Sewage sludge composting under semi-permeable film at full-scale: Evaluation of odour emissions and relationships between microbiological activities and physico-chemical variables
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URI: https://hdl.handle.net/10481/87888Metadata
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Robledo Mahón, Tatiana; Martín Santos, Maria Angeles; Gutierrez, M. C.; Toledo, M.; González, Inmaculada; Aranda Ballesteros, Elisabet; Chica, A. F.; Calvo Sáinz, ConcepciónEditorial
Elsevier
Date
2019Referencia bibliográfica
Environmental Research 177 (2019) 108624
Sponsorship
This study was conducted in the framework of the Project for Excellence “Study of biological processes and structure of microbial communities in urban wastewater sewage sludge composting under semi-permeable membranes” [P11.RNM.7370] of the Environmental Microbiology Group RNM-270 at the University of Granada. The authors are grateful by the support of the Spanish Ministry of Economy and Competitiveness (MINECO) through Project CTQ2014-60050-R. E. A. would like to thank the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (ERDF) funds [RYC-2013-12481]. We also wish to express our gratitude to Biomasa del Guadalquivir S.A. for collaborating in this study.Abstract
In the present study, physico-chemical characteristics, heavy metals content, odour emissions, microbial enumeration
and enzymatic activities were analysed during industrial scale composting of sewage sludge partially
pre-treated to evaluate the effect of a combined system of semi-permeable film and aeration on these parameters.
The results related to physico-chemical parameters showed a decrease in total organic carbon (TOC), organic
matter (OM), total carbon (TC) along the process. Volatile solids (VS) were also reduced, reaching 36% at 120
days, which is above the limit according to the current legislation. Similarly, metal content was found to be an
important variable in the evolution of enzymatic activity, while lead (Pb), zinc (Zn), and nickel (Ni) were the
most influential. Moreover, heavy metals were found below the limit of type B compost quality or European class
2 at the end of the process, which is suitable for agriculture soil. The odorous impact generated during the
hydrolytic stage was reduced to an average value of 4 ouE/s. This suggests that, covered stage with the semipermeable
film, could be a viable solution to mitigate odour emissions. The highest temperature was reached at
10 days and it was favoured by semi-permeable film. Temperature promoted the presence of thermophilic
bacteria and fungi and indicated an early biodegradation process mediated by microorganisms. Statistical
analyses revealed a high correlation of physico-chemical variables with microbial activity. Thus, samples from
the first 14 days were highly correlated with enzymatic activities such as β-glucosidase (Ac-βGlu), protease (Ac-
Pr), and dehydrogenase (Ac-De), which have usually been involved in the hydrolysis of organic matter.