Biochars From Solid Organic Municipal Wastes For Soil Quality Enhancement

The overall municipal organic waste in Qatar accounts for 57% of municipal waste generated annually. Organic solid wastes such as food, newspapers, packaging, furniture woods and wood from building demolition have traditionally been placed in landfill, which create issues of sustainability for a country like Qatar with small land mass. While the recently opened Doha solid waste treatment facility contributed to alleviating the pressure on Landfill sites through composting and incineration, new value-added use of solid organic waste are needed for environmental and economic sustainability. Fortunately, biochars from mixed organic solid wastes can be used in soil amendment for food security and long term carbon sequestration for environmental sustainability. We hypothesize that deficiencies in depleted Qatari soils can be remedied by the application of biochars that are custom-designed to possess the right physicochemical characteristics suitable to improve soil fertility. Hence, this study was conducted to (1) Optimize production of biochars from mixed organic waste for desired physicochemical characteristics as soil enhancers. (2) Produce and characterize designer biochars using optimum production conditions for testing in soil incubation experiments. Select municipal organic wastes (newspaper, cardboard, woodchips and landscaping residues) individually and in a 25% blend were used as a precursor for biochar preparation. These residues were chosen due to their commonality in municipal solid waste streams. A complete 5 × 3 × 3 factorial design was used in this study with five biochar precursors (the 4 solid waste materials and a 25% blend/mixture), 3 sets of pyrolysis temperatures (350, 500, and 750°C) and 3 sets of pyrolysis residence time (2, 4 and 6 hrs). Data obtained showed that biochar yield was in the range of 21- 62% across all feedstocks and pyrolysis conditions. The highest yield was observed in newspaper-based biochars pyrolized at 350°C for 2 hrs. Key parameters such as pH, electrical conductivity bulk density and surface area, which positively improve water and nutrient-holding capacity in biochar-amended soil, varied depending on the precursors and production conditions. Bulk density was high in woodchips-based biochars but was similar among all other biochars, irrespective of precursors and pyrolysis conditions. The total surface area of biochars was low but showed dramatic increase in all feedstocks at 700°C pyrolysis temperature. The highest electrical conductivity observed in cardboard-based biochars pyrolized at 700C. Biochars produced from selected waste precursors were acidic except those produced at 700°C temperature where pH became alkaline. The wide range of biochar pH suggests potential tailoring to remediate the specific soil acidity. Cumulatively, biochars showed promising results for improving soil fertility parameters such as better water holding capacity, pH stabilization, and increased electrical conductivity of soil for better aggregation. These findings indicate that solid organic municipal wastes hold promising potential as precursors for manufacturing of value-added biochars with varied physicochemical characteristics allowing them to be used not only as an alternative to bio-waste management and greenhouse gas mitigation but also as means to improve depleted Qatari soil as the country embarks on its ambitious goals of ensuring food security and environmental sustainability.qscienc

Mixed Solid Municipal Waste-Based Biochar for Soil Fertility and Greenhouse Gas Mitigation

Municipal solid waste management is one of the major challenges facing Qatar with more than 2.5 million tons of municipal solid waste each year, a very high waste generation rate in a country with small land mass. Solid waste in Qatar consists mostly of organic materials (60%) with the remaining made up of recyclables, such as glass, metals and plastics. Qatar's ambitious development strategy targets environmental sustainability and invests in research on key grand challenges including water/food security. Fortunately both can be addressed through value-added conversion of solid organic waste into biochars. Solid municipal wastes such as newspaper, cardboard, woodchips and plant residues from landscaping can be converted to biochar for mitigation of their environmental impact and value-addition. On the other hand, agricultural soils have significant deficiencies in a range of essential trace elements and macronutrients and often exhibit low water holding capacity. These deficiencies impact both the yield and the nutritional quality of edible crops with direct consequences cost-effectiveness and human health. Fortunately, these challenges can be advantageously addressed by production of biochars from organic sources such as mixed organic solid waste from municipalities as well as agricultural and landscaping operations. The landfill and composting of these solid municipal wastes generate greenhouse gases that contribute to climate changes. Biochars prepared from solid municipal wastes can greatly benefit the carbon content of soil. Additionally, biochar may interact with fertilizers to deliver indirect improvements in plant growth and reduce the emission of greenhouse gases from native organic matter. Biochars can also be custom-designed to increase/decrease native soil pH to bring it closer to the optimum range for microbial and plant growth. These applications give solid organic municipal wastes promising potential as precursors for value-added biochars with varied physicochemical characteristics allowing them to be used not only as an alternative to bio-waste management and greenhouse gas mitigation but also as means to improve depleted soil. We hypothesize that soil deficiencies in soil can be remedied by the application of biochars that are custom-designed to possess the right physicochemical characteristics suitable to improve soil fertility. The aim of this study was to: (1) produce biochars from mixed solid organic waste for use in soil quality enhancement, (2) investigate the effect of biochar addition to soil on plant germination and growth and (3) evaluate the potential of biochars in mitigating green house gas (GHGs) emissions. Select solid organic municipal wastes (newspaper, cardboard, woodchips and landscaping residues) were used as a precursor for biochar preparation. A blend of 25% of each precursor was used and pyrolyzed at 700°C for 2 hrs under N2 gas at a flow rate of 0.1 mL min− 1 using a Lindberg box programmable furnace equipped with an air-tight retort. Soil fertility parameters such as pH, water retention and macro and micronutrients were analyzed. Fine sandy clay loam soil from the Ap horizon (0-15 cm deep) was amended with biochar at the rate of 2% (w/w). To test the germination rate in soils, with and without biochars (produced from municipal solid waste precursors of 25% blend of four types of waste materials), hybrid savoyed spinach seeds were sown in germination trays (3 seeds/well) for two weeks in climate controlled greenhouse settings. Trays were watered twice daily to maintain moisture level between 10 and 12 percent. The percentage of seed germination was calculated and the plant growth measured as dry biomass. Incubation experiments were conducted to measure GHGs production in sealed glass vials containing soil with and without biochar or raw materials from which this biochar was produced. Greenhouse gases emission differential between the biochars and their corresponding raw feedstocks in treated soil was used as indicator of GHGs emission by biochars during the incubation period Biochars prepared from blends produced at 700°C pyrolysis temperatures and used at 2% application rate to soil showed higher pH (6.8), increased water retention, and high K and NO3-N content. The net effect of these changes in soil properties positively impacted both seed germination and biomass yield of the plants (up to two folds in soil amended with biochars). At the same time, conversion of solid organic wastes into biochar enabled 14% reduction in GHGs emission compared to the solid waste precursors, as indicated by lower CO2 emission. Biochar amendment in soil significantly reduced the CO2 emission (14%), which would otherwise have increased greenhouse gas due to solid waste decomposition in soil. This differential is mainly due to respiration controlled by microbes. Soil amended with biochar closely followed the trend of soil treatment signifying no additional contribution to CO2 efflux. The increase in CO2 efflux seen in feedstock-amended soil can be attributed to the decomposition of feedstock during the time incubation period. In summary, biochars from mixed solid organic wastes at 2% carbon to soil ratio improved seed germination, increased plant biomass yield, and reduced GHGs emission compared to precursors. To reach the maximum benefits, pyrolysis conditions and feedstock selection are critical steps to produce biochars with desirable properties for specific soil amendment. From the present study, it is clear that constituents of municipal solid organic wastes hold promising potential as inexpensive precursor for value-added biochar manufacturing with varied and customizable physicochemical characteristics that would be beneficial in soil amendments while alleviating the problem of solid waste disposal and contributing to mitigation of GHGs. Further studies are need needed to confirm the reported advantages in natural field settings.qscienc

Bioavailability and hypolipidemic effects of peanut skin polyphenols

Peanut skin is a rich source of polyphenols, such as proanthocyanidins. Peanut skin proanthocyanidins mainly consist of a subgroup called procyanidins. Peanut-based procyanidins contain oligomers of both type A and type B procyanidins. Recent studies have shown that peanut skin extracts exert protection against hepatic steatosis induced on rats fed with a high-fat diet. Studies have shown that proanthocyanidins protect against cardiovascular diseases (CVDs). The mechanism of CVD protection and hypolipidemic effect of peanut skin procyanidins has been gradually revealed in recent years. Due to the high molecular weight of procyanidins, they are not readily absorbed through the gut barrier. It is hypothesized that procyanidins exert their effect by inhibiting the absorption of dietary lipid and chylomicron secretion by enterocytes. In this review, we aim to highlight the hypolipidemic effects of peanut skin polyphenols and discuss the various molecular mechanisms, with which the polyphenols may exert the lipid-lowering function observed by weighing the absorption characteristics as well as gene expression mechanism responsible for lipid homeostasis

Biotechnological exploitation of microalgae.

Microalgae are a diverse group of single-cell photosynthetic organisms that include cyanobacteria and a wide range of eukaryotic algae. A number of microalgae contain high-value compounds such as oils, colorants, and polysaccharides, which are used by the food additive, oil, and cosmetic industries, among others. They offer the potential for rapid growth under photoautotrophic conditions, and they can grow in a wide range of habitats. More recently, the development of genetic tools means that a number of species can be transformed and hence used as cell factories for the production of high-value chemicals or recombinant proteins. In this article, we review exploitation use of microalgae with a special emphasis on genetic engineering approaches to develop cell factories, and the use of synthetic ecology approaches to maximize productivity. We discuss the success stories in these areas, the hurdles that need to be overcome, and the potential for expanding the industry in general

Photometric changes on Saturn's Titan: Evidence for active cryovolcanism

We report infrared spectrophotometric variability on the surface of Saturn's moon Titan detected in images returned by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Saturn Orbiter. The changes were observed at 7°S, 138°W and occurred between October 27, 2005 and January 15, 2006. After that date the surface was unchanged until the most recent observation, March 18, 2006. We previously reported spectrophotometric variability at another location (26°S, 78°W). Cassini Synthetic Aperture RADAR (SAR) images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity (Wall et al., companion paper, this issue). The VIMS-reported time variability and SAR morphology results suggest that Titan currently exhibits intermittent surface changes consistent with present ongoing surface processes. We suggest that these processes involve material from Titan's interior being extruded or effused and deposited on the surface, as might be expected from cryovolcanism

Photometric changes on Saturn's Titan: Evidence for active cryovolcanism

International audienceWe report infrared spectrophotometric variability on the surface of Saturn's moon Titan detected in images returned by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Saturn Orbiter. The changes were observed at 7°S, 138°W and occurred between October 27, 2005 and January 15, 2006. After that date the surface was unchanged until the most recent observation, March 18, 2006. We previously reported spectrophotometric variability at another location (26°S, 78°W). Cassini Synthetic Aperture RADAR (SAR) images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity (Wall et al., companion paper, this issue). The VIMS-reported time variability and SAR morphology results suggest that Titan currently exhibits intermittent surface changes consistent with present ongoing surface processes. We suggest that these processes involve material from Titan's interior being extruded or effused and deposited on the surface, as might be expected from cryovolcanism