How to Easily Remove Calcium in Water and Wastewater

Updated: Nov 16

Calcium is the fifth most abundant element in Earth's crust, and the third most abundant metal, that can be found in waters all over the world. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilized remnants of early sea life.


While calcium could provide health benefits in low quantity, it is one of the various dissolved minerals that make water hard. That hard water wreaks havoc on piping and plumbing over time, especially in wastewater treatment applications.


As a result, we need to remove calcium from water to avoid scaling and clogging of piping and industrial machinery. The most common methods include reverse osmosis, chemical treatment, water softening, and distillation.


Pipes Clogged Calcium Build-up
Clogged Pipes by Calcium Build-up in High Calcium Content Waters


Reverse Osmosis for Calcium Removal from Water

Reverse Osmosis remove calcium in water by pushing it through a membrane with very tiny pores. The membrane stops many contaminants, including calcium, while allowing water to pass through. Reverse osmosis usually removes between 93 and 99 percent of the calcium in drinking water, mostly depending on the equipment configuration.


If calcium in water level is high enough, the membranes will be easily clogged or damaged, and the efficiency of the equipment can drop drastically without proper maintenance. For this reason, a softening system is often required at the beginning of the treatment process.


By clicking on this link, you can find more information about Reverse Osmosis equipment.


Evaporation and Distillation for Calcium Removal from Water

Evaporation and distillation are processes that produce freshwater and concentrate from any water source by removing calcium, limestone, and other minerals.


In the evaporations process the steam rises and leaves contaminants, such as calcium behind. With proper operation, distillation machinery can remove nearly 100 percent of calcium and limestone in water.


Industrial evaporators, such as EVADEST, or crystallizers such as SOLIDEST can be used for this purpose as shown in the video below.


Water Softeners for Calcium Build-up Removal

Softeners equipped with anion exchange membranes are among the most common methods for removing large quantities of calcium build-up from water for residential, industrial and public supplies.


Softeners are commonly used for individual household water treatment applications but also for industrial applications, as shown in the picture below. This filtration process replaces ions of calcium and magnesium with sodium chloride or potassium chloride (salts).


Industrial Water Softeners installed in a factory for Calcium in Water Removal
Industrial Water Softeners For Calcium in Water Removal


The softening process for calcium in water removal is also suitable for pre-treatment functions for industrial applications. For example, for Reverse Osmosis (RO) systems such as REWATER.


Chemical Treatment for Calcium and Limestone Removal from Water

The chemical treatment uses Sodium Carbonate for water calcium and limestone removal from waters.

The principle of the chemical treatment is that the carbonate and calcium ions will bond to form insoluble precipitates, which will be forced out of the water and slowly soften it.


This chemical is easily found in grocery stores, hardware/home improvement stores, and pool supply stores.


The chemical treatment process can be used as pre-treatment for industrial applications. Equipment used for Electrodialysis (ED) or Electro-deionization (EDI) require high purity feed waters, so pre-treatment is a necessary step.


Calcium Sources in Water

Often, we are asked what’s the source of Calcium and other impurities in water. Some of the sources of calcium include:

  • Processes like filtration and disinfection introduce chemicals like chlorine and calcium hydroxide into water;

  • The insoluble calcium hydroxide reacts with the hard water to create hard scale deposits inside pipes;

  • Companies treat water with chemical additives to disinfect it before delivering it to you, which also reacts with the calcium in the water, causing hard deposits;

  • Hardening mineral tap water by adding a type of salt.

These are the most common sources for Calcium in residential applications, but this also applies in industrial processes. For instance, factories use the same water as tap water for their manufacturing, thus this water often must be softened or filtered before use.


High Calcium and Limestone Levels in Water Problems

The literature in this field clearly demonstrates that high calcium level in waters may have toxic effects on plants and animal organisms, including, among others, fishes, invertebrates and amphibians, and it may also have negative implications for human health.


In industrial and residential applications high calcium levels may build-up on pipes, particularly copper piping. Thus, in areas with high calcium levels pipes are often clogged and maintenance can be very costly. Moreover, the water requirements for industrial applications can be very strict, thus a pre-treatment system can be required.


Water with high calcium levels may cause many problems to filtration elements, such as RO equipment. For this reason, softening through FRP vessels with specific resins is our preferred choice when treating such kind of waters.


How to Measure Calcium Levels in My Water?

The only accurate way to measure Calcium levels in your water or wastewater is by a water test at a laboratory.


Once the levels of calcium in the water are assessed, then a treatment method can be chosen among the most effective ones.


Typically, freshwater Calcium concentrations range from 0 to 50 mg L−1, but these values can vary greatly depending on the water source.


Also, in industrial applications, the calcium levels can vary widely, thus it’s impossible to estimate those levels without a water content analysis for calcium ions. In this case you can book a water analysis at our laboratory.


Another way to measure the water hardness is by using a TDS meter, but this method doesn’t tell us which are the main components that harden our water.


How to Design a Calcium Removal Treatment System?

The first step to design a calcium removal treatment system is to run a complete laboratory analysis of the water and assess the precise levels of calcium in water.


Once the analysis is ready, we can choose and configure the best equipment design for your application, whether it’s a household drinking water or industrial application.


Our most common approach is to use water softeners specifically designed to reduce water hardness and then, depending on the project requirements, install an UF and RO system or vacuum evaporators.


Our company, YASA ET, designed and installed many treatment plants for companies and solved their high level calcium in water and wastewater treatment problems.



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