Anaerobic-aerobic treatment of toxic pulp effluents with biomass, immobilised on LEVAPOR carrier
1. The problem
Effluents of pulp mills using chlorine for pulp bleaching do contain several, under aerobic conditions only weakly degradable (35-45%) toxic chloroorganic pollutants.
2. The solution
Preliminary biotretment tests under anaerobic conditions, using specially adapted microorganisms, immobilised on adsorbing, porous LEVAPOR carrier showed a remarkably increased degradation. Results obtained in continuous tests in pilot scale have confirmed the previous results and served as basis for conception and design of a full scale plant, comprising of microaerobic pre-treatment, anaerobic step and aerobic post-treatment.
4. The effect of LEVAPOR
In order to confirm the contribution and efficiency of LEVAPOR, initially only two of three anaerobic reactors had been filled with LEVAPOR, the third one had been started with suspended anaerobic sludge. The activity of suspended biomass has never reached the activity and removal rates of immobilised biomass and crashed down after a toxic shock in May 90(Fig 5), followed by filling with LEVAPOR and by a new startup.