Juan Sebastian Arcila

Mycelium-based composites (MBCs) have emerged as eco-friendly alternatives, utilizing fungal mycelium as a natural binder for agro-industrial residues. This study focuses on developing an MBC based on abundant waste in Colombia, pith Arboloco (A) (Montanoa quadrangularis), a plant endemic to the Colombian–Venezuelan Andes with outstanding insulating properties, and natural fiber of Kikuyu grass (G) (Cenchrus clandestinus), utilizing Ganoderma lucidum as an agent to form a mycelium network in the MBC. Three formulations, T (100% A), F1 (70% A/30% G), and F2 (30% A/70% G), were evaluated under two different Arboloco particle size ranges (1.0 to 5.6 mm) for their physical, mechanical, and thermal properties. The Arboloco particle sizes did not show significant differences in the MBC properties. An increase in Kikuyu grass proportion (F2) demonstrated superior density (60.4 ± 4.5 kg/m³), lower water absorption (56.6 ± 18.4%), and better compressive strength (0.1686 MPa at 50% deformation). Both mixing formulations (F1–F2) achieved promising average thermal conductivity and specific heat capacity values of 0.047 ± 0.002 W m⁻¹ K⁻¹ and 1714 ± 105 J kg⁻¹ K⁻¹, comparable to commercial insulation materials. However, significant shrinkage (up to 53.6%) and high water absorption limit their scalability for broader applications. These findings enhance the understanding of MBC’s potential for non-structural building materials made of regional lignocellulosic waste, promoting a circular economy in waste management for developing countries.

BACKGROUND: Microalgal biofilm systems are a promising approach for wastewater treatment and for production of biodiesel precursors through simple biomass harvesting. However, the low concentration of nutrients in wastewater limits possible approaches for microalgal growth. The effective decoupling of the solid retention time (SRT) and the hydraulic retention time (HRT) in biofilm reactors as an alternative for increasing microalgae growth and biodiesel performance in low‐strength wastewater has not been investigated. In this study, we tracked how decoupling the SRT and the HRT influences the removal of organics and nutrients, the biomass productivity and the production of fatty acid methyl esters (FAME).RESULTS: Three perturbations of the HRT, SRT and liquid level (LL) with regards to the base case condition (HRT 2.6 h; SRT 21 days, LL 5 mm) performance were analyzed. The base case showed the highest TN and TP removal (>50%) outcomes with high pH values (>10). A decrease of HRT and SRT from 2.6 to 1.3 h and 21 to 10 days, respectively, promoted an increment of microalgal productivity ≤5.8 ± 0.7 g m⁻² day⁻¹. A short HRT of 1.3 h enhanced the nitrogen removal rate up to 1.2 g N m⁻² day⁻¹, which triggered an increase in the FAME productivity and microalgal density on the biofilms without affecting their productivity.CONCLUSION: Our study demonstrated that the strategy of decoupling HRT and SRT allows operation at shorter HRTs, promoting microalgal growth without affecting FAME production in low‐strength municipal wastewater. © 2023 Society of Chemical Industry (SCI).

This research investigates the effect of mixing wavelength light photoperiods (12 h blue, 8 h blue: 4 h green, 4 h blue: 8 h green, and 12 h green) and N/P ratios (1.3 to 8.3) on the growth microalgae–bacteria systems, organic matter, and nutrient removals. The highest microalgae–bacteria growth performance (μ = 0.2 d−1, 481.1 ± 15.3 mg DW L−1) was observed when a 8 h blue: 4 h green mixed wavelength and a low N/P ratio were used. For both N/P ratios, biomass productivity was favored when using the blue light dominated at longer time periods. Mechanisms for nitrogen removal by assimilation depend on the N/P ratio, achieving assimilation between 49 and 65% at a low N/P ratio. High nitrogen removal (>50%) showed a strong relation with alkalinity culture conditions (pH > 8.5). The mixing of wavelength photoperiods seems to be a promising strategy to achieve high biomass productivity and nutrient removal. However, for optimal conditions, N/P ratios in the wastewater should be considered.