Treatment of Pulp and Paper Mill Effluent Using immobilized biomass on Levapor Carriers

1. 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

2. 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.

3. Fig. 4 Some plant performance data after three years operation