Efficient Spray Washing/Rinse

Many improvements can be made to the water delivery system for washing and rinsing.
Proper selection, control, use and maintenance are essential. Consider these suggestions:

• Do not use a hose as a broom. This practice is a waste of valuable labor, water and energy.

• Use efficient spray nozzles with automatic shutoffs on the end of hoses. Garden hose nozzles are not very efficient.

• Consider high-pressure washers to clean more quickly and efficiently.

• Consider pressurized air-assisted spray nozzles to provide more cleaning force with less water.

• Use low-flow “fogging” nozzles to rinse parts efficiently.

• Use flow restrictors in water lines that supply hoses and pressure washers.

• Use timers to shut off process water rinses when process is shut down.

• Turn off running water when not in use.

• Ensure stationary spray nozzles are aimed properly.

• Review nozzle spray patterns for optimum application. Fan, cone, hollow cone, air atomizing, fine spray and fogging are a few examples of nozzle spray patterns.

• Replace worn spray nozzle heads. They can result in poor spray patterns and excessive water consumption.

• Use countercurrent washing techniques.

• Use conductivity controllers to regulate rinse water flow rates.

Other Improvements to the Cleaning Process

TeflonTM Surface Coatings

Tanks, vats, pipeline and other equipment surfaces can be coated with a TeflonTM nonstick surface. This allows for easier cleaning during process line changeovers and clean-up. Changes in the type, temperature and concentration of cleaning solutions can save water.

Cleaning Chemical Changes

Operational Controls and Maintenance Overflow controls should be in place for filling tanks and vessels.

Vehicle Washwater Recycling

Many commercial water recycle systems are available for fleet maintenance and vehicle cleaning. With a recycle water permit from the proper authority, facilities can install a washwater recycle system for vehicle cleaning. Washwater recycling systems provide several advantages over typical wastewater disposal:

1. These systems allow for simple cleanup of contaminants from spills or system failures by preventing entry to the sanitary sewer or septic system.
2. These systems reduce costs for water use and disposal.
   
3. Many of the systems are pre-engineered, have a proven track record, and can be submitted for permit issuance from previously approved plans and specifications.

Typical washwater recycling systems consist of a sedimentation basin for grit/sand removal,
an oil/water separator, filtration and a disinfection unit to prevent biological growth. Basin/sump compartments are used to settle grit, sand and other solids, and also used to skim any floating oils. Water then is filtered, typically using a multimedia filter that removes solids in the water larger than five to 20 microns in diameter. The filtered water is oxidized/sanitized to reduce organics and meet any health/safety standards for non-potable water reuse. Water then is stored and pumped back to the washing bay for reuse. Although such systems can be nearly closedloop, except for occasional solids removal and filter backwash wastewater, occasionally water must be changed due to buildup of dissolved solids (salts). Washing practices and discharges to the recycling system must be closely controlled, as they will not handle shock loads. Maintenance to the treatment/recycle equipment also is very important. Pre-engineered units for single wash bays cost approximately $20,000.