The earth's surface is comprised of approximately 70% water, and yet in many countries, including the United States, water is a precious commodity. In a 1907 Message to Congress, Theodore Roosevelt stated "To waste, to destroy our natural resources, to skin and exhaust the land instead of using it so as to increase its usefulness, will result in undermining in the days of our children the very prosperity which we ought by right to hand down to them amplified and developed." Roosevelt was referring to all of our natural resources and his death in 1919 denied him the satisfaction of seeing his words become realized.
Water reclamation plants utilize the highest technologies available to efficiently treat waste water and produce reclaimed water.
Photos courtesy of Irvine Ranch Water District.
It took the federal government many years to recognize the worth of his words. It was during the '50s and '60s that the federal government first began to encourage the development of wastewater treatment plants by making available the funds needed for construction. Even so, treatment plants weren't built fast enough to facilitate the amount of raw sewage that was being discharged by the ever-growing population and the industrial growth. In 1970, the National Environment Policy Act was signed into law and the Environmental Protection Agency was formed to regulate air, water, and solid wastes. Federal funding was increased, more treatment plants were built, and uniform effluent standards were established.
Landscape contractors and golf course superintendents rely heavily on water. In agriculture, approximately 15% of all cultivated land used for food production is irrigated, often producing more than twice the yield of non-irrigated fields. Where does some of the water come from to accommodate these professionals, especially in arid states? In many cases, the answer is reclaimed water. Golf courses, city parks, sports stadiums, and agri-business are among the end users of recycled water.
The Irvine Ranch Water District was one of the earliest waste water treatment facilities of its kind. Its philosophy is that water is too valuable to be used just once. In this facility, wastewater is collected and piped to the Michelson Water Reclamation Plant, where it is processed. The plant capacity is 15 million gallons per day, with an average daily flow of 11 million gallons per day. But the journey from raw sewage to usable, non-potable water is a complex venture.
Sewage is processed in three distinct stages: primary, secondary, and tertiary. Primary treatment removes about 60% of the total suspended solids. Secondary treatment removes more than 85% of suspended solids and is the minimum required stage by most municipalities for waste treatment plants before discharge to the ocean. Tertiary treatment removes more than 99% of all impurities from sewage, producing almost drinking quality water.
The first stage in the process is the primary treatment, where the raw wastewater is strained and large debris, which can damage the machinery is removed.
The water leaves this stage and goes into the preliminary clarification stage. Here it is left undisturbed for a few hours, allowing most of the solids, called sludge or biosolids, to settle to the bottom of the tanks. The sludge is pumped through underground pipes to the Sanitation Districts of Orange County, where it's further treated and eventually composted for fertilizer. The 'clarified water' that is left is referred to as primary effluent.
The primary effluent is now transferred to flow equalization basins. These basins control the primary effluent's entry into the system for more efficiency. The next stage is described as "the heart of the treatment process." The primary effluent flows into aeration tanks, which contain microbes like those found in nature, only in much higher concentration. These are present to decompose the organic material in the wastewater, but with these levels of concentration, air must be pumped into the tanks to keep the microbes alive. There is some removal of nitrogen here as the microbes utilize nitrates as a source of oxygen and the nitrogen gas is released into the atmosphere. The water remains in these tanks for five hours.
Reclaimed water is used to
irrigate recreational and
The microbes have now completed their job of consuming the waste material and the liquid is transferred to the secondary clarification tanks. It is in these tanks for about two hours, where more solids settle. Aluminum sulfate is added as the water leaves these tanks, acting as a coagulant, making for easy removal as it flows over 'weirs,' leaving the few remaining solids behind. At this point almost 90% of the contaminates have been removed and it is now referred to as secondary effluent.
In some waste treatment plants, this is the final stage. But in reclamation treatment plants such as the one in Irvine, there are still more steps to go through to bring it to the tertiary stage.
Filtration is the first step. The secondary effluent is pumped to the top of a two-story dual media filter. Here the water trickles through layers of anthracite coal and sand, much the same as rainwater is cleaned in nature by soaking into the ground. Leaving these filters, the water is "sparkling clear," with more than 99% of the contaminants removed.
The final treatment step is to transfer the water to contact tanks where chlorine is added to kill any bacteria or virus that might still be present. It's in these tanks a minimum of two hours. When it leaves these tanks, it is 'final effluent,' or tertiary effluent water. It's now ready for landscape and agricultural use.
Depending on the time of year, it's either pumped directly into the reclaimed water pipelines for immediate use, or during the cooler months, it's pumped into storage reservoirs. This entire process takes 12-16 hours to complete.
The Los Angeles Department of Water & Power has four treatment plants, three that treat the water to the tertiary stage, with one additional step over Irvine. Once the water is disinfected with chlorine, it's then de-chlorinated.
The Los Angeles-Glendale plant processes over 20 million gallons each day, with expansions underway that will increase the capacity to 50 million gallons per day, scheduled to be complete in 2001. The Donald C. Tillman plant processes over 65 million gallons each day. This plant also is the home of an authentic 6.5-acre Japanese Garden.
Reclaimed water is used on crops, golf courses, parks, school grounds, greenbelts, street medians, and freeway landscaping. In order to use tertiary effluent water, a dual distribution system must be in place. There are strict regulations regarding the construction of the facility, implementation, and final use of the tertiary water.
Holding pond for reclaimed water blends into a landscaped environment.
According to the Los Angeles Department of Water & Power Customer's Guide to Irrigating with Reclaimed Water, "All material, apparatus, piping, valves, controllers, sprinkler heads, pumps, etc., for a reclaimed water irrigation system shall be approved for use in a pressurized reclaimed water system and installed according to approved plans . . . The approved area shall be clearly marked. All outlets from the reclaimed water system shall be marked 'RECLAIMED WATER--DO NOT DRINK.' In addition, signs must be posted at all entrances to the use site indicating that reclaimed water is being used for irrigation purposes."
Most irrigation manufacturers have available a separate product line clearly marked, "For use with effluent water." These products have the same capabilities as the products used with potable water - the only difference is in the color and markings. Impact sprinklers cannot be used for effluent water and special attention should be given to spray patterns to eliminate ponding, runoff, and wind-blown spray conditions.
Piping used for effluent or non-potable water is marked with "three-inch minimum width purple tape and one-inch black or white contrast lettering with the continuous words of 'CAUTION--RECLAIMED WATER' permanently affixed at ten-foot intervals atop all horizontal piping, laterals and mains. Identification tape shall extend to all valve boxes and/or vaults and exposed piping." Purple colored pipe with the same continuous wording printed on opposite sides of the pipe is an accepted alternative to purple tape. Purple is used as the international symbol for reclaimed water.
Hose bibs are prohibited in areas open to the public. In these areas, quick coupling valves are used, and again these have to be properly labeled. In addition, a special coupler key is required for opening and closing the valve to prevent unauthorized use. Backflow prevention assemblies must be maintained and tested annually by a certified tester. These also must be clearly labeled for reclaimed water.
If an irrigation system is served by potable water and non-potable water, the potable water must be marked and tagged with yellow tape and tags. "These tags must indicate that the water should not be consumed, example: 'RECLAIMED WATER--DO NOT DRINK'."
All of the precautionary measures required may appear to be more trouble than they are worth, but if you are located in an area prone to drought, water shortages, and water restrictions, having this water available for your irrigation purposes is unquestionably worth it.
The Irvine Ranch Water District prices its non-potable water 10% less than the potable water. They encourage its use for irrigation, as well as commercial and industrial non-potable purposes such as toilet flushing in high-rise buildings and carpet dying. The Los Angeles Department of Water & Power estimates the cost to the end user of non-potable water to be 80% of the cost of potable water.
California is not alone in the endeavor to reclaim water for non-potable purposes. Other states include Colorado, Hawaii, and Florida. New Jersey recently approved the use of effluent water from the Evesham Township Municipal Utilities Authority for the irrigation of a nearby golf course and their own facilities, breaking ground for more eastern states to look at the use of effluent water for irrigation purposes.
As drought conditions continue to be a part of the forecast, more areas of the country that have not had to deal with water shortages in the past, will be looking at alternatives for their water needs. Tertiary or effluent water treatment plants have demonstrated how wastewater can be reclaimed and reused in a viable, environmentally safe and economically feasible form.