NAMS 2002 Workshop - ICOM 2008

Ultra- and Microfiltration II - Processes – 5
Thursday July 17, 11:00 AM-11:30 AM, Moloka’i
Hygienic Barrier Efficiency of a Coupled Coagulation / Flocculation and
Ceramic Microfiltration System for Potable Water Production
T. Meyn (Speaker), Norwegian University of Science and Technology, Trondheim, Norway -
thomas.meyn@ntnu.no
A. König, Technical University Berlin, Berlin, Germany
T. Leiknes, Norwegian University of Science and Technology, Trondheim, Norway
Due to climatic and geographical conditions, Norway has an abundance of water
resources and about 90% of drinking water supplies are from surface water
sources, mostly lakes with very low turbidity. In general, the drinking water
sources are characterized by high concentrations of natural organic matter
(NOM), low pH, low alkalinity and low turbidity. Typical values are; colour of 30-
80 mg Pt/l, TOC 3-6 mg C/l, COD 4-8 mg Mn/l, turbidity < 1 NTU, alkalinity < 0,5
meq/l and hardness < 5 mg Ca/l. The removal of NOM is a primary treatment
concern since coloured water is unattractive to consumers, results in colouring of
clothes during washing, can cause odour and taste, increases corrosion and
biofilm growth in the distribution network, and is a precursor to the formation of
disinfection by-products (DBP) when water is disinfected. Coagulation /
flocculation coupled with a MF ceramic membrane filtration plant is a promising
alternative membrane process for the removal of NOM to produce potable water.
National regulations for drinking water production requires minimum of two
hygienic barriers and the object of this study has been to assess the hygienic
barrier efficiency of this treatment alternative.
Bacteria and viruses in drinking water can cause diseases among consumers.
These viruses belong to the group of adenoviruses, astroviruses, enteroviruses,
hepatitis-A and hepatitis-E viruses, noroviruses and rotaviruses. These human
pathogenic viruses mostly reproduce themselves in the gastrointestinal tract and
get together with the faeces in big amounts into wastewater and the environment.
This especially becomes important because viruses can be regularly found in the
effluent of conventional treatment plants and the fact that the portion of treated
waste water in rivers can be high.
The MF ceramic membrane filtration unit used in this study is based on dead-end
operation of multi-bore tubular membranes with a pore size of 0,1 µm. The
filtration pilot plant consists of three trains with an integrated flocculation step.
The membranes were operated at a flux of 140 LMH. Two different coagulation
agents, polyaluminium chloride and iron chloride were tested. The virus and
bacteria removal capacity was determined by using MS2-bacteriophage and
Escherichia coli respectively. Possible virus inactivation by the applied