The objective of the study was to verify whether the method of determining the efficiency of sewage sludge disintegration, i.e. the disintegration degree (DD), can also be used to assess agro-waste ...disintegration. The following types of agro waste were tested: remains of fruits, sugar beet pulp and sugar beet pulp in the form of pellets. It was shown that DD as used for sewage sludge can also be a useful tool in assessing the disintegration efficiency of agro waste, although it requires the following modifications: (a) a methodology of chemical hydrolysis for each type of agro waste in order to determine the total amount of soluble COD (SCOD) that can be released from the sample and (b) possible changes in the SCOD value that may occur in the sample left in ambient conditions for a time period corresponding to the duration of the disintegration process. DD of agro waste determined according to the formula adopted for sewage sludge resulted in a considerable overestimation of the value in comparison to the formula proposed by the authors, i.e. DD determined for an energy density of 35 kJ L
−1
was higher by 55.9 ± 21.5%, and for an energy density of 140 kJ L
−1
it was higher by as much as 73.8 ± 28.1%. Taking into account the differences in the determined disintegration degree values that result from the methodology of conducting the chemical hydrolysis, it is recommended, in order to assess the efficiency of disintegration of agro waste, to use the efficiency of organic compound release.
Based on the marshalling station transfer operation process, this paper divides the marshalling transfer operation process into three sub-processes: arriving-disintegrating, ...disintegrating-marshalling and marshalling-dispatching. Considering the input of the facilities of the marshalling station, the intermediate output of the operating time and the final output of the number of transfer trains, an evaluation index system is constructed and a slacks-based network DEA model is established. For purposes of illustration, the model is applied in a design calculation example, the efficiency of the marshalling station transfer operation process is analysed, and the results show that the model is effective.
Climate scientists have long emphasized the importance of climate tipping points like thawing permafrost, ice sheet disintegration, and changes in atmospheric circulation. Yet, save for a few ...fragmented studies, climate economics has either ignored them or represented them in highly stylized ways. We provide unified estimates of the economic impacts of all eight climate tipping points covered in the economic literature so far using a meta-analytic integrated assessment model (IAM) with a modular structure. The model includes national-level climate damages from rising temperatures and sea levels for 180 countries, calibrated on detailed econometric evidence and simulation modeling. Collectively, climate tipping points increase the social cost of carbon (SCC) by ∼25% in our main specification. The distribution is positively skewed, however. We estimate an ∼10% chance of climate tipping points more than doubling the SCC. Accordingly, climate tipping points increase global economic risk. A spatial analysis shows that they increase economic losses almost everywhere. The tipping points with the largest effects are dissociation of ocean methane hydrates and thawing permafrost. Most of our numbers are probable underestimates, given that some tipping points, tipping point interactions, and impact channels have not been covered in the literature so far; however, our method of structural meta-analysis means that future modeling of climate tipping points can be integrated with relative ease, and we present a reduced-form tipping points damage function that could be incorporated in other IAMs.
The slake durability test is one of the most common laboratory tests used to predict the durability of rocks against disintegration. In literature, a lot of studies have reported a series of ...disadvantages that occur on the slake durability test. However, there are not enough numbers of studies written about the difficulties of preparing rock lump samples according to the current standards of International Society for Rock Mechanics and Rock Engineering (ISRM). Therefore, in regard of overcoming the difficulties encountered during sampling process of slake durability test, this study aims to investigate the effects of the sample’s shape and size on the slake durability test and develop a new sampling method that is both simple and efficient for the test conductors through the obtained data. In this study, the six different rock types including three types of volcanic tuffs, weathered andesite, micrite limestone and clayey limestone were used to carry out the slake durability test with the samples prepared in rounded lump, aggregate and disc shapes. The correlations based on the slake durability test results of the sample’s different shapes and sizes reveal that there is a correspondence notably between slake durability indices obtained from the standard and aggregate samples.
•The effects of the shape and size of the sample on the slake durability test were investigated.•Standard, aggregate, and disc-shaped specimens were used to perform the slake durability test.•Aggregate shape specimens can be used efficiently instead of the standard specimen.•It is more appropriate to use aggregate shape samples to determine the durability of soft rocks more precisely.
•Excess sludge was effectively disintegrated with KMnO4 oxidation.•Supernatant proteins and polysaccharides increased by 490% and 141% respectively.•Loosely bound EPS increased by 498% due to ...efficient release.•KMnO4/TS mass ratio was the most important factor for sludge disintegration.
Sludge disintegration destroys the sludge floc structure and releases the extracellular polymeric substances (EPS) and cell contents into the liquid phase, to enhance the sludge anaerobic digestion. Potential benefits of potassium permanganate (KMnO4) disintegrating excess sludge were investigated in this paper. Sludge disintegration feasibility was analyzed with soluble chemical oxygen demand (SCOD) increase in supernatant. Sludge disintegration mechanisms were explored with analyzing the change of particle size, EPS, oxidation reduction potential (ORP) and Mn state. Sludge disintegration process was optimized through analyzing disintegration degree (DDCOD). Results showed that KMnO4 effectively disintegrated the excess sludge with a SCOD increase of 3473% and more than 97% of Mn transferred into the solid phase. A slow decrease in particle size was observed. EPS was efficiently released into supernatant, and supernatant proteins and polysaccharides increased by 490% and 141%, respectively. Loosely bound EPS increased by 498%, which was much higher than slime EPS and tightly bound EPS. The main mechanism of sludge disintegration was KMnO4 oxidation. After sludge oxidation, KMnO4 mainly transferred to the sludge solids with the states of MnO2 and Mn3O4, and a state of KxMnO4 also existed in the solids. Optimization experiments showed that suitable reaction time was 30min, and KMnO4/sludge solid mass ratio was the most important factor and its optimal value was 0.1 with a stable DDCOD of about 34%.
Lime pretreatment was tested at different doses on high-solid sludge. Subsequently, the effects of this pretreatment were investigated in terms of the damage of extracellular polymeric substance and ...cell structures and the subsequent high-solid anaerobic digestion (HSAD). Moreover, the relationship between them was discussed. Results showed that higher lime dose was favorable to COD solubilization, wherein more proteins were released than carbohydrates under the same lime dose. When lime dose was below 0.04 g/g-TS, the COD solubilization was mainly caused by the disintegration of EPS, and when the lime dose was higher than 0.06 g/g-TS, the damages of cell walls and membranes were observed and led to the further COD solubilization. The HSAD process was accelerated by 7–16 days after lime pretreatment, and the biogas production increased by 22.9%–34.8% when lime dose was higher than 0.04 g/g-TS. Thermogravimetric analysis results suggested that Ca2+ could be removed from the liquid phase by precipitating with the CO2 produced during the HSAD process, thereby increasing the methane content.
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•COD solubilization was due to EPS damage when lime dose was below 0.04 g/g-TS.•Cell damage led to further COD solubilization when lime dose was above 0.06 g/g-TS.•The HSAD performance was accelerated and enhanced by lime pretreatment.•CO2 reacted with Ca2+ to form CaCO3 which resulted in higher methane content.
Synthetic polymers, commonly referred to as plastics, are anthropogenic contaminants that adversely affect the natural ecosystems. The continuous disposal of long lifespan plastics has resulted in ...the accumulation of plastic waste, leading to significant pollution of both marine and terrestrial habitats. Scientific pursuit to seek environment-friendly materials from renewable resources has focused on cellulose, the primary reinforcement component of the cell wall of plants, as it is the most abundantly available biopolymer on earth. This paper provides an overview on the current state of science on nanocellulose research; highlighting its extraction procedures from lignocellulosic biomass. Literature shows that the process used to obtain nanocellulose from lignocellulosic biomass greatly influences its morphology, properties and surface chemistry. The efficacy of chemical methods that use alkali, acid, bleaching agents, ionic liquids, deep eutectic solvent for pre-treatment of biomass is discussed. There has been a continuous endeavour to optimize the pre-treatment protocol as it is specific to lignocellulosic biomass and also depends on factors such as nature of the biomass, process and environmental parameters and economic viability. Nanofibers are primarily isolated through mechanical fibrillation while nanocrystals are predominantly extracted using acid hydrolysis. A concise overview on the ways to improve the yield of nanocellulose from cellulosic biomass is also presented in this review. This work also reviews the techniques used to modify the surface properties of nanocellulose by functionalizing surface hydroxyl groups to impart desirable hydrophilic-hydrophobic balance. An assessment on the emerging application of nanocellulose with an emphasis on development of nanocomposite materials for designing environmentally sustainable products is incorporated. Finally, the status of the industrial production of nanocellulose presented, which indicates that there is a continuously increased demand for cellulose nanomaterials. The demand for cellulose is expected to increase further due to its increasing and broadening applications.
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•Chemical pre-treatments used for removal of non-cellulosic components are described.•Methods used for efficient extraction of nanocelluloses are described and compared.•Techniques used for surface functionalization of nanocelluloses are highlighted.•Application of nanocelluloses for designing sustainable products is detailed.•Current status of industrial production of nanocelluloses is presented.
Soil disintegration is one of the most important engineering geological properties. It refers to the durability of soil when in contact with Still water. When precipitation and groundwater level ...change, the soil becomes saturated and disintegration occurs. Soil disintegration leads to various engineering and natural disasters. The primary goal of this research is to start with the morphological characteristic of soil disintegration to analyze the time and rate of soil disintegration in different water content and comprehensively probe into the process and mechanism of disintegration. Cryolithogenic clay loam covering loam (prQIII) collected from Moscow Region, Russian Federation is used as the research object, and the disintegration test is conducted using a disintegration tester designed by Znamenskii–Khaustov. Results indicate that water content significantly affects the disintegration of covering loam. The lower the water content of the soil sample, the faster it will disintegrate. The “critical water content” is introduced, and it can be used to predict the durability of soil in water. For covering loam, the “critical water content” is found to be approximately 7%. The disintegration rate indirectly reflects the morphological characteristics of disintegration as follows. 1) For covering loam with relatively high water content, the changes in disintegration rate are relatively smooth and disintegration morphology is lumpy. 2) For covering loam with low water content, the changes in disintegration rate are fluctuant and disintegration morphology displays a lamellar surface.
•The lower the water content of the soil, the faster it will disintegrate.•The “critical water content” can be used to predict the durability of soil in water.•The disintegration rate indirectly reflects the disintegration morphological characteristics.
•Recent developments in production of cellulose nanofibrils (CNF) were reviewed.•Mechanical disintegration processes and biological/chemical pretreatments were discussed.•Issues of CNF fractionation ...and quantification of the extent of fibrillation were addressed.•An overview of various CNF products, e.g., powders, films, hydrogels and aerogels was proposed.
This review describes the recent advances in production of cellulose nanofibrils (CNF), otherwise known as nanofibrillated cellulose (NFC), microfibrillated cellulose (MFC) or cellulose nanofibers, a material with significant barrier, mechanical and colloidal properties, low density, renewable and biodegradable character. The above properties make CNF promising for applications in such fields as papermaking, composites, packaging, coatings, biomedicine and automotive. In this review, CNF production methods are summarized, covering raw materials selection, structural and chemical aspects necessary for understanding the nanofibril extraction process, conventional and novel mechanical disintegration techniques, as well as biological and chemical pretreatments aimed at facilitating nanofibril isolation. The issues of fractionation, performed with the objective of retrieving the residual microscopic fiber fragments from CNF suspensions, are addressed. Additionally, the preparation of CNF in various forms, such as suspensions, water-redispersible powders, films or nanopapers, hydrogels and aerogels, is discussed.
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