Water Reuse

Society continually searches for additional sources of water for its ever growing demand. Concerns for groundwater depletion, minimum stream flow for fisheries, and other environmental issues can prevent additional construction of dams and wells. Add the increasing numbers of people living in higher concentrations along coastal areas and we have a recipe for water rationing and limits on development.

Fortunately, lawmakers and government agencies have passed forward thinking laws and regulations that facilitate innovative technological advances that are able to treat what was considered “wastewater” to very high levels. Some states have re-defined water that has been treated to “reclaimed” levels as a water source! Gone are the days where the concern was “how to get rid of the wastewater”. Water that has been previously used can be turned into a commercially valuable resource that can be reused or sold to end users.

Garden grown with treated water

Garden grown with treated water

The uses of reclaimed/reuse water are variable. Reclaimed water has been used for ground water recharge, stream flow augmentation, surface and sub-surface irrigation of landscapes and agricultural crops, cooling towers, boilers, toilet flushing, and many more.

The definition of  reclaimed water varies from state to state, but generally include the same constituent levels for “Class A” reclaimed water: biological oxidation demand, total suspended solids (10/10 mg/l), total coliform (2 colonies MPN / 100 ml), turbidity (2.2 NTU), and in some cases total nitrogen (<10 mg/l). There are two recognized generic processes to achieve Class A reclaimed water:

  1. Oxidation, coagulation, filtration, and disinfection.
  2. Oxidation, membrane filtration, and disinfection.

And a third option for newer innovative approaches:

  1. Other methods that meet the same standards as those listed above.

Lowridge Onsite Technologies has developed a process train that utilizes three of the four steps listed in method #1: oxidation, filtration (physical and biological), and disinfection. Lowridge meets the process requirements in the following way:

  • Oxidation:LOWeFLOW™ treatment system (10/10 mg/l BOD5 and TSS)
  • Filtration:Lowridge polishing filter Called OSCAR (turbidity < 2 NTU, TC <200 MPN / 100 ml).
  • Disinfection: Ultra violet light (TC <1 MPN / 100ml).

Treatment Utilization

Green beans grown with treated water

Green beans grown with treated water

As useful as reclaimed water is, there are a great deal of regulations that can hinder the use of this valuable resource. Another option to take advantage of “previously used water” is to incorporate the drainfield design with areas suitable for growing above ground food crops. This method is referred to as “treatment utilization”. The concept is to plant vegetation in and around the area used for treated wastewater dispersal. The permits required are simple septic (or onsite sewage treatment systems) installation permits. After the systems are installed and approved, strategic planting of fruit trees, tomatoes, herbs, cucumbers, beans, and other above ground food crops are implemented to take advantage of the water and nutrients discharged into the soil. The best method of dispersal for “treatment utilization” is subsurface drip technology or the OSCAR System.

With the OSCAR system, very shallow soils can be used for food production. The World Health Organization has studied the use of secondary treated wastewater and found its use to be safe as well as the most productive way to irrigate and grow many food crops. Studies have shown that the most efficient way to irrigate and fertilize crops is through subsurface drip with treated wastewater.