Recycling food and agriculture by-products to mitigate climate change: a review

Food loss and waste is a major issue affecting food security, environmental pollution, producer profitability, consumer prices, and climate change. About 1.3 billion tons of food products are yearly lost globally, with China producing approximately 20 million tons of soybean dregs annually. Here, we review food and agricultural byproducts with emphasis on the strategies to convert this waste into valuable materials. Byproducts can be used for animal and plant nutrition, biogas production, food, extraction of oils and bioactive substances, and production of vinegar, wine, edible coatings and organic fertilizers. For instance, bioactive compounds represent approximately 8–20% of apple pomace, 5–17% of orange peel, 10–25% of grape seeds, 3–15% of pomegranate peel, and 2–13% of date palm seeds. Similarly, the pharmaceutical industry uses approximately 6.5% of the total output of gelatin derived from fish bones and animal skin. Animals fed with pomegranate peel and olive pomace improved the concentration of deoxyribonucleic acid and protein, the litter size, the milk yield, and nest characteristics. Biogas production amounts to 57.1% using soybean residue, 53.7% using papaya peel, and 49.1% using sugarcane bagasse.

     

Sulfonated graphene nanomaterials for membrane antifouling,pollutant removal,and production of chemicals from biomass: a review

Water pollution and the unsustainable use of fossil fuel derivatives require advanced catalytic methods to clean waters and to produce fine chemicals from modern biomass. Classical homogeneous catalysts such as sulfuric, phosphoric, and hydrochloric acid are highly corrosive and non-recyclable, whereas heterogeneous catalysts appear promising for lignocellulosic waste depolymerization, pollutant degradation, and membrane antifouling. Here, we review the use of sulfonated graphene and sulfonated graphene oxide nanomaterials for improving membranes, pollutant adsorption and degradation, depolymerization of lignocellulosic waste, liquefaction of biomass, and production of fine chemicals. We also discuss the economy of oil production from biomass. Sulfonated graphene and sulfonated graphene oxide display an unusual large theoretical specific surface area of 2630 m²/g, allowing the reactants to easily enter the internal surface of graphene nanosheets and to reach active acid sites. Sulfonated graphene oxide is hydrophobic and has hydrophilic groups, such as hydroxyl, carboxyl, and epoxy, thus creating cavities on the graphene nanosheet’s surface. The adsorption capacity approached 2.3–2.4 mmol per gram for naphthalene and 1-naphthol. Concerning membranes, we observe an improvement of hydrophilicity, salt rejection, water flux, antifouling properties, and pollutant removal. The nanomaterials can be reused several times without losing catalytic activity due to the high stability originating from the stable carbon–sulfur bond between graphene and the sulfonic group.

     

Materials,fuels, upgrading,economy, and life cycle assessment of the pyrolysis of algal and lignocellulosic biomass: a review

Climate change issues are calling for advanced methods to produce materials and fuels in a carbon–neutral and circular way. For instance, biomass pyrolysis has been intensely investigated during the last years. Here we review the pyrolysis of algal and lignocellulosic biomass with focus on pyrolysis products and mechanisms, oil upgrading, combining pyrolysis and anaerobic digestion, economy, and life cycle assessment. Products include oil, gas, and biochar. Upgrading techniques comprise hot vapor filtration, solvent addition, emulsification, esterification and transesterification, hydrotreatment, steam reforming, and the use of supercritical fluids. We examined the economic viability in terms of profitability, internal rate of return, return on investment, carbon removal service, product pricing, and net present value. We also reviewed 20 recent studies of life cycle assessment. We found that the pyrolysis method highly influenced product yield, ranging from 9.07 to 40.59% for oil, from 10.1 to 41.25% for biochar, and from 11.93 to 28.16% for syngas. Feedstock type, pyrolytic temperature, heating rate, and reaction retention time were the main factors controlling the distribution of pyrolysis products. Pyrolysis mechanisms include bond breaking, cracking, polymerization and re-polymerization, and fragmentation. Biochar from residual forestry could sequester 2.74 tons of carbon dioxide equivalent per ton biochar when applied to the soil and has thus the potential to remove 0.2–2.75 gigatons of atmospheric carbon dioxide annually. The generation of biochar and bio-oil from the pyrolysis process is estimated to be economically feasible.

     

Possible human health risk of some heavy metals from consumption of tilapia fish from Lake Mariut,Egypt

Environmental Science and Pollution Research - Lake Mariut Main Basin (MB) is not only one of the three basins composing Lake Mariut (LM) but is also the main source of the popular tilapia fish to...     

Properties of concrete paving blocks made with waste marble

Marble industry produces large amounts of waste marble - what causes environmental problems. In paving blocks based on two cement types we have partly replaced aggregate with waste marble. Physical and mechanical tests were performed on blocks so produced. The cement type turns out to be an important factor. Mechanical strength decreases with increasing marble content while freeze-thaw durability and abrasive wear resistance increase. Waste marble is well usable instead of the usual aggregate in the concrete paving block production.     

X-ray metal assessment and ovarian ultrastructure alterations of the beetle,Blaps polycresta (Coleoptera,Tenebrionidae), inhabiting polluted soil

Environmental Science and Pollution Research - X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium,...     

Comparative Thermodynamic Study on the Contribution of the Autocondensation and Copolymerization Reactions for the Tannins of the Subspecies of Acacia nilotica

Autocondensation and copolymerization reactions of the Acacia nilotica subspecies tomentosa (Ant) and the subspecies adansonii (Ana) tannins extracts solutions have been studied at several pH values by thermomechanical analyzer. Results of chemical analysis of these tannins revealed that the studied tannins, Ant and Ana contained high percentages of extractable tannins (54 and 57 %) for and polyphenolic materials (78 and 80 %) respectively. Different hardeners such as paraformaldehyde, Urea and pMDI were added at different ratios and their polycondensation reactions was studied and compared with their autocondensation ones. The aim was to evaluate the tannins suitability for the production of commercially and technically viable tannin adhesives with reduced Formaldehyde emission for wood products and to study the interference between the autocondensation and the copolymerization reaction. The obtained results of autocondensation reaction for both of the tannins studied showed that the best Young’s modulus values for Ant (3,500 and 2,750 MPa) and Ana (2,650 and 2,620 MPa) were obtained at pH 5 and 7. The Young’s modulus values obtained by the tannins Ant were higher than those achieved by Ana. This indicates that the Ant is more reactive than Ana. These results were also in line with results achieved by the gel time for both of the tannins. Gel time results indicate that the reactivity of both tannins increased towards alkalinity with Ana being more reactive at alkaline pH. Addition of 8 % of paraformaldehyde was adversely affecting the autocondensation reactions, as the best Young’s modulus values were achieved at pH 4 for Ant tannins. As for Ana the higher Young’s modulus values (2,000 and 2,310 MPa) were achieved at pH 5 and 7. This indicates that autocondensation reaction was contributed to the final network of the copolymerization reaction. When smaller ratio of paraformaldehyde and Urea (5 %) was added to Ant tannins it favors the autocondensation reaction and the best Young’s modulus values were obtained at pH 5 and 7. Addition of pMDI (10–30 %) was found to decrease the temperature of copolymerization and the obtained Young’s modulus values by Ant were lower than those obtained by autocodensation reaction. Best Young’ modulus values were obtained by Ant at pH 5 and 7. Ana gave the best Young’s modulus values at pH 4 and 5 indicating that the autocondensation appears to depress the copolymerization reactions. The obtained results by both reactions were very important from technical and economical point of view as they concluded that it is very possible to produce adhesives system with zero emission depending on the tannins autocondensation reaction and pH values. Reduction of formaldehyde emission was also possible upon addition of smaller amount of paraformaldehyde and Urea.     

Potential utilization of burned wood in manufacture of medium density fiberboard

The potential utilization of burned wood in the manufacture of medium density fiberboard (MDF) was investigated. For this aim, the MDF panels were made of various mixtures of burned pine wood (Pinus sylvestris L.), unburned beech (Fagus orientalis L.) and oak (Ouercus robur L.) woods under commercial conditions in an MDF company. The mixture ratio of the unburned beech and oak woods to the burned pine wood were 50/50 wt%. The mixing ratios of burned wood chips with unburned wood chips were 0:100, 25:75, 50:50, 75:25 and 100:0, %, respectively. A commercial urea–formaldehyde resin was used as a binder. The physical properties measured in the investigation included density and thickness swelling, while the mechanical properties examined were bending strength, modulus elasticity, internal bond, screw holding ability perpendicular to the plane of panel, and janka hardness perpendicular to the plane of the panel. Surface roughness and color of the panels were also measured. The results indicated that all the panels met the mechanical properties of general-purpose MDF requirements of EN 622-5. The surface roughness of the MDF panels containing burned wood decreased with increasing burned wood content but remained higher than the control panels. The dimensional stability of the MDF panels decreased with the incorporation of burned wood fibers as compared with the control MDF panels.     

A Microprocessor-Based Air Quality Monitoring System

Portable air quality monitoring systems may be required to supplement fixed installations or to provide for quick response to a transient situation, possibly at a remote location. A microprocessor-based monitoring unit has been developed for use with existing sensors. The unit is portable and its operational sequence can be programmed to adapt it to any unique requirements existing at the deployment site. Selectable on-site calculations are performed on raw data, and a hard copy or tape record of results can be produced.     

Assessment of municipal solid waste generation and recyclable materials potential in Kuala Lumpur,Malaysia

This paper presents a forecasting study of municipal solid waste generation (MSWG) rate and potential of its recyclable components in Kuala Lumpur (KL), the capital city of Malaysia. The generation rates and composition of solid wastes of various classes such as street cleansing, landscape and garden, industrial and constructional, institutional, residential and commercial are analyzed. The past and present trends are studied and extrapolated for the coming years using Microsoft office 2003 Excel spreadsheet assuming a linear behavior. The study shows that increased solid waste generation of KL is alarming. For instance, the amount of daily residential SWG is found to be about 1.62 kg/capita; with the national average at 0.8–0.9 kg/capita and is expected to be increasing linearly, reaching to 2.23 kg/capita by 2024. This figure seems reasonable for an urban developing area like KL city. It is also found that, food (organic) waste is the major recyclable component followed by mix paper and mix plastics. Along with estimated population growth and their business activities, it has been observed that the city is still lacking in terms of efficient waste treatment technology, sufficient fund, public awareness, maintaining the established norms of industrial waste treatment etc. Hence it is recommended that the concerned authority (DBKL) shall view this issue seriously.