Biomass Processing

The current electricity demand of the Kingdom of Saudi Arabia (KSA) is around 55 GW, which is projected to reach up to 120 GW by 2032. This energy is mainly produced from fossil fuels, posing a serious risk to human health and environment. Moving towards a sustainable model, KSA government has initiated a plan called the King Abdullah City of Atomic and Renewable Energy (KACARE) to utilize the indigenous renewable energy resources to generate a further 54 GW energy from solar, wind, nuclear, geothermal and waste-to-energy (WTE). The arid nature of the KSA increases the importance of water in daily life and makes the country the third-largest per capita water user worldwide. About 12 thousand industries are working in different sectors, which produce large quantities of wastes and waste sludge on a daily basis. It has been estimated that 2.4 and 0.77 billion m3/ year of municipal and industrial wastewater respectively are produced in KSA, totaling to 3.17 billion m3/ year. Therefore, there is a huge potential of producing bioenergy and bioproducts, if this wastewater is treated in algae biorefinery. Algae as a ‘natural chemical factory’ has gained significant attention to produce several energy carriers, including starches for alcohols, lipids for diesel fuel, and bio-hydrogen (H2) for fuel cells and valuable materials and chemicals. Considerable progress has been made in recent years to optimize the production of energy and value-added products by utilizing algae under algae biorefinery concept. The biorefinery is a multi-process and multi-product system, similar to a petroleum refinery. It utilizes various feedstock to produce useful materials, chemicals, and bioenergy in the form of fuel, power, and heat in an integrated system. Algae contain natural oils, carbohydrates, and proteins for the production of biodiesel, ethanol, and H2. The leftover or residues of algae after oil extraction can be digested anaerobically to produce methane (CH4) as an energy carrier. Furthermore, the AD digestate can be a source of animal feed and organic fertilizer. Although, theoretically algae can produce various fuels, an array of valuable materials and capture carbon emissions, but in practice, profitable algal biofuel production has proven to be quite challenging. Most of these challenges lie in algae production methods, including a selection of suitable algae strain, its cultivation, harvesting, and extraction of value-added materials for energy and bioproducts along with their conversion pathways. The aim of this paper is to review the potential of algae biorefinery in KSA for the treatment of wastewater and production of bioenergy and bioproducts.

Biochar is a carbonaceous porousmaterial deliberately applied to soil to improve its fertility. Themechanisms through which biochar
acts on fertility are still poorly understood. The effect of biochar texture size on water dynamics was investigated here in order
to provide information to address future research on nutrient mobility towards plant roots as biochar is applied as soil
amendment. A poplar biochar has been stainless steel fractionated in three different textured fractions (1.0–2.0mm, 0.3–
1.0mm and <0.3mm, respectively). Water-saturated fractions were analyzed by fast field cycling (FFC) NMR relaxometry. Results
proved that 3D exchange between bound and bulk water predominantly occurred in the coarsest fraction. However, as porosity
decreased, water motion was mainly associated to a restricted 2D diffusion among the surface-site pores and the bulk-site ones.
The X-ray μ-CT imaging analyses on the dry fractions revealed the lowest surface/volume ratio for the coarsest fraction, thereby
corroborating the 3D water exchange mechanism hypothesized by FFC NMR relaxometry. However, multi-micrometer porosity
was evidenced in all the samples. The latter finding suggested that the 3D exchange mechanism cannot even be neglected in
the finest fraction as previously excluded only on the basis of NMR relaxometry results. X-ray μ-CT imaging showed heterogeneous
distribution of inorganic materials inside all the fractions. The mineral components may contribute to the water relaxation
mechanisms by FFC NMR relaxometry. Further studies are needed to understand the role of the inorganic particles on water dynamics.

The biofuel industry is rapidly growing with a promising role in producing renewable energy and tackling climate change. Nanotechnology has tremendous potential to achieve cost-effective and process-efficient biofuel industry. Various nanomaterials have been developed with unique properties for enhanced biofuel production/utilization. The way forward is to develop nanotechnology-based biofuel systems at industrial scale.

An investigation was conducted to determine the effect of addition of different levels of AK2, a fuel additive that reduces ash fusion for agricultural biomass, on the physico-chemical properties of biomass pellets.    Three different biomass straws, barley, oat, and wheat were ground at two hammer mill screen sizes of 0.8  mm  and 1.6 mm.  Each ground biomass sample was mixed with three levels of AK2, 0.05%, 0.10%, and 0.15% by mass and also a blank (no AK2) was set aside for
comparison.    Pellets  were  made  using  single-pelleting  unit  at  a  pre-set  load  of  4  400  N  corresponding  to  a  pressure  of 138.9  MPa.    Physical  quality  of  pellets  were  determined  by  measuring  pellet  density,  relaxed  density,  durability,  and  the specific  energy  required  to  make  a  pellet.    Pellets  having  higher  durability  values  (74%-88%)  were  obtained  from  ground straw at hammer screen size of 0.8 mm and AK2 level of  0.15% compared to other treatments.    Carbon, hydrogen, nitrogen, and sulfur content of blank pellets and those with 0.15% AK2 at hammer screen size of 0.8 mm were determined.    Pellets made with 0.15% AK2 at hammer screen size of 0.8 mm, manufactured by pilot-scale pellet mill, were gasified and the tar content was determined.    The tar content of pellets with 0.15% AK2 was significantly lower than blank pellets.

Biomass pyrolysis is a promising renewable sustainable source of fuels and petrochemical substitutes. It may help in compensating the progressive consumption of fossil-fuel reserves. The present article outlines biomass pyrolysis. Various types of biomass used for pyrolysis are encompassed, e.g., wood, agricultural residues, sewage. Categories of pyrolysis are outlined, e.g., flash, fast, and slow. Emphasis is laid on current and future trends in biomass pyrolysis, e.g., microwave pyrolysis, solar pyrolysis, plasma pyrolysis, hydrogen production via biomass pyrolysis, co-pyrolysis of biomass with synthetic polymers and sewage, selective preparation of high-valued chemicals, pyrolysis of exotic biomass (coffee grounds and cotton shells), comparison between algal and terrestrial biomass pyrolysis. Specific future prospects are investigated, e.g., preparation of supercapacitor biochar materials by one-pot one-step pyrolysis of biomass with other ingredients, and fabricating metallic catalysts embedded on biochar for removal of environmental contaminants. The authors predict that combining solar pyrolysis with hydrogen production would be the eco-friendliest and most energetically feasible process in the future. Since hydrogen is an ideal clean fuel, this process may share in limiting climate changes due to CO 2 emissions.
Keywords Sustainable and renewable energy source; Fossil-fuel alternatives; Biomass pyrolysis; Biofuel (bio-oil, biogas, biochar); Charcoal (activated carbon); Hydrogen fuel

BACKGROUND: When direct current (DC) is used in electrocoagulation processes, an impermeable oxide layer may form on the cathode and corrosion of the anode may occur due to oxidation. This prevents effective current transfer between the anode and cathode, so the efficiency of the electrocoagulation process declines. These disadvantages of DC have been reduced by adopting alternating current (AC). The main objective of this study is to investigate the effects of AC and DC on the removal of fluoride from water using an aluminum alloy as anode and cathode.RESULTS: Results showed that removal efficiencies of 93 and 91.5% with energy consumption of 1.883 and 2.541 kWh kL−1 was achieved at a current density of 1.0 A dm−2 and pH 7.0 using an aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of fluoride fitted the Langmuir adsorption isotherm. The adsorption process follows second-order kinetics and temperature studies showed that adsorption was exothermic and spontaneous in nature.CONCLUSIONS: The aluminum hydroxide generated in the cell removed the fluoride present in the water and reduced it to a permissible level thus making it drinkable. It is concluded that an alternating current prevents passivation of the aluminum anode during electrocoagulation and avoids the additional energy wasted due to the resistance of the aluminum oxide film formed on the anode surface. Copyright © 2010 Society of Chemical Industry

Cet ouvrage est destiné à faire le point sur les enzymes qui catalysent l'hydrolyse ou la dépolymérisation des molécules d'origine biologique. Il rassemble les textes d'une série de conférences prononcées au cours d'un séminaire animé par Annette Mouranche et Claude Costes au Centre de Grignon de l'Institut national agronomique. Lorsqu'il s'agit de macromoléeules, comme par exemple l'amidon, la cellulose ou les caséines, leur utilisation industrielle implique souvent une simplification chimique préalable. Cette simplification est souvent à l'origine l'hydrolyse d'une fonction ester ou amide. Cette réaction hydrolytique est à la base de bien des processus technologiques dans les industries alimentaires: fromagerie, industrie des viandes, industrie des jus de fruits, brasserie, amidonnerie. De même la valorisation de la biomasse lignocellulosique commence par une série de réactions de dépolymérisation. L'ensemble de ces réactions est le plus souvent réalisé par voie enzymatique. Une meilleure connaissance des enzymes concernées permettra un élargissement des technologies alimentaires, un renouvellement de certaines stratégies phytosanitaires, une exploitation plus rationnelle des déchets animaux et végétaux ou la fabrication de substances nouvelles par hémisynthèse industrielle. Quelle est l'origine biologique de ces enzymes? Que sait-on sur leur structure, leurs propriétés et leur mode d'action? Comment les met-on en œuvre ou comment peut-on élargir leur utilisation industrielle? Cet ouvrage essaie de présenter une analyse de ces problèmes et propose des perspectives nouvelles. La vaste catégorie des nucléases n'a pas été abordée dans ce travail qui s'adresse principalement à tous ceux qui, étudiants, ingénieurs, responsables d'entreprise ou enseignants, sont concernés par la transformation industrielle de la production agricole, végétale ou animale.