The world’s population is expected to increase dramatically between now and the year 2020 - and with this growth will come an increased need for water to meet various needs, as well as an increased production of wastewater. Many communities throughout the world are approaching the limits of their available water supplies, and water reclamation and reuse will almost become necessary for conserving and extending available water supplies. Water reuse may also present communities with an alternate wastewater disposal method as well as provide pollution abatement by diverting effluent discharge away from sensitive surface waters. Already accepted and endorsed by the public in many urban and agricultural areas, properly implemented non-potable reuse projects can help communities meet water demand and supply challenges without any known significant health risks.
Water reuse is driven primarily by four factors: increased demand for water; reduced availability of water supply; affordability; and the practicality of water reuse as a local solution and public policy. Independent research studies project over a 150 percent increase in global water reuse capacity from 19.4 million cubic meters a day in 2005 to 54.5 million cubic meters a day in 2015. A majority of the additional capacity will involve tertiary or quaternary treatment. The remainder, predominantly in emerging markets, will involve secondary treatment only. Tertiary treatment technologies include natural systems, disinfection, filtration, coagulation/filtration and other systems.
Water reclamation for non-potable reuse has been adopted in the U.S. and elsewhere without the benefit of national or international guidelines or standards. The World Health Organization guidelines for agricultural irrigation reuse (dated 1989) are under revision. EPA’s Guidelines for Water Reuse (625/R-04/108, updated in September 2004) is a set of guidelines in a format that could be used by states as a technical basis to establish standards for water recycling and reuse. These guidelines are not regulatory; they are informational, and the agency does not propose any water reuse standards.
Twenty-five U.S. states currently have regulations regarding water reuse, which vary considerably from state to state. Several states have developed regulations or guidelines that strongly encourage water reuse as a water resources conservation strategy and have developed comprehensive regulations or guidelines specifying water quality requirements, treatment processes, or both, for the full spectrum of reuse applications.
Among tertiary filtration technologies, deep bed media filtration is compiling a strong record of performance in the United States and other countries. One technology, the TETRA® DeepBed™ filtration system from Severn Trent Services, is a down-flow unit that features a gravity sand filter. The system achieves excellent retention of solids at high hydraulic and solids loading rates, does not require the effluent to be pre-screened and can be readily switched on and off to optimize operating costs. Its high-efficiency backwash process maximizes solids release after a single operation with virtually no media loss.
In Florida, the state’s wastewater treatment plants and water reclamation facilities so commonly use the TETRA DeepBed system that 12 of the last 15 winners of the Florida Water Environment Association’s Earle B. Phelps Award in the advanced wastewater treatment plant category have used the system.
And in China, where the Central Government has recently enacted a number of measures to manage natural resource consumption and environmental degradation, the TETRA DeepBed technology is being used in several new wastewater treatment facilities. In Jiashan City, located in Southeast China’s Zhejiang province, the filtration system was part of a pilot test of a patented three-stage biofiltration process in which the system is preceded by an up-flow submerged denitrification filter reactor and a submerged aerated filter reactor. During the two-month pilot study, average BOD was reduced from 200 to 2mg/L, NH4-N from 82 to 3 mg/L, TN from 88 to 11 mg/L and TSS from 165 mg/L to non-detect.
For more information, e-mail info@severntrentservices.com.
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