LEVAPOR GmbH Biofilm Technologies www.levapor.com

Project : SAPPI , Pulp and Paper Mill , Ehingen, Germany

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.

Fig. 1 Process flow diagram of SAPPI WWTP

Fig.2 . Picture of SAPPI WWTP

3. Technical data

Legend Dimension Value

Water flow m³/day 20.000

COD-load, concentrated kg/day 40000- 45000

COD-removal % 80 – 85

Biogas production m³/day

m³/t COD

11000-15000 470

Excess sludge production kg/day 4500- 6200

Volume anaerobic reactors m³ 3 x 6000

Volume aerobic reactors m³ 4 x 3000

Tab. 1. Technical data of the WWTP and plant performance

4. Confirmation of advantages of LEVAPOR carrier 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 3), followed by filling with LEVAPOR and by a new startup.

Fig. 3 COD – loading rates of the methanogenic reactors with suspended, respective immobilised biomass in the startup phase.

Fig. 4 Some plant performance data after three years operation