Conversion of Lignin to Heat and Power, Chemicals or Fuels into the Transition Energy Strategy

Energy transition toward low carbon, high sustainable and efficient generation and distribution systems will change the supply matrix of the world and create new opportunities but challenges still remain. Energy generation from biomass, or bioenergy, is one of such renewable sources and its use might be generalized in the following years. Bioenergy is a very promising strategy to provide energy not only for mobility but also for onsite places for heat and power generation. Besides, bioenergy differentiates from other renewable energies that biomass may be the source of a myriad of molecules enabling the bio-based economy and allowing the replacement in an extent of solvents, petrochemicals, and polymers produced by the petroleum industry. Biomass is generally composed of some large polymers found in nature such as cellulose, hemicellulose, proteins, starch, chitin, and lignin. The latter is a complex phenylpropanoid biopolymer conferring mechanical strength to plant cell walls and one of major spread in nature along with cellulose and chitin. Lignin has a plenty of potential uses in modern bio-based economy, from conventional paper industry uses to more challenging conversion to useful chemicals, materials, and clean biofuels. This chapter undertakes a rapid overview on lignin applications in order to describe the basis of a lignin-based economy

Sugarcane Bagasse Valorization Strategies for Bioethanol and Energy Production

The use of sugarcane bagasse pith as solid substrate for fungi and microbial growth is well known, as well as a source of microorganisms that can be isolated from it. Pith has also been used as a bulking agent for soil bioremediation. More recently, bagasse pith has been used for bioethanol production involving pretreatment and hydrolysis followed by fermentation and dehydration. However, little is reported about biomass valorization for the development of environmentally sound and innovative strategies to process sugarcane bagasse from sugar mills. Incineration of sugarcane bagasse pith is a very common and mature technology for waste disposal and generation of electrical and thermal energy. However, this approach may not be satisfactory in organic waste management due to pollutant emissions, economic and labor costs, loss of energy, and bad odor. In addition, no valuable product is generated from its decomposition process. Instead of incineration, recent research has focused on its utilization as biofuel source. In this chapter, the use of sugarcane bagasse pith as a waste material for incineration versus biomass to produce bioethanol is discussed in terms of energy ratio and emissions, in addition to elucidate the potential of sugarcane bagasse valorization for a more sustainable society

Growth response and heavy metals tolerance of Axonopus affinis, inoculated with plant growthpromoting rhizobacteria

Different microorganisms have been used for bioremediation based on their resistance and ability to sequester heavy metals. The use of plant growth-promoting rhizobacteria (PGPR) for bioremediation of these contaminants has been successful. A PGPR isolated from hydrocarbons-contaminated soil identified as Bacillus sp., by microbiological and molecular tools and characterized as heavy metal tolerant by minimal inhibitory concentration (MIC) assay was inoculated into Axonopus affinis plants. Both of them were exposed to cadmium, nickel, and zinc and the effect of their relationship was analyzed by multivariate analysis. The results did not show a significant growth promotion and development of this Poaceae with rhizobacteria alone, but the presence of heavy metals plus the PGPR assured the survival of plants. This suggests that the plant’s response is related with the metal concentration and the exposure time to the contaminants, as well as with its intrinsic tolerance. The Bacillus sp strain allowed the growth maintenance of A. affinis and enhanced its tolerance to the assayed heavy metals, suggesting a synergistic effect between this species and the rhizobacterium in response to contaminating agents.Keywords: Bioremediation, heavy metals, microorganisms, plant

Two naphthalene degrading bacteria belonging to the genera Paenibacillus and Pseudomonas isolated from a highly polluted lagoon perform different sensitivities to the organic and heavy metal contaminants

Two bacterial strains were isolated in the presence of naphthalene as the sole carbon and energy source from sediments of the Orbetello Lagoon, Italy, which is highly contaminated with both organic compounds and metals. 16S rRNA gene sequence analysis of the two isolates assigned the strains to the genera Paenibacillus and Pseudomonas. The effect of different contaminants on the growth behaviors of the two strains was investigated. Pseudomonas sp. ORNaP2 showed a higher tolerance to benzene, toluene, and ethylbenzene than Paenibacillus sp. ORNaP1. In addition, the toxicity of heavy metals potentially present as co-pollutants in the investigated site was tested. Here, strain Paenibacillus sp. ORNaP1 showed a higher tolerance towards arsenic, cadmium, and lead, whereas it was far more sensitive towards mercury than strain Pseudomonas sp. ORNaP2. These differences between the Gram-negative Pseudomonas and the Gram-positive Paenibacillus strain can be explained by different general adaptive response systems present in the two bacteria

Impacts of microbial activity on trace metal behavior during the bioremediation of phenanthrene-contaminated soils

A novel method for the bioremediation of phenanthrene using the fungus Penicillium frequentans was utilised to remove phenanthrene (200 mg kg$^{-1}$) from soil containing both metals and phenanthrene, over 29 days. Bioremediation of phenanthrene and its effects on trace metal behaviour has been investigated. Metal behaviour studied includes metal speciation and the kinetics of exchange between solution and solid phase and plant uptake of the more labile and mobile, and potentially more bioavailable metal species. Phenanthrene removal by P. frequentans was optimised in terms of both soil water and nutrient composition. Slightly lower removal rates were obtained using P. frequentans alone (73%) and plants alone (67%). However, the highest phenanthrene removal (77%) was obtained using both fungus and plant. Assessment of the metal behaviour before and after phenanthrene biodegradation showed that the removal of phenanthrene by either fungal or mixed fungal and native microflora resulted in an increased flux of metal from solid to solution, an increased pool of potentially bioavailable and toxic metal species and increased plant uptake to both Echinochloa polystachia and Triticum aestivum, by factors of 4-13. In the presence of plants alone, metal mobilisation and uptake increased by smaller factors. In some cases, there was no increase in metal mobilisation and a maximal increase of 2 was found in Ni and Pb. These results highlight the impact of bioremediation process on metal behaviour. In addition, it is suggested that phytoremediation and not bioaugmentation using P. frequentans is the best overall option to obtain a considerable phenanthrene removal, reducing the increased pool of potentially bioavailable and toxic metal specie