Effect of linear alkylbenzene sulphonates (LAS) on the anaerobic digestion of sewage sludge

• Published in: Water research (Oxford) Vol. 40; no. 15; pp. 2958 - 2964
• Main Authors: Garcia, M.T., Campos, E., Sánchez-Leal, J., Ribosa, I.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2006; Elsevier Science
• Subjects: Adsorption; Alkanesulfonic Acids - analysis; Alkanesulfonic Acids - chemistry; Anaerobic digestion; Applied sciences; Bacteria, Anaerobic; Bioavailability; Bioreactors; Exact sciences and technology; LAS; Other industrial wastes. Sewage sludge; Pollution; Sewage; Sewage sludge; Surface Properties; Surface-Active Agents - analysis; Temperature; Time Factors; Toxicity; Waste Disposal, Fluid - methods; Wastes; Water Pollutants - analysis; Water Purification - methods; Water treatment and pollution; Bioavailability; Toxicity; Sewage sludge; Anaerobic digestion; LAS; Biodegradation; Liquid solid interface; Pollutant behavior; Waste treatment; Biogas; Surfactant; Sewage treatment plant; ABS; Adsorption; Batchwise; Anaerobe; Methanogenesis; Biological treatment
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2006.05.033

Batch anaerobic biodegradation tests with different alkylbenzene sulphonates (LAS) at increasing concentrations were performed in order to investigate the effect of LAS homologues on the anaerobic digestion process of sewage sludge. Addition of LAS homologues to the anaerobic digesters increased the biogas production at surfactant concentrations ⩽5–10
g/kg dry sludge and gave rise to a partial or total inhibition of the methanogenic activity at higher surfactant loads. Therefore, at the usual LAS concentration range in sewage sludge, no adverse effects on the anaerobic digesters functioning of a wastewater treatment plant (WWTP) can be expected. The increase of biogas production at low surfactant concentrations was attributed to an increase of the bioavailability and subsequent biodegradation of organic pollutants associated with the sludge, promoted by the surfactant adsorption at the solid/liquid interface. When the available surfactant fraction in the aqueous phase instead of the nominal surfactant concentration was used to evaluate the toxicity of LAS homologues, a highly significant relationship between toxicity and alkyl chain length was obtained. Taking into account the homologue distribution of commercial LAS in the liquid phase of the anaerobic digesters of a WWTP, an EC
50 value of 14
mg/L can be considered for LAS toxicity on the anaerobic microorganisms.