Recycling makes wastewater safe for reuse.
Water recycling is the process of treating wastewater so it can be safely reused. There are various processes for reclaiming water, and the method of recycling determines how the water can be used.
While some systems yield water suitable for drinking and food crop irrigation, most recycled water is not potable. Recycled water is widely used for landscaping, industrial and recreational use.
Greywater Systems
These are basic systems suitable for the individual homeowner. Blackwater, or sewage, flows to a septic tank or municipal system, while greywater from the shower, dishwasher and laundry, is filtered, commonly by sand, and collected for reuse. Greywater is used for landscape irrigation, toilet flushing and dust control.
Greywater systems are prohibited in some areas, but with growing interest in water reuse, more and more places are changing their zoning ordinances. The trend is towards regulating greywater systems instead of prohibiting them.
Sedimentation Systems
Untreated water flows into a holding tank or basin. Screens filter out sticks, pebbles, and similar solids. Other solids are simply left to settle to the bottom and removed for further, separate processing. Fats and oils float to the surface where they can be easily removed and also reclaimed. All reclaimed water goes through physical filtering as a first step in the recycling process.
Biological Systems
Microorganisms added to a holding tank consume contaminants in the water and convert them into easily-filtered solids. The water is then clarified to remove the microorganisms. You have probably seen warnings about disposing household chemicals in the toilet. Dumping of chemically-contaminated water is hazardous to the water supply because some chemicals kill the microorganisms and disrupt the water purification process.
At this stage of recycling, the water is suitable for industrial uses such as power plant cooling and dust control. It's also used for irrigation of non-edible crops, some wetlands restoration, and fire suppression.
Chemical Systems
These systems are often the third step in a recycling process that includes biological and sedimentation treatment. Chlorine or other chemical compounds destroy any contaminants left following bioprocessing. Additional disinfection and filtration removes any hazards from the chlorine. After this stage the water can be used for irrigation of edible crops, recreational uses such as artificial lakes, and groundwater treatment.
