A Drinking Water tube-well in Extremadura Spain

 

Dryden Aqua have provided AFM for the removal of arsenic from drinking water system in Spain.  The following is a review of the gthe results and copies of the the water anaysis from two of the installations.A three year research and field trial project is also in progress in India supported by the European Commission under the FP7 program and by the DST Deptartment of Science and Technology for India, www.Eco-India.eu.  

It has been acknowledge that Dryden aqua have an integrated sustainable solution to treat arsenic in Drinking Water and remove it to safe levels. System are now running in Europe as well as Asia. Trials and reseach are also continuing to further refine the process and develop it into a standard technology to deal with a problem that affects nearly 1 billion people.

All of the water was analysed by independent laboratories and a snap shot copy of the analysis is included in this report.

 
water flow
pre-treatment
inflent
AFM treated water
percentage removal
City: Herreruala, date 14/3/2011    4m/hr  

Fe 1.44 mg/l

As 40ug/l

<0.02mg/l

<10 ug/l

>98%

>75%

City: Herreruala, date 23/12/2012    4m/hr  

Fe 4.5mg/l

AS 60ug/l

<0.02mg/l

<10 ug/l

>98%

>75%

City: Carcaboso, date 18/1/2012   12m/hr 45mins aeration and ZPM As 8.8 ug/l < 2ug/l

>75%

 

City: Carcaboso, date 18/1/2012   12m/hr 45 mins aeration and ZPM As 11 ug/l < 3ug/l >73%

Discussion

Table 1 below provides data regarding the effectiveness of existing technologies to remove arsenic from potable water.  The most effective approach is ferric co-precipitation combined with lime to increase the pH.  Increasing the redox potential also helps to change the oxidation state of arsenic and make it insoluble.  Most problems with arsenic are with ground water or tube-wells.  Currently Dryden Aqua is working on an FP7 project funded by the European commission to help develop new water treatment technology which will hopefully help to solve the problems in West Bengal and Bangladesh as well as many other countries that have arsenic ground water problems. For more information check out www.eco-india.eu

Dryden Aqua systems for Arsenic control of ground water to provide safe drinking water.

The upper level under WHO guidelines is 10ug/l

The Dryden Aqua system comprise of the following;

  • stage 1; pump the water out of the ground
  • stage 2; aerate the water using our air diffusers to blow off VOC`s (volatile organic carbon) and raise the redox potential >100 mv, the aeration tank should have at least a 30 minute residence time for the water
  • stage 3; In the aeration tank add sufficient MagpHlow media to raise the pH to between pH8.0 and 8.3. MagPhlow is pelletised product that you simply add to the aeration tank every few weeks or months. There is no requirement to use a control system, it naturally holds the pH at the correct levels if you have sufficient in the aeration tank
  • stage 4. A small amount of a multi-spectrum flocculent and coagulant such as our APF is dosed into the aeration tank.  There may not be a requirement to add APF, it will depend upon the quality of the water. Usually it is not required.
  • state5; After the aeration tank, the water is passed through our AFM filtration media contained in either a pressure filter or an open gravity filter. At the adjusted pH, redox potential and in then presence of ferric, over 90% and often more than 98% of the arsenic will drop out of solution and will be removed by AFM active filter media.  The arsenic particles have a +ve charge. For arsenic removal AFM is modified to have  a higher -ve surface charge and nano-structure shape to adsorb the particles of arsenic that are smaller than a bacteria.
  • stage 6; a small amount of chlorine may be added to the water after the AFM filter to give a residual of 0.1mg/l,
  • stage 7;  the water is now safe to drink

 

 

 

 

 

Table 1. Effectiveness of  existing technologies for Arsenic Water Treatment

TREATMENT

TECHNOLOGY

INITIAL ARSENIC CONCENTRATIO N

FINAL ARSENIC CONCENTRATION*

REFERENCE

 

Iron

Coprecipitation

Oxidized Arsenic 56 mg/L

10 µg/L

Brewester 1992

 

Arsenate 350 µg/L

6 µg/L

Logsdon 1974

 

Arsenite 350 µg/L

140 µg/L

Logsdon 1974

 

Arsenate 560 µg/L

10 µg/L

Shen 1973

 

Arsenate 300 µg/L

6 µg/L

Sorg 1978

 

Arsenite 300 µg/L

138 µg/L

Sorg 1978

 

Alum Coprecipitation

Arsenate 350 µg/L

74 µg/L

Logsdon 1974

 

Arsenite 350 µg/L

263 µg/L

Logsdon 1974

 

Arsenate 300 µg/L

30 µg/L

Sorg 1978

 

Arsenite 300 µg/L

249 µg/L

Sorg 1978

 

Lime Precipitation

Arsenate 500 mg/L

4 mg/L

Nishimura 1985

 

Arsenite 500 mg/L

2 mg/L

Nishimura 1985

 

Arsenate 2 mg/L

20 µg/L

Nishimura 1985

 

Arsenite 2 mg/L

160 µg/L

Nishimura 1985

 

Activated Alumina

Arsenate 100 µg/L

4 µg/L

Frank 1986

 

Arsenite 100 µg/L

Ineffective

Frank 1986

 

Arsenate 57 µg/L

ND at pH 6.0

Clifford 1991

 

Arsenite 31 µg/L

Ineffective

Clifford 1991

 

Ion Exchange

Arsenate 100 mg/L

< 800 µg/L

Vance

 

Arsenate 68 mg/L

12.2 to 0 mg/L

Calmon 1973

 

Reverse Osmosis

Arsenite 37 µg/L

7 µg/L

Clifford 1991

 

Arsenate 51 µg/L

1.5 µg/L

Clifford 1991

 

Electrodialysis

Arsenite 188 µg/L

136 µg/L

Clifford 1991

 

Sulfide Precipitation

Arsenate 132 mg/L

26 mg/L

Rosehart 1972

 

Activated Carbon

Arsenite 500 µg/L

300 µg/L

Rosehart 1972

 

Some data for AFM Dryden Aqua systems

The following analysis confirms that AFM is able to reduce the concentration of ferric or arsenic to concentrations below detection level.

 

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