title: Temperature-phased anaerobic digestion (TPAD) to obtain class A biosolids: a semi-continuous study.
abstract: Regulations regarding the land application of sewage sludge require the performance of highly efficient treatments for pathogen reduction, such as temperature-phased anaerobic digestion (TPAD). Several semi-continuous experiments with different solid residence times (SRTs) have been made to find the best combination - TPAD 15/15, TPAD 5/15, TPAD 3/15 or TPAD 3/12. TPAD systems showed better performance in terms of VS destruction, gas production, sludge dewaterability, and process stability at total SRT of 15 days, compared with single-stage mesophilic or thermophilic digestion at the same SRT. Average VS reductions (VSR) using the overall TPAD 5/15 (78%), TPAD 3/15 (87%), and TPAD 3/12 (87%) were significantly higher than mesophilic control operating with an SRT of 15 days (40% VSR). The best results were obtained for TPAD 3/15 with 0.62 LCH(4) g(-1) VS(r), faecal coliform 10(3) MPN/g TS, and Salmonella spp. 1 MPN/4 g TS. Although both TPAD 3/15 and TPAD 3/12 were efficient enough to obtain Class A biosolids.
authors.affiliation: Department of Environmental Technologies, Faculty of Sea and Environmental Sciences, University of Cádiz, 11510 Puerto Real, Cádiz, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Riau
authors.forename: M Angeles
authors.initials: MA
authors.lastname: De la Rubia
authors.forename: Montserrat
authors.initials: M
authors.lastname: Pérez
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D002849:Chromatography, Gas; D008697:Methane / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D012722:Sewage; D008697:Methane