Are there solutions for Arsenic and Heavy Metals in natural water systems? Is there scope for an environmental friendly product that reduces As, Cu, Fe, Mn, Al, Zn in this space? I know there is external treatments like RO and Ion Exchange but don't know of any in situ treatments?
I know you mention that you weren’t looking for ion exchange, but I wouldn't rule this out. For low level concentrations ion exchange and adsorption can be the most economical and environmentally friendly. There are high capacity, selective medias for the contaminants you mention which can be operated for long periods of time (sometimes 1-2 years) on a single charge, without the need for creating environmentally harmful regenerant wastes.
There are multiple solutions for your contaminant list, and the best technology selection (adsorption, ion exchange, precipitation/filtration, biological treatment, etc.) really depends on what the water chemistry of that system is and what the treatment goals are. The most cost effective is often a combination of technologies, especially with multiple contaminants of concern. If you have a specific case in mind I'd be willing to help you evaluate, feel free to send me a message at sean.kennedy@denora.com
Electrocoagulation works well for all of these at the same time. The water conductivity should be above about 1000 microSiemens for the process to be cost effective. Check out: www.avividwater.com
Yes there are sustainable solutions built on- site for specific siutations using loval materials, as developed by my colleagues at the WHO Centre of Environmental Health and Engineeringat University of Surrey , for India and Siberia .
Hi Hannah, I would like to find out more about these solutions if possible. Can I make contact with one of your friends to extend a few questions about the application?
My company specializes in constructed wetland bioremediation systems that have proven to be highly effective at removing the metals your are interested in. The systems use no or very limited chemical reagents (non-toxic coagulants are sometimes required to facilitate gravity settling of ultrafine Fe/Al hydroxides, but this is not required on most sites) and operate on gravity flow with minimal maintenance and oversight. Our "latest and greatest" system is located in Southwest Colorado and has been written about in local media there:
Typical removal rates for As, Cu, Fe, Mn, Al, and Zn at that system are 90-99% and meet Colorado's stringent water quality standards for public drinking water supplies and cold water fisheries. Take a read through those articles and if your are interested in hearing more you can email me at dan@rmc-ut.com or call at 801-255-2626.
I am definitely interested in hearing more about the water source you are hoping to treat.
Infinite Water provides a method through which arsenic, manganese, iron, bacterial contamination, Total Dissolved Solid (TDS) are removed in a fully automated system by advanced oxidation process and using petite amount of chemicals. This technology is environmental friendly and is able to reduce the arsenic concentration under WHO guideline value. As the plant is fully automated it is highly user friendly where there is no chance for intrusion of foreign particles both chemical and microbiological in the treated water, resulting to safe drinking water.
I conducted three months of piloting with weekly sampling frequency for laboratory test, it is observed from test results that “Infinite Water Plant” is performing very satisfactory levels by removing arsenic from 188 ppb to 5-2 ppb level, manganese from 1mg/l to 0.03 mg/l, iron from 6mg/l to 0.04mg/l, TDS from 4600mg/l to 252mg/l and zero bacteria in treated water. Finally, the treated water also maintains its integrity, meaning that the Hydroxon™ process maintains all the necessary minerals in the water and the water does not require re-mineralization. Keeping minerals in treated water is extremely important for human health.
Key Contaminants Treated by this technology claimed by proponent:
Heavy metal & metalloid’s including Manganese; Iron; Copper; Arsenic; Molybdenum; Vanadium; Cadmium; Copper; Nickel; Lead; Mercury; Chromium.
Bacteria and virus can completely remove by this technology.
Hi Dr, thank you for this useful information. It seems like a good product for external use but cannot be applied to natural water bodies and lakes. My approach is not just the human factor but the environmental factor and the effects on water life, plants etc.
I am 100% in support of constructed wetlands and do some treatments to reduce size and improve efficacy in that space, but I don't think that can be applied to natural lakes and water systems.
Just to clarify my question, I am referring to the reduction of Arsenic and other heavy metals in Natural Water Systems where I believe current solutions can not be applied due to the environmental impact... Also referring to the breakdown of Arsenic and not via coagulation.
We offer RO Pre-Treatment, Scale causing Sulphates Removal, organic solids reduced < 1/2 Micron size, Heavy Metal Removal, Water Softening without Chemicals using patented “Electro-Oxidation” Technology. Oxidant reactions 400+
Clearflow Group may be able to provide assistance. Our Water Lynx Gel Block Flocculants can reduce heavy metals. They are specifically designed for in situ application requiring no power or technical skill for use. 780 965 0177
Also, you can't break down arsenic to non toxic materials. You would have to remove it if it is a problem. Iron oxides will adsorb arsenic, but it would settle to the bottom and then be released slowly.
Lime can be used in lakes for metals, although it will change the pH which high harm the fish. Iron oxide and alumina have been used for lake contamination to precipitate metals but they can also have major effects on fish.
Joseph, I am referring to the break down of Arsenic into non-toxic elements in natural lakes and water systems. Not so sure if adding lime will achieve this.
You cannot "break down" arsenic into benign compounds like you can with organic pollutants like solvents or hydrocarbons. Metals (well, technically arsenic is a metalloid) are irreducible. All you can do is precipitate the dissolved ions out of solution through various means. Arsenic and most heavy metals are stable and non-leachable under anaerobic reducing conditions (i.e., in sediments). Thus, if you precipitate them in situ they will settle to the bottom of the water body, become incorporated into sediments and generally not create problems in the ecosystem, but this is somewhat site-specific.
It is difficult to help you further without knowing more about the water body(s) your are trying to remediate and what the source of the pollutants is. Since you are in South Africa I am guessing the pollutant source is mining-related and ongoing. In that case, you should first look into options for source control, i.e., installing low-permeability covers over waste rock and tailings piles, plugging or installing treatment systems at draining tunnels and adits, etc.