A Comparative Study of Profile and Scraping Methods for Emittance Measurements in the PS Booster

It is important to have a clear understanding of the transverse emittance in a circular accelerator in order to achieve optimum brilliance. Experience with comparing emittance data from different instruments has shown that systematic errors can be important. In an attempt to detect such errors in the PS Booster, the emittance measurements are made according to two different principles: measurement of density distribution and measurement of amplitude distribution. In this paper we i) discuss these two principles and the theory behind them; ii) show how the data can be compared; iii) describe the instrumentation used for these measurements; and iv) present results for the typical PS Booster beams

Admissible invariant similar tests for instrumental variables regression

March 12, 200

Synergies between BECCS and Biochar - Maximizing Carbon Sequestration Potential by Recycling Wood Ash

Bioenergy carbon capture and storage (BECCS) and biochar are key carbon-negative technologies. In this study, synergies between these technologies were explored by using ash from wood combustion, a byproduct from BECCS, as an additive (0, 5, 10, 20, and 50 wt %) in biochar production (wood pyrolysis at 450 °C). The addition of wood ash catalyzed biochar formation and increased the yield of fixed carbon (FC) (per dry, ash-free feedstock), i.e., the sequestrable carbon per spruce wood input. At the highest ash addition (50%), 45% less wood was needed to yield the same amount of FC. Since the land area available for growing biomass is becoming scarcer, our approach significantly increases biochar’s potential to sequester carbon. However, increasing the feedstock ash content results in less feedstock carbon available for conversion into FC. Consequently, the yield of FC per pyrolysis run (based on dry feedstock) in the 50% ash-amended material was lower than in the control. An economic analysis showed that the 20% ash-amended biochar brings the biggest cost savings over the control with a 15% decrease in CO₂-abatement costs. Biochar–ash composites increase the carbon sequestration potential of biochar significantly, reduce the CO₂-abatement costs, and recycle nutrients which can result in increased plant growth in turn and more biomass for BECCS, bringing synergies for BECCS and biochar deployment

Designing activated mineral biochar composites for the adsorption and degradation of emerging contaminants

The emergence of micropollutants such as pharmaceuticals in wastewaters presents a potential risk for human health as well as the aquatic environment. Current wastewater treatment plants are generally not capable of removing these pollutants without additional treatment steps. Adsorption on activated carbon is an effective way to remove these contaminants, however, the use of non-renewable feedstocks as well as low regeneration efficiencies increase the environmental costs of this method1. Biochar as an alternative carbon platform material can be specifically designed to overcome these drawbacks2. This study is aimed at designing activated mineral biochar composites with enhanced adsorption capacity for pharmaceuticals while simultaneously increasing its regeneration performance. Two standard biochars from the UK Biochar Research Centre produced at 550°C from softwood and wheat straw were activated in CO2 at 800°C. Mineral biochar composites were produced by the addition of ochre – a Fe-rich mining waste - in a wet mixing step prior to pyrolysis for both feedstocks. The activated biochars were analysed for their maximum adsorption capacity for two common micropollutants. Furthermore, to test their regeneration performance, the biochars were loaded with a mix of 10 pharmaceuticals covering antibiotics, fungicides and antidepressants. The loaded biochars were then subjected to a high pressure treatment in a hydrothermal reactor at temperatures ranging from 160 to 320°C to determine the degradation rate of pharmaceuticals loaded on the different materials. Hydrothermal treatment was found to successfully degrade the micropollutants across all biochars. The mineral biochar composites showed increased pollutant degradation, lowering the necessary treatment temperature to achieve full decontamination. The results show that while designing biochar for certain applications, a simultaneous focus on both the application as well as the regeneration of the material can give a more comprehensive picture of the overall requirements for further optimisation of biochar adsorbents. Please click Additional Files below to see the full abstract

Hydrothermal recycling of activated biochar

Emerging pollutants such as pharmaceuticals are of increasing concern in wastewaters. Carbon materials such as activated carbons prove to be effective filter materials for the removal of these pollutants, but regeneration of the adsorbents is necessary to improve their economic efficiency. However, common thermal regeneration methods using dry adsorbents and high treatment temperatures are expensive and hinder large scale applications in wastewater treatment plants 1. Novel adsorbents such as biochars are seen as an alternative due to their lower production costs 2. However, considering their generally lower adsorption capacity, costly regeneration will abolish the initial economic advantage of biochar. In contrast to fully regenerating the original adsorptive properties, we argue that a recycling step to prepare biochar for different subsequent applications can produce a higher value product. In this study we propose a method using hydrothermal treatment to decontaminate activated biochars. Two standard biochars from the UK Biochar Research Centre produced at 550°C from softwood and wheat straw were activated in CO2 at 800°C. Additionally, the same raw feedstocks were mixed with 5% Ochre, pyrolyzed and activated at the same conditions to produce two activated mineral biochar composites. The biochars were loaded with 10 pharmaceuticals commonly found in wastewaters and decontaminated in a hydrothermal reactor at temperatures ranging from 160 to 320°C for 4 hours at autogenic pressure. To avoid catalytic effects from the reactor walls, a novel experimental design based on standard borosilicate test tubes was developed. The sample is placed into a test tube, filled with water, flame sealed and placed into a hydrothermal reactor. The outer reactor is filled to the same level as the sample tube to counterpressure the glass and avoid bursting during the experiment. With this set-up, an inert and disposable reactor liner ensures comparable reaction conditions between runs and eliminates potential cross contamination. After the hydrothermal treatment, the biochars as well as the process water were analyzed by LC-MS/MS for remaining pharmaceuticals. Hydrothermal treatment was found to fully degrade 8 out of 10 investigated pharmaceuticals at a treatment temperature of 200°C, with almost complete degradation of the remaining pharmaceuticals at 320°C. The results show that hydrothermal treatment has the potential to recycle activated biochar and enable its use in subsequent applications such as gas filtration systems for the removal of H2S or as an additive for increased gas production in anaerobic digestion plants. Please click Additional Files below to see the full abstract

Hydrothermal recycling of carbon absorbents loaded with emerging wastewater contaminants

Adsorption using carbon materials is one of the most efficient techniques for removal of emerging contaminants such as pharmaceuticals from wastewater. However, high costs are a major hurdle for their large-scale application in areas currently under economic constraints. While most research focuses on decreasing the adsorbent price by increasing its capacity, treatment costs for exhausted adsorbents and their respective end-of-life scenarios are often neglected. Here, we assessed a novel technique for recycling of exhausted activated biochars based on hydrothermal treatment at temperatures of 160–320 °C. While a treatment temperature of 280 °C was sufficient to fully degrade all 10 evaluated pharmaceuticals in solution, when adsorbed on activated biochars certain compounds were shielded and could not be fully decomposed even at the highest treatment temperature tested. However, the use of engineered biochar doped with Fe-species successfully increased the treatment efficiency, resulting in full degradation of all 10 parent compounds at 320 °C. The proposed recycling technique showed a high carbon retention in biochar with only minor losses, making the treatment a viable candidate for environmentally sound recycling of biochars. Recycled biochars displayed potentially beneficial structural changes ranging from an increased mesoporosity to additional oxygen bearing functional groups, providing synergies for subsequent applications as part of a sequential biochar system