Recycling of waste engine oils using a new washing agent

This paper addresses recycling of waste engine oils treated using acetic acid. A recycling process was developed which eventually led to comparable results with some of the conventional methods. This gives the recycled oil the potential to be reused in cars' engines after adding the required additives. The advantage of using the acetic acid is that it does not react or only reacts slightly with base oils. The recycling process takes place at room temperature. It has been shown that base oils and oils' additives are slightly affected by the acetic acid. Upon adding 0.8 vol% of acetic acid to the used oil, two layers were separated, a transparent dark red colored oil and a black dark sludge at the bottom of the container. The base oils resulting from other recycling methods were compared to the results of this paper. The comparison showed that the recycled oil produced by acetic acid treatment is comparable to those recycled by the other conventional methods

Effect of colloidal particles associated with the liquid bridge in sticking during drying in superheated steam

It is important in the design of a drying system to evaluate the sticking behaviour of the materials being dried. A new approach to the sticking issue is applied in this study by carrying out a sticking test for the liquid associated with the materials under study. It was found that the liquid bridge is responsible for the initial sticking of the materials to the contact surfaces. The colloidal material in this liquid is eventually responsible of building a sticky solid bridge during drying. The glass transition temperature for the Brewers Spent Grain (BSG) particles and the colloidal solution expelled from these particles were tested using Differential Scanning Calorimetric (DSC). However, the chopped BSG particles showed no glass transition temperature; there were an appreciable number of particles stuck to the rotary drum dryer and the sample holders during drying. The colloidal particles in the liquid bridge were filtered and concentrated through evaporation and then analysed by DSC where they showed a glass transition temperature at (-23) and (-33) oC. In addition, the associated liquid thus prepared showed a honey consistency and a sticky touch when concentrated. These two properties are indications that this colloidal material may be responsible for sticking the BSG to the steel surfaces during drying

Anaerobic digestion and biogas potential: simulation of lab and industrial-scale processes

In this study, simulation was carried out using BioWin to test the capability of the software in predicting biogas potential for two different anaerobic systems. The two scenarios included; 1) a laboratory scale batch reactor and 2) an industrial scale anaerobic continuous lagoon digester. Measured data relating to operating conditions, reactor design parameters, and chemical properties of influent wastewater were entered into BioWin. A sensitivity analysis was carried out to identify the sensitivity of the most important default parameters in the software's models. BioWin was then calibrated by matching the predicted data with measured data and used to simulate other parameters which were unmeasured or deemed uncertain. In addition, statistical analyses were carried out using evaluation indices such as coefficient of determination (R-squared), correlation coefficient (r) and its significance (P value), general standard deviation (SD) and Willmott index of agreement to evaluate the agreement between the software prediction and the measured data. The results have shown that after calibration, BioWin can be used reliably to simulating both small scale batch reactors and industrial scale digesters with an absolute relative error less than 10% and very good indexes' values. Also, by changing the default parameters in BioWin, which is a way of calibrating the models in the software as well, it may provide information about the performance of the digester. Furthermore, the results of this study showed there may be an over estimation for biogas generated from industrial scale digesters. More sophisticated analytical devices may be required for reliable measurements of biogas quality and quantity

A critical review on processes and energy profile of the Australian meat processing industry

This review article addresses wastewater treatment methods in the red meat processing industry. The focus is on conventional chemicals currently in use for abattoir wastewater treatment and energy related aspects. In addition, this article discusses the use of cleaning and sanitizing agents at the meat processing facilities and their effect on decision making in regard to selecting the treatment methods. This study shows that cleaning chemicals are currently used at a concentration of 2% to 3% which will further be diluted with the bulk wastewater. For example, for an abattoir that produces 3500 m3/day wastewater and uses around 200 L (3%) acid and alkaline chemicals, the final concentration of these chemical will be around 0.00017%. For this reason, the effects of these chemicals on the treatment method and the environment are very limited. Chemical treatment is highly efficient in removing soluble and colloidal particles from the red meat processing industry wastewater. Actually, it is shown that, if chemical treatment has been applied, then biological treatment can only be included for the treatment of the solid waste by-product and/or for production of bioenergy. Chemical treatment is recommended in all cases and especially when the wastewater is required to be reused or released to water streams. This study also shows that energy consumption for chemical treatment units is insignificant while efficient compared to other physical or biological units. A combination of a main (ferric chloride) and an aid coagulant has shown to be efficient and cost-effective in treating abattoir wastewater. The cost of using this combination per cubic meter wastewater treated is 0.055 USD/m3 compared to 0.11 USD/m3 for alum and the amount of sludge produced is 77% less than that produced by alum. In addition, the residues of these chemicals in the wastewater and the sludge have a positive or no impact on biological processes. Energy consumption from a small wastewater treatment plant (WWTP) installed to recycle wastewater for a meet facility can be around $500,000

Selective Electrodialysis for Copper Removal from Brackish Water and Coal Seam Gas Water

This study investigates the removal rate of divalent ions during partial desalination of brackish water using electrodialysis (ED). An experiment was conducted with a benchtop PCCell electrodialysis instrument in batch mode with a non-ion selective membrane. The removal rate of total copper, a valuable plant micronutrient, was analysed. Both copper chloride and copper sulphate removal compared to sodium chloride removal were studied. The copper and the sulphate content in the diluate declined logarithmically with a removal rate of around 98 % for copper in both experiments, and 100 % for sulphate over three hours at a starting temperature of 23 °C. Copper and sulphate were removed faster than sodium chloride at 72 %. The temperature of the diluate increased by 15 % during the three-hour run. The loss of water from the diluate was approximately 10 %, limiting brine production. Modelling indicated that the Mass/Charge ratio of ions could be an indicator of the removal rate of anions, especially if they have, like sulphur, a large effective radius, whereas the Effective Ionic Radius can be an indicator for the removal of cations. The smaller the ionic radius, the faster the removal rate of the cation. This model can be used to customise nutrient concentration in the water end product. The customised water has a potential to be used for fertigation, saving the farmer money by retaining beneficial plant nutrients in the water

Experimental study of spray characteristics, engine performance and emission levels of acetone-butanol-ethanol mixture-diesel blends in a diesel engine

This paper investigates spray and engine performance of an acetone-butanol-ethanol (ABE) mixture blended with diesel fuel in a single-cylinder direct injection (DI) diesel engine. Spray images were evaluated using a high-speed camera under 300 bar injection pressure. Engine performance such as brake power (BP), brake-specific fuel consumption (BSFC) and in-cylinder pressure were measured. Exhaust gas emissions such as oxides of nitrogen (NOx), carbon monoxide (CO) and unburned hydrocarbon (UHC) were also assessed. The test was carried out at three engine speeds (1400, 2000 and 2600 rpm) at full load. The experiment results showed that: liquid penetration of ABE-diesel is longer than that of diesel. BP of ABE-diesel blends was comparable with pure diesel at 2600 rpm, while the peak in-cylinder pressure was higher compared to diesel at 2000 rpm. UHC and CO emissions were significantly reduced as a result of the addition of ABE to the neat diesel, while NOx emissions were slightly increased

Conical Fluidized Bed with Arc Design for Improved Performance of Gas Distributor

Particles distributions along a conical fluidized bed were predicted by an alternative arrangement of the minimum fluidization velocity equation. The proposed approach introduces two new equations which present the particle diameter in the bed as function of: height in the bed (Z), angle of inclination of the fluidized bed wall (θ), input flow rate (Qo), and gas distributor diameter (Do, 2ro). A novel arc-shaped design of the gas distributor was suggested, which provides enhanced distribution of the gas and enables greater control on the direction of the gas inlet. The model showed that the inclination of the fluidized bed wall should not exceed a critical angle, which can be determined with the set of equations specially developed for this purpose, to prevent inhomogeneous fluidization across the bed and accumulation of particles along the walls. By applying the Box Wilson Method, theoretical data were obtained for constant column diameter at the base (0.05 m), and varying bed height, Z, (range: 0.5 to 1.5 m), velocity of gas inlet, U, (range 0.25 to 1 m s-1), and balance factor, a, (range: 0.5 to 1, a new factor), respectively. The angle of inclination of the wall was first predicted based on the above parameters, and subsequently, the particle size distribution along the column was determined. Theoretically the novel arc-shaped distributor design has shown the potential of generating homogeneous fluidization regimes along the bed

Bone char as a green sorbent for removing health threatening fluoride from drinking water

Millions of people around the world suffer from or prone to health problems caused by high concentration of fluoride in drinking water sources. One of the environmentally friendly and cost-effective ways for removing fluoride is the use of bone char. In this review, the structural properties and binding affinity of fluoride ions from different water sources was critically discussed. The effect of experimental conditions on enhancing the adsorption capacity of fluoride ions using bone char samples was addressed. It appears that surface properties, and conditions of the bone char production such as temperature and residence time play an important role in designing the optimal fluoride removal process. The optimum temperature for fluoride removal seems to be in the range of 500–700 °C and a residence time of 2 h. Applying various equilibrium adsorption isotherms for understanding fluoride adsorption mechanism was presented. The effect of bone char modification with different elements were discussed and recommendations for a further increase in the removal efficiency was proposed. Cost of bone char production and large-scale treatment systems were also discussed based on information available from scientific and commercial sources. Challenges with existing domestic defluoridation designs were highlighted and suggestions for new conceptual designs were provided

Description of seedless grape drying and determination of drying rate

This article compares some empirical models, with one or two parameters, used to describe seedless grape drying at low temperature. Chosen models have, as a common characteristic, an analytical expression for the derivative of dimensionless moisture content with respect to time. Comparison of the results for the simulations of drying kinetics indicates that, despite Page and Silva et alli models well represent the process, the best model is Peleg. For this model, the statistical indicators of the simulation can be considered excellent (the determination coefficient is R2 = 0.99944 and the chi-square is χ^2 = 1.2335 x 10-3)

Issues related to waste sewage sludge drying under superheated steam

Sewage sludge was dried in a rotary drum dryer under superheated steam. Particle size and moisture content were shown to have significant influences on sticking and agglomeration of the materials. Pouring partially dried sludge (70–80% moisture content, wet basis) directly into the screw feeder of the drum dryer resulted in a significant sticking to the surface of the drum and the final particle size of the product was greater than 100 mm in diameter. The moisture content of this product was slightly less than its initial value. To overcome this issue, the sludge was mixed with lignite at variety ratios and then chopped before being introduced to the feeding screw. It was found that mixing the sludge with lignite and then sieving the chopped materials through a four millimetre mesh sieve was the key to solve this issue. This technique significantly reduced both stickiness and agglomeration of the material. Also, this enabled for a significant reduction in moisture content of the final product