Bioresource Technology Reports最新文献

This study addresses the challenge of removing Congo red (CR) from aqueous solutions using activated carbon (AC) derived from macadamia nutshells (MNS). A unique two-step carbonization and pyrolysis process was employed to produce MNS-AC with high surface area and porosity. Key experimental variables, including initial CR concentration, contact time, and pH, were systematically varied in batch mode. Results indicated that the modified AC achieved significantly higher removal percentages compared to unmodified charcoal. At pH 2.0 and an initial dye concentration of 50 mg L⁻¹, CR removal reached 97.48 % for MNS-AC3. The maximum adsorption capacity (q_max) of 58.29 mg g⁻¹ was observed at an initial dye concentration of 200 mg L⁻¹. The pseudo-second-order kinetic model closely matched the experimental data, and equilibrium data analysis using Langmuir and Dubinin-Radushkevich (D-R) isotherm models provided excellent fits. This research demonstrates the potential of using industrial biomass waste to develop sustainable solutions for dye removal in wastewater treatment.

Propionate constituting up to 25 % of volatile fatty acids in municipal wastewater, presents metabolic challenges for microorganisms. This study investigated the combined use of propionate along with granular activated carbon (GAC) for aerobic granular sludge (AGS) development and biological nutrient removal (BNR), particularly bio-P removal in granular reactors. GAC addition decreased granulation time and facilitated stable BNR pathways with propionate. AGS demonstrated robust settling properties (≥1 mm, 6 g/L MLSS, 40 mL/g SVI) with increased alginate-like exopolysaccharide (ALE) content up to 400 mgALE/gSS, indicating stable granule formation. Effective ammonium removal via simultaneous nitrification and denitrification was achieved. By day 90, phosphate removals reached 89 %, due to enrichment of polyphosphate accumulating organisms (PAOs) in GAC-containing AGS. The sludge fraction (>0.5 mm) comprised of granules and GAC-biofilms showed efficient phosphate removal through enhanced biological phosphate removal (EBPR). Enrichment of denitrifying PAO, Thauera sp., contributed to enhanced granulation, granular stability and nutrient removals.

Vermicomposting – the production of fertilizers and bioactive substrates for plants using soil oligochaetes – is an actively developing area of agricultural technology. Beneficial properties of vermicompost are provided, for the most part, by communities of bacteria that live in the digestive system of the worm and process the incoming substrate. Moreover, in light of modern trends towards biorecultivation a closest attention is paid to the ability of earthworms' microbial communities to transform organic waste from agricultural or other industries substrates into vermicompost. The aim of our study was to analyze the microbiota of the widespread soil oligochaete Eisenia fetida cultivated on commercial peat and sludge obtained from water treatment plants. Using metagenomic sequencing, we analyzed the dynamics of microbiome in digestive system of the worm during the vermicomposting.

The diversity of bacteria in sludge was significantly higher than in peat. The diversity of the microbiome during vermicomposting of peat remained relatively stable compared to sewage sludge. We revealed that Eisenia fetida may absorb most of the bacteria living in the substrate in which the worms were cultivated. Most of the engulfed bacteria pass through the worm's digestive system and return to the substrate; however, part of them might be digested by the worm or remain in the gut as a functional part of its microbiome. Proteobacteria and Bacteroidetes were the dominant phyla in the earthworm gut microbial communities, regardless of the cultivation substrate. We also demonstrated the possible autochthonous microbiome of Eisenia fetida, including at least 11 genera. A stable bacterial set (including Bacillus sp., Bradyrhizobium sp., Cupriavidus sp., Cutibacterium sp., Leifsonia sp., Paeniclostridium sp., Roseomonas sp., Sphingomonas sp., Staphylococcus sp., Streptococcus sp., and Trichococcus sp.) was registered as common for the empty guts of Eisenia fetida cultivated in peat and sludge. These core bacteria may play a key role in the vermicomposting process and bioremediation, especially in such disturbed substrates as wastewater sludge, being introduced by the earthworm itself.

Black soldier fly frass is the nutrient-rich waste produced by black soldier fly larvae. This study aimed to enhance the frass by co-composting it with fish meal, bone meal, boiler ash, and sawdust. The co-composting process involved blending frass with the selected materials to achieve C:N ratio of 20, 25 and 30. After co-composting, characterization of total carbon, nitrogen, phosphorus and potassium contents and germination test were conducted. Fish meal increased nitrogen from 2.47 % to 3.10 %, bone meal improved phosphorus from 0.024 % to 0.042 %, and boiler ash raised potassium from 0.0023 % to 0.0039 %. Nevertheless, all the NPK source additives are required to balance and enhance all the nutrient level. Additionally, composts BSFF, fish meal, bone meal, and boiler ash, resulted in 100 % seed germination. The study demonstrates that co-composting frass with these materials effectively improves its nutrient content, providing a sustainable alternative for organic waste management and nutrient recycling.

The increasing damage to the environment caused by synthetic plastics has raised the demand for sustainable substitutes, which has led to a rise in interest in biopolymers such as Polyhydroxyalkanoates (PHAs). PHAs have the potential to be useful materials in a variety of industries, including packaging, biomedical engineering, and agriculture, because of their physical qualities similar to ordinary plastics, biodegradability, and biocompatibility. This article offers a thorough analysis of the latest developments in PHA biosynthesis, with a particular emphasis on the β-oxidation pathway and microbial production techniques. It also explores PHA generation on an industrial scale, explaining the many substrates that are used to improve microbial productivity and efficiency. An in-depth review of the industrial processes in existence now highlights the difficulties in producing and purifying products at a reasonable cost, emphasizing the necessity of optimizing microbial strains and extraction methods to increase output and lower expenses. Furthermore, the review delves into the environmental uses of PHAs, emphasizing their contribution to the reduction of plastic pollution and the advancement of sustainability. Future approaches to increasing PHA production are explored, with particular attention paid to process optimization, genetic engineering, and the development of innovative recovery techniques. With the increasing need for environmentally acceptable materials, PHA production technology development will have a key role in solving the world's environmental problems.

Urban residential garden waste offers a valuable biomass resource, but its energy potential is often underutilized. This research investigates the gasification potential of Samanea saman leaves and twig pellets for energy production. Gasification experiments were conducted using a fixed-bed updraft gasifier with air as the gasifying medium. Experiments covered equivalent ratios (ER) ranging from 0.185 to 0.314 and temperatures ranging from 500 °C to 816 °C. Gas composition, energy yield, tar content, and biomass and char morphology were evaluated. The gasification of S. saman pellets yielded syngas with hydrogen content between 7.00 % and 7.40 % vol, indicating good energy potential. Twig pellets demonstrated higher carbon conversion efficiency (65.0 % to 70.6 %) and cold gas efficiency (26.5 % to 30.3 %) compared to leaf pellets. This exploration highlights the potential of S. saman gasification for effective urban garden waste management and renewable energy generation.

Carbon substrate is a pivotal factor influencing polyhydroxyalkanoate (PHA) properties of varied industrial importance. Three synthetic sucrose samples with varying manufacturing purity levels were selected as carbon substrates to synthesize diverse PHAs using a wild-type Bacillus cereus AAR-1. Comparative monomeric analyses of the extracted biopolymers revealed Poly (3-hydroxytetradecanoate) (P3HTD), Poly(3-hydroxybutyrate-co-2-hydroxytetradecanoate) [P(3HB-co-2HTD)], and Poly(3-hydroxybutyrate) (P3HB) with carbon elemental contents that ranged from 39 to 53 % and no nitrogen detected. The decomposition temperature of [P(3HB-co-2HTD)] was 279 °C, indicating higher thermal stability than the individual monomeric units. Notably, the homopolymer P3HTD exhibited an increased melting temperature of 172.4 °C and a reduced crystallinity percentage (X_c % = 20.7 %), crucial properties for bioplastics and medical sector applications. All the biopolymers displayed a low specific heat capacity ranging between 0.03 and 0.05 J/g°C, suitable for applications such as thermal storage materials and temperature-regulating textiles. The results suggest that different carbon purity grades influenced homopolymer accumulated in Bacillus cereus AAR-1.