Activity Of Different Metals In Disinfection Of Activated Sludge By A Fenton-Like Process

Abstract

Treatment technologies of the activated sludge (AS) for its use as a fertilizer should include a hygienization process to meet legislative criteria. Numerous approaches have a strong effect on sludge stabilization and dewatering, while disinfection efficiency is unsatisfactory. In this respect, a combination of different physical (e.g., thermal) and chemical processes could develop hybrid methods for converting the sludge into a qualitative fertilizer with safe microbiological characteristics. Our study was focused on the comparison of the efficiency of Fe(II), Cu(II), Co(II), Mn(II), and Zn(II), which mediated the Fenton-like reaction in combination with H2O2, - for disinfection of AS from the municipal wastewater treatment plant. The enzymatic activity, i.e., fluorescein diacetate (FDA) hydrolysis, served as an integral criterion of cell inhibition. After 72h treatment of AS with 7 mM Me and 200 mM H2O2, an inhibition efficiency was ranged as follows:
[Fe+Co]>>[Co]≥[Fe+Cu+Co+Mn+Zn]>[Mn]>[Fe+Cu+Co]>[Cu]>[Zn]>[Fe+Zn]>[Fe].The effect of Fe(II) and Co(II) as single metals and binary mixtures on AS ecotoxicity was evaluated. No toxic effect was detected in a 24h immobility test with Artemia sp. and 72h root elongation of Raphanus sativus seeds. The AS treatment with Fe(II)+Co(II) in the presence of H2O2 leads to additional antimicrobial resistance of AS microbial community towards amikacin, piperacillin / tazobactam constant 4, doripenem, impenem, meropenem, and cefepime, as compared to untreated AS.