Microbial Uptake of Heavy Metals in Slow Sand Filters

Abstract

This paper is concerned with the microbiological uptake of heavy metals in slow sand filtration (SSF) and the determination of active biomass by organic nitrogen analysis described herein. The heavy metal accumulation and the total biomass in the schmutzdecke scrapings were determined and compared. The heavy metals were extracted from the sand scrapings by means of HNO₃-HCl digestion. The percentage nitrogen content of volatile solids (VS) for the same sand scrapings were determined, and this measure was taken as being directly equivalent to the biomass in the schmutzdecke scrapings. The results show that the more the biomass, the greater the metal accumulation, which indicates microbiological accumulation/uptake rather than simple adsorption of heavy metals in SSF.

Keywords:

• Slow sand filters (SSF)
• schmutzdecke
• metal accumulation
• biomass
• microbiological uptake
• nitrogen content
• volatile solids (VS)