• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 54
  • 31
  • 5
  • 3
  • 1
  • 1
  • Tagged with
  • 112
  • 112
  • 49
  • 45
  • 43
  • 42
  • 41
  • 31
  • 27
  • 25
  • 19
  • 16
  • 15
  • 14
  • 14
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Criteria for solid recovered fuels as a substitute for fossil fuels – a review

Beckmann, Michael, Pohl, Martin, Bernhardt, Daniel, Gebauer, Kathrin 05 June 2019 (has links)
The waste treatment, particularly the thermal treatment of waste has changed fundamentally in the last 20 years, i.e. from facilities solely dedicated to the thermal treatment of waste to facilities, which in addition to that ensure the safe plant operation and fulfill very ambitious criteria regarding emission reduction, resource recovery and energy efficiency as well. Therefore this contributes to the economic use of raw materials and due to the energy recovered from waste also to the energy provision. The development described had the consequence that waste and solid recovered fuels (SRF) has to be evaluated based on fuel criteria as well. Fossil fuels – coal, crude oil, natural gas etc. have been extensively investigated due to their application in plants for energy conversion and also due to their use in the primary industry. Thereby depending on the respective processes, criteria on fuel technical properties can be derived. The methods for engineering analysis of regular fuels (fossil fuels) can be transferred only partially to SRF. For this reason methods are being developed or adapted to current analytical methods for the characterization of SRF. In this paper the possibilities of the energetic utilization of SRF and the characterization of SRF before and during the energetic utilization will be discussed.
32

Compréhension et optimisation d'un procédé de biodégradation d'effluents agricoles composés de pesticides en mélange / Optimization of a biodegradation process for agricultural effluents composed of mixed pesticides

Thevenin, Nicolas 11 July 2016 (has links)
Ces travaux ont consisté à développer un procédé de traitement biologique des eaux contaminées en produits phytosanitaires (PF) issues du lavage des matériels de pulvérisation de PF. Ce procédé s’appuie surl’inoculation d’une culture bactérienne mixte sélectionnée et d’un matériau sorbant constitué de rafles de maïs broyées.Tout d’abord, un mélange modèle de PF,constitué de 6 herbicides, 3 fongicides et 1 insecticide, a été créé. Après avoir mis au point la production de l’inoculum en présence de ce mélange et étudié les propriétés sorbantes des rafles de maïs, les paramètres de traitement ont été définis à petite échelle de laboratoire et validés en réacteur.Finalement, le procédé développé est un traitement en réacteur batch séquentiel de 28 jours qui permet de réduire de plus de 50 % la masse initiale des PF du mélange modèle. Malgré la réduction des teneurs en PF, la phytotoxicité due aux résidus d’herbicides des effluents traités est encore trop élévée et ne permet pas de valider l’épandage sur un lit planté de roseaux comme post-traitement de la fraction liquide. / Aim of this work was to treat effluentsobtained from rinsing pesticide (PF) spraying equipments by developing biological treatment process into bioreactor with selected mixed bacterial culture and adsorption support consisting of crushed corn cobs. First, a model PF mixture was designed to represent agriculturaleffluents at watershed scale. This mixture was composed by 6 herbicides, 3 fungicides and 1 insecticide. Then, inoculum production under PF pressure was developed and sorption properties of corn cobswere investigated. Process parameters were defined at small-scale laboratory and validated into bioreactors. Thus, developed processwas a28 days sequential batch reactortreatment, which reduced more than 50% of molecules weight of model mixture.Despite of this process significantely reduced treated effluents PF contents, remaining phytotoxicity due to herbicide residues failed validation of their post-treatment on a bed planted with reeds.
33

A Case Study Analysis of Parameter Effects within the Nitrification and Denitrification Processes of Rendering Wastewater using Data Mining Techniques

Elrod, Jon L., B.S. 14 October 2013 (has links)
No description available.
34

Evaluation of an Industrial Byproduct Glycol Mixture as a Carbon Source for Denitrification

Liang, Wei 24 June 2013 (has links)
In order to meet increasingly stringent total nitrogen limits, supplemental carbon must be added to improve the performance of the biological nutrient removal process. An industrial by-product that contained ethylene glycol and propylene glycol was used as a substitute carbon source for methanol in this study. The objectives of this study were to investigate the efficiency of using the glycol mixture as carbon source, including the calculation of denitrification rate and yield at two different initial concentrations of glycols. Possible inhibition effect on nitrification was also investigated. Three SBR reactors were operated by adding methanol, a low dosage of glycol, and a high dosage of glycol into the reactors. The low dosage glycol reactor exhibited the best performance, with the highest denitrification rate of 11.55 mg NOx-N/g MLVSS"h and the lowest yield of 0.21 mg VSS/mg COD. Small nitrite accumulation was observed in the low dosage glycol reactor (COD=185"•15 mg/L), but effluent quality was not influenced. Excess glycol in the reactor caused deteriorated performance. The high dosage glycol reactor (COD=345"•20 mg/L) performed with the lowest denitrfication rate of 8.56 mg NOx-N/g MLVSS"h and the highest yield of 0.55 mg VSS/ mg COD. The reactor with the high dosage of glycol also inhibited the lowest nitrification rate of 1.15 mg NH3-N oxidized/g MLVSS"h, which indicated that excess glycol may cause nitrification inhibition. / Master of Science
35

Application of Differential Scanning Calorimetry to Characterize Thin Film Deposition Processes

Snell, Andrew John Roger 06 August 2010 (has links)
No description available.
36

A STUDY OF AEROBIC METHANOL ADDITION IN DENITRIFYING SEQUENCING BATCH REACTORS

PARSONS, MICHAEL E. 04 April 2007 (has links)
No description available.
37

Process for Synthesis of Biodiesel from Used Cooking Oil: Feasibility and Experimental Studies

Patel, Rajnikant, Dawson, K., Butterfield, R., Khan, Amir, Ahada, B., Arellano-Garcia, Harvey January 2014 (has links)
No / Biodiesel has turned out to be an integral part of the discussion of renewable energy sources and has diverse advantages in terms of its flexibility and applicability. Considering the characteristics of the transesterification reaction, a laboratory-scale system has been developed in this work. Waste Vegetable Oil (WVO), mainly sunflower oil, from local sources has been used and the transesterification carried out using methanol in the presence of sodium hydroxide catalyst. Characterisation of the biodiesel produced has been carried out using a number of different techniques including rheology, calorimetry, and gas liquid chromatography. The main factors affecting the % yield of biodiesel are temperature, catalyst, and alcohol to triglyceride ratio. Thus, experimental work has been carried out so as to study the rate and yield of the reaction as a function of those factors. A model has also been developed to validate the experimental data and this should help in increasing the efficiency of these processes and reducing the energy input. Moreover, the novel use of ultrasound as a method of measuring progression of the reaction is correlated with in-situ pH monitoring of the reaction process.
38

Effect of Reactor Feeding Pattern on Performance of an Activated Sludge SBR

Cubas Suazo, Francisco Jose 06 December 2006 (has links)
The possible effects of changes in the feeding pattern on activated sludge properties related to bioflocculation have been analyzed in lab scale sequencing batch reactors (SBR) in order to determine if these changes in effluent water quality and settling and dewatering properties are significant, so they can be considered in future studies or if they can be recommended as crucial when operating and designing wastewater treatment plants. The activated sludge process is widely used to treat wastewater from both industrial and municipal sources. Biomass from industrial facilities containing high monovalent to divalent ion content usually settles poorly, which leads to low quality effluents that fail to meet environmental requirements. Therefore, the combined effect of feeding pattern plus the addition of sodium to activated sludge reactors was studied in this experiment. A series of SBRs were operated at different sodium concentrations that ranged from 1.5 - 15 meq/L and different feeding times that ranged from 1 minute to 4 hours. Biomass samples were taken from each reactor to study the settling and dewatering properties and effluent samples were used to analyze the amount of organic matter and exocellular polymeric substances present due to deflocculation. As expected, the changes in feeding strategies affected all of the properties measured. When the feeding time was maintained low (pulse feed) the effluent quality and settling properties were the best. As the feeding time was increased the effluent quality, settling, and dewatering properties increased suggesting that the way in which the reactors were fed affected the overall bioflocculation process. The causes of the high deflocculation observed are not well understood, but data suggest that a microbial community change could have affected exocellular biopolymers which are believed to play an important role on bioflocculation. This research demonstrates the importance of the interaction between cation content and feeding pattern when operating a wastewater treatment plants and when reporting lab-scaled results related to settling and bioflocculation. / Master of Science
39

Alternative Waste Treatment System for Poultry Processing Plants

Roshdieh, Rana 30 December 2010 (has links)
The objective of this research was to design an alternative wastewater treatment system for turkey processing plants to recover energy and reduce N and P to allowable discharge levels. The objective included: 1. Determine the quantity and quality of biogas produced from the turkey processing wastewater (TPW) and COD reduction efficiency. 2. Design a waste treatment system and validate proof of concept for simultaneous P and N removal with a goal of attaining effluent concentrations of 0.1 mg/L and 4 mg/L, for P and N, respectively. A lab-scale complete mixed anaerobic digester was used for turkey processing wastewater (TPW) digestion and biogas recovery running for 6 months. Along with the anaerobic digester, a two-sludge system called A2N-SBR consisting of an anaerobic-anoxic sequencing batch reactor and an attached growth post-nitrification reactor was added for biological nitrogen and phosphorus removal running for 3 months. Biogas production yields of 778 + 89 mL/gVSadded and 951.30 mL/g COD were obtained through anaerobic digestion. Also, an energy balance was conducted on a pilot scale digester for a turkey processing plant with wastewater production of 2160 m3/d and using a combined heat and power (CHP) enginefor conversion of biogas to heat and electricity. Although the biogas yield achieved in a complete mixed reactor was relatively lower than yields obtained in previous studies using reactors such as UASB, still a complete mixed reactor can be a good choice for biogas recovery from TPW and can be used for codigestion with some specific turkey processing byproducts for biogas recovery. Nitrogen and phosphorus removal in the A2N-SBR system were 47% and 75%, respectively, and during the study the nitrogen and phosphorus removal mean concentration in effluent did not meet the nutrient limits specified in the objectives. Average TP and TN in the effluent were 3.2 mg/L and 137 mg/L, respectively. Throughout the study, the nitrification reactor biofilm was not completely developed. Incomplete nitrification and poor settling might be the reasons that quality obtained in effluent was low. To improve the process condition in A2N-SBR, online monitoring of pH, dissolved oxygen (DO) and oxidation reduction potential (ORP) can help to optimize each stage in the SBR and stages duration can be set based on the results. / Master of Science
40

Enhancement of light naphtha quality and environment using new synthetic nano-catalyst for oxidative desulfurization: Experiments and process modeling

Jarullah, A.T., Ahmed, G.S., Al-Tabbakh, B.A., Mujtaba, Iqbal 31 March 2022 (has links)
Yes / Batch oxidative desulfurization (ODS) process is investigated here for the removal sulfur compound from light naphtha using homemade new nano-catalyst. The catalyst is made of manganese dioxide supported on zeolite nanoparticles which shows an excellent catalytic performance with good impregnation, high activity, good pore size distribution and larger surface area. Different reaction temperature, time and initial sulfur concentration are used to have a deeper insight of the process. The experimental results reveal that the conversion of sulfur compound is increased by increasing the initial sulfur concentration, the reaction temperature and batch time. A mathematical model of the process is developed and validated using the experimental data within gPROMS software with high accuracy. The validated model (errors less than 5% between experimental and predicted results) is then utilized to obtain the optimal operation conditions of the process giving maximum conversion of sulfur (higher than 99%) resulting in an environmentally friendly fuel.

Page generated in 0.0587 seconds