AWWA WKICO66045

The objective of this powerpoint presentation was to design and optimize a system for sustained perchlorate removal. Background information on perchlorate is presented, along with fixed-bed (FXB) biologically active carbon (BAC) bioreactors at both bench-scale and pilot-scale. Bench-scale conclusions: sustained removal of perchlorate and nitrate achieved; dechloromonas is the dominant perchlorate reducing bacteria in the system; phosphorous addition increased relative abundance of Dechloromonas substantially (from ~15% to ~45%); increase in relative abundance of Dechloromonas is apparently the reason for improved reactor performance; and, microorganisms use acetic acid adsorbed on GAC during the lowacetic- acid period for some period, but the adsorbed acetic acid is not enough to support this for the entire period of low-acetic-acid tested (6 hours). Pilot-scale conclusions: efficient, robust perchlorate removal achieved in a FXB bioreactor; short contact times required; minimal impact from various process upsets; H₂O₂ + 2nd-Stage Biofilter + Chlorination provided effective post-treatment polishing; DO addition, removal of DOC/DBP formation potential, H₂S, turbidity, HPCs, perchlorate buffer; perchlorate is destroyed, not concentrated; and, overall system efficiency is 95+ percent. Includes figures.