Fate of wastewater organic pollution during activated sludge treatment: nature of residual organic matter

• Published in: Water research (Oxford) Vol. 34; no. 17; pp. 4185 - 4194
• Main Authors: Dignac, M.-F, Ginestet, P, Rybacki, D, Bruchet, A, Urbain, V, Scribe, P
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2000; Elsevier Science
• Subjects: Activated Sludge; Activated sludge process; Applied sciences; Biodegradation; Biological and medical sciences; Biological treatment of waters; Biological water treatment; Biotechnology; Chemicals removal (water treatment); Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; Hydrolysis; Industrial applications and implications. Economical aspects; molecular analysis; organic matter; Pollution; pyrolysis; refractory structures; wastewater; Wastewaters; Water treatment and pollution; organic matter; wastewater; pyrolysis; activated sludge; molecular analysis; refractory structures; Activated sludge; Organic matter; Chemical composition; Waste water purification; Biological purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(00)00195-0

Activated sludge treatment is used to remove wastewater organic matter (OM) and residual OM is found at low levels in treated water. The molecular composition of OM of waters and sludge was determined in order to understand the fate of the organic substances during biological treatment and the nature of residual OM. Proteins, sugars, lipids and polyphenolic compounds were quantified in a municipal wastewater treatment plant via chromatographic analysis after chemical hydrolysis. The concentration of OM was decreased by more than 90% by biological treatment. However, if 63% of the OM were characterized in activated sludge, molecular analysis did not allow us to characterize all the OM in the water samples. Relatively higher amounts of total organic carbon (TOC) were identified in wastewater (50%) than in treated water (20%). Likewise, for total nitrogen, 33% were identified as amino acid nitrogen in wastewater, and only 10% in treated water. Analytical pyrolysis suggested that some of the difficulties in identifying OM of treated water with common analytical methods are due to the presence of complex structures, refractory to hydrolysis. These structures may also be refractory to microbial degradation since they are concentrated during the biological treatment of wastewater. Suggestions on the possible origin and structure of resistant OM were formulated according to the analytical results.