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Lactic acid fermentation as a waste activated sludge (was) hygienization treatment
  • Joseph Garrido
Joseph Garrido
University of London

Corresponding Author:[email protected]

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Aiming to test the lactic acid fermentation ability to reduce the pathogenic microbial content in a waste activated sludge, fermentation reactors were tested in real conditions of sludge (4.3 x 104 MPN/g fecal coliform). Therefore, pH and titratable acidity (% lactic acid) were monitored during the fermentation process and statistically evaluated on day 5. According to these results and to evaluate the remaining concentration of pathogenic microbial content after treatment, the lactic acid fermentation reactors were microbiological and physic-chemically characterized. Additionally, at 3 % of lactic acid microbial consortium and 18 % of molasses, optimum conditions such as pH 3.57, 2.2 % lactic acid (titratable acidity) and fetid odour-free were achieved. Furthermore, the final product has < 3 MPN/g of fecal coliform, achieving 99.9 % efficiency at day 5 of the treatment and is maintained all the experimental time control (30 days). Finally, the presence of lactic acid bacteria and antimicrobials presence was not inhibited by heavy metals content present in sludge in a real condition, supporting the hygienization process. Key words: waste activated sludge, hygienization, sanitization, lactic acid fermentation, sludge treatment.