Nitrate removal from drinking water through the use of encapsulated microorganisms in alginate beads.
Biological treatment for removal of nitrate from drinking water is of great significance, as traditional physical and chemical methods could not effectively remove soluble nitrate. In this report immobilized microorganisms with co-immobilized calcium tartrate were used for reducing nitrate concentration (110 mg l(-1) NO3-N) in a model solution. The carbon source also functions as a stabilizing agent for the immobilization matrix. Experiments of denitrification showed a high nitrate removal rate while nitrite residual was at a concentration higher than expected. The nitrate concentration was reduced to nearly zero (0.2-1.4 mg l(-1)) after 3 days of operation. The calcium tartrate (4%, w/w) co-immobilized alginate beads had better nitrate removal performance than tartrate in solution. The nitrite-N residual concentration was approximately 1.1-2.9 mg l(-1) at the end of the experiments, showing the desirability of further denitrification. The stability of alginate beads was also tested both to evaluate their behaviors and investigate the efficacy of bead recycling. It was found that the beads could be used for 8-13 days consecutively without any structural deterioration and leaking of microbes.
Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, New Jersey 08901-8520, USA.
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Liu
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Hermanowicz
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Peng
D000464:Alginates; D001419:Bacteria; D001673:Biodegradation, Environmental; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D009566:Nitrates / Q000302:isolation & purification*; D012995:Solubility; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D000464:Alginates; D006603:Hexuronic Acids; D009566:Nitrates; D014873:Water Pollutants; D020723:Glucuronic Acid