Aerobic biotransformation of Sargassum fluitans in combination with sheep manure: optimization of control variables

ABSTRACTSargassum fluitans was composted alongside sheep manure, in a transformative process that significantly enhanced the algal material’s properties. Post the screening/washing/screening pretreatment, the content of total volatile solids escalated to 73.20%, while ash content reduced to 16.45%. Concurrently, lignin values surged to 30.12% as the biodegradability factor declined to 21%. The pretreatment decreased electrical conductivity from 11.60 to 1.32 DS/m. Employing a central composite design and response surface analysis pinpointed the optimal substrate combinations for carbon/nitrogen ratios of 35:1 and 25:1. The chosen combinations presented a high coefficient of determination (R2 = 0.9589, carbon/nitrogen ratio; R2 = 0.6584, pH), indicative of a robust statistical fit. Over a 45-day period, composting was conducted using bioreactors or biopiles, maintaining near-neutral pH values and temperatures slightly above ambient levels. The composting process reduced up to 94% of fecal coliforms in the 1:1 combination. Physicochemical analyses confirmed that the final product is a valuable compost-soil improver, with great potential for usage in organic agriculture, reforestation, and urban green spaces. Hence, this research underscores composting as an efficient technique in managing organic waste, including the emergent and seasonal Sargassum fluitans, thus addressing a pressing environmental concern with an innovative, effective solution.KEYWORDS: Central composite methodcompostingresponse surfacewaste AcknowledgementsWe appreciate the attention and kindness of those responsible for the ‘El Rodeo’ Ranch, a sheep meat and milk production unit. For the donation of manure for carrying out the experimental work. We recognize the facilities granted by the Council of Science and Technology of the State of Tabasco (CCYTET).Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by Consejo de Ciencia y Tecnologí­a del Estado de Tabasco.Notes on contributorsMaría I. López-TorresMaría I. López-Torres Environmental Engineer Student. Contribution: Physicochemical and experimental analyses.José A. Sosa-OlivierJosé A. Sosa-Olivier PhD in Science in ecology and management tropical system student and Research Professor. Contribution: Central composite design, data manipulation and response surface analysis.José R. Laines-CanepaJosé R. Laines-Canepa PhD in Science in ecology and management tropical system and Head of pilot plant 3 – treatment of air and solid waste. Contribution: Bibliographic review and application of the NMX-AA-180-SCFI-2018 standard.Alejandro Padilla-RiveraAlejandro Padilla-Rivera PhD in Sustainability and urban studies, and Research Professor. Contribution: Literature review and language translation.Irma Santiago-CortezIrma Santiago-Cortez. Environmental Engineer Student. Contribution: Microbiological and physicochemical analysis.Fabiola J. Jiménez-HernándezFabiola J. Jiménez-Hernández (PhD in Science in ecology and management tropical system student). Contribution: Microbiological analysis.