What is the most effective way for reducing the calcium level in water?

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I am working as a Community Water Supply and Sanitation Officer in Salima, Malawi, Central Africa, I am responsible for rural water supply in my project area.

We are facing a problem of frequent pipe breakdowns in our Chipoka Gravity Fed scheme (GFS). The breakdowns are due to high levels of calcium in the water which accumulate in pipes, this accumulation further lead to blockages or intermittent flow of water. After some period of time the pipeline breaks down. 

Because of these frequent breakdown, the scheme is hardly in use.  Otherwise the scheme has potential to supply water throughout the year as we have perennial springs and rivers as a water source.

So I  seek for some ideas on how best we can reduce the calcium percentage in water in a sustainable way?

As said we are using gravity fed piped schemes and it is for domestic water supply. 

 

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21 Answers

  3. Dear Waki, Deposit in pipeline may not be directly connected with calcium in water. Calcium salts, being reverse soluble, tend to deposit when the try to heat water especially on hot surface. Unless there is hot surface, scaling possibility is remote! Deposition can occur when presence of salts insoluble in water are suspended as turbidity and these salts can be precipitated especially at low velocity area. Such deposition can be enhanced / or initiated by presence of certain bacteria. Perhaps this could be the real problem and to understand the reason and to suggest appropriate remedial measure, detailed water analysis is essential including BOD, COD organic matter etc. You can send this to me directly to vm@vmbiotech.com or can post it to this forum. Regards, VM Kulkarni

  4. Hi Walki to remove or reduce calcium level in the water is a common practice in the industrial sectors but it is necessary to know more about your project e the finality of the water application; are you talking for industrial water or for potable water ? what is the amount of water involved in your case ? Do you have a simplify scheme and full water analysis and again first needs to know if we are talking for industrial water ( cooling, boilers) or potable water ; try to collect more info and after I can better assist you cheers  

  5. Hi Waki, there are a multitude of technologies for the softening of water, all have pros and cons depending on the water chemistry, volume of treated water required, power/space available and budget. Feel free to contact us in South Africa (www.wps.co.za) if you would like assistance with the process of identifying the best solution for you.

  6. Let me consult our water chemist to provide the detailed analysis

  10. Dear Waki, Martin Calcium in water leaves the distinct tell-tale sign of crusty white scaling, or calcification, on your water fixtures and dishes. High levels of calcium can cause calcification which blocks faucets and causes low water pressure. In addition, another sign of calcium in your water is the lack of suds from soaps and shampoos. Primary Standards are based on health considerations and Secondary Standards are based on taste, odour, colour, corrosively, foaming, and staining properties of water. There is no Primary or Secondary standard for water hardness. Water hardness is classified by the U.S. Department of Interior and the Water Quality Association as Soft-0 - 17.1 mg/lit or ppm, slightly hard-17.1 – 60, moderately hard-60 – 120, Hard-120 – 180, Very Hard-180 ppm & over. Depending on the concentration of Calcium, there are several removal methods such as 1. lime softening, 2. resin softening, 3. electro dialysis, and 4. Reverse osmosis, they can be effective but some of them are costly. Reverse Osmosis systems remove impurities from water by forcing the water through a membrane which only allows water to pass. Reverse Osmosis systems are highly effective, easy to maintain, and low cost. Improve your water’s taste and odour with a Reverse Osmosis system from Water Softeners& Filters. 5. Cost effective electrolysis + filtration system that can effectively remove the calcium. Hard water is water that is high in mineral content, making it more likely to cause scaling that reduces water flow and less able to properly clean your laundry, dishes, and even yourself. Water softeners decrease the amount of calcium and magnesium found in hard water. Water Softeners & Filters specializes in all types of water softeners. 6. With the presence of electricity current, calcium in water passing through the electrolysis reactor will be attracted to and form scale on the cathode, which is then removed by a scraper and filtered out from the system by the subsequent filter. If the calcium concentration is not causing healthy issue but just clogging the pipes, we can offer another solution the prevent scale formation. Both solutions are highly effective and sustainable. 7. Precipitating water softeners include washing soda and borax. These products form an insoluble precipitate with calcium and magnesium ions. The mineral ions then cannot interfere with cleaning efficiency, but the precipitate makes the water cloudy and can build up on surfaces. Precipitating water softeners increase the alkalinity of the cleaning solution and this may damage skin and other materials being cleaned. 8. Non-precipitating water softeners-use complex phosphates to sequester calcium and magnesium ions. There is no precipitate to form deposits and alkalinity is not increased. If used in enough quantity, non-precipitating water softeners will help dissolve soap curd for a period of time. Mechanical water softening units can be permanently installed into the plumbing system to continuously remove calcium and magnesium. Water softeners operate on the ion exchange process. In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium. The ion exchange process takes place as hard water passes through the softening material. The hardness minerals attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a salt (brine) solution through the resin. The sodium replaces the calcium and magnesium which are discharged in the waste water. Hard water treated with an ion exchange water softener has sodium added. According to the Water Quality Association (WQA), the ion exchange softening process adds sodium at the rate of about 8 mg/liter for each grain of hardness removed per gallon of water. The illustration depicts a negatively-charged zeolite to which [positive] sodium ions are attached. Calcium or magnesium ions in the water displace sodium ions, which are released into the water. In a similar way, positively-charged zeolites bind negatively-charged chloride ions (Cl–), which get displaced by bicarbonate ions in the water. As the zeolites become converted to their Ca2+ and HCO3– forms they gradually lose their effectiveness and must be regenerated. This is accomplished by passing a concentrated brine solution though them, causing the above reaction to be reversed. Herein lies one of the drawbacks of this process: most of the salt employed in the regeneration process gets flushed out of the system and and is usually released into the soil or drainage system— something that can have damaging consequences to the environment, especially in arid regions. For this reason, many jurisdications prohibit such release, and require users to dispose of the spent brine at an approved site or to use a commercial service company. Regards, Prem Baboo

  12. Dear Waki Martin Chungwa, would you send me a note, We can help you with this problem in a easy way and are glad, to be in contact with you. info@baleari.de thank you Heidi

  13. It seems that your conveyance system suffers from deposition of sediments in the concave points and therefore clogs the way of transporting water to the destination over time. If I am right, the possible solution for this issue is to consider a drain valve in the concave points of the conveyance system in order to be able to discharge deposited sediments whenever you want. Regards Shahram

  15. Dear Sir, some questions: what kind of pipes are you using? we faced that problem too in West Africa, and found a solution: better planning. Control sinks, where you have the opportunity to clean (maintain) your network permanently by flushing with citrus-acid , brushing and flushing. The acid can be forgotten if the maintenance plan is adjusted due to usage...for more information: info@wewaco.com

  17. The method should consist to add acid to reduce alkalinity, Ca in water is due to excess of salt. Nano-filtration, CO2 can also be used for softening despite they are not very effective for the removal of alkalinity.

  18. Hi

    You can use lime softening i.e addition of lime as it is relatively cheap and readily available. You can also use ion exchange resins

  19. Hi Waki, depending on the concentration of Calcium, there are several removal methods such as lime softening, resin softening, electro dialysis, and even reverse osmosis, they can be effective BUT some of them are costly. We have a cost effective electrolysis + filtration system that can effectively remove the calcium. With the presence of electricity current, calcium in water passing through the electrolysis reactor will be attracted to and form scale on the cathode, which is then removed by a scraper and filtered out from the system by the subsequent filter. If the calcium concentration is not causing healthy issue but just clogging the pipes, we can offer another solution the prevent scale formation. Both solutions are highly effective and sustainable. If you want to know more about them, you can write to me at stevelizhong@gmail.com.

  20. The presence of calcium in water means what you have passing through the pipe is hard water. So, you have to softening the water (soft water) before entering into the gravity fed pipes. Since your source are rivers and springs and your end point is homes for domestic water use, I recommend a system that goes this way: Source -> water reservoir -> water treatment plant (to improve water quality and also soften the water) -> water reservoir for domestic use. This system is capital intensive but the benefit is immense.

  21. Use Zeolite Softners before feeding the water to Pipeline. The Softner will reduce the Calcium Hardness.

    1 Comment

    1. You may not need to reduce calcium. You need to control scaling tendency by controlling LSI. Run the water analysis for pH, alkalinity, conductivity and Ca. Run LSI calculation. See if pH control with a mineral acid can be done economically. Compare that to the operating cost (CAPEX and OPEX) for a lime softener and IX softener for partial flow to blend to desired water quality that keeps LSI at non-scaling levels. This assumes you are referring to potable water and not waste water issues.