Exhaustive extraction of linear (LAS) and branched (TPS) alkylbenzene sulphonates, nonylphenol (NP) and nonylphenol monoethoxylate (NP1EO) from landfilled sludge were attained by using a polar solvent (methanol) and by adding sodium hydroxide (20%, w/w) to the dry sludge. In the absence of NaOH, or if moderately polar (dichloromethane) to apolar (hexane) solvents were used, poor extraction efficiencies (< 50%) were obtained, in contrast to the results obtained for fresh sludges. In one set of the examined sludge-only landfills, removal by biodegradation of LAS, NP, and NP1EO was minimal over 15 years. In the other set of landfills, both LAS and NP, NP1EO disappeared to a great extent (> 90%) over the same time period. The remarkably different behaviour of these compounds was ascribed to the landfill operating conditions, to be anaerobic when no biodegradation was observed, and aerobic when the title compounds were removed.