PhD student, The University of Adelaide
This study will convert the unwanted waste into the valuable biodiesel to substitute the fossil fuel
Grease trap waste (GTW) that is collected from the sanitary system is a very potential feedstock for biodiesel production since it has very high a content of free fatty acids. In Adelaide (South Australia), more than 10 million liters of grease trap waste was collected every year via an environmental service. With nearly 10% of fog, oil, and grease (FOG) presented in the untreated GTW, approximately 1 million liters of raw oil is available for biodiesel production. This will make up a sufficient fuel resource to fill up a truck team which is operated to pump up GTW from the sanitary system around Adelaide while lowering a cost for GTW treatment at the plant. However, there is a lack of literature reviews and study on the production of biodiesel from this feedstock due to a commercial feasibility. Moreover, it is significant to develop a simple technology that can provide a technical solution for the environmental treatment plant which is mostly constructed in the remote regions where lacks of electrical utilities. In this present work, biodiesel production from grease trap waste was carried out employing sulphuric acid and potassium carbonate as catalysts for esterification and transesterification synthesis process respectively. To provide a safer process for the industry, ethanol which can be produced from sugarcane cultivated on the environmental treatment plant was used to replace methanol as a reagent for the biodiesel synthesis reaction.
The main variables involved in the synthesis of biodiesel, including ethanol to FOG ratio, the amount of catalyst, reaction time, and reaction temperature, were studied. The complicated two-step process including esterification and transesterification has been applied due to the higher level of free fatty acid in comparison to the total glycerides in the feedstock. Gas chromatography was applied to analyze the concentration of each ethyl component in the product so that a conversion rate can be determined. The optimum experimental conditions, which were obtained from the esterification process, were ethanol to FOG ratio 3:1, with 5 wt% sulphuric acid catalyst, reaction time 120 minutes, and reaction temperature at 65oC. For the transesterification reaction, the optimum conditions were ethanol to oil ratio 9:1, with 5% Potassium carbonate catalyst at 65 Celcius degree after 1 hour.
Abstract: The undesirable properties of pyrolysis bio-oil such as high fractions of oxygenated and nitrogenated compounds, high viscosity, and high instability, limit its usage for transportation and energy applications. In this work, the upgrading of sludge-derived bio-oil using nickel-modified HZSM-5 catalyst was explored to determine the effects of temperature, ethanol to bio-oil mass ratio and reaction time on sewage sludge-derived (SSD) biodiesel yield and the degrees of denitrogenation and deoxygenation. The SSD biodiesel yield was found to be decreasing when the reaction temperature was increased, while the nitrogen and oxygen removal were both improved. Increased yield and deoxygenation were also observed at higher ethanol amounts, while denitrogenation was enhanced at longer reaction time. The optimum conditions for SSD biodiesel production (temperature – 258.5 °C, ethanol to bio-oil mass ratio – 2.50, reaction time – 3.23 h) were determined using response surface methodology and obtained the following results: 67.2% biodiesel yield, 20.4% degree of denitrogenation, and 33.6% degree of deoxygenation. Catalytically upgrading the bio-oil from sewage sludge into biodiesel resulted in better properties and quality and an increased heating value of 39.97 MJ/kg, generally comparable to commercial biodiesel.
Pub.: 18 Mar '17, Pinned: 02 Aug '17
Abstract: Disposal of sewage sludge is one of the most important issues in wastewater treatment throughout Europe, as EU sludge production, estimated at 9.5 million tons dry weight in 2005, is expected to approach 13 million tons in 2020. While sludge disposal costs may constitute 30-50% of the total operation costs of wastewater treatment processes, waste sewage sludge still contains resources that may be put to use, like nutrients and energy, that can be recovered through a variety of approaches. Research has shown that waste sewage sludge can be a valuable and very productive feedstock for biodiesel generation, containing lipids (the fats from which biofuels are extracted) in amounts that would require large areas cultivated with typical biodiesel feedstock, to produce, and at a much lower final cost. Several methods have been tested for the production of biodiesel from sewage sludge. To date, among the most efficient such process is pyrolysis, and in particular Microwave-Assisted Pyrolysis (MAP), under which process conditions are more favorable in energetic and economic terms. Sludge characteristics are very variable, depending on the characteristics of the wastewater-generating service area and on the wastewater treatment process itself. Each sludge can be considered a unique case, and as such experimental determination of the optimal biodiesel yields must be conducted on a case-by-case basis. In addition to biodiesel, other pyrolysis products can add to the energetic yield of the process (and not only). This paper discusses how feedstock properties and process characteristics may influence biodiesel (and other products) yield from pyrolytic (and in particular, MAP) processes, and discusses future possible technological developments.
Pub.: 09 Apr '17, Pinned: 02 Aug '17
Abstract: Oleaginous yeast Trichosporon oleaginosus was studied for lipid production using municipal sludge with or without fortification of crude glycerol in a 15-L fermenter. The maximum lipid content (concentration) was 32.0% w/w (9.35 g/L), 33.6% (10.13 g/L), 33.3% (9.13 g/L), and 33.1% (9.03 g/L) w/w with the addition of 25, 50, 100, and 150 g/L glycerol, respectively. Glycerol concentration had little effect on lipid accumulation. However, glycerol concentration substantially affected increase of biomass concentration and cell count. The suitable glycerol concentration was approximately 40 g/L for Trichosporon oleaginosus growing in sludge medium with initial suspended solids (SS) concentration 30 g/L. Addition of nitrogen to sludge-glycerol medium enhanced lipid and biomass concentration. The energy conversion efficiency was 1.78, 1.55, and 1.71 with no nitrogen added, with addition of 1 g/L urea, and 3.7 g/L peptone, respectively. The biodiesel production cost was estimated nearly 0.75 US$/L.
Pub.: 27 Apr '17, Pinned: 02 Aug '17