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INTRODUCTION TO THE TREATMENT OF TANNERY EFFLUENTS every tanner What every tanner should know about effluent treatment Part II J. Buljan, I. Kral Compiled by J. Buljan, I. Kral U nited N ations I ndustrial D evelopment O rganization Slide 2 within 2. Treatment within tannery compound A.Pre-treatment for discharge into CETP collection network Screening Grit & grease chamber B.Physical-mechanical (primary) treatment for discharge into municipal sewage Screening Lifting lifting pumps Equalization homogenization, ejectors pH adjustment, coagulation, flocculation Primary clarification/flotation Flow-chart of the physical-chemical (primary) treatment Slide 3 ROUGH BAR SCREEN bar screen Collected solids Raw Raw effluentFromTANNERY Screened Screened effluentToTREATMENT CHANNEL rake Slide 4 BAR SCREEN CLEANING Manual Rotary curved 360 0 Continuous chain raked Auto chain Rotary curved 90 0 Slide 5 SLUDGE SCUM Screen 20 mm Screen 10 mm Screen 6 mm NON-AERATED GRIT AND FLOATING MATTER REMOVAL CHAMBER Periodically to the sludge disposal site Slide 6 SELF-CLEANING SCREEN SELF-CLEANING SCREEN PARKWOOD TYPE Effluent inflow Slide 7 SUBMERSIBLE PUMP SUBMERSIBLE PUMP FOR EFFLUENT LIFTING Pump Lifting chain Water inlet Pump maintenance Slide 8 Filtering gap Trapezoidal shaped bars WASTWATER INLET WITH SUSPENDED SOLIDS SOLIDS RECOVERY FILTERED WATER DISCHARGE ROTARY DRUM SCREEN ROTARY DRUM SCREEN KONICA TYPE outer flow Slide 9 Rotary fine screen (inner flow) Internal screw Filtering panel Brush Raw effluent Filtered effluent Solids Slide 10 ROTARY DRUM SCREEN Slide 11 Screw (Archimedes) type pump for effluent lifting Driving mechanism The principle Effluent intake Slide 12 Screw (Archimedes) type pump for effluent lifting Slide 13 Equalization homogenization tank Equalization homogenization tank Schematic view Free board EFFLUENT INFLOW Pump dry protection level Continuous level measuring High level alarm Bypass TO SUCCESSIVE TREATMENT Slide 14 Coagulation and flocculation (scheme) DRAIN Dosing pump Dosing pump Dosing pump ALUMLIME POLY- ELECTROLYTE COAGULATION TANK FLOCCULATION TANK WASTEWATER INLET WASTEWATER OUTLET Service water Slide 15 Wastewater Ejector for mixing and aeration Air inlet Air-wastewater mixture outlet Wastewater inlet Submersible pump Ejector Slide 16 Type of sedimentation tanks Rectangular horizontal flow Slide 17 Type of sedimentation tanks Circular, radial-flow Slide 18 Type of sedimentation tanks Hopper-bottomed, upward-flow Slide 19 Typical sedimentation tank Scraper bridge Scraper Slide 20 Typical sedimentation tank Schematic cross-section view Influent Influent well Skimmer Scum trough Scraper Sludge concentrator Drive Effluent Scum draw off Sludge draw-off Slide 21 Rectangular sedimentation tank with travelling bridge Sludge hopper Screw cross collector Rail Scum trough INFLUENT SLUDGE DRAWOFF EFLUENT TRAVELLING BRIDGE TRAVELLING BRIDGE Slide 22 Dissolved air flotation unit (DAF) Air saturation tank Pressure release valve RAW EFFLUENT TREATED EFFLUENT FLOTATEDSLUDGEDRAWOFF RECYCLE FLOW SETTLED SLUDGE PRESSURED RECYLE WTH DISSOLVED AIR Recycle pump Floated sludge skimmer Slide 23 Purification efficiency of the treatment stages referred to raw effluent Parameter Physical-chemicalBiological ReductionApprox. value Reduction * Approx. value %mg/l% SS 80 90300 60095 9820 50 BOD 5 50 65750 150097 9920 30 COD 50 651500 300087 93250 400 TKN 40 50250 30060 70100 200 Cr 92 975 1099 99.5< 1 S 2- 80 9010 2099 99.5< 1 TDS mainly Cl - and (SO 4 ) 2 No reduction *Approximately at the load level of 0.30 kg BOD 5 /kg MLSS, oxygen requirement of 2.0 kg O 2 /kg BOD 5 and MLSS 3300 g/m 3.