Arsenic removal from Water - VSN-33

ADSORBSIA FOR ARSENIC REMOVAL FROM WATER

A convenient and cost effective alternative for removing arsenic in drinking water.

ADSORBSIA titanium based media from Dow was specially designed to assist on reaching the newest WHO requirement for arsenic: 10 ppb. The new filter media has improved capabilities compared to all other commercially available media. Advantages include:

  • Highest capacity over a wide range of water conditions.
  • Nanocrystalline structure results in fastest kinetics allowing for smaller diameter vessels and a smaller system footprint
  • Removes both As(III) and As(V) across a wide pH range without use of pretreatment
  • Stable performance during pH fluctuations, without pretreatment.
  • Dry, white bead that is easily installed and maintained
  • Spent media from arsenic loading tests have been shown to pass both the TCLP and CA WET extraction protocols
  • NSF/ANSI Standard 61 certified without limitations

ADSORBSIA media's high capacity makes it an ideal non-regenerable single-use product. It offers an affordable, easy to operate approach, especially for small or mid-sized systems. Eliminating regeneration means avoiding the hassles and cost of chemical storage and usage while eliminating waste stream disposal issues. ADSORBSIA media's strong affinity for arsenic also allows the media to maintain a strong hold on the removed arsenic, allowing for easier and safer disposal. ADSORBSIA media also features a longer useful life than traditional adsorbent media, for more productive, cost-advantaged operation.

Its main advantages against other oxide and hydroxide media can be seen on the following comparisons.

Next, life expected for different filter media using the same water quality, where it can be seen that ADSORBSIA capacity is over seven times higher than other media.

ARSENIC LEAKAGE CURVES

NSF Challenge Water (300 ppb As(V); pH = 7,5; 180 seg EBCT).
Low Silica (10ppm).

http://unitek.com.ar/english/img_info/arsenico.jpg

Variation of pH, which occurs often on all kinds of water, affects retention capacity of filter media, being ADSORBSIA the one that shows lowest fluctuation, as next figure shows. On both pH changes, treated water was held below the maximum limit (10 ppb) when passing through ADSORBSIA; however, it produces arsenic concentration well higher that the maximum when treated with Ferric oxide.

ARSENIC LEAKAGE CURVES

NSF Challenge Water (50 ppb, pH =6.5, 120 s EBCT).

http://unitek.com.ar/english/img_info/arsenico3.jpg

High silica waters (above 40 ppm) present a reduction on filter media capacity for the removal of arsenic. This reduction is less significant for ADSORBSIA media, which translates into a longer life expectance.

SILICA IMPACT

NSF Challenge Water (50 ppb, pH =6.5, 120 s EBCT).

http://unitek.com.ar/english/img_info/arsenico2.jpg

Applications where ADSORBSIA better shows its higher capacity compared to other media are:

  • Mineral water production where chemical addition is not allowed. Other media require pH regulation (to obtain a consistent arsenic removal), or dosage of oxidants, to oxidize As(III) to As(V) and be removed more efficiently.
  • Reverse osmosis installations that were successful complying with the previous limit of arsenic (50 ppb) but no longer comply, requiring a polishing unit. In these cases, low pH and low silica concentration increase media capacity, reducing operating cost over 20 times.