Electro-Fenton pretreatment for the improvement of tylosin biodegradability.
The feasibility of an electro-Fenton process to treat tylosin (TYL), a non-biodegradable antibiotic, was examined in a discontinuous electrochemical cell with divided cathodic and anodic compartments. Only 15 min electrolysis was needed for total tylosin degradation using a carbon felt cathode and a platinum anode; while 6 h electrolysis was needed to achieve high oxidation and mineralization yields, 96 and 88 % respectively. Biodegradability improvement was shown since BOD₅/COD increased from 0 initially to 0.6 after 6 h electrolysis (for 100 mg L(-1) initial TYL). With the aim of combining electro-Fenton with a biological treatment, an oxidation time in the range 2 to 4 h has been however considered. Results of AOS (average oxidation state) and COD/TOC suggested that the pretreatment could be stopped after 2 h rather than 4 h; while in the same time, the increase of biodegradability between 2 and 4 h suggested that this latter duration seemed more appropriate. In order to conclude, biological cultures have been therefore carried out for various electrolysis times. TYL solutions electrolyzed during 2 and 4 h were then treated with activated sludge during 25 days, showing 57 and 67% total organic carbon (TOC) removal, respectively, namely 77 and 88% overall TOC removal if both processes were considered. Activated sludge cultures appeared, therefore, in agreement with the assessment made from the analysis of physico-chemical parameters (AOS and COD/TOC), since the gain in terms of mineralization expected from increasing electrolysis duration appeared too low to balance the additional energy consumption.
Université de Rennes 1, Ecole Nationale de chimie de Rennes, CNRS, UMR 6226, 11 allée de Beaulieu CS 50837, 35708, Rennes, Cedex 7, France.
Fatiha
F
Ferrag-Siagh
Florence
F
Fourcade
Isabelle
I
Soutrel
Hamid
H
Aït-Amar
Hayet
H
Djelal
Abdeltif
A
Amrane
D057919:Biological Oxygen Demand Analysis; D002244:Carbon / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D004572:Electrolysis; D007501:Iron / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry; D012722:Sewage / Q000382:microbiology*; D015645:Tylosin / Q000737:chemistry* / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism*
D012722:Sewage; D014874:Water Pollutants, Chemical; D010984:Platinum; D002244:Carbon; D007501:Iron; D015645:Tylosin