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This paper examines the effects of hydroxyapatite (HA) and bone- particle (BP) doping on the removal of fluoride and bacteria by ceramic water filters (CWFs). The CWFs were produced by mixing clay, sieved sawdust, and either HA or BPs in a weight ratio of 30:50:20 and sintered at 850°C or 900°C to produce micro-/ nano-porous structures that remove microbial pathogens (by geometric occlusion) and fluoride (by adsorption) from contaminated water. The HA-doped filters exhibited similar flow characteristics to the BP-doped filters. However, BP-doped CWFs were more effective in removing fluoride and microbial pathogens (such as E. coli) from contaminated water than HA-doped filters. The water flow rates and fluoride removal depended on sintering temperature, with CWFs sintered at 850°C enabling faster flow rates of 2.2Lh−1 and higher fluoride removal of 2.74 mol.cm−2 than the CWFs sintered at 900°C. Fluoride removal by the HA- and BP-doped filters was well characterized by Freundlich isotherms that reveal the occurrence of spontaneous but heterogeneous adsorption. The implications of the results are discussed for the design of point-of-use CWFs for the removal of fluoride and microbial pathogens. [ABSTRACT FROM AUTHOR]

This paper presents the results of a combined experimental and theore- tical study of the effects of sintering temperature on the mechanical and filtration properties of clay ceramic water filters (CWFs). CWFs produced from 50:50 volume proportion mixtures of clay and sieved sawdust (porogen) were sintered at 850°C, 900°C and 950°C to produce micro- and nano-porous structures. The sintered clay structures were then characterized using X-ray diffraction and scanning electron microscopy. The flow and filtration characteristics of the filters were then elucidated using a combination of theory and fluid flow experiments, before exploring the effects of porosity on E. coli removal and flow rates through the filter. The E. coli removal efficiency is shown to be inversely proportional to the sintering tempera- ture, with log removal values (LRV) of 4.89, 4.59 and 4.46 for the CWFs sintered at 850°C, 900°C and 950°C, respectively. The paper also examines the effects of sintering temperature on the compressive and flexural strengths, as well as the fracture toughness of the CWFs. The compressive strengths of the CWFs increased (between 6.55 and 7.02 MPa), whereas the flexural strengths (between 3.05 and 2.22 MPa) and the fracture toughness values (between 0.21 and 0.14 MPa pm) both decreased in response to the increased porosities induced by the increased sintering temperature. The underlying fracture and toughening mechanisms are then eluci- dated before discussing the implications of the results for the fabrication, trans- portation, and handling of robust ceramic water filters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Observations show varied toughening (crack bridging, deflections) based on laterite content. • Toughening due to crack-bridging occurs at lower laterite content (0–20 wt%). • Combined crack-bridging/deflection at 20–40 wt% and crack-deflection dominant at >40 wt%. • Results suggest mycelium bio-composites can be designed with tunable fracture toughness. This study presents a combined experimental and analytical study of the fracture behavior and toughening mechanisms of bioprocessed mycelium-based biocomposites. The composites comprise hemicellulose hemp ducts (as nutritional and reinforcing components) intertwined with increasing weight percentages of laterite particles. Single-edge notched fracture experiments and in-situ observations of crack growth were used to explore the effects of varying proportions of laterite on the composite resistance-curve behavior. The toughening mechanisms, fracture modes, and crack-microstructure interactions were also elucidated. Since crack-bridging and crack-deflection were observed to be the dominant toughening mechanisms, they were modeled using fracture mechanics approaches. Crack-bridging was shown to dominate the toughening at lower weight fractions of laterite (0–20 wt%). However, as the laterite content increases (20–40 wt%), a combination of crack-bridging and crack-deflection was observed. Finally, at higher laterite weight fractions (>40 wt%), crack-tip shielding occurred primarily via crack deflection. The fracture mechanics predictions of resistance-curve behavior are shown to be consistent with the experimental measurements. The results suggest that mycelium-based and mycelium-laterite composites can be engineered with tunable fracture toughness. The implications of the results are also discussed for the development of sustainable building materials. [ABSTRACT FROM AUTHOR]

Low- and middle-income countries have tremendous potential for renewable energy production, including production of renewable carbon from locally prolific crops. In this work, bamboo endemic to West Africa (Bambusa vulgaris) was studied as a feedstock for the production of renewable sugars as the gateway to the local production of biofuels and bio-based chemical products. The effectiveness of delignification and amorphization pretreatments was evaluated, with the observation that quantitative (97 ± 4%) sugar yields could be obtained with a rapid initial hydrolysis rate (82 ± 4 mg g−1 h−1) but only when amorphization was performed following delignification. Experimental measurements and further characterization using 13C solid state nuclear magnetic resonance (NMR) helped establish the importance of amorphization and delignification and explained why the order of these treatments determined their effectiveness. The economics of the bamboo-based process were compared with those projected for corn stover, selected as a well-studied benchmark crop. Because of the higher bamboo growth rate compared with corn stover and the effectiveness of the pretreatment, the projected net present value (NPV) of the bamboo biorefinery was positive ($190 MM, U.S.), whereas the corn biorefinery projected to negative NPV (−$430 MM, U.S.). A socially sustainable framework for deployment of a bamboo biorefinery in a low- or middle-income economy was then proposed, guided by the principle of local ownership and stakeholder buy-in. The findings presented here motivate further investment in development of bamboo cultivation and conversion to sugars as a rapid route to decarbonization of low- and middle-income economies. [ABSTRACT FROM AUTHOR]