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 0.57N NaOH solution under an N2 atmosphere. The separation of the humid and fulvic acid fractions was carried out using Matricel type filters (0.45‐µm 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.

Organic compounds in re-circulated leachates of aerobic biological treated municipal solid waste

“…The addition of sewage sludge increased the DOC proportion from 72% (L1-MSW+SS) to 94% (L2-MSW+SS) of TOC. Such an increase in DOC proportion as percent of TOC as found in the MSW and MSW+SS variant (Table 2) was previously described as an indicator of largely completed organic matter stabilization in old landfills (Artiola-Fortuny 1982;Christensen et al 1998). Therefore, the BOD:COD ratio £ 0.03 and the high DOC proportions in the leachates (L2-MSW and L2-MSW+SS) showed the low biodegradability of the remaining organic matter in both variants.…”

“…Infrared spectroscopy indicated carbohydrates, peptides, lipids and lignin compounds in leachates (Artiola-Fortuny & Fuller 1982). Curie-point pyrolysis-gas chromatography/mass spectrometry (Cp Py-GC/MS) of non-biodegradable organic matter fractions from leachates showed predominant signals of phenols, aromatics and N-containing compounds (Go¨bbels & Pu¨ttmann 1997).…”

Analytical pyrolysis of re-circulated leachates: Towards an improved municipal waste treatment

“…The concentrations of TOC and DOC in the leachates showed, that the high percentage of DOC of 97% (StartEluate) drastically decreased with the increasing COD and BOD of L2-LYSI to 64%. As a low percentage of DOC is known as an indicator for low organic matter stabilization [21,22], the above described hypothesis of a reduced microbial decomposition after 6 months of re-circulation (L2-LYSI), expressed as increased COD and BOD, is proven by the increased proportion of the DOC. Thus, the recently described decomposition of organic matter during recirculation of leachates at the laboratory-scale [5] also occurred at the larger lysimeter-scale.…”

Feasibility Assessment of Spectroscopic Methods in Characterising Leachate Dissolved Organic Matter

“…A considerable amount of recalcitrant organic compounds can remain after treatment in particular for the biological processes which are the most commonly used methods of leachate treatment in the UK (Robinson and Knox, 2003). An influential component of many recalcitrant organic compounds are also humic substances (Artiola-Fortuny and Fullar, 1982;Christensen et al, 1998) which can significantly affect the accumulation and migration of some priority substances and hence, play an important role in the natural environment (Weis et al, 1989). Therefore, it is essential to understand the evolution and the chemical and structural composition of different organic compounds of leachates.…”