Arsenic mitigation in high volume water flow

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 I'm looking for recommendations for technical solutions for removing Arsenic from Municipal level water with flow rates such as 140 cubic meters of flow per second. The current level of Arsenic is 2.5 times higher than the accepted standard of LMP 0.01mg/liter. Many thanks.

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13 Answers

  1. Assuming you meant per minute and not second, there are mine water treatment systems that remove As at those flowrates. The use co-precipitation with ferric hydroxides. And contrary to what some may say, oxidation of As3+ to As5+ is not necessary, it only means that the iron dosage has to be a little higher. 

  2. oxidation with chlorine, addition of ferric chloride or ferric sulphate, some level of mixing and a good filter is all you need. Iron dosed at between 10:1 to 20:1 to the amount of arsenic you want to remove will be required. Removal of 0.25 mg/l of As will require somewhere between 2.5 & 5.0 mg/l of iron dosage. Chlorine is required for correct As speciation. Don't fall for "gimmicks".

  4. Hello Ian,

    Irrespective of the flow rates can offer a bioremediation based method, The only limitation would be you need to hold water in some place for sometime. Have tested it for 28M in the lab and it works. All scientific evidences can be shared.Again Arsenic can be reused elsewhere and that again gives dollars.

  5. Dear Mr Percy. I would think adsorption is the best solution at your As levels. We have the material that can adsorb As and the technology to regenerate the material and recapture the As which could subsequently be transformed in a harmless material. It will take however a substantial investment to treat 140 m3/s.    

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    1 Comment

    1. Many thanks, great responses. There are questions about the flow rate mentioned so I'm checking with my client. Have a feeling it should have been 'per minute'. I've also forwarded all responses to them. I'm very appreciative. 

  6. Hello Ian,

    We are manufacturer of Zirconium base Arsenic removal media which has the world highest adsorption value at 254.1 mg/g of arsenic. Proven record of removing AS level of 2,680ppb to 0ppb. Span material are certified safe for landfill with NO re-pollution or release of arsenic back into the water.

    Please contact me david.kang@asxban.com if you are interested.  

  7. Dear IAN,

    For such big capacity, the best solution could be 1) Conventional Coagulation with coagulant dosed at higher concentration than normal (say 2x, 3x), then As can be removed 2) If budget allows, put a preO3 upstream. In combination with high dosage of coagulant, As can be effectively removed 3) You can perform the jar tests to confirm the coagulant type (alum or FeCl3) and the concentration.

    BR

    1 Comment

    1. Many thanks, great responses. There are questions about the flow rate mentioned so I'm checking with my client. Have a feeling it should have been 'per minute'. I've also forwarded all responses to them. I'm very appreciative. 

  8. are you correct on the 140 M3/sec and not per minute? 140/sec = 2,219,028gallons/min => 3.2billion gals/day.  That is 10 times more than the flow from the City of Houston, TX.

    1 Comment

    1. Thanks Terry. I copied and pasted the note from my client so I'll check again with them. Very likely you are right. 

       

      1 Comment reply

      1. Hi 'terry. A quick follow-up on this issue - that is indeed the level of water flow. My client said he checked that that was the case numerous times. What is misleading is his use of "municipal." Actually this is a major water source going to many communiities over a large geographical area. Arsenic is a problem for them all. Have passed along all suggestions but haven't heard back yet. 

  9. Having processed high flows to low ppb levels can be relatively easy. We needed to get to 2ppb (0.002mg/L). What we did was a ferric coagulation followed by filtration and then running the filtered water thru anion vessels in the chloride form. Lots of ways to handle the process depending on how long the process is needed. 

  10. “A University of Florida professor has developed a quick, cheap and easy way to filter from water one of the world's most common pollutants: arsenic.

    Bin Gao's team used iron-enhanced carbon cooked from hickory chips, called biochar, to remove the toxin. He is an associate professor with the Institute of Food and Agricultural Sciences' in agricultural and biological engineering.

    "Because biochar can be produced from various waste biomass, including agricultural residues, this new technology provides an alternative and cost-effective way for arsenic removal," Gao said.

    In a study to be printed in the January issue of the journal  Water Research , Gao and his team describe the process: The wood chips were first ground, then heated in nitrogen gas, but not burned. The resulting biochar, which has the consistency of ground coffee, was then treated with a saltwater bath to impregnate it with iron. Tests showed that plain biochar had no effect on arsenic, but the iron-enhanced product effectively removed the poison from water.

    Current methods to remove arsenic include precipitation, adding lime or coagulants to water, using membranes to filter it out, or using an ion exchange process. But using a filter for removal is one of the most commonly used methods due to its ease of operation, relatively low cost and high effectiveness.

    Gao said water treatment plants could use large biochar filters to extract the arsenic. Homeowners could use a small filter attached to their tap.

    Additional investigations are still needed to optimize the process and to develop commercially available filters, he said. Gao's study was partly supported by the National Science Foundation.”

    Story Source:

    Materials provided by  University of Florida .

    Journal Reference :

    1. Xin Hu, Zhuhong Ding, Andrew R. Zimmerman, Shengsen Wang, Bin Gao.  Batch and column sorption of arsenic onto iron-impregnated biochar synthesized through hydrolysis .  Water Research , 2015; 68: 206 DOI: 10.1016/j.watres.2014.10.009
    2. University of Florida. "Inexpensive, easy way to filter arsenic from water." ScienceDaily. ScienceDaily, 3 November 2014. .

    1 Comment

    1. Many thanks, great responses. There are questions about the flow rate mentioned so I'm checking with my client. Have a feeling it should have been 'per minute'. I've also forwarded all responses to them. I'm very appreciative. 

       

  11. ferric co-precipitation is the only high flow low cost method. Speciate the As with an oxidizer, (chlorine) and ferric chloride (assumes no native iron) with a ratio up to 20:1 and filter.

    1 Comment

    1. Many thanks, great responses. There are questions about the flow rate mentioned so I'm checking with my client. Have a feeling it should have been 'per minute'. I've also forwarded all responses to them. I'm very appreciative. 

  12. That's a big flow rate for one location. Global Water, in partnership with the DOE through its National Renewable Energy Laboratory (NREL), has now received a patent in over 60 countries for a Nano Technology- Water Purification Filter which we will soon be put into production. It is designed to remove all parasites, all hazardous chemicals and heavy metals (including Arsenic), and to remove all bacteria and viruses: i.e.: a total (fresh water) purification process. Volume should be no problem; cost should be relatively low. Contact me at amweiss@globalwater.com or call at 214-563-6505.

    1 Comment

    1. Many thanks, great responses. There are questions about the flow rate mentioned so I'm checking with my client. Have a feeling it should have been 'per minute'. I've also forwarded all responses to them. I'm very appreciative.