Activated sludge immobilization using the PVA-alginate-borate method.
The PVA-alginate-borate method was used successfully to immobilize activated sludge. The optimum polyvinyl alcohol (PVA) concentration in the immobilized sludge was determined to be 10-12.5%. A minimal alginate of 1% in the beads was needed to prevent bead agglomeration. If the pH of the saturated boric acid was adjusted to 7.0 prior to allowing droplets of the mixture of PVA, alginate and sludge to enter the solution, a high level of sludge activity could be maintained in the beads formed. During the continuous operation of a fluidized bed reactor, with hydraulic retention time (HRT) in the range of 24-3 h (BOD loading from 0.176 to 0.766 kg/d/m3) and an aeration rate at 1.0 L/min, more than 90% of BOD5, NH4(+)-N and TKN were removed. The immobilized sludge exhibited satisfactory mechanical stability without apparent breakage.
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Department of Chemical and Biological Engineering, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4 Canada.
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D000464:Alginates / Q000737:chemistry; D001888:Boric Acids / Q000737:chemistry; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000378:metabolism; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*
D000464:Alginates; D001888:Boric Acids; D006603:Hexuronic Acids; D012722:Sewage; D020723:Glucuronic Acid; D011142:Polyvinyl Alcohol; C032688:boric acid; D010100:Oxygen