Pulp and Paper Mill Effluent , Anaerobic-Aerobic Treatment
LEVAPOR GmbH Biofilm Technologies www.levapor.comProject : SAPPI , Pulp and Paper Mill , Ehingen, GermanyAnaerobic-aerobic treatment of toxic pulp effluents with biomass, immobilised onLEVAPOR carrier1. The problemEffluents of pulp mills using chlorine for pulp bleaching do contain several, underaerobic conditions only weakly degradable (35-45%) toxic chloroorganic pollutants.2. The solutionPreliminary biotretment tests under anaerobic conditions, using specially adaptedmicroorganisms, immobilised on adsorbing, porous LEVAPOR carrier showed aremarkably increased degradation. Results obtained in continuous tests in pilot scalehave confirmed the previous results and served as basis for conception and design ofa full scale plant, comprising of microaerobic pre-treatment, anaerobic step andaerobic post-treatment.Fig. 1 Process flow diagram of SAPPI WWTPFig.2 . Picture of SAPPI WWTP
3. Technical dataLegend Dimension ValueWater flow m³/day 20.000COD-load, concentrated kg/day 40000- 45000COD-removal % 80 – 85Biogas production m³/daym³/t COD11000-15000470Excess sludge production kg/day 4500- 6200Volume anaerobic reactors m³ 3 x 6000Volume aerobic reactors m³ 4 x 3000Tab. 1. Technical data of the WWTP and plant performance4. Confirmation of advantages of LEVAPOR carrierIn order to confirm the contribution and efficiency of LEVAPOR, initially only two ofthree anaerobic reactors had been filled with LEVAPOR, the third one had beenstarted with suspended anaerobic sludge. The activity of suspended biomass hasnever reached the activity and removal rates of immobilised biomass and crasheddown after a toxic shock in May 90 (Fig 3), followed by filling with LEVAPOR and by anew startup.Fig. 3 COD – loading rates of the methanogenic reactors with suspended, respectiveimmobilised biomass in the startup phase.
Fig. 4 Some plant performance data after three years operation