Recycling of Solid Waste for Biofuels and Bio-chemicals

This book presents the latest advances in and current research perspectives on the field of urban/industrial solid waste recycling for bio-energy and bio-fuel recovery. It chiefly focuses on five main areas, namely bioreactor landfills coupled with energy and nutrient recovery; microbial insights into anaerobic digestion; greenhouse gas emission assessment; pyrolysis techniques for special waste treatment; and industrial waste stabilization options. In addition, it compiles the results of case studies and solid waste management perspectives from different countries

Biodegradation and Bioconversion of Hydrocarbons

This book details three main topics: the screening and characterization of hydrocarbons from air, soil and water; tehnologies in the biodegradation of hydrocarbons; and the bioconversion of hydrocarbons for biofuel/chemicals, as well as recent developments in the remediation of hydrocarbons and their environmental benefits. The first section focusses on screening methods, qualitative and quantitative analysis of hydrocarbons from soil, air and water environments. The second section examines technologies for removing hydrocarbon contaminants from various environments, especially advanced technologies for the removal of hydrocarbons and in-situ and ex-situ remediation strategies and problems, as well as concrete case studies. The last section, covering the bioconversion of hydrocarbons for biofuel/chemicals highlights the biochemicals and bioproducts developed from hydrocarbons, with a particular focus on biochemical and chemical technologies used to produce biopolymers, biofuel precursors and commodity chemicals from hydrocarbons

Editorial: Biomass, Bioenergy and Biofuels for Circular Bioeconomy

The huge demand for energy and products, mostly based on fossil fuels, have caused severe environmental impacts, that are based on pollution, greenhouse gas (GHG) emissions, and finally of climate changes. While energy can be supplied from different renewable sources, such as solar, wind or hydro energy, they are intrinsically impossible or hard to control, or dependent on climatic conditions that are becoming more and more unpredictable. In this context, biomass has come, once more, as one of the potential solutions to add to the renewable energy mix.info:eu-repo/semantics/publishedVersio

Metal(loid) speciation and transformation by aerobic methanotrophs

Abstract: Manufacturing and resource industries are the key drivers for economic growth with a huge environmental cost (e.g. discharge of industrial effluents and post-mining substrates). Pollutants from waste streams, either organic or inorganic (e.g. heavy metals), are prone to interact with their physical environment that not only affects the ecosystem health but also the livelihood of local communities. Unlike organic pollutants, heavy metals or trace metals (e.g. chromium, mercury) are non-biodegradable, bioaccumulate through food-web interactions and are likely to have a long-term impact on ecosystem health. Microorganisms provide varied ecosystem services including climate regulation, purification of groundwater, rehabilitation of contaminated sites by detoxifying pollutants. Recent studies have highlighted the potential of methanotrophs, a group of bacteria that can use methane as a sole carbon and energy source, to transform toxic metal (loids) such as chromium, mercury and selenium. In this review, we synthesise recent advances in the role of essential metals (e.g. copper) for methanotroph activity, uptake mechanisms alongside their potential to transform toxic heavy metal (loids). Case studies are presented on chromium, selenium and mercury pollution from the tanneries, coal burning and artisanal gold mining, respectively, which are particular problems in the developing economy that we propose may be suitable for remediation by methanotrophs. 6g_ZKsLH11vt1AExshJzH4Video Abstrac

Methane emission potential of open dumps in Chennai: a case study

Monitoring of atmospheric levels of methane and other Greenhouse Gases (GHGs) holds great promise for the mitigation of global warming resulting from increasing radioactive trapping by atmospheric gases. Since, the direct measurements of landfill methane emission found to be difficult, the methane emission potential of the open dumps in Chennai has been estimated using first-order decay models such as TNO, LandGEM and zero-order model (EPER model, Germany). The resulted methane emission was around 33 × 106 m3, 36 × 106 m3 and 52 × 104 m3 based on the TNO, LandGEM and zero-order models, respectively. The results concluded that the methane emission from the Chennai dumps contributed to 0.13% of the overall global landfill methane emission and 1.3% of Indian landfill methane emissions within the years between 1986 and 2003

Sustainable bio-plastic production through landfill methane recycling

Plastics are an indispensable part of day-to-day life. Environmental implications of these non-biodegradable plastics in landfills raise major concerns. Use of biodegradable plastics is the best alternative as they are environmental friendly, with great recycling potential, and can be produced using renewable resources such as waste materials, methane (CH₄) and simple carbon sources. Whilst the biodegradable plastics are eco-friendly, they pose a risk of emitting CH₄ under anaerobic conditions in landfills. As a cradle-to-cradle approach, landfill CH₄ could be effectively used for biodegradable plastic production by methanotrophs. This review briefly reviews approaches to plastic disposal, alternatives to plastic waste management and outlines issues arising. The focus of the review is to examine the potential for cost-effective production of polyhydroxybutyrate (PHB) using methanotrophs for manufacturing biodegradable plastics. The data input into this analysis is derived from Australian landfill CH₄ emissions, the average PHB content of methanotrophs and applied to a case-scenario in Sydney, Australia.. The results suggest that this approach to biodegradable plastic production can be economically viable and price-competitive with synthetic plastics. In our case study, landfills were sized small, medium and large (5,000, 35,000 and 230,000 t of waste per year, respectively). In small landfills, 162 t of CH₄ can be recovered to produce 71 t of PHB per year, whilst in large landfills 7,480 t of CH₄ can be recovered to produce 3,252 t of PHB. The cost of PHB production can be reduced to 1.5–2.0 AUD meeting the market value of synthetic plastic by increasing production volumes through building a centralised extraction and refinement facility suitable for large metropolitan cities

Enzyme-mediated biodegradation of long-chain n-alkanes (C₃₂ and C₄₀) by thermophilic bacteria

Removal of long-chain hydrocarbons and n-alkanes from oil-contaminated environments are mere important to reduce the ecological damages, while bio-augmentation is a very promising technology that requires highly efficient microbes. In present study, the efficiency of pure isolates, i.e., Geobacillus thermoparaffinivorans IR2, Geobacillus stearothermophillus IR4 and Bacillus licheniformis MN6 and mixed consortium on degradation of long-chain n-alkanes C 32 and C 40 was investigated by batch cultivation test. Biodegradation efficiencies were found high for C 32 by mixed consortium (90%) than pure strains, while the pure strains were better in degradation of C 40 than mixed consortium (87%). In contrast, the maximum alkane hydroxylase activities (161 µmol mg −1 protein) were recorded in mixed consortium system that had supplied with C 40 as sole carbon source. Also, the alcohol dehydrogenase (71 µmol mg −1 protein) and lipase activity (57 µmol mg −1 protein) were found high. Along with the enzyme activities, the hydrophobicity natures of the bacterial strains were found to determine the degradation efficiency of the hydrocarbons. Thus, the study suggested that the hydrophobicity of the bacteria is a critical parameter to understand the biodegradation of n-alkanes

Gradient packing bed bio-filter for landfill methane mitigation

We assessed the suitability of various biogenic materials for development of a gradient packed bed bio-filter to mitigate the methane (CH4) emission from landfills. Five different biogenic materials (windrow compost-WC; vermicompost-VC; landfill top cover-LTC; landfill bottom soil-LBS; and river soil sediment-SS) were screened. Among these materials, the VC showed a better CH4 oxidation potential (MOP) of 12.6 μg CH4 gdw−1 h−1. Subsequently, the VC was used as a packing material along with wood chips in proto-type bio-filters. Wood chips were mixed at 5–15% to form three distinct gradients in a test bio-filter. Under the three different CH4 loading rates of 33, 44 and 55 gCH4 m−3 h−1, the achieved MOPs were 31, 41, and 47gCH4 m−3 h−1, respectively. The gradient packed bed bio-filter is effective for landfill CH4 mitigation than the conventional bio-filter as the latter shows gas channeling effects with poor MOPs

A biotechnological approach to convert methane into bio-polymer

[Extract] Preliminary outcomes:\ud \ud • Mixotrophic cultures are more suitable than pure cultures for effective CH4 remediation and to produce high levels of PHB. Isolation of pure strains and PHB quantification/production optimization are on-going.\ud \ud • N2-fixing cyanobacteria represent an inexpensive source of PHB (1-20% dry weight ) with CO2 (product of CH4 oxidation) as the sole carbon source. Therefore dual culturing would be ideal. \ud \ud • Globally, conventional plastic production consumes ≈ 270 million tons of oil and gas annually resulting in high GHG emissions. Therefore, synthesis of PHA/PHB from waste gas such as CH4 would be an economically feasible and sustainable approach

Bio-refining of carbohydrate-rich food waste for biofuels

The global dependence on finite fossil fuel-derived energy is of serious concern given the predicted population increase. Over the past decades, bio-refining of woody biomass has received much attention, but data on food waste refining are sorely lacking, despite annual and global deposition of 1.3 billion tons in landfills. In addition to negative environmental impacts, this represents a squandering of valuable energy, water and nutrient resources. The potential of carbohydrate-rich food waste (CRFW) for biofuel (by Rhodotorulla glutinis fermentation) and biogas production (by calculating theoretical methane yield) was therefore investigated using a novel integrated bio-refinery approach. In this approach, hydrolyzed CRFW from three different conditions was used for Rhodotorulla glutinis cultivation to produce biolipids, whilst residual solids after hydrolysis were characterized for methane recovery potential via anaerobic digestion. Initially, CRFW was hydrolysed using thermal- (Th), chemical- (Ch) and Th-Ch combined hydrolysis (TCh), with the CRFW-leachate serving as a control (Pcon). Excessive foaming led to the loss of TCh cultures, while day-7 biomass yields were similar (3.4–3.6 g dry weight (DW) L−1) for the remaining treatments. Total fatty acid methyl ester (FAME) content of R. glutinis cultivated on CRFW hydrolysates were relatively low (~6.5%) but quality parameters (i.e., cetane number, density, viscosity and higher heating values) of biomass extracted biodiesel complied with ASTM standards. Despite low theoretical RS-derived methane potential, further research under optimised and scaled conditions will reveal the potential of this approach for the bio-refining of CRFW for energy recovery and value-added co-product production