Diesel fuel and olive-cake slurry: Atomization and combustion performance

Because of possible future energy crises, it is increasingly desirable to search for alternative and renewable energy resources. This paper presents a detailed experimental study of direct combustion of a diesel and olive-cake (OC) slurry in a vertical, cylindrical, water-cooled combustor. An air-atomized nozzle was used in this study and experiments were undertaken to characterize the atomizer's performance. Axial and radial flame temperature profiles, the heat transfer distribution for the water jacket, flame stability and combustion efficiency were obtained over wide ranges of air:fuel ratios, and at different percentages of OC in the diesel fuel.

The rate of heat transfer to the water jacket and the combustion efficiency were improved as the percentage of OC in the diesel fuel was increased to 7 wt%. Also, as the percentage of OC in the diesel fuel increased, the stability loop became narrower. Stable flames were observed for up to 20 wt% of OC. Based on these results and on the availability of the OC, it may be concluded that the potential of OC as a source of energy is significant.     

Daily doses of light in relation to the growth of Scenedesmus obliquus in diluted three‐phase olive mill wastewater

BACKGROUND: The use of olive‐oil mill wastewater (OMW) from a three‐phase centrifugation process used in the olive‐oil industry, has been studied in relation to the production of the microalga Scenedesmus obliquus CCAP 276/3A. The chemical characteristics of OMW indicated nitrogen deficiency. RESULTS: S. obliquus is able to assimilate nutrients present in a culture medium (water‐OMW 5%) and grow at its maximum specific growth rate of 0.026 h^?1, both under mixotrophic as well as heterotrophic conditions. The different daily doses of light (DDL) used, in the range 0–36 E m^?2 d^?1, determined light‐limited and light‐inhibited cultures. The light‐inhibited mixotrophic cultures bore characteristics similar to those of the heterotrophic cultures, and became more so when the dose of light received was higher. The low protein yield (258 mg g^?1) and high percentage of carbohydrates of the biomass (65.8%) confirmed a nutritional‐stress situation associated with nitrogen limitation. CONCLUSION: The similarity between the fatty‐acid composition of the heterotrophic and mixotrophic cultures strongly inhibited by light appeared to indicate the cancelling of the photosynthetic behaviour of the cells at high DDL values. The biomass generated can be used for biofuels. The maximum elimination of biological oxygen demand (BOD₅) per unit of biomass was achieved in the heterotrophic cultures. Copyright © 2009 Society of Chemical Industry     

Influence of hydrodynamic stress in the growth of Scenedesmus obliquus using a culture medium based on olive-mill wastewater

The wastewater from olive oil elaboration (OMW) constitutes a major environmental problem in producing countries of olive oil. OMW from the three-phase system is harmful due to its high organic load and the presence of phytotoxic phenolic compounds. The culture medium was constituted with 5% OMW. The effects of mechanical agitation and aeration rates on the microalga Scenedesmus obliquus growth, in a batch photobioreactor were studied. A maximum specific growth rate, μ_m = 0.031 h⁻¹, was obtained using a rotational impeller speed around 350 rpm without aeration and was greater than that found in the absence of stirring 0.024 h⁻¹. The chlorophyll contents were independent of the stress and light intensity in the cultures, but did boost the nutrient concentration in the medium. The stress induced by stirring or by aeration of the cultures did not alter the final cell-protein and carbohydrate content, 18% and 48% as mean value, respectively.     

Alkali treatment of jute fibers: Relationship between structure and mechanical properties

The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and modulus. Isometric NaOH‐treated jute yarns (20 min at 20°C in 25% NaOH solution) lead to an increase in yarn tensile strength and modulus of ∼ 120% and 150%, respectively. These changes in mechanical properties are affected by modifying the fiber structure, basically via the crystallinity ratio, degree of polymerization, and orientation (Hermans factor). Structure–property relationships, developed for cellulosic man‐made fibers, were used with a high correlation factor to describe the behavior of the jute fiber yarns. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 623–629, 1999     

Industrial Plant for Olive Mill Wastewater from Two-Phase Treatment by Chemical Oxidation

Olive-oil production generates high and variable amounts of wastewaters from the olives and olive-oil washing (OMW), resulting to great environmental impact. These waters are normally stored in large holding ponds for evaporation during the summer. The present study examines the chemical-oxidation process using ferric chloride catalyst for the activation of H2O2 (Fenton reaction). Tests have been made on an industrial scale. The final average value of chemical oxygen demand (COD) was close to 371?mg?O2?L?1 (%CODremoval = 86%, CODinitial = 2684?mg?O2?L?1), and the water produced can be used for irrigation or can be discharged directly into the municipal wastewater system for tertiary treatment.     

Effect of commercial breakfast fibre cereals compared with corn flakes on postprandial blood glucose,gastric emptying and satiety in healthy subjects: a randomized blinded crossover trial

Background  

Dietary fibre food intake is related to a reduced risk of developing diabetes mellitus. However, the mechanism of this effect is still not clear. The aim of this study was to evaluate the effect of commercial fibre cereals on the rate of gastric emptying, postprandial glucose response and satiety in healthy subjects.     

Threshold flux measurement of an ultrafiltration membrane module in the treatment of two-phase olive mill wastewater

The critical and threshold flux theories represent an important advance in membrane knowledge. Comprehension of the flux behavior of ultrafiltration (UF) membranes is key to control the fouling issues during the steady operation of the plant. In this regard, differing between critical or threshold flux patterns in the treatment of wastewater effluents by UF is relevant to confirm the level of fouling expected and to verify if no fouling is predictable or if certain amount of fouling cannot be avoided. In the present study, the hydrodynamic behavior of a polymeric UF membrane was analyzed by means of both critical and threshold flux theories and diverse patterns were found depending on the feedstock pollutants concentration and particle size distribution. Results obtained from the pressure-cycling experiments point for a threshold flux pattern in the case of UF of the effluent derived from the extraction process (OMW) disregarding the applied pretreatment, whereas for 1:1 (v/v) mixture of the latter with the wastewater from the fruit washing (OWW) the membrane fits a critical flux trend, indistinctly of the performed pretreatment too, with negligible fouling below the critical conditions. These conclusions are supported by the experimental permeate flux profiles during batch-run operation experiments.     

About the surface characteristics of natural fibres

The surface characteristics of corona and silane treated jute fibres were studied using dynamic contact angle (DCA), capillary rise and resin adsorption methods as well as inverse gas chromatography (IGC). First of all it was shown that corona treatment increases the polarity of jute fibres, whereas the dispersive part was constant over the whole range of corona energy output. This was leading to an improvement in the wettability of the fibres by a polar epoxy resin. The fibre surface energy was dependent on corona energy output used with a maximum in polarity by 130 mJ/mm². Further it was shown that the contact angles on the jute fibres for the different test liquids depend on the contact time due to the absorption of test liquid. Because of this fact, an improved method to characterise cellulose based fibre surfaces was developed based on DCA and capillary rise method. For the silane treated fibres increased specific interaction terms were characteristic.     

Load-increasing fatigue test to characterize the interface of composites under fatigue loadings

The effect of glass-fiber epoxy interface in cross-ply reinforced composites on the fatigue behavior is studied by using load-increasing fatigue test. The damage as measured by stiffness reduction is more significant for the composites with poor bonded fibers as was found for EP sized ones, dependent on test conditions. Energy loss is shown to be a sensitive tool to characterize the nature of fiber matrix adhesion. The energy loss for composites with poor adhesion between fiber and matrix results in significantly higher amounts of consumed energy during a single stress-strain loop than those composites containing well-bonded fibers.     

Effect of commercial rye whole-meal bread on postprandial blood glucose and gastric emptying in healthy subjects

Background  

The intake of dietary fibre has been shown to reduce the risk of developing diabetes mellitus. The aim of this study was to compare the effects of commercial rye whole-meal bread containing whole kernels and white wheat bread on the rate of gastric emptying and postprandial glucose response in healthy subjects.