The final solution to Abilene's drinking water dilemma was to blend the RO treated water from the Sand Springs Aquifer with a second source of wells in the River Alluvium. The alluvium wells did not have nitrate contamination. The blend produces a final product that is noncorrosive to the distribution system and which includes some hardness for flavor.

Other factors about Reverse Osmosis that prevailed in its selection as the preferred treatment by the City of Abilene for its 4.0 million gallon per day facility include:

The modular design of these facilities where additional capacity can easily be installed, in a very short time frame, as the demands become apparent. This allows the capital expense of the units necessary to meet the demand to be delayed until there is a need and capital is available;

The cost of RO membranes has decreased and membrane technology is accelerating. Estimates of cost between a conventional plant and a reverse osmosis plant were comparable; A strong ancillary benefit is the potential compliance with all predictable future regulations which might be imposed on public water supply systems.

Reverse Osmosis (RO) can effectively remove nearly all inorganic contaminants from water. The contaminants are removed by using semipermeable membranes that permit only water, and not particulates or dissolved ions (such as sodium and chloride), to pass through its pores.

Contaminated water is subject to a high pressure that reverses the natural osmosis direction and forces pure water through the membrane. Membranes are available with a variety of pore sizes and characteristics.

Typical RO system components include, pre treatment (pre-filtration and addition of chemicals), high pressure pumping and finally the membrane.

Configuration of the RO system with other typical components of potable water production (raw water pumps, disinfection, storage and distribution) allows for the generation of virtually any desired quantity or quality of water.

Advantages of RO

Removes nearly all contaminant ions and most dissolved non-ions.
RO operates immediately, without any minimum break-in period.
Low effluent concentration possible.
Bacteria and particles are also removed.
Operational simplicity and automation allow for less operator attention and make RO suitable for small system applications.