Preliminary Economic Assessment Research Articles

Biogas upgrading to biomethane with zeolite membranes: Separation performance and economic analysis

Biogas represents an important renewable source alternative to fossil fuels, which can significantly contribute to the reduction of global warming and the gradual decarbonisation. In this work, the purification of CH4 and CO2 from a biogas mixture was investigated using DD3R zeolite membrane modules, as a possible solution to replace the traditional techniques at higher environmental impact (i.e., solvent absorption and cryogenic distillation). Multistage membrane configurations operating at 25°C and 30 bar were proposed and explored to get highly pure biomethane (concentration of 98 %) and carbon dioxide (concentration of 99.5 %), imposing a recovery of both the species higher than 90 %. Then, an economic analysis was carried out, evaluating the economic potential of each configuration as a function of several parameters, such as membrane module cost, biomethane selling price, CO2 permeance, CO2/CH4 selectivity, feed flow rate and pressure. The multistage schemes were found to be promising in a wide range of zeolite membrane module cost (i.e., up to 2000 $/m2), providing positive values of the economic potential, due to the good recovery of both the components, which produced high revenues. The increment of the CO2 permeance and, especially, of the feed flow rate (i.e., plant size) allowed for a more profitable process. In particular, if feed flow rate increased from 100 to 1000 Nm3/h, the economic potential would grow of about 12 times, from 113 to 1370 thousand dollars per year. Hence, this preliminary economic assessment showed that zeolite membranes can be successfully used in biogas treatment to get pure CH4 and CO2. Such an analysis can be applied to any membrane materials, once permeance and selectivity are fixed.

Working Fluid Selection and Thermodynamic Optimization of the Novel Renewable Energy-Based RESTORE Seasonal Storage Technology

Abstract Seasonal-based energy storage is expected to be one of the main options for the decarbonization of the space heating sector by increasing the renewables dispatchability. Technologies available today are mainly based on hot water and can only partially fulfill the efficiency, energy density and affordability requirements. This work analyzes a novel system based on pumped thermal energy storage (PTES) concept to maximize renewables and waste heat exploitation during summer and make them available during winter. Organic fluid-based cycles are adopted for the heat upgrade during hot season (heat pump (HP)) and to produce electricity and hot water during cold season (power unit (PU)). Upgraded thermal energy drives an endothermic reaction producing dehydrated solid salts, which can be stored for months using inexpensive and high energy density solutions. This paper focuses on thermodynamic cycles design, comparing the performance attainable with several working fluids. Two different configurations are investigated: coupled systems, sharing the fluid and heat exchangers in both operating modes, and decoupled systems. A preliminary economic assessment completes the study, including a sensitivity analysis on electricity and heat prices. Cyclopentane is identified as a promising working fluid for coupled systems, reaching competitive round trip efficiencies (RTEs), maximizing the ratio between performance and HX surfaces, without excessive turbomachinery volume ratios and volumetric flows. Economic analysis shows that solutions with lower efficiency, but also lower capital cost, can achieve competitive payback times (PBT). On the contrary, decoupled systems are less attractive, as they reach slightly higher thermodynamic performance, but require higher capital costs, possibly being of interest only in specific applications.

Prospects for systematization of lignite deposits to provide Ukraine with raw materials in the postwar period

The contribution of the mining industry to the economy of Ukraine and the current state of coal mining are analyzed on the basis of statistical data on balance sheet reserves of black coal by grade. The indicators of balance reserves and quality characteristics of lignite and associated minerals (coal clays) of the Dnipro Basin are specified. Prospects for the resumption of production are presented and a preliminary economic assessment of the attractiveness of the lignite application is made. The lignite reserves are partially recalculated taking into account the extraction of coal clays to increase the capacity of the country’s fuel and energy sector. The prospects for compiling a catalog of lignite raw materials are determined, taking into account the mining and geological conditions of occurrence and the quality characteristics of the mineral. The scientific novelty of the research is to catalog the deposits of the Dnipro Basin and rank them with a preliminary technical and economic assessment of lignite production. The practical significance is to create a ready catalog of lignite raw materials that will allow a potential investor to implement his or her economically viable project for the development of the deposit.

ALGORITHM FOR DETECTING HYDROCARBON LEAKS IN PIPELINE TRANSPORT WITH INTERMEDIATE REMOVAL OF PART OF HYDROCARBON

Currently, the main part of hydrocarbons consumed both in the Russian Federation and in the world as a whole is transported through pipelines. This type of transport has many advantages, however, despite this, problems arise during operation related to ensuring the integrity of the pipelines themselves and providing settlements located along the linear part with fuel using intermediate branches to local oil depots. It is worth noting that in this case there is a problem of ensuring constant and highquality monitoring of the state of the oil product pipeline-branch pipeline system, for which constant monitoring methods based on mathematical modeling are often used to solve, which make it possible to investigate the integrity without changing the pumping mode. However, in order to improve the accuracy of these methods, it is necessary to constantly improve existing or develop new mathematical models of pipeline systems.The main aim of the research. Improvement of mathematical modeling methods for detecting leaks or unauthorized tie-ins during intermediate scheduled discharges of hydrocarbons on the linear part of the main pipeline.Mathematical modeling of the operating mode of the technological section of the main pipeline, taking into account the discharge on the linear part, the need to regulate the operating modes of pumping stations.An algorithm has been developed to determine the location of a leak or illegal tie-in on a trunk pipeline with an intermediate branch to a local oil depot. A graph of the hydraulic slope line is constructed in the presence of damage to the integrity of the pipeline. A preliminary economic assessment of the damage to the supplier company from the loss of the pumped product was carried out.

Use of an inexpensive carbon source for the production of a cellulase enzyme complex from Penicillium ucsense S1M29 and enzymatic hydrolysis optimization

AbstractThe high cost of cellulolytic enzyme complexes (CECs) has been a significant impediment to the commercial production of bioproducts from lignocellulose biomass. This study aimed to develop a cost‐effective CEC derived from Penicillium ucsense (former Penicillium echinulatum), utilizing diverse forms of pretreated sugarcane bagasse as the primary carbon/inductor source. Among the different pretreatments used, the hydrothermal pretreatment followed by NaOH delignification (BHD) produced higher FPase and xylanase activities (4.5 FPU mL–1 and 120 IU mL–1) in bioreactor experiments at 20 g BHD L–1 initial concentration. A batch‐mode assay conducted across a range of initial carbon source (5 to 60 g L–1) confirmed the highest FPase activity (4.0 to 5.0 FPU mL–1 at 120 h), in the range of 20–40 g BHD L–1. During these assays the agitation rate, controlled by dissolved O2, tended to stabilize at lower levels, indicating substrate limitation. Conversely, higher initial carbon source concentrations led to an excess of glucose, likely triggering carbon catabolite repression and inhibiting cellulase production. This insight prompted the development of a controlled pulsed fed‐batch strategy, resulting in FPase activity of 11 FPU mL–1 at 220 h using 90 g L–1 BHD controlled fed into the bioreactor. An enzymatic hydrolysis procedure using the generated CEC was also optimized using a central composite rotational design (CCRD). The optimized enzyme hydrolysis conditions achieved a reducing sugar concentration of 80.9 g L–1 in 48 h using 170 g L–1 of BHD as the substrate at a ratio of 15 FPU of enzyme substrate per g of BHD. A preliminary economic assessment demonstrated that, for a first‐ and second‐generation (1G + 2G) ethanol biorefinery, the cost contribution of enzymes would be about US$0.2/L of biofuel. In conclusion, an efficient and highly productive procedure was developed successfully for the production of a CEC. It was particularly effective for the enzymatic hydrolysis of pretreated sugarcane bagasse.

Green hydrogen production via reverse electrodialysis and assisted reverse electrodialysis electrolyser: Experimental analysis and preliminary economic assessment

In the climate changing context, hydrogen is leading the energy transition path. The present work focuses on the green hydrogen production exploiting salinity gradients via Reverse Electrodialysis (RED), in short-circuit condition (REDSC), and Assisted RED (ARED), studied for the first time in hydrogen production as an improvement of the low current densities generated by RED. An extensive experimental campaign was carried out by feeding a RED stack with different salinity gradients and testing short-circuit-RED and Assisted RED operative conditions. Hydrogen was produced successfully with ∼100 % Faradic Efficiency (FE) and productivity up to 1.7 mol h−1 m−2. Also, the technology was compared with similar technologies and with the most established state-of-the-art electrolysers to identify advantages and disadvantages of the proposed route. Finally, a preliminary economic analysis was carried out and a minimum Levelized Cost of Hydrogen (LCOH) of 3.2 € kg−1H2 was found, thus leaving room for further studies.

Preliminary Environmental and Economic Assessment of Mineral Carbonation of Steel Slags as a Carbon Capture, Utilization and Storage Technology

To shift towards a sustainable steel production practice, circular economy principles can be applied in the value chain by valorizing the 2 in flue gases and the generated steel slags to produce stable silicates and carbonates via mineral carbonation, leading to long-term stable carbon sequestration. Carbonated slags can then be considered as a carbon capture, utilization and storage technology. However, it is important to quantify the environmental benefits and economic viability to evaluate a system's sustainability. This study aims (1) to evaluate the environmental and economic impacts of steel slag mineral carbonation and (2) to identify hotspots and process parameters of the systems. In this study, lab-scale experimental mineral carbonation data is upscaled to a TRL 6 scenario via an upscaling simulation with a power law learning curve. Subsequently, life cycle assessment and life cycle costing are performed to quantify the environmental and economic performances in agriculture. Contribution analyses are performed to ascertain the hotspots and process parameters of the systems. The results obtained in this study can encourage industrial symbiosis among different stakeholders in and around the steel industry to promote a more sustainable steel manufacturing value chain, incorporating circular economy principles.

Combining fungal bioremediation and ozonation for rinse wastewater treatment

In this work, agricultural rinse wastewater, which is produced during the cleaning of agricultural equipment and constitutes a major source of pesticides, was treated by fungal bioremediation and ozonation, both individually and combined in a two-stage treatment train. Three major pesticides (thiacloprid, chlortoluron, and pyrimethanil) were detected in rinse wastewater, with a total concentration of 38.47 mg C L−1. Comparing both technologies, ozonation in a stirred reactor achieved complete removal of these pesticides (720 min) while proving to be a more effective approach for reducing colour, organic matter, and bacteria. However, this technique produced transformation products and increased toxicity. In contrast, fungal bioremediation in a rotating drum bioreactor attenuated toxicity levels and did not produce such metabolites, but only removed approximately 50 % of target pesticide - hydraulic retention time (HRT) of 5 days - and obtained worse results for most of the general quality parameters studied. This work also includes a preliminary economic assessment of both technologies, revealing that fungal bioremediation was 2 times more cost-effective than ozonation. The treatment train, consisting of a first stage of fungal bioremediation followed by ozonation, was found to be a promising approach as it synergistically combines the advantages of both treatments, achieving high removals of pesticides (up to 100 %) and transformation products, while reducing operating costs and producing a biodegradable effluent. This is the first time that fungal bioremediation and ozonation technologies have been compared and combined in a treatment train to deal with pesticides in agricultural rinse wastewater.

Economic advantages of starting up of inherently safe fast reactors with a closed fuel cycle on fortificated uranium

The publication substantiates the economic advantages of using in the starting loads of inherently safe fast reactors with a closed fuel cycle of enriched uranium instead of uranium-plutonium regenerate obtained by reprocessing of thermal reactors spent nuclear fuel (SNF). The justifications are given taking into account both the preliminary technical and economic assessments carried out by the basic enterprises of TVEL JSC and SHK JSC, and the neutron-physical and system-economic studies performed at the Private Institution of the ITCP Proryv (Breakthrough). It is shown that the starting-up of a fast reactor on enriched uranium instead of uranium-plutonium fuel, taking into account the costs of preliminary reprocessing of thermal reactors spent fuel, allows achieving a significant economic gain at the stage of construction and commissioning of nuclear power plants. It is also shown that even at moderately high values of the discount coefficient, the uranium start of a fast reactor with a closed fuel cycle is economically preferable in comparison with the option of starting on uranium-plutonium fuel from the positions of the break-even tariff.

A hybrid anaerobic osmotic membrane bioreactor - membrane distillation for water reclamation: aquatic toxicity, membrane fouling characterization, and economic assessment

The incomplete removal of pharmaceutically active compounds (PhACs) by conventional wastewater treatment has been challenging due to their ecological implications. Therefore, advanced technologies are necessary to remove PhACs efficiently. In the present study, an anaerobic osmotic membrane bioreactor - membrane distillation (AnOMBR-MD), aiming to remove seven PhACs, was evaluated by an integrated approach, considering the environmental toxicity, fouling characterization, and economic assessment. PhACs removal was evaluated using liquid chromatography coupled with mass spectrometry. Besides, organic matter and nutrient removal were evaluated. The FO and MD membrane fouling was characterized with scanning electron microscopy and energy dispersive spectroscopy. Toxic effects were analyzed for Aliivibrio fischeri, Daphnia similis, and Raphidocelis subcapitata. Furthermore, a preliminary economic assessment was carried out using capital and operating expenditures. The results showed a DOC, N-NH4+, and P-PO43- removal of 92%, 97%, and 99.9%, respectively, while removal of PhACs was >96%. However, the distillate was classified as very toxic forR. subcapitata, and a strong correlation was found between toxicity and the Mg2+ originating from the draw solution (DS). This result showed the importance of including toxicity tests in the selection of DS. The economic evaluation indicated that the higher cost is related to the membrane replacement due to the decrease in the permeate flux, pointing out the need for future studies that address cleaning strategies to solve the organic and inorganic fouling on the membrane's surface. In this sense, this study promoted an improvement in understanding the AnOMBR-MD technical-economic viability aiming at full-scale application.

Optimizing the subcritical water valorization of insect (Hermetia illucens l.) farming waste for biodiesel production

To counter the proliferation of secondary waste streams generated on insect (black soldier fly) farms, the present study integrated green water technology and acid-catalyzed transesterification as a basis to assess further value extraction potentials. By valorizing the waste streams, a process was developed to promote the circular economy paradigm. In this regard, wastes generated from a local insect farm were initially subjected to subcritical water extraction (SWE) for lipid recovery. The SWE process was optimized such that an enhanced lipid yield of 13.31 wt% was obtained at temperature, time, and solid loading conditions of 236.8 °C, 10 min of extraction, and 1 g/ 100 mL respectively. The lipids recovered were then subjected to an acid-catalyzed transesterification reaction for the production of a fatty acid methyl ester (FAME) mixture. A preliminary economic assessment of the process was also undertaken. The results showed that the wastes had the potential to be economically employed in the production of biodiesel that satisfied fuel property standards. In addition, the potential of employing the side streams as an animal feed was also highlighted due to the determined dominance of oligopeptides, which are known for their favorable bioactive properties. The results indicated that insect farming waste is a promising renewable source for high-quality biodiesel and animal feed production through the environmentally friendly biorefinery.

Hydrolase Production via Food Waste Fermentation and Its Application to Enhance Anaerobic Digestion of Sewage Sludge

In the present study, a novel strategy for the effective production of hydrolase via fermentation of food waste was developed to improve methane production from anaerobic digestion of waste activated sludge (WAS). Via the pre-fermentation of food waste, hydrolase could be efficiently enriched and then directly used to enhance sludge hydrolysis with no need for extraction and purification of the enzymes. The results of this study indicate that the activities of the predominant hydrolase, mainly including protease and amylase enriched in the pre-fermented food waste, could reach 4861.10 U/g and 3909.14 mg/(mL·min), respectively. The elevated activities of hydrolases evidently enhanced sludge hydrolysis by more than 50% with the addition of 15 g fermented food waste per 200 g sludge. The released organic matter presented much better biodegradability, of which the BOD5/COD (B/C) increased from 0.33 of the raw WAS to 0.41 of the pretreated sludge. Moreover, methane production from sludge digestion was substantially improved and increased from 2140 mL to 7187 mL by adding 30 g fermented food waste into 200 g sludge, about 24.3% of which was contributed by the addition of the enriched hydrolase. The preliminary economic assessments of this present study indicate the net profit of sludge digestion of 7.99 USD/m3 sludge is likely to be harvested via applying this strategy. Furthermore, the results in this present study provide another innovative route to further optimize the conventional co-digestion process of WAS.

Switching from Risks to Opportunities: The Application of a Superbonus Tax Incentive to Heritage Buildings from the 1960s in Fragile Mountain Contexts

This paper introduces actual considerations for the progressive disuse of residential space in the Alpine territory, considering possible actions. Nowadays, the building complexes built around the 1960s and 1970s (a symbol of mass tourism) are suffering and searching for a new identity. The generation of owners who bought them has aged and the propensities of the new generations for holiday in those places has changed, which means fewer opportunities for leisure, particularly in the winter. Due to the great attention (and seeming opportunities) of current incentive policies toward improving the energy use of the existing stock, the authors investigate the private conveniences of transformations through the refurbishment of these buildings. Starting from a study of the territory and the dynamics of the local population, this research analyzes a possible set of energy works, based on a new (2020) incentive measure, the 110% Superbonus, which consists of a series of facilitation mechanisms, deductions, and reimbursements for building interventions. A large part of the insight is focused on a technical and economic feasibility study of the possible actions, following a process based on the evolution of the legislation. This work is based on a specific case study, located in a small municipality in the Piedmont mountain area, consisting of three apartment blocks of mostly second homes. The methodology adopted lends itself on the one hand, as a guide for preliminary economic energy assessments and, on the other hand, as a policy evaluation tool from the public and private perspectives.

Integrated use of lignite resources to provide fuel for the energy sector of Ukraine in the war and post-war periods

The object of research is technological processes for the complex development of lignite resources, including extraction, processing and the possibility of further use of derived products in the energy sector. The problem solved in the work is related to the underestimation of the complex use of lignite resources of Ukraine to provide fuel for the energy sector, which is suffering significant damage as a result of military operations. In the course of research, the current state, prospects for the development and use of lignite as an energy resource at thermal power plants (TPP) were analyzed. Using the example of the Myronivka lignite deposit, new technological solutions for its complex development are proposed, which include the following stages: – development of technological schemes for conducting mining operations with the possibility of selective extraction of minerals; – identification of promising areas of lignite processing technologies with the involvement of carbonaceous clays; – calculation of technical and economic indicators, social and economic efficiency of field exploitation. It is proposed to determine the rational parameters of the overburden zones during the extraction of at least two minerals in the deposit with the use of internal dumping of overburden rocks in the produced space. In order to minimize the impact of field waterlogging, various options for draining the quarry field will be considered based on three-dimensional modeling. Based on the methodology of expected operating costs, a preliminary economic assessment of the attractiveness of the proposed technological solutions was calculated for a conventional mining enterprise. Graphs of the dependence of mining costs and cost on the productivity of the cut and the overburden ratio were constructed, which made it possible to assert the feasibility of comprehensive development of lignite deposits of Ukraine. It has been established that the expansion of lignite raw materials due to accompanying minerals (coal clay) will lead to an increase in production by mass from 30 to 100 %, and in some cases even more.

Assessing the impact of granular anaerobic membrane bioreactor intensification on treatment performance, membrane fouling and economic balance

Anaerobic membrane bioreactors (AnMBRs) have attracted much attention for mainstream domestic wastewater treatment. However, membrane fouling, operating costs, energy consumption and low filtration flux are important challenges slowing the scale-up of the technology. In this study and for the first time, granular sludge, submerged membrane, no gas sparging and low permeate flux were chosen to mitigate membrane fouling and to improve the energy and economic balance of an AnMBR. A granule-based AnMBR (G-AnMBR) was operated under four organic loading rates (between 0.5 and 1.6 kgCOD.m–3.d–1) with hydraulic retention times ranged from 13.9 to 4.9 h, and instantaneous permeate flux levels (Jp20,inst) ranged from 2.8 to 6.0 LMH to evaluate OLR impact on anaerobic digestion performance, membrane fouling extent and economic balance. Results show that COD removal rates above 83 % were achieved during the four experimental periods. Membrane fouling was directly correlated to the flux and OLR and increased from 0.03 to 2.86 kPa.d–1 as the Jp20,inst increased from 2.8 to 6.0 LMH and the OLR increased from 0.5 to 1.6 kgCOD.m–3.d–1, respectively. In all the periods, macromolecules and colloidal proteins were the major foulants deposited on the membrane. Most of the fouling was reversible and was easily removed by physical cleaning (>97.7 %). A preliminary economic assessment revealed that the permeate flux and OLR are key economic drivers for the G-AnMBR economic balance and allowed to define the satisfactory compromise between membrane purchase and chemical consumption for the long-term control of membrane fouling.

Особенности оценки экономической эффективности капитального ремонта скважин нерентабельных газовых и газоконденсатных месторождений Ставропольского края

Gas industry plays a significant role in the economy of the Stavropol Krai, providing other industries with necessary natural resources and employment for a significant part of the population. However, in modern conditions, it has a number of problems that hinder its dynamic development. One of them is the final stage of field development, characterized by a decrease in hydrocarbon production, a worn-out state of wells and the in-field transport system. One of the ways to solve these problems is the timely overhaul of wells, which will allow maintaining the level of hydrocarbon production at a given level and save jobs. The implementation of these measures requires significant investments, therefore, when planning the volume and timing of their implementation, it is necessary to give a preliminary technical and economic assessment in order to determine their effectiveness. This study analyzes the major repairs of wells carried out at the fields of the Stavropol Krai over the past ten years, identifies the main causes of well stoppage, determines the consequences for the development of the field from the untimely disposal of wells. The authors analyzed the existing methodology for assessing the economic efficiency of well capital repairs, and proposed additions that allow taking into account not only the stage of field development, but also social consequences due to the refusal to carry out capital repairs of the well.

Recent Progress in Electrochemical Upgrading of Bio-Oil Model Compounds and Bio-Oils to Renewable Fuels and Platform Chemicals.

Sustainable production of renewable carbon-based fuels and chemicals remains a necessary but immense challenge in the fight against climate change. Bio-oil derived from lignocellulosic biomass requires energy-intense upgrading to produce usable fuels or chemicals. Traditional upgrading methods such as hydrodeoxygenation (HDO) require high temperatures (200−400 °C) and 200 bar of external hydrogen. Electrochemical hydrogenation (ECH), on the other hand, operates at low temperatures (<80 °C), ambient pressure, and does not require an external hydrogen source. These environmental and economically favorable conditions make ECH a promising alternative to conventional thermochemical upgrading processes. ECH combines renewable electricity with biomass conversion and harnesses intermediately generated electricity to produce drop-in biofuels. This review aims to summarize recent studies on bio-oil upgrading using ECH focusing on the development of novel catalytic materials and factors impacting ECH efficiency and products. Here, electrode design, reaction temperature, applied overpotential, and electrolytes are analyzed for their impacts on overall ECH performance. We find that through careful reaction optimization and electrode design, ECH reactions can be tailored to be efficient and selective for the production of renewable fuels and chemicals. Preliminary economic and environmental assessments have shown that ECH can be viable alternative to convention upgrading technologies with the potential to reduce CO2 emissions by 3 times compared to thermochemical upgrading. While the field of electrochemical upgrading of bio-oil has additional challenges before commercialization, this review finds ECH a promising avenue to produce renewable carbon-based drop-in biofuels. Finally, based on the analyses presented in this review, directions for future research areas and optimization are suggested.

ВИСОКОПЕРСПЕКТИВНІ ОБ'ЄКТИ МІНЕРАЛЬНО-СИРОВИННОЇ БАЗИ УКРАЇНИ. ЧАСТИНА 1. МЕТАЛІЧНІ КОРИСНІ КОПАЛИНИ

A short description of the highly promising mineral and raw material base of metallic minerals of Ukraine is provided. It includes the following deposits and occurrences: complex carbonatite rare metal-apatite Novopoltavske deposit (REE, Nb, Ta, P2O5); complex zirconium-rare-earth-niobium Mazurivske (Oktyabrske) deposit (REE, Zr, Nb); complex rare earth-zirconium Azovske deposit (REE, Zr); Anadolske rare earth deposit (REE); rare earth occurrences Petrovo-Hnutivske (RZE) and Balka Korabelna (RZE); placer complex ilmenite-zirconium deposits Malyshevske (Ti, Zr) and Tarasivske (Ti, Zr); indigenous complex rare-earth-zirconium Yastrubetske deposit (REE, Zr); Shevchenkivske deposit of spodumene ores (Li); Polokhivske deposit of petalite ores (Li); Stankuvatske deposit of spodumene-petalite ores (Li); manifestation of Kruta Balka (Li); Zhovtorichenske complex iron-uranium-vanadium-scandium deposit (Sc, Fe, U, V); coal of the Donetsk basin (Ge). Among the metallic minerals of Ukraine, these deposits have the highest level of investment attractiveness, the lowest investment risks, are characterized by an average level of competition and can be recommended as priority objects for investment in their study and industrial development. To determine the investment prospects of specific objects, a preliminary geological and economic assessment of the feasibility and profitability of their industrial development is necessary.

Acetone–Butanol–Ethanol Fermentation Phenomenological Models for Process Studies: Parameter Estimation and Multi-Response Model Reduction with Statistical Analysis

A phenomenological multi-response multi-parameter Acetone–Butanol–Ethanol fermentation dynamic model is developed and calibrated for fermentation process studies. The model was constructed based on other models reported in the literature and was calibrated with a maximum likelihood parameter estimation over Acetone–Butanol–Ethanol fermentation experimental data from the literature. After parameter estimation, a rigorous statistical analysis was conducted to evaluate standard deviations of estimated parameters and predicted responses as well as their respective 95% probability confidence intervals for correct parameters and responses. The significance of parameters was assessed via a Fisher’s F test. From the Base-Model with 17 parameters, a tight, more compact, Reduced-Model was developed with 9 highly significant parameters after deleting 8 nonsignificant parameters from the Base-Model and re-estimating the remaining 9 parameters. This Reduced-Model showed good adherence to the experimental data and had better performance comparatively relative to the Base-Model with 17 parameters using two different inhibition functions reported in the literature. The Reduced-Model is sufficiently good for preliminary engineering and economic assessments of ABE fermentation processes.

“Different pretreatments of beach-cast seaweed for biogas production”

The increasing amount of seaweed accumulated in the coasts calls for a proper disposal or treatment in order to reduce secondary pollution effects. Anaerobic digestion of seaweed is a treatment technology that simultaneously produces biogas, supporting the further expansion of the renewable energy production through sustainable bioresources. In this study, three pretreatments (alkaline, hydrothermal and thermo-acidic) were applied on beach-cast seaweed of the Baltic Sea in order to improve the methane yield. The thermo-acidic pretreatment resulted to the highest increase of the methane yield (78% higher than the raw seaweed), while the alkaline pretreatment resulted to a 36% increase of the methane yield and to the highest reduction of the methane production cost compared to raw seaweed based on a preliminary economic assessment. Determination of the different sugars and sugar acids of the seaweed before and after the pretreatments assisted in understanding the effects of each pretreatment on the seaweed matrix. • Beach-cast seaweed was analyzed for its composition in sugars and sugar acids. • A hydrothermal, an alkaline and a thermo-acidic pretreatment was applied. • The thermo-acidic pretreatment resulted to the highest increase of CH 4 yield (78%). • The hydrolysis rate of seaweed was improved by all the pretreatments applied. • Alkaline pretreatment resulted to the lowest cost of CH 4 production from seaweed.