Biological water purification

  • Top notch biological water purification

    In the coking plant, coal is transformed into coke. During this process, polluted water is formed due to organic contaminants. We purify this water in our state-of-the-art biological water purification installation.

    Biological water purification

    The water purification is done in two steps: First, the contaminants are microbiologically reduced to water, CO2 and other nitrates in an oxygen injected basins. Next, the nitrates are transformed into nitrogen.

    Germs at work

    The micro-organisms that purify the waste water, are the so-called ‘garbage eating’ bacteria. Different families of this type of bacteria help in purifying the impure water. The following table gives us an overview of the different processes:

    Offered pollution load Altered by Via a chemical reaction transformed into
    C6H5OH (phenols) Organic bacteria
    (family pseudomonas)
    C6H5OH + 7O2 → 6CO2 + 3H2O + energy
    Organic carbon and nitrates Organic bacteria
    (family pseudomonas)
    C + 2NO3 + 2H+ → N2 + 5/2O2 + H2O + CO+ energy
    S2O3 (thiosulphates) Chemolithotrofe bacteria
    (family thiobacillus)
    S2O3 +2O2 + H2O → 2SO4 + 2H+ + energy
    CNS (thiocyanates) Chemolithotrofe bacteria
    (family thiobacillus)
    CNS- + 2O2 + 2H2O → SO2 + NH4 + NH4 + CO2 + energy
    NH4 (ammonium) Chemolithotrofe bacteria
    (family nitrosomonas)
    NH4 + + 3/2 O2 → NO2 + H2 + 2H+ + energy
    NO2 (nitrites) Chemolithotrofe bacteria
    (family nitrobacter)
    NO2 + ½ O2 → NO3 + energy

    Closed circuit

    In the sedimentation basin of our biological water purification installation, micro-organisms are- as much as possible- kept separate from the purified water.

    The sedimentation is, once formed, scraped off for the main part and then sent back to the oxygen injection installation. Around 20% of the sedimentation is been thickened before being sent back to the coals supply (coking plant) so that it can be re-used in combination with coal. By doing so, we created a closed-off ‘garbage’ circuit which has no environmental impact.

  • More process innovation