Effects of lipids and oleic acid on biomass development in anaerobic fixed-bed reactors. Part II: Oleic acid toxicity and biodegradability

• Published in: Water research (Oxford) Vol. 35; no. 1; pp. 264 - 270
• Main Authors: Alves, M.M, Mota Vieira, J.A, Álvares Pereira, R.M, Pereira, M.A, Mota, M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2001; Elsevier Science
• Subjects: Adsorption; Anaerobic digestion; Applied sciences; Biodegradation; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Biomass; Bioreactors; Biotechnology; Effluent treatment; Environment and pollution; Euryarchaeota - drug effects; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Kinetics; Lipids; Methane - analysis; Oleic acid; Oleic Acid - pharmacokinetics; Oleic Acid - toxicity; oleic acid biodegradability; Pollution; Sewage; Sewage sludge; Stearic Acids - pharmacokinetics; Toxicity; Wastewaters; Water treatment and pollution; oleic acid biodegradability; oleic acid toxicity; Anaerobiosis; Biodegradation; Bioreactor; Oleic acid; Toxicity; Methanogenesis; Fixed bed reactor; Unsaturated fatty acid; Lipids; Waste water purification; Experimental study; Biological purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(00)00242-6

Oleic acid toxicity and biodegradability were followed during long-term operation of two similar anaerobic fixed-bed units. When treating an oleate based effluent, the sludge from the bioreactor that was acclimated with lipids during the first operation period, showed a higher tolerance to oleic acid toxicity (IC
50=137 mg/l) compared with the sludge fed with a non-fat substrate (IC
50=80 mg/l). This sludge showed also the highest biodegradation capacity of oleic acid, achieving maximum methane production rates between 33 and 46 mlCH
4(STP)/gVS.day and maximum percentages of methanization between 85 and 98% for the range of concentrations between 500 and 900 mg oleate/l. When oleate was the sole carbon source fed to both digesters, the biomass became encapsulated with organic matter, possibly oleate or an intermediate of its degradation, e.g. stearate that was degraded at a maximum rate of 99 mlCH
4(STP)/gVS.day. This suggests the possibility of using adsorption–degradation cycles for the treatment of LCFA based effluents. Both tolerance to toxicity and biodegradability of oleic acid were improved by acclimatization with lipids or oleate below a threshold concentration.