Physico-Chemical Effluent Treatment

Testing and optimisation of a practicable treatment technology for the removal of arsenic in drinking water treatment

Four processes for the removal of arsenic from drinking water have been compared in a pilot plant on the basis of technical and economic factors. Adsorption in granulated iron hydroxide has emerged as an effective, extremely reliable, low maintenance and cost-effective alternative for small and medium-sized water utility companies. 

Summary

The reduction of the limiting value for the arsenic content of drinking water to  10 µg/l with effect from 1st January 1996 has made it necessary for some 300 German water utility companies, in areas where the geogenous arsenic content of groundwater is high, to undertake the technical retrofitting of their drinking water abstraction plants.

Under these conditions, a pilot plant with four identical filter units has been constructed in a municipal waterworks for the comparison of the following processes on the basis of technical and economic factors:

  • Precipitation/flocculation with iron (III) chloride,
  • Precipitation/flocculation with iron (III) sulphate,
  • Adsorption in granulated iron hydroxide, and
  • Adsorption in activated alumina.

Results:

  • With the exception of adsorption in activated alumina, all the processes considered have achieved reliable compliance with the permissible limiting value.
  • For precipitation and flocculation, the addition of iron in a concentration of 0.8 g/m3 has proved to be sufficient.  The external disposal of sludge with high levels of arsenic contamination has been necessary. Iron (III) chloride has proved to be particularly suitable on the grounds of the significantly lower volume of sludge generated, reduced maintenance costs and improved operational reliability.
  • A newly-developed granulated iron hydroxide process featuring two simultaneously exposed adsorbers has achieved the effective, extremely reliable and low-maintenance removal of arsenic from drinking water.  It has been possible to discharge the backwash sludge into the public sewage system.  Treatment costs of €0.09/m3 of raw water have been established.
  • The reduction of the pH value has not proved to be cost-effective, on the grounds of the additional consumption of chemicals involved.

More Project Informations

Project title:  Removal of arsenic in drinking water treatment: pilot process for the testing and optimisation of a practicable treatment technology

Project number:  02WT9662/1

Project period:  1996 - 1999

Project region:  Germany (North Rhine-Westphalia)

Project contact:

Herr Prof. Dr. Jekel

This email address is being protected from spambots. You need JavaScript enabled to view it.

View Publication

Source:  German National Library of Science and Technology Hannover (TIB)