Humic Substances in Landfill Leachates: I. Humic Acid Extraction and Identification

Abstract A useful extraction for humic acid from anaerobic municipal solid‐waste landfill leachate is presented. Extraction was accomplished by adding NaOH pellets to give a 0.57 N NaOH solution under an N 2 atmosphere. The separation of the humid and fulvic acid fractions was carried out using Matricel type filters (0.45‐ µ m pore size diam). The infrared characterization of leachate humic acids was markedly improved in time and sample‐size‐requirement reductions by using a Matricel filter made out of a PVC copolymer as a support for these acids. The results obtained compared very favorably with the infrared KBr pellets. The infrared spectra of leachate humic acids proved to be similar to the lake‐ooze humic acid spectra reported by Stevenson and Goh (1971). Humid substances represent > 60% of the total organic C found in anaerobic landfill leachates. Fulvic acid predominates in young unstable leachates, and decreases in concentration with age. Humic acids increase with the age of the leachates, eventually decreasing as the leachate becomes more stable and diluted.