reuse sium and sodium can cause foaming (WPCF, 1989)
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From page 31... ...
, receives secondary effluent from the Metro Wastewater Treatment Plant. Treatment at the Water Recycling Plant, which is located in close proximity to the Cherokee Station, includes the following • Nitrification with biologically aerated filters • Coagulation with aluminum sulfate for phosphorus reduction • Flocculation and high rate sedimentation • Filtration with deep-bed anthracite filters • Chlorine disinfection with free chlorine or chloramines depending on season and need The cooling towers typically run four to five cycles, and sodium hypochlorite is used as a biocide.
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From page 32... ...
The facility uses reclaimed water for cooling purposes and has zero discharge. The sources of the cooling water are two secondary wastewater treatment plants, located in Phoenix and Tolleson, Arizona.
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irrigation. More than 30 individual onsite wastewater treatment There are numerous examples of agricultural irsystems in the United States provide reclaimed water rigation water reuse projects in the United States.
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The city of St. Petersburg subsequently decided to upgrade its wastewater treatment plants to secondary treatment and eliminate wastewater discharge to surface waters by implementing a water reuse and deep-well injection program.
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. Design of the treatment plant facilities, collectively named the Salinas Valley Reclamation Project, was completed in 1994 along with design of the distribution system, known as the Castroville Seawater Intrusion Project.
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From page 36... ...
In cases where some of following ingestion or irritating to the eyes or skin, the reclaimed water from the seawater barrier reaches and should be safe from a microbiological standpoint. wells used for drinking water supply, the practice is Other concerns are temperature, pH, chemical comconsidered potable water reuse.
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From page 37... ...
the disposal of wastewater effluent or as an inexpensive means of improving water quality prior to surface water discharge. Nevertheless, the use of wastewater effluHabitat Restoration ent for habitat restoration or creation is a potentially In locations where surface water has been diverted important application of reclaimed water, especially for agriculture, industrial, or urban uses, decreases in in rapidly growing regions with limited availability of water availability have had adverse impacts on aquatic surface water.
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Therefore, to provide acceptable habitat, wetlands are usually supplied with wastewater POTABLE WATER REUSE effluent that has been subjected to additional treatment to remove ammonia (see Chapter 4)
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Between approximately 20 and 35 MGD (76,000 to 130,000 m3/d) of wastewater effluent flows through the wetland before being discharged to the St.
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From page 40... ...
were essential to potable water reuse projects. For the water supplies that were subjected to discharges of raw community, environmental buffers have been crucial to sewage.
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From page 41... ...
P-removal None Ultrafiltration, Ozone filtration Ongoing Media filtration, Reverse osmosis Reverse osmosis Reverse osmosis Microfiltration, microfiltration Chlorination Ongoing Microfiltration Reverse osmosis, UV Reverse osmosis Reverse osmosis Microfiltration, UV Ongoing Media filtration Soil-aquifer treatment Soil-aquifer treatment None Chlorination Ongoing Microfiltration Reverse osmosis, UV/ Reverse osmosis Reverse osmosis Microfiltration; UV AOP Ongoing Media filtration Reverse osmosis, UV/ Reverse osmosis Reverse osmosis Chlorination AOP Ongoing Microfiltration; Reverse osmosis, UV/ Reverse osmosis Reverse osmosis Chlorination ultrafiltration AOP Ongoing Riverbank filtration Riverbank filtration, UV/ Riverbank filtration; Precipitative Riverbank filtration, UV, AOP, BAC, GAC artificial recharge and softening chlorination recovery Under construction Ultrafiltration Reverse osmosis, UV- Reverse osmosis Reverse osmosis Chlorination AOP Ongoing Microfiltration Reverse osmosis Reverse osmosis Reverse osmosis Microfiltration the role of the environmental buffer in providing public sume that contaminant attenuation by photochemical health protection under the conditions encountered in processes occurs at the same rates in these two types of planned potable reuse systems has not always been well systems. Without good data on site-specific characterdocumented.
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From page 42... ...
of contaminants in reclaimed water depends on the The overview of potable reuse projects in the fol- source of the sewage and the treatment processes lowing section is intended to provide representative ex- used. For example, wastewater reclamation plants usamples of potable reuse projects, to illustrate the role of ing advanced treatment produce reclaimed water that environmental buffers, and to describe current trends in contains lower concentrations of contaminants than potable water reuse.
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From page 43... ...
The first of several planned seawater intrusion, land subsidence, and exhaustion indirect potable water reuse projects in the watershed of wells (NRC, 2008c)
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From page 44... ...
complex the aquifer, usually through unsaturated surface soils. of spreading basins recharges a mix of reclaimed water, Generally, surface spreading is accomplished in large local stormwater runoff, and imported water to an bermed basins with sand or permeable soil above an aquifer that serves as a potable water supply for resiunconfined aquifer where reclaimed water can percolate dents located as close as approximately 65 ft (20 m)
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From page 45... ...
The sea- the Talbert Gap and spreading at Kraemer and Miller basins. water barrier was a potable water reuse project because The source water for the 70-MGD (260,000-m3/d)
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From page 46... ...
. Düsseldorf has been using riverbank filtration of an Given the rapid growth in population in com- effluent-impacted section of the Rhine River water as munities that do not have access to ocean outfalls for a potable water supply since 1870.
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From page 47... ...
Manufactured water storage structures, not connected to the reservoir, thereby allowing them such as blending ponds or artificial aquifers, employed to maintain ownership of the water. Because the blend- in direct potable water reuse systems, can provide many ing pond would be a manmade structure that does not of the same benefits as natural environmental buffers, receive water from other sources, this potable reuse both in terms of public perception and contaminant project would not include an environmental buffer.
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From page 48... ...
United States EXTENT OF WATER REUSE The current extent of reuse is summarized in the Statistics on the extent of water reuse in the United following section, focusing on the United States, with States remain somewhat limited. Every 5 years, the additional information on other countries with large USGS releases data on U.S.
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In 2009, variability have created recent water supply challenges. an advanced water treatment plant with a capacity of 0.10 Water reuse in these states has become commonplace MGD (380 m3/d)
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From page 50... ...
In general, agricultural irrigation makes up a larger percentage of water reuse in California compared with Florida, while landscape irrigation Recreational and industrial reuse represent smaller portions of the Impoundment Landscape 7% Habitat overall portfolio. Both states have comparable extents Irrigation 4% 18% of reuse in the area of groundwater recharge (including Groundwater seawater intrusion barriers in California)
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From page 51... ...
In at relied upon agricultural water reuse as part of its water least five countries -- Kuwait, Israel, Qatar, Singapore, supply portfolio. Initially, wastewater from urban areas and Cyprus -- water reuse represented more than 10 was used directly for irrigation.
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From page 52... ...
A distinctive aspect of the planned ties, practitioners, and regulatory authorities. Nonwater reuse projects in Brisbane and Canberra was potable reuse currently accounts for a small part of blending of reclaimed water directly in drinking water the nation's total water use, but in a few communities reservoirs -- a practice that deviated from the estab- (e.g., several Florida cities)
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From page 53... ...
of NEWater currently is used for potable reuse via discharge to raw water reservoirs, accounting for slightly more than 2 R02129 percent of the total raw water supply in the reservoirs. However, the contribution of NEWater to the potable water supply is expected to increase Figure 2-19 in the coming decades.
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From page 54... ...
Potable of the nation's water systems, with some drinking reuse projects built in the United States between 1960 water treatment plants using waters from which a and 2010 employed environmental buffers in response large fraction originated as wastewater effluent from to concerns about public health risks and the possibilupstream communities, especially under low-flow ity of adverse public reaction to potable water reuse. In conditions.
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