Necessity of Arsenic removal in water treatment

Where does the arsenic in our drinking water come from, and why is the arsenic removal in water treatment necessary? This toxic element (Arsenic (As)) cannot be found very often in pure form, but it can be present dissolved in water, especially groundwater. This toxic semimetal can cause cancer and so there is an urgent need for arsenic removal in water treatment all over the world.

Arsenic removal is a big issue in Asia
Arsenic removal in water treatment is particularly important in Asia, especially in the Himalaya Region, where the element can be found in groundwater and drinking water as well. The main source for the arsenic contamination comes from ores that are in contact with the groundwater, where the arsenic is washed out. This contaminated water is also used not only for drinking but for watering rice fields or other fields, where it is absorbed by the plants and in the end gets into the food.
To have access to pure, or almost pure drinking water, people in Asian countries like India have to drill their wells into great depths, because microbial contamination is less likely in the deeper layers. But normal people do not have the chance to check their water supplies and find out if it contains arsenic or not. So a good protection is an “arsenic filter” which works very effective and guarantees arsenic removal from drinking water.


WHO recommends a limit value for arsenic in drinking water
Studies from the 1990s showed that even small amounts of arsenic can be harmful and can poison you slowly, beside this they can have carcinogenic effects. Many countries have special standards which make sure, that according to the recommendation of the WHO in 1992, the drinking water is limited to 10 μg arsenic per liter, which is followed by the EU since 1999. But despite this, many wells in countries like India or Vietnam still exceed this limit by 5 or more times.
Back then, there has not been a satisfying technical solution for smaller waterworks or even medium-sized facilities for arsenic removal from drinking water within the recommended limits. At this point GEH® has been developed, a modern filter material which could quite easily and effectively accomplish arsenic removal.


Procedures for arsenic removal in water
Arsenic can be present in water dissolved as arsenate (AS5+) or arsenite (AS3+) and there are some effective procedures for arsenic removal in water treatment.

Arsenic removal in water treatment through adsorption

Arsenentfernung durch Adsorption

The first of four possible solutions for the arsenic removal in water treatment is the adsorption process. During this process, arsenic is bound to a solid adsorbents surface. In the beginning “activated alumina” has been used for this issue, but has soon been sorted out because of its low capacity.
Instead of the aluminum-based adsorbents, the iron hydroxide-based adsorbents have been used for arsenic removal in water treatment. This modern solution for arsenic removal in water treatment is easier and safe at the same time and can also assure that arsenic removal from drinking water meets the requested limits.
Another positive effect is that neither wastewater streams nor contaminated sludge are generated during the arsenic removal process in water treatment. Beside this, the removal of arsenate and arsenite does not affect the natural composition of the water from which they are removed.

What are the pros and cons of this kind of arsenic removal in water treatment?
There are only two cons for the adsorption as an arsenic removal in water treatment, but several pros.

Pros of adsorption as an arsenic removal in water treatment

  • Very simple system configuration
  • Comfortable operation
  • Very high capacity due to the high arsenic selectivity
  • Low maintenance
  • High plant availability
  • Reliable technology, which is already globally applied at more than 2000 sites
  • Easy arsenic removal in water treatment without generating sludge

Cons of adsorption as an arsenic removal in water treatment

  • Retention times are determined by the Water matrix
  • The adsorbent needs to be replaced at regular intervals

You have questions or want to get to know us? We are looking forward to your message!

Simon Kellmann

Your contact person:

M.Sc. Simon Kellmann
Tel. +49 541 1220-09

simon.kellmann@geh-wasserchemie.com Copy to clipboard

Arsenic removal in water treatment by flocculation

Arsenentfernung durch Flockung/Filtration

The so-called flocculation/filtration is the second possible method for the necessary arsenic removal in water treatment. In this process, iron or aluminum salts are used. The arsenic which is dissolved in the water will bind to the surface of these flocs and can be removed from the water by filtration. As the arsenic concentration determines the amount of necessary flocculant, it has to be checked with an analysis on a regular basis. This is absolutely necessary for the successful removal of arsenic from drinking water by this method. The sludge which is left after the arsenic removal in water treatment has to be disposed according to local regulations, mostly as special waste or as residual waste.


What are the pros and cons of this kind of arsenic removal in water treatment?

Pros of flocculation/filtration as an arsenic removal in water treatment:

  • It is a standard process in drinking water treatment
  • Several contaminants can be removed at the same time
  • The chemical costs are rather low

Cons of flocculation/filtration as an arsenic removal in water treatment

  • The efficiency of the arsenic removal depends on the dosage of the flocculant
  • The user is responsible for the correct treatment and disposal of the arsenic contaminated sludge
  • This kind of arsenic removal in water treatment causes high investment costs
  • Due to the high investment costs this solution is not worthwhile for small facilities
  • Once implemented, qualified personnel is necessary to handle the very complex technology

Arsenic removal in water treatment with ion exchange

Arsenentfernung durch Ionenaustauscher

The third possibility for arsenic removal from drinking water works with ion exchange resins. During this process you can remove either anions or cations from the water (depending on the type of material you use) and while they are removed, other ions are released back into the raw water. This arsenic removal in water treatment is possible for arsenate contamination in drinking water or groundwater only. This method is rarely used because the capacities are low and the effort and costs are too high. Besides this, there are several other disadvantages which outweigh the advantages.

Pros of ion exchange method for arsenic removal in water treatment

  • It is possible to remove various ions, even at the same time
  • The ion exchangers are regenerable
  • High reaction kinetics possible

Cons of ion exchange method for arsenic removal in water treatment:

  • Only minimal selectivity for arsenic possible
  • Strong interference from other ions highly possible
  • You cannot remove Arsenite (AsIII)
  • Due to low capacity you need frequent regeneration cycles
  • Expensive due to high material costs
  • You have to use chemicals for regeneration and generate solutions which contain arsenic which have to be treated later

Method of membrane processes for the arsenic removal

Arsenentfernung durch Membranverfahren

This last possible process works with a high pressure through which the water constituents are removed through the membrane material.
Membranes used for this process are usually nanofiltration or reverse osmosis membranes because only these have a small pore size through which arsenic cannot pass. Arsenic and other parts which are held back by the membranes can be directed into a waste water stream which needs a further treatment in order to get rid of the arsenic. As the composition of water is changed during this process, it highly depends on the usage of the water, if the application of a membrane process is feasible or not. It can either be an advantage or a disadvantage.

Pros of this method for the arsenic removal in water treatment:

  • It is a very reliable method
  • As it is not a selective process for arsenic only you can remove other impurities simultaneously
  • The modular design can be easily expanded

Cons of this method for the arsenic removal in water treatment:

  • After all impurities are removed you have demineralised water
  • You need a pre-treatment to condition the water
  • You need a post-treatment for the contaminated wastewater
  • This membrane process has a high energy demand
  • The complex technology is very expensive
  • The plant with that technology can only be operated by high-skilled personnel

Hopefully you enjoyed this short and exciting insight into the possibilities of arsenic removal in water treatment. We would be very happy to explain to you in a personal conversation how we can support your projects for clean drinking water.
For inspiration and reference, you can follow our previous projects on the GEH Wasserchemie website. Here you will also find more information about us and can also easily get in touch with us.

You have questions or want to get to know us? We are looking forward to your message!

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Did you know... ?

180 Mio m³
of water are treated annually using GEH®
3100 kg
of pure arsenic are removed from our environment annually thanks to GEH®
992 t CO₂
saved since 2013 by optimizing GEH® production
35 %
increase in energy efficiency thanks to optimization of GEH® production
61
countries where GEH projects have been completed
180 Mio m³
of water are treated annually using GEH®
3100 kg
of pure arsenic are removed from our environment annually thanks to GEH®
992 t CO₂
saved since 2013 by optimizing GEH® production
35 %
increase in energy efficiency thanks to optimization of GEH® production
61
countries where GEH projects have been completed