1,721,025 research outputs found
Coupling chemical degumming with enzymatic degumming of ultrasound pre-treated ramie fiber using Bacillus subtilis ABDR01
No full textIn this study, we designed, developed, and optimized an enzymatic fiber degumming process. First, a Partially Purified Enzyme Solution (PPES) containing pectinase, cellulase and xylanase was co-produced via ultrasound-assisted fermentation of orange peels using Bacillus subtilis ABDR01. Then, degumming with PPES was optimized for pH, temperature, incubation time and PPES concentration. Finally, three sets of ultrasound-assisted degumming experiments - chemical, enzymatic, and coupled enzymatic-chemical degumming with reduced alkali concentration (0.5% NaOH, 30 min) were performed. Chemical degumming for 2 h with 1% NaOH at 98 degrees C resulted in residual gum content of 5.9%, whereas ultrasound-assisted (30 min, 25 kHz) chemical degumming reduced the gum content to 3.1%. At a pH of 7.5, temperature of 45 degrees C, 30 h incubation and 2% PPES, gum removal efficiency of >60% and fibers with <10% residual gum were produced. Coupling the ultrasound-assisted enzymatic degumming with reduced alkali chemical degumming resulted in gum content of <3%. (C) 2022 The Author(s). Published by Elsevier B.V
Urine-derived solids as nutrient sources to enhance microbial wood degradation in a composting environment
Full text linkHuman urine and woody biomass are two abundant biological resources that can be co-valorized through biological wood oxidation (BWO), a meso-thermophilic composting process that generates low-temperature heat and nutrient-rich soil amendment. Here, we investigated the potential of three urine-derived solid formulations as nutrient supplements to enhance microbial wood degradation at 40 °C: phosphoric acid-dehydrated urine (PDU), oxalic acid-dehydrated urine (ODU), and struvite. Among these, PDU achieved the highest wood dry mass loss (27.5 % after 42 days) and oxygen consumption, with its effectiveness attributed to greater phosphorus availability, biochemically stabilized urea that gradually hydrolyzed in situ, and a sustained mildly acidic pH, conditions which collectively supported fungal colonization and carbohydrate degradation in wood. In contrast, struvite exhibited low solubility, high alkalinity, and an unfavorable N/P ratio (0.4) that limited nutrient availability and suppressed microbial activity, resulting in minor wood degradation. Complementary experiments with synthetic nutrient solutions showed that N supplied as urea was more effective than its hydrolyzed products (ammonium bicarbonate and ammonium hydroxide) and ammonium sulfate, likely because it released ammonium gradually and buffered pH shifts during composting. These findings highlight the potential of integrating acid urine dehydration with BWO as a means to advance nutrient circularity and energy sustainability
Disruptive Innovation on Two Wheels: Chinese Urban Transportation and Electrification of the Humble Bike
Full text linkThis communication argues that the electrification of the conventional bicycle could perhaps be a solution to the issues surrounding urban transportation in emerging economies. As illustrated through the trajectory of E-Bike development and adoption in China, such innovations can be disruptive when implemented in untapped mass markets of the developing world. A historical as well as prospective lens was adopted to describe the socio-economic significance of E-bike expansion in China. Further, by simultaneously considering the current Chinese urban transport mix, the primary energy use in transport as well as projections of future E-Bikes sales, it is also asserted that that, although the E-Bike is not an entirely sustainable solution to urban transport; it however is a solution that has the potential to achieve high sustainability. The realization of any environmental co-benefits due to the adoption of the E-Bike hinges primarily upon the adoption of improvements in other sectors of the economy (electricity generation). Indeed, the E-Bike does exemplify that grass-root, inexpensive and sustainable solutions to our urban transportation problems do exist
Inter-Modal Shifts and Sustainability: Call for Freight Transport Privatization in the Indian Railways
Full text linkGiven the inherent limitations of state-financed infrastructural development, it is unrealistic to keep looking towards the government in emerging economies to fund the much needed restructuring of their transportation segment. With the Indian Railways facing an unchecked decline in freight transport mix, this study examines the politically romanticized ‘public good’ nature of Indian Railways to elaborate the need for a modal shift in policy for achieving sustainable transportation. Based on the analysis of historic data, the projected modal split in freight transport is modelled through two scenarios. The business as usual scenario indicated continued preference by the industry for road-based cargo movement. Although the government’s National Transport Development Policy Committee calls for increased investment in rail infrastructure and technologies to reach the targeted modal split of 50:50 by 2030 it fails to elaborate where, and who, will finance this venture. This communication thus calls for the privatization of the Indian rail-freight shipment through vertical integration and sub-networks creation. Arguments are supported by scrutinizing past inter-modal shifts in demographically similar Latin American countries
The review paper boom: We need fewer, better reviews in emerging water research niches
Full text linkLeveraging a sanitation value chain framework could address implementation challenges and reinvent China's Toilet Revolution in rural areas
Full text linkWe evaluated the operational, financial, and management challenges within China's Toilet Revolution by surveying 656 rural households across 10 provinces. The results revealed that the majority of households which renovated their toilets under the Toilet Revolution perceived positive impacts of this on their quality of life and living conditions. Households that had undertaken toilet renovations viewed the program more favorably than households which had not undertaken renovation, and were more willing to engage with the program. Despite the perceived benefits, households were generally hesitant to personally invest in toilet renovation. We uncovered a gap in strategic sanitation planning for post-construction operation and maintenance of toilets, reflecting a "build first, manage later" approach in the Toilet Revolution. We also identified a widespread lack of formal models for management of toilets and toilet products, coupled with high reliance among households on government support and subsidies to fund renovation. To address operational inefficiencies and financial sustainability issues in the program, we propose a novel "Toilet Business" model that leverages a sanitation value chain approach. In this model, private sector engagement, cost management, and market revitalization are crucial components that must be implemented to ensure the program's long-term success. Overall, our study provides valuable insights into the complexities of implementing large-scale sanitation programs such as the Toilet Revolution
Approaches for bridging the sanitation delivery gap in urban informal settlements in Namibia
Full text linkShacks in urban informal settlements will be the most common form of housing in Namibia by 2025. Informal settlements are usually not connected to municipal sewage systems for multiple reasons, including lack of land tenure and lack of official capacity to invest in infrastructure in unplanned spaces. On-site decentralised sanitation is therefore the norm for shack dwellings in Namibia, but any official opposition to this system results in complete absence of sanitation and inadvertently promotes open defecation. This grey zone of urban informality and the gap in sanitation delivery is the focus of this study, which evaluates interactions between local communities, non-government organisations (Clay House Project and Development Workshop Namibia) and an international development agency (GIZ) as they navigate the physical, economic and political landscape of implementing bottom-up sanitation solutions for informal settlements in Namibia. In critical analysis of the three different sanitation delivery models of these organisations, we consider their historical development, underlying philosophies and technical solutions. We also examine how products from different sanitation systems are managed and whether urine source separation could improve their management. Overall, the results provide insights into bridging gaps in sanitation delivery in informal settlements, which are home to more than a billion people worldwide
Alkaline Urine Dehydration : how to dry source-separated human urine and recover nutrients?
Full text linkHuman urine is a renewable resource from which water, nutrients and energy can be recovered and safely recycled. This thesis presents a novel on-site technology, called alkaline dehydration, for recovering nutrients from source-separated urine.
To recover urea (the major nitrogenous compound in fresh urine) and prevent its urease enzyme-catalysed hydrolysis to ammonia, fresh urine was alkalised to pH ≥10 by anion exchange or use of alkaline substrates. To reduce the volume and concentrate the nutrients, the alkalised urine was dried in different substrates at temperatures of 40-60 °C. To evaluate alkaline urine dehydration at pilot-scale, a prototype dryer with capacity to treat 30 L urine d–1 was built and field-tested for three months at a military camp in Finland.
More than 90% of the urine mass was reduced and dehydration rates of up to 40 L urine d–1 m–2 were obtained. Up to 98% of the nitrogen (N) and 100% of the phosphorus (P) and potassium (K) in urine were recovered. A dry solid containing 10% N, 1.5% P and 6.0% K, with similar salt and heavy metal content to synthetic fertilisers available in Sweden was produced.
At least 12.5 g Ca(OH)2 or 6.8 g MgO per litre of fresh urine was required to buffer the pH of urine against absorption of CO2 during dehydration. The energy demand for evaporating urine was similar to that of incineration toilets, but could be reduced if heat energy from the dryer’s exhaust air were recovered.
Overall, this thesis shows that a new sanitation system that safely collects, treats, transports and applies urine as fertiliser could be created by integrating alkaline urine dehydration with existing infrastructure. If implemented globally, this system could recycle 31 Tg N y–1 and 2.8 Tg P y–1, which would reduce the transgression of the planetary boundary for N and P by 35% and 25%, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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