Biodiesel Production Plant Research Articles

Ambivalent effects of mass cultivation of biodiesel producible green alga Tetraselmis striata on a microbial ecosystem: Evidence from mesocosm experiments

A 280-ton plant for the mass cultivation of Tetraselmis striata was operated from 2012 to 2019 to produce biodiesel fuel in western Korean coastal waters (Incheon) as a pilot project. This was the first instance globally where a microalgal mass cultivation plant for biodiesel production was implemented in coastal waters, and no prior studies had investigated the impact of microalgal mass cultivation plant on surrounding microecosystems. In this study, bioreactors (1× and 10×) mimicking a large-scale T. striata cultivation plant were installed in semi-permeable a mesocosms (5 tons) to assess their impact on the microbial ecosystem. The results showed that the release of large amounts of dissolve organic carbon (DOC) from the T. striata bioreactors. The 10× pond had a DOC concentration of 21.3 mg/L compared to the control pond of 2.1 mg/L. For the Water Quality Index (WQI), the 1× and 10× bioreactor installed mesocosms improved from Class II (Good) at the beginning of the experiment to Class I (Excellent) via decreasing nutrient levels and increasing of DO levels. However, from a biodiversity perspective, the microbial ecosystem deteriorated, with reductions in the diversity of zooplankton, ciliates, and phytoplankton. The correlation analysis and random forest variable importance measures indicated that the primary factor driving these changes was the alteration of the bacterial community due to elevated DOC levels. These findings indicate that while the mass cultivation of T. striata may improve physicochemical water quality, it has adverse effects on biological environments. Therefore, it is crucial to monitor physical, chemical, and biological factors comprehensively when cultivating microalgae on a large scale in marine environments.

Design and Simulation of the Biodiesel Process Plant for Sustainable Fuel Production

The biodiesel production process is extensively studied in the literature, focusing on mechanisms, modeling, and economic aspects, yet plant design and fluid flow losses remain underexplored areas. The study addressed this gap by designing a biodiesel production plant, analyzing flow losses, and developing a pipe network and suitable pump models. In this study, an integration of biodiesel production plant design and simulation of continuous production of Calophyllum inophyllum biodiesel was investigated. Biodiesel production encompasses complex stages that involve systematic planning and system design. The goal of the plant design is to reduce the losses that occur during the conversion process, which can reduce the capital cost of the plant. A few assumptions were made when selecting biodiesel plant materials, such as pipes, pumps, fittings, and bends. These assumptions were based on considerations of the biodiesel fluid properties and pressure requirements. On the other hand, Aspen Plus was used to simulate the biodiesel production process. Calophyllum inophyllum was considered oil as the biodiesel feedstock and was inputted to the Aspen Plus as triglyceride composition. The simulation was carried out with rigorous kinetic reactions using the Non-Random Two-Liquid (NRTL) method to predict the liquid equilibrium in the reactor. Results revealed that the designed steel pipe meets safety requirements with a bursting pressure of 49.68MPa, capable of withstanding the maximum pressure of 4 bar and turbulent flow conditions. Additionally, the selected pump satisfies the required head and flow rate, ensuring efficient fluid movement. Moreover, simulation results closely matched experimental data, and 88% of biodiesel yield was recorded.

Hierarchical MPC‐based control structure for continuous biodiesel production

AbstractThis paper presents an advanced control strategy for a continuous biodiesel production plant based on a steady‐state optimizer and model predictive control (MPC). The proposed control system aims to optimize the production process and maintain product quality within required specifications. First, two steady‐state optimizers were developed with the aim of minimizing the steady‐state deviations of the manipulated and controlled variables and minimizing the biodiesel production cost. An MPC was then formulated to track the set points imposed by the steady‐state optimizers in real time and manipulate the control inputs accordingly. The scope of this work is limited to measured disturbances only. The effectiveness of the proposed control strategy is demonstrated through dynamic simulation studies performed using HYSYS and MATLAB. The results obtained using the proposed control methodology show significant improvements in performance compared to conventional control strategies. Furthermore, it avoids the quality problem reflected in the amount of water in the final product that the original plant presented due to an inadequate design of the control strategy. Overall, the results of this research indicate that the proposed advanced control strategy has the potential to improve the efficiency and profitability of continuous biodiesel production plants.

Advancing Biodiesel Production System from Mixed Vegetable Oil Waste: A Life Cycle Assessment of Environmental and Economic Outcomes

This study aims to evaluate the environmental and economic performance of biodiesel production from mixed vegetable oil waste using the life cycle assessment (LCA) model. Due to its huge potential, Pakistan is taken as a case study. It produces 468,842 tons of vegetable oil waste annually. As no biodiesel production plant exists to process it, the environmental performance of biodiesel prototypes has not been investigated. Therefore, the current study is conducted to support the design of a plant to produce biodiesel from mixed oil waste. An attributional LCA was conducted using ReCiPe (H) and found that 400 kg of biodiesel can be produced from 1 t of mixed oil waste. The results, based on a functional unit of 1 ton, showed that biodiesel production from mixed vegetable oil waste is more eco-friendly than the existing landfilling practices with a global warming potential of 1.36 × 10−4 kg CO2 eq, human toxicity of 5.31 kg 1.4 DB eq, ozone depletion potential of 0.00271 kg CFC-11 eq, eutrophication potential of 0.0118 kg P eq, acidification potential of 123 kg SO2 eq, and photochemical ozone formation of 51.4 kg NOx eq. Scenario modelling was conducted using electricity from photovoltaic solar cells, which decrease fine particulate matter formation from 44.5 to 0.725 kg PM2.5 eq, instead of using electricity from a grid to the plant. Hotspot identification was carried out to highlight the effects of individual impact categories. An economic analysis showed that 638,839 USD/year revenue would be generated. Generating energy from discarded vegetable oils through biodiesel production presents a sustainable and economically viable approach. This process benefits the environment and contributes to cost savings by reducing waste disposal in landfills. Furthermore, it aligns with the principles of a circular economy, in which resources are reused and recycled. It also supports the pursuit of the United Nations’ Sustainable Development Goals (SDGs), particularly SDG-7, which focuses on affordable and clean energy, and SDG-12, which emphasizes responsible consumption and production.

Strategy planning for sustainable biodiesel supply chain produced from waste animal fat

The rapid depletion of fossil fuels and the adverse environmental effects of combustion has growing concerns about the sustainability of fossil fuel and the world turns its focus on cleaner energy sources. Animal fat-based biodiesel is a sensible alternative to non-renewable energy sources as it's produced from inedible, affordable, and easily available biomass. The effective design of a biodiesel supply chain is pivotal for making it more advantageous than fossil fuels from a social, economic, and environmental standpoint. This model reduces the biodiesel supply chain cost while minimizing its environmental impact and maximizing its social impact. It is planned to have multi-supply sites for providing beef, chicken, and mutton fat, and numerous biorefineries, rendering factories, and distribution depots. The augmented ϵ-constraint approach combined with the lexicographic optimization technique is used to solve the multi-objective optimization model. A numerical example is analyzed, and the results show that the environmental impact of establishing biodiesel production facilities is 99.5% of the environmental impact of the entire biodiesel supply chain and that the cost of installing biodiesel production plants is 99% of the cost of the entire biodiesel supply chain. A heterogeneous fleet of trucks is incorporated to distribute the material throughout the supply chain whereby the impact of transportation on the environment is 0.0007% of the total environmental impact of the biodiesel supply chain and transportation cost amount to 0.0014% of the total costs of the biodiesel supply chain. The model demonstrates the biodiesel supply chain network under a sustainability framework and addresses the environmental and social impact based on the life cycle assessment which accelerates the transition to a renewable energy future.

Liquid–Liquid Equilibria of Glycerol + Alcohol + Safflower Biodiesel Systems: Measurement and Modeling

Liquid–liquid equilibrium (LLE) for the biodiesel + glycerol + alcohol system is essential for the design, operation, process optimization, and economic evaluation of a biodiesel production plant. In this work, methyl and ethyl safflower biodiesels were produced from safflower (Carthamus tinctorius L.) seed oil. New LLE experimental datasets were obtained for the glycerol (1) + methanol/ethanol (2) + methyl/ethyl safflower biodiesel (3) systems at 298.15 and 318.15 K under atmospheric pressure. Binodal curves, tie-lines, distribution coefficients, and selectivity were determined. Data reliability was confirmed using the Othmer–Tobias correlation. LLE data were correlated with the UNIQUAC model satisfactorily, with deviations between 0.70 and 2.79% for all studied systems. The consistency of the estimated binary interaction parameters of the UNIQUAC model was ascertained. Finally, through process simulations in Aspen Hysys software, it was verified that the UNIFAC LLE model, along with the UNIQUAC model, can also be used adequately to describe the liquid–liquid behavior of biodiesel separators, provided that the biodiesel composition is accurately known.

Automation and Control of a Multi-feedstock Biodiesel Production Plant

The increasing need to develop renewable sources of energy to complement the energy generated via fossil fuel necessitates this study. This study demonstrates the process control and automation of a biodiesel processing plant. The developed biodiesel processing plant has a total output capacity of 200 litres per day with nine compartments divided into three major sections. The first section (pre-processing section) has the oil storage, pre-treatment, methanol and mixing tanks. The second section (main processing section) comprises of the reactor. The last section (post-processing section) comprises of the water, wash and separating tanks as well as the glycerol and biodiesel storages. The control and automation was achieved with the following components; three 3 kW variable speed electric motor, four 2.5 kW pumps, three 300 kW electric heater that are thermostatically controlled. Other materials used for the control and automation include: real time clock, Atmega328 microcontroller, LM6009 and LM 2596 modules, Liquid Crystal Display (LCD), switches, relay, LED, three temperature probes, 220 V AC alarm, four flow switches, 220 V timer relay, 220 V and 60 A contactor. Sensors are incorporated to measure the temperature, pressure, and flow level in the main reactor and the measured variables compared with the threshold values pre-set on the micro controller for control actions. The results obtained indicated that the performance of the plant was enhanced with the capacity to independently execute control actions during the biodiesel production. Thus, this study adds to the practical knowledge of system's control and automation for biodiesel production.

Environmental and cost analysis for polyhydroxyalkanoate production from glycerol byproduct: A case study from integrated soap and biodiesel plants

This work focuses on the sustainable integrated production of bioplastic, also known as Polyhydroxyalkanoate (PHA). Glycerol by-product generates from soap production and biodiesel production plant were utilized as the feedstock to overcome the current drawbacks in PHA production. Different purities of glycerol (i.e,16 wt%, 40 wt% and 60 wt%) were undergone pretreatment steps such as acidification, filtration, evaporation, hexane washing, methanol recovery and ion exchange to obtain 98 wt% of glycerol prior to PHA production. Capital of equipment purchase was estimated by using correlation and graphical method. It was found that, cost of chemical purchase for pretreatment has a high impact on the overall economy of the production. Economic feasibility of all proposed process routes was assessed by calculating the Payback period. Lastly, environmental impact of each pretreatment method was assessed by conducting an LCA by setting the annual target of 750,000 kg as the functional unit. Global warming potential, acidification potential and ecotoxicity of freshwater were chosen as the impact categories in this process. It was found that route 4 with feedstock purity of 60 wt% CG and pretreatment steps of methanol recovery, neutralization, centrifugation, water evaporation and distillation was found to be the most economically and environmentally sustainable among the assessed process routes.

Operational readiness: Good practices for process plant start‐up to avoid process safety accidents

AbstractThe start‐up of a process plant is subject to deviations that can become initiating causes of process safety events. Even a process plant that has been in operation for a long time and has not undergone any significant changes is subject to risks during the start‐up procedure. The objective of this work is to share good practices related to the start‐up of process plants that were implemented at Cargill's Biodiesel production plant in Três Lagoas, Brazil in order to avoid Process Safety accidents.

Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

With the increasing consumption of coffee beverages, an increased amount of food waste—spent coffee grounds (SCG)—is generated and disposed into landfills or combusted in incinerators. SCG are characterized as a highly polluting substance with partial toxicity due to the presence of caffeine, tannins, and polyphenols. It also contains 15% of oil on average, and its potential for biodiesel production is thus considerable. The aim of the presented work is to evaluate the possibility and technical potential of biodiesel production from the SCG oil (SCGO) by esterification and transesterification reaction. According to the characterization of the studied SCGO, this stream must be adjusted and purified to be utilized in the existing biodiesel production plant. Fatty acids (FA) represent 85.85% of the SCGO, with two dominant FAs—linoleic and palmitic acids. The necessity of removal and disposal of unsaponifiable matter, which accounts for 15% of the SCGO content, must be highlighted when producing biodiesel from the SCG. The objective of this research was the comparison of different biodiesel production processes, where a two-step transesterification process has been identified as the most successful method for biodiesel production from the SCGO with the highest ester content of 89.62% and the lowest content of unsaponifiable and unidentified matter in the final product. The novelty of the analyses is a characterization of the d unsaponifiable matter present in the SCGO, and the article highlights the importance of progression to be considered when evaluating the technical potential of the SCG biodiesel production integrated into a biorefinery. Nevertheless, the SCG biodiesel can contribute to fulfilling the mandatory share of advanced biofuel in the fuel energy mix given by national legislation and contribution to the circular economy approach of biorefineries.

Biodiesel-Petrodiesel Blends Physicochemical Characterization and Economic Assessment of Designing a Plant in Iran

Introduction: By substituting conventional fossil fuels, biofuel can emerge as a potential sustainable energy source with favorable environmental outcomes. Biodiesel, in particular, is increasingly attracting attention due to its high potential to increase the consumption of biofuel and contributing to sustainable development. Experimental studies have revealed that biodiesel can play a considerable role of biodiesel in improving petroleum-based characteristics.
 Materials and Methods: Physicochemical properties of pure biodiesel produced through esterification and transesterification, petroleum diesel, and biodiesel-diesel blends were experimentally measured. Ninety percent of the filtered and dried waste cooking oil (WCO) was converted to biodiesel, and it was shown that cetane index, flash point, and fire point increased by applying B10 (10% biodiesel + 90% petrodiesel) instead of petrodiesel.
 Results: B10 exhibited an adequate depression in pour point and cloud point by 6°C and 3°C at low temperature, respectively. Also, in this study, an economical study and a sensitivity analysis of a biodiesel production plant from WCO with a capacity of 90 tons per day was carried out, using COMFAR III software. The highest proportion of operating cost belonged to WCO (75%) followed by methanol (10%) and machinery, service, and maintenance expense (5%).
 Conclusion: Biodiesel showed a positive influence on petrodiesel characteristics, in which the desired green fuel contributed to save the environment. Eventually, economic analysis provides the possibility of running a plant in Iran as a sustainable solution to energy issues.

Investigations on evaluation of marine macroalgae Dictyota bartayresiana oil for industrial scale production of biodiesel through technoeconomic analysis

The investigation on utilizing macroalgae for industrial scale biodiesel production is an imperative action needed for commercialization. In the present research work, the biooil from marine macroalgae Dictyota bartayresiana was used for biodiesel production using calcium oxide nanocatalyst synthesized using waste collected from building demolition site. The optimization results obtained were the calcination temperature 573 °C, concentration of catalyst 5.62%, methanol to oil molar ratio 14.36:1, temperature 55.7 °C and time 67.57 min for the transesterification with the biodiesel yield of 89.6%. The techno-economic aspects of biodiesel production were investigated for 20 MT/batch. The return on investment and internal rate of return from the biodiesel production plant was found to be 25.39% and 31.13% respectively. The plant payback period was about 3.94 years with a positive NPV value of about 14,053,000 $/yr. Thus, Dictyota bartayresiana biomass can be efficiently used for the sustainable production of biodiesel.

A comparative life cycle assessment of different spent coffee ground reuse strategies and a sensitivity analysis for verifying the environmental convenience based on the location of sites

Spent Coffee Ground (SGC) represents the most abundant waste generated in coffee beverage preparation and instant coffee production, with a total annual amount estimated at 60 million tons worldwide. These quantities justify the need to enhance and reuse this waste, by implementing successful circular economy strategies. For this purpose, the production of compost, biofuels, and the incorporation of limited quantities of SCG in the bricks-making process represents a promising solution, which can avoid the impacts due to its disposal but also, result in lower greenhouse gas emissions. The present study aims to assess the environmental performance of different SCG reuse scenarios, compared to traditional landfill disposal. To evaluate environmental impacts, a comparative Life Cycle Assessment is performed among the aforementioned scenarios. The results showed that in terms of emissions to air, all the reuses investigated involve benefits compared to landfill, resulting in a decrease of 18% in composting, 1% in biodiesel production, and 76% in bricks-making. For this purpose, the success and real applicability of circular economy models are influenced by numerous factors, including distances and transport, which represent crucial elements in the evaluation of environmental benefits. Furthermore, a sensitivity analysis was implemented, to evaluate the maximum break-even distances within which the analyzed scenarios guarantee an environmental benefit, compared to landfill disposal. According to the obtained results and considering a distance of 100 km for the transport of SCG to the landfill, the calculated break-even distances are 500 km for composting, 150 km for biodiesel production, 1800 km for bricks-making; for longer distances, the additional impacts due to transport would cancel out the benefits deriving from the reuse of waste. Finally, the calculated break-even distances were compared with the average distances of the real sites in the Italian scenario, resulting in average distances for composting and brick production less than the break-even ones (40 km and 460 km respectively). On the other hand, the average distance among biodiesel production plants in Italy (500 km) is much higher than the calculated break-even one.

Application of thermogravimetric analysis method for the characterisation of products from triglycerides during biodiesel production

In this present work, thermogravimetric analysis (TGA) was used to study the thermal degradation of a range of lipids and lipid-derived compounds associated with the production of biodiesel. Thereafter, the procedure was used to successfully quantify the compounds of three process streams from a biodiesel plant. Relevant organic chemicals involved in biodiesel production chemistry, including glycerol, oleic acid (fatty acid), palmitic acid (fatty acid), rapeseed oil (model triglyceride) and fatty acid methyl esters (FAMES) have been studied to determine their volatilisation/thermal degradation patterns. The developed method was then applied for the quantitative characterisation of three samples from a 3-stage biodiesel production plant, including two in-process samples and the final biodiesel product. The method was able to clearly distinguish between two main sets of compounds namely, early - mid volatiles (glycerol, fatty acids and fatty acid methyl esters) and late volatiles (incompletely converted and unreacted triglycerides). In addition, the FAMES in the industrial samples were extracted into petroleum ether and analysed by gas chromatography - mass spectrometry (GC/MS), with good agreement between the two analytical methods. For instance, GC/MS analysis showed that the three industrial samples contained 31.2 ± 0.1 wt%, 60.6 ± 0.2 wt% and 91 ± 0.53 wt% of FAMES, respectively. Similarly, the TGA method gave the FAMES contents of the three samples as 33.9 ± 0.4 wt%, 57.8 ± 0.2 wt% and 85.3 ± 0.52 wt%. This study shows that TGA is a fast and simple method for accurately monitoring the triglyceride conversion stages and the purity of the final product during biodiesel production, without the need for extensive sample preparations and expensive standard solutions.

A Critical Review of Croton as a Multipurpose Nonedible Tree Plant for Biodiesel Production towards Feedstock Diversification for Sustainable Energy

Oil demand has risen steadily due to the growing industrialization and modernization of the world. In addition to rising costs, the supply of fossil fuels is also declining. These and many other concerns couple with food shortages have drawn attention of scientists to a substitute fuel that is generated from feedstocks that can be renewed. Biodiesel as an alternative fuel with a lot of expectations is produced using edible grown conventional vegetable oils such as sunflower, rapeseed, palm, and soybean. The production of biodiesel from edible oils has, meanwhile, worsened the existing competitiveness of oil used for food and fuel. Emphasis on using nonedible feedstock is currently guided by research to discover more potential nonedible feedstock such as croton. Differences between perceptions and facts about these nonedible oils necessitate efforts to diversify feedstocks into sources that can warrant the production of energy without impacting on the security of food. Croton is a multipurpose evergreen plant that is nonedible and is commonly present and cultivated under environmental and socio-economic conditions, which are complex in nature. This plant, referred to as a golden tree, has various uses including fuels, medicinal, ornamentals, dyes, feed, enriching of soil, and afforestation. This research was therefore carried out to investigate the multipurpose use croton. Among the highlighted areas include croton (feedstock) used for biodiesel, the necessity for croton seed oil and its value chain, the process for the modifying croton oil to biodiesel, factors that influence the production of biodiesel, the application of croton biodiesel in engines for efficiency and emission characteristics, and prospects for croton biodiesel.

Process optimization, economic and environmental analysis of biodiesel production from food waste using a citrus fruit peel biochar catalyst

The concept of sustainably reusing food waste to produce value-added byproducts, such as biodiesel , was studied. Food waste is an organic-rich source of lipids. An optimization study of the extraction of oil from food waste using a solvent for biodiesel production was undertaken. A biochar catalyst derived from citron ( Citrus medica ) peel containing a rich carbon source. A biodiesel yield of 96.3% was obtained under the optimized reaction conditions of a 1:10 oil to methanol molar ratio , 4 w% catalyst loading, reaction temperature of 55 °C, and a reaction time of 52 min. The conditions were optimized by response surface methodology with a central composite design . The biochar catalyst maintained a significant biodiesel yield for four cycles. This techno-economic analysis found that the annual plant revenue was $24,140,000 for a project lifetime of 20 years, the payback time was 3.16 years, the internal rate of return after tax was 39.92%, and the net present value at 10.0% interest was $55,017,000. A minimum biodiesel selling price of 0.46 $/kg was used, and the environmental sustainability of the produced biodiesel was assessed by a life cycle assessment . The impact of global warming potential on the FW-based biodiesel scenario was −3.967 kg CO 2 equivalent. • Oil extraction and biodiesel production process parameters were optimized. • Biochar catalyst from waste Citrus medica peel was used for biodiesel production. • 10 MT/h biodiesel production plant payback period is 3.16 years with NPV 55.02 M$. • Process global warming was −3.967 kg CO 2 equiv (Well to Wheel).

A Grey-Fuzzy Programming Approach towards Socio-Economic Optimization of Second-Generation Biodiesel Supply Chains

This study aims to develop a multi-objective second-generation-based socially responsible supply chain (SGB-SRSC) network design model that considers all dimensions of sustainability: economy, environment, and social. The dynamic nature of the biodiesel supply chain (SC) impairs the SGB-SRSC model decisions; thus, a grey-fuzzy solution approach is developed. Biodiesel is a promising renewable energy resource produced from a variety of easily accessible domestic wastes. For a swift transition towards commercially feasible biodiesel production, integrated optimization of the biodiesel SC system is critical. Using the latest social impact assessment tools, this study provides a decision-support system for developing a biodiesel SC network. A comprehensive computational analysis is performed on a case study to validate the proposed model. The results show that significant investment is required to achieve social well-being goals and secure decisions against uncertainty associated with SGB-SRSC model parameters. Further, it is observed that the expenses of biodiesel production and biodiesel plant installation accounted for a large portion of the overall SC cost. As a result, finding more cost-effective biodiesel production methods is critical to the industry’s economic viability. Regulators and policymakers involved in biodiesel production projects may find the framework useful in obtaining a compromise solution for socio-economic goals based on their preferences.

Innovative biodiesel production plant: Design, development, and framework for the usage of biodiesel as a sustainable EDM fluid

Biodiesel is a chemically modified eco-friendly fuel mainly used as a fuel in compression ignition engines. It is prepared from vegetable oil or animal fat. It is gaining worldwide popularity because it is a renewable, non-toxic, biodegradable, and non-flammable fuel. This paper gives an insight into various aspects of biodiesel. Literature review of biodiesel production, its performance in diesel engine, and the electrical discharge machining process are discussed along with other applications. An innovative biodiesel production plant of 20 L capacity has been designed and developed successfully. The conversion reaction was carried out for 20 L of used cooking oil and 4 L of methanol. The biodiesel production yield of 95.8% was observed for a 1:6 M ratio of methanol and used cooking oil using 200 gm of KOH catalyst at 60 °C for 1 h. In the second phase of the work, a framework for using biodiesel as a dielectric fluid during spark machining is presented. Using biodiesel during the spark machining process can reduce pollution and also enhances the sustainability of the process.

Process simulation and economic analysis of dolomite catalyst based biodiesel production from Nepalese Jatropha Curcas

This study presents a detailed design, cost estimation and sensitivity analysis to determine the commercial viability of a Jatropha biodiesel plant with Nepal as a representative case. Here, we present a biodiesel production process utilizing dolomite PB-20, an inexpensive solid catalyst, that allows easy retrieval of catalysts for reuse and easier product separation compared to the conventional liquid catalyst based production process. The transesterification and the subsequent separation processes were simulated using Aspen Plus to determine the amount of raw materials, the sizes of the equipment's and the total utility required for producing 43 million liters biodiesel per year. The total capital cost and the production cost for the plant of this scale was calculated to be $23 million and $51 million respectively. Similarly, the final biodiesel selling price was calculated to be $1.23/l. The selling price of the biodiesel was found to be highly sensitive to the purchase cost of the Jatropha oil. A 25% reduction in the Jatropha oil purchase cost from the base case price of $0.97/l will lower the biodiesel selling price to $1.00/l making it competitive with petro-diesel (current selling price of $1.02/l). The economic viability of the dolomite catalyst based biodiesel production plant and thus, the adoption of biodiesel as a substitute for petro-diesel is strongly dependent on the purchase cost of the Jatropha oil. This study illustrates the potential of dolomite catalyst based biodiesel production process and provides an important reference value for a more detailed policy level study to develop appropriate biofuel policies and to make investment decisions.

Performance assessment of ultrasonic sludge disintegration in activated sludge wastewater treatment plants under nutrient-deficient conditions

Although biological oxidation is a commonly applied technique for the removal of pollutants in industrial and municipal wastewater, one major drawback is its excess sludge production, having both an environmental and economic impact. The integration of ultrasonic sludge disintegration in a conventional biological wastewater treatment plant was explored experimentally via assessing the long-term effects on excess sludge reduction by conducting on-site pilot tests at a food processing company and a biodiesel production plant. Two sequencing batch reactors, each with a maximum active volume of 700 L, were operated in parallel for the treatment of industrial wastewater with nutrient deficient characteristics (COD/N/P ratio of 100/1.4/0.12) for over 6 months. One of the reactors was equipped with a side-stream recirculation system to enable the ultrasonic treatment of part of the settled sludge, whereas the other was operated in a conventional way as a reference. The experimental results show a reduction of the observed sludge production yield by 15% to 45% for the ultrasonically treated sequencing batch reactor compared to the conventional one, at a relatively low specific energy of less than 6,000 kJ/kg DS when 15 to 30% of the total sludge mass is treated per day. It was proven that the sludge reduction efficiency is directly proportional to the applied sludge retention time, suggesting that the ultrasonic treatment converts part of the hardly biodegradable particulate material in the activated sludge and improves its biodegradability. During the long-term pilot experiment at the biodiesel production plant, the electrical energy needed for decreasing the excess sludge production by 1 ton could be reduced by more than 80% when the sludge retention time was increased from 11 to 44 days. In addition, the sludge settling characteristics at the food processing company were considerably improved by the ultrasonic treatment, enabling to reduce or even avoid the need for external addition of expensive nutrients to prevent sludge bulking. Finally, an improved effluent quality was observed. Improvements of 7 to 17%, 9 to 20% and 17 to 30% for COD, nitrogen and phosphorus removal, respectively, were established.