Water Reuse at Highway Rest Stations

About the report:

A laboratory biological wastewater treatment system was operated to investigate the effects of wastewater effluent recycle on the treatment system and the effluent water quality. This concept is being investigated for use at highway rest areas in the Commonwealth of Virginia where it is desirable to utilize biologically treated and filtered effluent for flushing toilets because of water supply problems and difficulty in meeting water pollution stream standards. Although the concept of recycle has been applied to facilities with similar problems, there are no recycle systems of this nature in operation, at any rest area in the United States. Various percentages of treated effluent from an extended aeration pilot plant were reused to transport a synthetic waste to the pilot plant for treatment. The synthetic waste, which was similar in characteristics to bodily wastes and comparable-in quality to that produced at highway rest areas, was made with laboratory chemicals and biological culture media. The effluent was analyzed to determine the quality of water produced and the treatment efficiency at each recycle rate. Because recycling caused an increase in the organic load to the treatment system, biological suspended solids greatly increased in the extended aeration unit. The quality of effluent produced at high recycle rates was primarily dependent on the ability of the system to retain these biological solids, because a lower food-to-mass ratio was required to produce a satisfactory quality effluent for reuse. The dissolved salt concentration increased with the recycle rate and may have hindered biological activity. Since the field design includes sand filtration of effluent before reuse and filter backwash recycle, retention of the biomass is assured, and satisfactory plant performance and water quality are expected. Further research is recommended to determine whether intentional sludge wastage would provide better control and operation than would effluent wastage.

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