Available technologies for arsenic treatment:
Advantages and disadvantages

 
 
Method
Advantages
Disadvantages
Co-precipitation: No monitoring of a break through is required.
Relatively low cost simple  chemicals.
Low capital costs.		 Serious short and long term problems with toxic sludge.
Multiple chemicals requirement
Operation requires training and discipline.
        Alum coagulation 
 Durable powder chemicals normally available.  Efficient pre-oxidation is a must.
        Iron coagulation
 More efficient than alum on weigh basis.  Medium removal of As (III).
        Lime softening
 Most common chemicals  Re-adjustment of pH is required.
Sorption techniques: No daily sludge problem.
  • Requires monitoring of break through or filter use.
  • Requires periodical regeneration or medium shift.
    		•
          Activated alumina
    		 Relatively well known  and commercially available. Re-adjustment of pH is required.
          Iron coated sand
  • Expected to be cheap.
  • No regeneration is required.
    		•
  • Yet to be standardized.
  • Toxic solid waste. 
    		•
          Ion exchange resin 
    		 Well defined medium and hence capacity.
  • High cost medium.
  • High tech operation & maintenance.
  • Regeneration creates a sludge problem.
    		•
          Other Sorbents 
    		 Plenty of possibilities & combinations Not yet  properly studied.
    Membrane techniques:
  • Well defined performance.
  • High removal efficiency.
  • No solid waste. 
  • Low space requirement.
  • Capable of removal of other contaminants, if any. 
    		•
  • High running costs.
  • High investment costs.
  • High tech operation and maintenance.
  • Toxic wastewater.
  • Re-adjustment water quality is required.
    		•
          Reverse Osmosis
    		 Membrane does not withstand oxidizing agents.
          Eleetrodialysis
    		 Membrane does not withstand oxidizing agents. 

    Arsenic Page
    Copyright: EngConsult Limited
    masud@eng-consult.com
    Last modified: August 2001