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Domestic sewage sludge composting in a rotary drum reactor: optimizing the thermophilic stage.
J Environ Manage. 2012 Dec 15; 112:284-91.JE

Abstract

The aim of this paper was to study the influence of four process variables (turning frequency, gas-phase oxygen level, type of bulking agent and sludge/bulking agent mixing ratio) on the performance of the sewage sludge composting process using a rotary drum pilot scale reactor, in order to optimize the thermophilic stage and reduce the processing time. Powdered sawdust, wood shavings, wood chips, prunings waste and straw were used as bulking agents and the thermophilic stage temperature profile was used as the main indicator for gauging if the composting process was developing correctly. Our results showed that a 12 h(-1) turning frequency and an oxygen concentration of 10% were the optimal conditions for the composting process to develop. The best results were obtained by mixing the sewage sludge with wood shavings in a 3:1 w/w ratio (on a wet basis), which adapted the initial moisture content and porosity to an optimal range and led to a maximum temperature of 70 °C being reached thus ensuring the complete removal of pathogens. Moisture, C:N ratio, pH, organic matter, heavy metals, pathogens and stability were all analysed for every mixture obtained at the end of the thermophilic stage. These parameters were compared with the limits established by the Spanish regulation on fertilizers (RD 824/2005) in order to assess if the compost obtained could be used on agricultural soils. The right combination of having optimal process variables combined with an appropriate reactor design allowed the thermophilic stage of the composting process to be speeded up, hence obtaining a compost product, after just two weeks of processing that (with the exception of the moisture content) complied with the Spanish legal requirements for fertilizers, without requiring a later maturation stage.

Authors+Show Affiliations

Department of Chemical Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela s/n, 13071 Ciudad Real, Spain. luis.rromero@uclm.esNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22940458

Citation

Rodríguez, Luis, et al. "Domestic Sewage Sludge Composting in a Rotary Drum Reactor: Optimizing the Thermophilic Stage." Journal of Environmental Management, vol. 112, 2012, pp. 284-91.
Rodríguez L, Cerrillo MI, García-Albiach V, et al. Domestic sewage sludge composting in a rotary drum reactor: optimizing the thermophilic stage. J Environ Manage. 2012;112:284-91.
Rodríguez, L., Cerrillo, M. I., García-Albiach, V., & Villaseñor, J. (2012). Domestic sewage sludge composting in a rotary drum reactor: optimizing the thermophilic stage. Journal of Environmental Management, 112, 284-91. https://doi.org/10.1016/j.jenvman.2012.08.005
Rodríguez L, et al. Domestic Sewage Sludge Composting in a Rotary Drum Reactor: Optimizing the Thermophilic Stage. J Environ Manage. 2012 Dec 15;112:284-91. PubMed PMID: 22940458.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Domestic sewage sludge composting in a rotary drum reactor: optimizing the thermophilic stage. AU - Rodríguez,Luis, AU - Cerrillo,María I, AU - García-Albiach,Valentín, AU - Villaseñor,José, Y1 - 2012/08/30/ PY - 2012/02/28/received PY - 2012/07/18/revised PY - 2012/08/03/accepted PY - 2012/9/4/entrez PY - 2012/9/4/pubmed PY - 2013/3/9/medline SP - 284 EP - 91 JF - Journal of environmental management JO - J. Environ. Manage. VL - 112 N2 - The aim of this paper was to study the influence of four process variables (turning frequency, gas-phase oxygen level, type of bulking agent and sludge/bulking agent mixing ratio) on the performance of the sewage sludge composting process using a rotary drum pilot scale reactor, in order to optimize the thermophilic stage and reduce the processing time. Powdered sawdust, wood shavings, wood chips, prunings waste and straw were used as bulking agents and the thermophilic stage temperature profile was used as the main indicator for gauging if the composting process was developing correctly. Our results showed that a 12 h(-1) turning frequency and an oxygen concentration of 10% were the optimal conditions for the composting process to develop. The best results were obtained by mixing the sewage sludge with wood shavings in a 3:1 w/w ratio (on a wet basis), which adapted the initial moisture content and porosity to an optimal range and led to a maximum temperature of 70 °C being reached thus ensuring the complete removal of pathogens. Moisture, C:N ratio, pH, organic matter, heavy metals, pathogens and stability were all analysed for every mixture obtained at the end of the thermophilic stage. These parameters were compared with the limits established by the Spanish regulation on fertilizers (RD 824/2005) in order to assess if the compost obtained could be used on agricultural soils. The right combination of having optimal process variables combined with an appropriate reactor design allowed the thermophilic stage of the composting process to be speeded up, hence obtaining a compost product, after just two weeks of processing that (with the exception of the moisture content) complied with the Spanish legal requirements for fertilizers, without requiring a later maturation stage. SN - 1095-8630 UR - https://www.unboundmedicine.com/medline/citation/22940458/Domestic_sewage_sludge_composting_in_a_rotary_drum_reactor:_optimizing_the_thermophilic_stage_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0301-4797(12)00401-X DB - PRIME DP - Unbound Medicine ER -