A couple of weeks ago we wrote a blog post about treating turbidity without chemical injection. One reader recently wrote to us to ask whether he could effectively treat his water’s turbidity with alum injection and a Pro-OX iron filter.
The answer is yes, you can certainly treat cloudy water by injecting alum and filtering with a Pro-OX filter. As we mentioned in our last post on the topic, alum is probably the most popular method of treating turbidity. In fact, it’s probably used by your municipal treatment center to treat turbidity in your local water supply.
For the uninitiated, alum is a chemical compound that, when introduced to water, stimulates flocculation (the process by which small particulate clumps together to form a larger mass) in the turbidity-causing organic matter and other colloidal solids, making them much more easily filterable.
We recommend using a contact tank when injecting alum, as this will ensure proper contact time between the water and alum, and stimulate flocculation by mildly agitating the mixture.
After the contact tank, you could use either a Pro-OX filter or a sediment backwash filter to remove the flocculated turbidity particles.
We recommend the Pro-OX filter if your water is high in iron and manganese as well as turbidity; if not, a Chemsorb Sediment Backwash Filter will be just as effective. The diagrams below illustrate how these systems are typically installed:
Some people use both systems to treat turbidity – if you choose to use both systems be sure to install the sediment backwash filter before the iron filter.
You can also treat cloudy water without injecting any chemicals with a reverse osmosis or ultra-filtration system, or by using a cartridge filter before your sediment backwash filter, though this latter option is not quite as effective as the others mentioned here.
Also, note that both ultra-filtration and reverse osmosis systems will require a pre-filter to preserve the integrity of their UF/RO membranes – consider an alum injector and sediment backwash filter followed by a UF or RO system for maximum effectiveness.