Every water treatment project comes with its own set of challenges. Many times, these can involve selecting the right pretreatment equipment, configuration or setup, working within space constraints or meeting a budget. Another specific challenge can be for treating higher-than-normal levels of calcium and magnesium carbonate or water hardness. A traditional water softener is sometimes not the best choice or an option at all under certain circumstances.
The solution is a membrane antiscalant used in conjunction with a dosing pump system that takes up less space and provides effectiveness in protecting the reverse osmosis (RO) membranes. Many water treatment professionals use antiscalants and/or antifoulants in order to address hardness and contaminants, which can plague a RO system with performance issues. These can range from calcium to magnesium, with the added benefits of silica, iron, manganese and strontium.
In city feedwater applications, hardness can be measured on average at 10-15 grains per gallon, in comparison to well feedwater levels which can reach up to 300 grains per gallon. The practice of injecting antiscalant in either of these situations is suitable and will not require wasted water for regeneration like typical water softeners or salt replacement. This will also allow for the decrease of the pre-treatment equipment footprint instead of requiring larger resin tanks and salt reservoirs.
For many applications, pressure drop is a concern, especially when adding many stages of pretreatment. Antiscalant injection systems do not rely on the use of a timer/meter valve system which can often produce a 5-psi pressure drop. Antiscalant injection is dosed using chemical injection which feed into the feedline of the RO. Mixing of the antiscalant occurs in the pump stage when the impeller agitates the antiscalant. Suppliers of membrane chemicals can assist installers with the calculation for the chemical injection rate and overall setup of the systems.