An automatic bench‐scale unit for clarification of animal wastewater by dual means of cohesion and ultrafiltration

Abstract

For the purpose of clarifying animal wastewater, an automatic administration with inorganic cohesion and ultrafiltration was tried. As an inorganic agglutinant, 0.385g Ferric Trichloride was added to 1g total suspended solids of slurry. The ultrafiltration module, which had the membrane made of vacant string tubes of poly sulfon, had an effective membrane area 1.0m² . Maximum tolerable pressure of the module was 3kg/cm . For an automatic operation of the unit, a programmable controller PL 40‐III was used. The administration procedure was as follows; Pumping up of the wastewater ———‐Addition of agglutinant solution —‐ Agitation (circulation) of the slurry in the tank —‐ Pumping out to the sedimentation tank —‐ Sedimenting administration —‐ Drainage of the muddy slurry —‐ Ultrafiltration of the supernatant —‐ Reverse cleansing of the filter. The unit worked according to the program. During the experimental operation, original sewage(diluted 125 fold), supernatant and sediment after inorganic cohesion, and filtrate after ul‐trafiltration were sampled, and the following slurry indices were analyzed; PH, T‐S, V‐S, T‐SS, V‐SS, COD, BOD, NH₄‐N, T‐N, T‐P and permeability. Two hours were adequate for a sedimentation by the inorganic cohesion. Removal ratios of organic matters only by the cohesion were 47.8% of T‐S, 53.3% of V‐S, 91.4% of T‐SS, 95.0% of V‐SS, 91.2% of GOD, 89.0% of BOD, 25.7% of NH₄‐N, 57.1% of T‐N, and 80.0% of T‐P. Removal ratios of organic matters by the ultra‐filtration compared with indices of the original sewage were 91.3% of T‐S, 90.0% of V‐S, 96.3% of T‐SS, 98.5% of V‐SS, 93.1% of COD, 98.0% of BOD, 44.3% of NH₄‐N, 81.6% of T‐N, and 92.0% of T‐P. One part of fine particles in the supernatant was removed by the subsequent ultrafiltration. The additional ultrafiltration administration was effective to clarify the wastewater, but the flow bundle through the filter was small on condition of the pump pressure utilized.

Key words:

• Animal wastewater
• Cohesion
• Ultrafiltration
• Automatic bench‐scale unit