Document Detail

Inhibitory effect of a surfactant on pure cultures of a filamentous and a floc forming micro-organism.
MedLine Citation:
PMID:  17396407     Owner:  NLM     Status:  MEDLINE    
Activated sludge is the most widely used biological process for wastewater treatment. Inorganic and organic compounds are removed by a biotic community in the aeration basin. Problems of these systems are loss of settleability and poor sludge compaction due to excessive growth of filamentous micro-organisms. The filamentous bulking can be controlled by the addition of chemical agents. Strong oxidants, such as chlorine, are utilized to eliminate filamentous bacteria; however, these substances also tend to attack floc-forming bacteria and to cause process breakdown. Besides, chlorine may become hazardous owing to the formation of chemical products as chloramines. Surfactant addition constitutes an interesting alternative for the control of filamentous bulking. In this work the effect of a surfactant Triton X-100 (octylphenol ethoxylate), on the respiratory activity (RA) of pure cultures of a filamentous (Sphaerotilus natans) and a floc-former microorganism (Acinetobacter anitratus) was evaluated. In the concentration range tested (60-220 mg l(-1)), the surfactant was observed to exhibit high RA specific inhibition of the filamentous micro-organism with no significant effect on the floc-forming bacteria. Light microscopy observations showed that the surfactant induced cell lysis, leaving only empty sheaths in the case of filamentous micro-organisms. A kinetic equation to predict the microbial RA fraction of a S. natans pure culture as a function of surfactant concentration and contact time was proposed. The effect of Triton X-100 on the inactivation of pure cultures of both micro-organisms was compared to that of chlorine. Triton X-100 results were adequate to eliminate filamentous bacteria emerging as an alternative for filamentous bulking treatment.
A Caravelli; L Giannuzzi; N Zaritzky
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental technology     Volume:  28     ISSN:  0959-3330     ISO Abbreviation:  Environ Technol     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-04-02     Completed Date:  2007-05-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9884939     Medline TA:  Environ Technol     Country:  England    
Other Details:
Languages:  eng     Pagination:  137-46     Citation Subset:  IM    
Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata-CONICET, 47 y 116, La Plata 1900, Argentina.
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MeSH Terms
Acinetobacter / drug effects*,  physiology
Chlorine / toxicity
Models, Biological
Octoxynol / toxicity*
Oxygen / metabolism
Sphaerotilus / drug effects*,  physiology
Surface-Active Agents / toxicity*
Waste Disposal, Fluid / methods
Reg. No./Substance:
0/Surface-Active Agents; 7782-44-7/Oxygen; 7782-50-5/Chlorine; 9002-93-1/Octoxynol

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