Effect of immobilized microalgal bead concentrations on wastewater nutrient removal

N. F.Y. Tam, Y. S. Wong

Research output: Contribution to journalArticlepeer-review

176 Citations (Scopus)

Abstract

A unicellular green microalga, Chlorella vulgaris, entrapped in calcium alginate as algal beads were employed to remove nutrients (N and P) from simulated settled domestic wastewater. A significantly higher nutrient reduction was found in bioreactors containing algal beads (at concentrations ranging from 4 to 20 beads ml-1 wastewater) than the blank alginate beads (without algae). A complete removal of NH4/+-N and around 95% reduction of PO4/3--P was achieved within 24 h of treatment in bioreactors having the optimal algal bead concentration (12 beads ml-1, equivalent to 1:3 algal beads:wastewater, v/v). The NH4/+-N removal was significantly lower at low (around 4 beads ml-1) and high (>15 beads ml-1) algal bead concentrations. On the other hand, the effect of bead concentration on phosphate removal was less obvious, and bead concentrations ranging from 8 to 20 beads ml-1 showed comparable percentages of phosphate reduction. Algal uptake and adsorption on alginate gels were found to be the major processes involved in the removal of N and phosphate in the present study. In addition, NH4/+-N could be lost via ammonia volatilization while PO4/3--P was removed by chemical precipitation, as alkaline pH was recorded in the immobilized microalgal treatment system.

Original languageEnglish
Pages (from-to)145-151
Number of pages7
JournalEnvironmental Pollution
Volume107
Issue number1
DOIs
Publication statusPublished - Jan 2000
Externally publishedYes

Keywords

  • Alginate
  • Ammonium
  • Bead concentration
  • Chlorella
  • Immobilization
  • Phosphate

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