| Tertiary Treatment | |||
|---|---|---|---|
| Overview | Nitrogen Removal | Phosphorus Removal | |
| Land Treatment | Membrane Filtration | References | |
Membrane Filtration
As more stringent regulations crack down on wastewater effluent quality, membrane filtration may become the future of tertiary treatment. There are numerous filtration technologies ranging in pore size and filtration capabilities ( freedrinkingwater.com, 2008 ). They all utilize a pressure gradient in which water is forced through the membrane and contaminants left behind. Smaller membranes filter out more contaminants or nutrients, require more pressure (and hence, energy), and produce less water. The price of installation and maintenance on membrane filters is high and remains a deterrent for wastewater plants in a adopting this technology (Membrane Filtration 2008).
Figure 5: Stacked reverse osmosis filters used for water purification (ROC SERIES 2008).
Types of Membranes
Current Project
The Orange County Water District is using wastewater filtered through micro filtration and reverse osmosis to recharge the aquifer in the locality and keep seawater from entering their aquifer. This will allow them to keep using wells that were in danger of drawing in salt water due to over pumping. By 2020 this system will recharge the aquifer with enough freshwater year round to support the water requirements of 200,000 people (Brown and Caldwell 2008).