Expanded Clay Aggregate, ECA, Leca, Filtration of Humic Wate

Filtration of Humic Waters

  • Contact filtration performance of a coarse Expanded Clay Aggregates (ECA) filter is compared to a conventional/normal filter media sand filter/anthracite. 
  • In a contact filtration experiment, humic water was coagulated using iron chloride sulphate, aluminum sulphate, poly-aluminum chloride or the bio-polymer chitosan. 
  • Contact filtration experiment was conducted at optimum pH level and conditions for each coagulant found from previous optimization experiments in filter plant. 
  • The results reveal two main challenges in coagulation/filtration of humic waters, namely:
  •     Short filtration timing for the most commonly used metal residuals and metal salts in treated water.  However, the best ways to overcome these problems in waters high in organic matter is to coarse filter bed using Expanded Clay Aggregate (ECA) with chitosan.
  •     An increased turbidity level in the raw water as a result of bentonite clay accumulation and this in turns increase removal of humics and also increase the filterability of the flocs formed.