Cost (i.e., the present ...
Published by Malcolm Fabiyi, President at Hydromantis, USA
Cost (i.e., the present worth, which includes capital and operating costs) should be the key determining factor for selecting a technology that sustainably meets treatment goals.
- Treated wastewater is simply sewage that has been processed to meet a regulatory target (COD only, COD and N, or COD, N and P removal).
- For water reuse, the cost of treating the water and making it suitable for reuse should be cheaper than the cost of getting potable/drinking water. That is what allows the approach to make sense, an be sustainable.
- The first question to ask in determining the treatment method to be used is what the reuse water will be applied for. Watering lawns, cleaning factory floors, cooling industrial applications, flushing toilets, or drinking. Those applications determine the treatment required. E.g., water for drinking water purposes must be low in pathogens, Nitrates and TDS. Water for agricultural reuse should still have decent levels of N and P to augment the nutrient requirements of crops, and can possibly tolerate high TDS.
- Water from the aquifer tends to be low in organics (COD of