Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
4.4 Reuse (Topic d)
Wastewater reuse is an issue in arid regions, and in other areas where water
costs are high. In 1993 the USEPA developed a guide for wastewater reuse. Many
states and provinces now have specific guidelines for reuse of reclaimed
wastewater, with the standards and criteria set in California being considered
the most stringent and progressive.
A standard reuse of wastewater is as utility water for the wastewater
treatment plant which produced it, especially for larger plants. The chlorinated
effluent water is used for washdown and for irrigation of the treatment plant
grounds, to save city water charges.
Irrigation methods are discussed under topic e, as they are also a disposal
method. Irrigation of golf courses, grassed playing fields, and highway medians
using treated wastewater is common in many arid and semi-arid areas of North
Large scale groundwater recharge is practiced in California, New Jersey and
Georgia. Orange County in California injects reclaimed water to prevent
saltwater intrusion to the local aquifer. Los Angeles has practiced surface
spreading to recharge local aquifers since the 1960s. The City of Perth Amboy,
NJ, operates two open water recharge reservoirs to supplement the local drinking
water aquifer and to prevent salt water intrusion. Clayton, County in George
applies reclaimed wastewater to its potable water watershed.
Wastewater is also reused by industries. In Texas, the Southwestern Public
Service Company of Amarillo Texas, operating gas fired steam generation electric
power stations, has used treated wastewater in its cooling towers since 1971.
Blowdown water from the cooling towers is used on local grazing land for
Dual plumbing systems reuse treated wastewater for non-potable purposes. At the
Las Vegas Treasure Island Resort Hotel, graywater mixed with groundwater is
treated with activated carbon, straining, preliminary disinfection, polymer
dosage, pressure filtration, reverse osmosis and UV disinfection before being
used to supply the hotel's "pirate sea". In Toronto, Ontario, the
Healthy House, a demonstration project, treats septic tank effluent with a
Waterloo Biofilter, multi-media sandfilters and ozonation and reuses the product
for laundry, toilets, baths and showers. At the Sandy Hill cooperative housing
project, part of the communal greywater is screened and treated with ozone for
reuse for toilet flushing in apartments. (Jowatt and Pask 1997). Many states and
provinces now have Plumbing Codes that permit dual plumbing (potable and
non-potable) systems that enable wastewater to be reused for flushing toilets
There are also instances of reuse as drinking water. Since 1978, Upper
Occaquan Sewage Authority in Alexandria, Va., has been blending 75.7 million L/d
of repurified water into a reservoir before being converted to potable water.
In San Diego, California, a wastewater effluent project was conceptually
approved for construction by the California State Department of Health Services,
which would discharge reuse treated wastewater into the City’s watershed for
use as drinking water. A water reclamation plant presently provides up to 10.7
million m3 /year of reclaimed wastewater for landscape irrigation and other
non-potable uses. By 2004, up to 18.5 million m3 you would have been further
treated in a water repurification plant for human consumption. The process
included micro-filtration, reverse osmosis, nitrate removal by ion exchange, and
ozonation. (Richman 1997). However, the City Council suspended the project in
January, 1999 and is now looking at other alternatives.
Another reuse project in Tampa Bay, Florida, which was also carefully
researched and pilot tested, was recently shelved in March, 1998 due to
difficulty building public consensus in several political jurisdictions, and the
availability of new desalination technology.