Water and wastewater (WWW) treatment – a look at the energy used for water in the US

While water and wastewater (WWW) treatment accounts for a surprising 5% of total U.S. electric power generation, topographically-variable WWW conveyance account for a more surprising 15% of the same total [Pod06; Coh04]. In addition, while wastewater contains energy in dilute form, current goals for recovering such energy represent only 0.02% of the total generation, through the use of microbial fuel cells of the future [Log04]. If, on the other hand, WWW were decentralized, up to 15% of total U.S. electric power production could be saved.

While centralization of WWW treatment was implemented to concentrate resources and ensure water quality, today many monitoring, quality control, and operation and maintenance (O&M) functions can be decentralized electronically. Imagine, if each building of the future contains a direct potable reuse system, then maintenance personnel, rather than driving to a central facility daily, would be dispatched electronically to neighborhoods for routine annual maintenance. Moreover, decentralization would increase the accountability of neighborhood residents in terms of responsible use of water, personal care products, and household chemicals.

Beyond energy savings, autonomous net-zero water (ANZW) buildings would not need to treat for most pesticides (US, 5 billion lbs/y) and industrial chemicals (US, 6 billion lbs/y), representing a total mass loading of 2 mg/L on U.S. surface and groundwater runoff. Treatment instead would focus on effective destruction of endocrine disrupting compounds (EDCs) such as pharmaceuticals, which cannot be as easily regulated in terms of environmental half-life as pesticides and other chemicals, by advanced oxidation. This latter advantage would address the current 6% feminization of male fish across all species (20%, black bass) in U.S. river basins [Hin09]. Finally, an urban demand for e.g. one million gallons of water every day in Southeast Florida would be removed from the (Everglades) natural system. Eliminated would be water rationing, and the need to treat seawater with total impurity levels two orders of magnitude higher than drinking water standards, to drinking water standards when impurities in treated wastewater e.g. in S. Florida currently meet 87 of the 93 numerical drinking water standards on average without further treatment.

Increased construction activity in the outlined areas over the last 10+ years. Many infill projects and zero lot line developments. Increased population growth in the target area with increased load (people) and demand (use per individual). Overall individual load has increased over X years by X gallons per day. Strain on water treatment system and infrastructure, especially close to water ways cited. Septic tanks systems that are undersized, outdated or broken, without eh owner knowledge. Purposeful (non permitted or documented) re-routing of sewage water to nearby water ways and excess burden on municipal sewer system with surface water runoff, increased rainfall intensity and more man-made diversions of water. Quantity of subsurface runoff (stormwater).

Estimates of water use in the United States indicate that about 410 billion gallons per day (Bgal/d) were withdrawn in 2005 for all categories summarized in this report. This total is slightly less than the estimate for 2000, and about 5 percent less than total withdrawals in the peak year of 1980. Freshwater withdrawals in 2005 were 349 Bgal/d, or 85 percent of the total freshwater and saline-water withdrawals. Fresh groundwater withdrawals of 79.6 Bgal/day in 2005 were about 5 percent less than in 2000, and fresh surface-water withdrawals of 270 Bgal/day were about the same as in 2000. Withdrawals for thermoelectric-power generation and irrigation, the two largest uses of water, have stabilized or decreased since 1980. Withdrawals for public-supply and domestic uses have increased steadily since estimates began. http://pubs.usgs.gov/circ/1344/