MICROBIAL ECOSYSTEMS IN COMPOST AND GRANULAR ACTIVATED CARBON BIOFILTERS

Compost and granular activated carbon biofilters operated at a wastewa ter treatment plant simultaneously removed low concentrations of hydro gen sulfide and volatile organic compounds. Through the use of phospho lipid fatty acid analyses, the effects of declining pH caused by sulfi de oxidation were established for microbial growth, microorganism stre ss, and microbial community structure. Microorganisms on both media de monstrated increases in microbial densities, varying degrees of enviro nmental stress, and domination by gram-negative bacteria. However, the declining pH had little effect on compound removal, which was greater than 99% for the hydrogen sulfide and greater than 70% for the oxygen ated and aromatic hydrocarbons. The microbial communities adjusted to difficult environmental conditions through acclimation of the species present or by growth of low-pH-tolerant species. (C) 1997 John Wiley & Sons, Inc.