Process Design for Biohydrogen Production from Waste Materials and Its Application

Biohydrogen is regarded as an attractive future clean energy carrier due to its high energy content and environmentally friendly conversion. Biohydrogen reactor is widely used in studies concerning the anaerobic co-digestion of food waste, sewage sludge, wastewater and other organic solids. Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material (biomass or waste feedstock) in the absence of oxygen to produce biogas, which may generate electricity and heat, or can be processed into renewable natural gas and transportation fuels. This review article explains the scientific processes of anaerobic digestion process such as hydrolysis, acidogenesis, acetogenesis and hydrogenesis as well as methods to produce biohydrogen gas such as fermentation and biophotolysis for the waste management technology and sources of renewable energy and concludes with solutions that may allow anaerobic digestion to become more widely adopted throughout the developing countries to control the waste management system.

Preliminary Investigation on Degradation Behavior and Cytocompatibility of Ca-P-Sr Coated Pure Zinc

Zinc and its alloys show a good application prospect as a new biodegradable material. However, one of the drawbacks is that Zn and its alloys would induce the release of more Zn ions, which are reported to be cytotoxic to cells. In this study, a Ca-P-Sr bioactive coating was prepared on the surface of pure zinc by the hydrothermal method to address this issue. The morphology, thickness, and composition were characterized, and the effects of the coating on the degradation, cell viability, and ALP staining were investigated. The results demonstrated that the degradation rate of pure zinc was reduced, while the cytocompatibility was significantly improved after pure zinc was treated with Ca-P-Sr coating. It is considered that the Ca-P-Sr bioactive coating prepared by the hydrothermal method has promising application in the clinic.

The effect of eggshell as a reinforcement on the mechanical and Corrosion properties of Mg-Zn-Mn matrix composite

Magnesium is a promising lightweight metal required in many industries such as automobile, aerospace, electronics, etc. It is also a biodegradable material, which eliminates the secondary removal procedure of the implant. Furthermore, its mechanical properties are similar to the mechanical properties of human bone. In this research, eggshells were used as an environmentally friendly composite reinforcement material in the Mg-2.5Zn-1Mn matrix. Composites were prepared using the powder metallurgy route. The effect of eggshells on the morphology, mechanical, and corrosion behaviour of Mg-2.5Zn-1Mn alloy was investigated. The results revealed an enhancement in grain refining ability and mechanical properties of Mg-2.5Zn-1Mn with eggshell additives. The corrosion behaviour improved at a higher percentage of eggshells (10%).

Recycling Polymer Blend made from Post-used Styrofoam and Polyethylene for Fuse Deposition Modelling

Styrofoam is widely used as packaging material for many applications like home furniture and electrical appliance. Styrofoam is a non-biodegradable material which its disposal causes serious environment issues. This research demonstrates an alternate recycling method of Styrofoam waste by converting it into 3D printing filament for Fused Deposition Modelling (FDM). For this research, the recycled polystyrene (rPS) was extracted from Styrofoam waste and blended with low-density polyethylene (LDPE), then extruded into filament using a filament extruder. The formulated rPS/LDPE blend with different blend ratio exhibited a good printability when the printing temperature and extrusion rate fixed at 240°C and 120%. However, the tensile strength of printed specimens with rPS/LDPE blends were lower than printed specimen with neat rPS. The tensile strength and modulus of printed specimens with rPS/LDPE were decreased due to the increase of LDPE content. The decrease of tensile strength mainly caused by the incompatibility between the rPS and LDPE phases. However, the addition of more LDPE content in the blend enhanced the ductility of rPS/LDPE blends. Furthermore, the increase of LDPE content also increased the thermal stability of rPS/LDPE blends. Overall, the rPS/LDPE blend is a potential alternate material for producing FDM filament.

Study of Thermal, Mechanical and Barrier Properties of Biodegradable PLA/PBAT Films with Highly Oriented MMT

In order to improve the properties of biodegradable polylactide (PLA), mixtures with polybutylene adipate-co-terephthalate (PBAT) were prepared. PLA is a bio-based and renewable biodegradable material, made from starch. PBAT is a biodegradable polyester for compostable film. In order to improve the composite properties, two types of additives were implemented via melt mixing, a chain extender (CE) and montmorillonite (MMT). CE was used as an interfacial modifier to enhance the adhesion between components. Montmorillonite is a widely studied clay added to polymer nanocomposites. Due to the lamellar structure, it improves the barrier properties of materials. PLA/PBAT films were oriented in the extrusion process and the amounts of filler introduced into the PLA/PBAT nanocomposites were 1.0, 3.0, and 5.0%. The improvement in the PLA barrier properties by the addition of PBAT and 5% of MMT was confirmed as the oxygen permeability decreased almost by a factor of 3. The addition of the biodegradable polymer, chain extender, montmorillonite, and the implemented orientation process resulted in a decrease in composite viscosity and an increase in the PLA crystallinity percentage (up to 25%), and the wettability tests confirmed the synergic behavior of the selected polymer blend.

Characterization of Sustainable Robotic Materials and Finite Element Analysis of Soft Actuators Under Biodegradation

Biodegradability is an important property for soft robots that makes them environmentally friendly. Many biodegradable materials have natural origins, and creating robots using these materials ensures sustainability. Hence, researchers have fabricated biodegradable soft actuators of various materials. During microbial degradation, the mechanical properties of biodegradable materials change; these cause changes in the behaviors of the actuators depending on the progression of degradation, where the outputs do not always remain the same against identical inputs. Therefore, to achieve appropriate operation with biodegradable soft actuators and robots, it is necessary to reflect the changes in the material properties in their design and control. However, there is a lack of insight on how biodegradable actuators change their actuation characteristics and how to identify them. In this study, we build and validate a framework that clarifies changes in the mechanical properties of biodegradable materials; further, it allows prediction of the actuation characteristics of degraded soft actuators through simulations incorporating the properties of the materials as functions of the degradation rates. As a biodegradable material, we use a mixture of gelatin and glycerol, which is fabricated in the form of a pneumatic soft actuator. The experimental results show that the actuation performance of the physical actuator reduces with the progression of biodegradation. The experimental data and simulations are in good agreement (R2 value up to 0.997), thus illustrating the applicability of our framework for designing and controlling biodegradable soft actuators and robots.

Locomotor behavior of Neocaridina palmata: a study with leachates from UV-weathered microplastics

Weathering of plastics leads to the formation of increasingly smaller particles with the release of chemical compounds. The latter occurs with currently unknown environmental impacts. Leachate-induced effects of weathered microplastics (MPs) are therefore of increasing concern. To investigate the toxicity of the chemical mixtures from such plastics, we exposed the freshwater shrimp Neocaridina palmata to enriched leachates from unweathered and artificially weathered (UV-A/B light) MPs (≤1 mm) from recycled low-density polyethylene (LDPE-R) pellets and from a biodegradable, not fully bio-based starch blend (SB) foil. We analyzed the individual locomotor activity (moved distance and frozen events) on day 1, 3, 7 and 14 of exposure to five leachate concentrations equivalent to 0.40–15.6 g MPs L−1, representing the upper scale of MPs that have been found in the environment. The median moved distance did not change as a function of concentration, except for the unweathered SB treatment on day 14 that indicated hyperactivity with increasing concentrations. Significant impacts were solely detected for few concentrations and exposure days. Generally, no consistent trend was observed across the experiments. We further assessed the baseline toxicity of the samples in the Microtox assay and detected high bioluminescence inhibitions of the bacterium Aliivibrio fischeri. This study demonstrates that neither the recycled nor the biodegradable material are without impacts on test parameters and therefore cannot be seen as safe alternative for conventional plastics regarding the toxicity. However, the observed in vitro toxicity did not result in substantial effects on the behavior of shrimps. Overall, we assume that the two endpoints examined in the atyid shrimp N. palmata were not sensitive to chemicals leaching from plastics or that effects on the in vivo level affect other toxic endpoints which were not considered in this study.

A retrospective towards a biodegradable material concept for future Indonesian sustainable architecture

The awareness of the negative effect of the intensive usage of synthetic material has led to a significant phenomenon in recent global development. Moving forward to become a fully ready developed country, Indonesia shall move toward a more sustainable architecture for presenting a greener environment. Despite blessed with a distinctive collection of tropical material variants, reflected in its vernacular architecture, advanced material development must be invented to promote more progressive architecture in Indonesia. This research illustrates a new perspective regarding biodegradable material concepts for future Indonesian sustainable architecture. It is produced by respecting local and global development trends by using a bibliographic coupling and experimental methods in the laboratory to contribute to Indonesian sustainable architecture. A retrospective is aimed to highlight Indonesian biodegradable material and Indonesian vernacular architecture potency; it is presented as follows; (1) Understanding local–global trends in biodegradable architecture; (2) Indonesian potency on biodegradable materials; (3) A biodegradable material concept as an alternative perspective for Indonesian sustainable architecture. As a result, a new concept is proposed as an alternative for developing Indonesian biodegradable building materials. A more profound sustainable architecture is expected to engage local craftsmanship while highlighting unique biodegradable materials easily found in the surrounding environment, such as Indonesian Kombucha Tea and Indonesian Coffee.

Investigation of Antibiotic Release from Bone Allograft in an Experiment on Rabbits

BACKGROUND: The treatment of chronic osteomyelitis, despite the use of new methods, is still an urgent problem. Local use of antibacterial drugs in combination with systemic antibiotic therapy has become popular in recent decades. Autologous bone grafts are considered ideal for bone defects filling. Different methods of allograft preparation may have differences in the rate and duration of antibiotic release. Moreover, it can affect the effectiveness of microbial agent eradication. The study analyzed the differences in the release of gentamicin from different types of allografts in dynamics and methods of preparation: «PerOssal» medium, whole bone allograft soaked in antibiotic, whole bone allograft, welded with an antibiotic, and perforated bone allograft soaked in an antibiotic solution. AIM: The objective of the study was to study the stability of antibiotic release and to determine the effectiveness of local transport systems. Evaluation of the difference in gentamicin release from different types of allografts in dynamics and methods of preparation had been realized: “PerOssal” medium, whole bone allograft soaked in antibiotic, whole bone allograft welded with an antibiotic, and perforated bone allograft, soaked in antibiotic solution. MATERIALS AND METHODS: The research was conducted between September 2020 and March 2021. The experiments were performed on 120 laboratory rabbits (weight – 3000–3500 g, age – 6–8 months), which were divided into four groups (30 animals in each group). Group 1 consisted of animals treated with “PerOssal.” The whole bone allograft soaked in an antibiotic was used in the treatment of animals of Group 2. The whole bone allograft, welded with an antibiotic, was used in the treatment of animals of Group 3. Perforated bone allograft soaked in an antibiotic was used in Group 4. Osteomyelitis of the proximal femur was formed in experimental animals. RESULTS AND DISCUSSION: Statistically insignificant decrease in the concentration of gentamicin was observed by the 7th day in all experimental groups. In rabbits whose bone defect was filled with a whole bone allograft welded with antibiotic and perforated bone allograft impregnated with an antibiotic (Groups 3 and 4), the most stable concentration of gentamicin was noted throughout the study period. Statistically significant differences were revealed between the experimental groups in relation to the dynamics of changes in the concentration of gentamicin in blood plasma. It was found that the group using the biodegradable material “PerOssal” on the 1st day showed a high concentration of the antibiotic in the blood plasma. However, by the 2nd day, a lower concentration of the antibiotic was recorded compared to all comparison groups of the bone allograft. CONCLUSIONS: The results of the analysis of the dynamics of gentamicin concentration may indicate significant differences between the methods of graft preparation, especially in the relationship with antibiotic release into the blood plasma. The most stable antibiotic concentration was registered in the groups of animals that underwent the filling of bone defect using a whole bone allograft welded with an antibiotic and a perforated bone allograft impregnated with antibiotic. A significant decrease of gentamicin concentration in the femur homogenate by the 7th day after transplantation was observed when using a whole bone allograft impregnated with an antibiotic. At the same time, a stable concentration of the antibiotic in the blood plasma was registered. The highest initial antibiotic concentration in the homogenate with a gradual decrease over 7 days was observed when using the antibiotic-impregnated biodegradable material “PerOssal.”

Microbial Biotextiles for a Circular Materials Economy

Harnessing microbial biofabrication and inspired by indigenous practices, we engineer high-performance microbial nanocellulose (MC) biotextiles with a sustainable circular life cycle. Specifically, our plant-based lecithin phosphocholine treatment modulates cellulose cross-linking through phosphate and methylene groups, to yield a biodegradable material with superior mechanical and flame-retardant properties. Coloration is achieved using natural dyes and waste-to-resource strategies. Life cycle impact assessment reveals MC biotextiles mitigate the carcinogenics of leather by a factor of 103 and the carbon footprint of synthetic leather and cotton by ~97%, for widespread application in fashion, interiors, and construction. The translational potential of this approach is tremendous, as using microbes and green chemistry to engineer regenerative, high-performance products will disrupt linear production models and mitigate its environmental threats in a circular economy.