title: Optimization of the skimmed-milk flocculation method for recovery of adenovirus from sludge.
abstract: Return of treated sludge to the environment poses concerns and has stimulated the development of studies on viral monitoring in this matrix, in order to assess its potential risks for public health. Human adenovirus (HAdV) has been identified as a putative viral marker of faecal contamination due to its stability and resistance to the sewage treatment process. The aim of this study was to optimize the organic flocculation procedure in order to establish an appropriate methodology for HAdV recovery from sewage sludge samples. Four protocols (A-D) have been proposed, with changes in the initial sample dilution, in the stirring time and in the final concentration of skimmed-milk. A single sludge sample was obtained in Wastewater Treatment Plant (WWTP) and divided into aliquots. In each protocol, three aliquots were inoculated with HAdV and bacteriophage PP7 and a non-inoculated one was used as negative control. Viral load and recovery rate were determined by quantitative PCR. HAdV recovery rate varied between the protocols tested (p=0.016) and the best result was obtained through the protocol C. In order to confirm this result a field study with activated, thickened and digested sludge samples was carried out. Different types of sludge were obtained in two WWTPs and processed using protocol C. HAdV was detected in all samples, with a similar or higher viral load than those obtained with other concentration techniques already applied to sludge. Protocol C proved to be really efficient, with the advantage of showing low cost and practicability in routine laboratories.
authors.affiliation: Laboratory of Virology, Microbiology Department, Institute of Biological Science, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil. Electronic address: andressasilvino@yahoo.com.br.
authors.forename: Andrêssa S F
authors.initials: ASF
authors.lastname: Assis
authors.affiliation: Brazilian Agricultural Research Corporation, Embrapa Dairy Cattle, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Marcelo Henrique
authors.initials: MH
authors.lastname: Otenio
authors.affiliation: Laboratory of Virology, Microbiology Department, Institute of Biological Science, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Betânia P
authors.initials: BP
authors.lastname: Drumond
authors.affiliation: Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Tulio M
authors.initials: TM
authors.lastname: Fumian
authors.affiliation: Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marize P
authors.initials: MP
authors.lastname: Miagostovich
authors.affiliation: Laboratory of Virology, Microbiology Department, Institute of Biological Science, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Maria Luzia
authors.initials: ML
authors.lastname: da Rosa E Silva
mesh_terms: D000260:Adenoviruses, Human; D005427:Flocculation; D006801:Humans; D012722:Sewage / Q000821:virology*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage
keywords: Human adenovirus; Internal control; Organic flocculation; Quantitative PCR; Sewage sludge; Wastewater treatment plant