The number of effluent treatment plants in Bangladesh have grown steadily in the last two decades in accordance with national environmental laws. Although such laws have been in existence since 1997, ...there were gaps in it especially when it came to how sludge generated from effluent treatment will be managed. This gap was addressed in 2015 through publication of national standards and guidelines for sludge management detailing some management options. These options have not yet reached the level necessary to address the scale of the problem, about which relevant data & information from all industries are unavailable. This study attempts to address the data gap by mapping the sources of sludge generation and available management options using geographic information system. Although these maps are not comprehensive in coverage of all sources and options, it offers basic assessment for developing a supply chain to route sludge from treatment plants to existing options offering productive uses. Several studies have investigated productive uses of sludge in the context of Bangladesh, but a macro perspective of developing an industrial symbiosis remain unexplored. This paper recommends use of sludge as partial substitute of clay for brick making in the short run mainly because of existing spatial distribution of kilns near generating sources. In the long run, investments are needed to develop infrastructure and supply chain to avail other management options including transportation for dealing with this resource. The need for additional studies is highlighted to understand capacities and costs involved in developing this system while also considering resource conservation and environmental sustainability.
Display omitted
•This paper presents maps of effluent treatment sludge sources & management options.•Review of research discusses productive uses of sludge in the country context.•Spatial distribution of sources & options offers macro perspective for circularity.•Research gaps & logistical challenges hindering development of industrial symbiosis.
The thermal and catalytic decomposition of waste plastics through pyrolysis is one of the best approaches of handling plastics waste and most prospective alternative of converting waste to wealth by ...transforming the waste plastics into lighter fuel oils which has potential to at least replenish petroleum resources if not replace the fossil fuels through this process of recycling. Further advancement in this area of research was to co-process waste plastics along with petroleum residues and other used oil with a similar intention, opening up a new prospect of reclaiming and upgrading altogether, two relatively low graded materials to a superior quality product which may be further refined for reprocessing in the petroleum refinery. In this paper, an attempt has been made to review the literature on cracking of plastics waste and it’s co-processing with petroleum residues and other heavy oil, the types of reactors and the catalyst employed in the process. The resulting product especially the liquid product from the co-processing of waste oil with polyolefin waste material has been found to possess good calorific values in the range of 44–47 MJ kg−1 while the heating value of the gaseous product was found to be in the range of 27–32 MJ Nm−3 and other characteristics similar to those of conventional fuel like diesel and thereby have a very good potential to be used as transportation fuel and other chemical feedstocks on further refining, while co-processing with other heavy oils residues have been found to have similar potential and prospect as an alternative to the conventional fuels and energy.
•Review on pyrolysis of plastics waste and its co-processing with waste heavy oil.•Petroleum or heavy lubricant oil acts as solvating medium for polymer degradation.•Co-pyrolysis enhances liquid oil yields and properties of the pyrolysis products.•Optimization of process variables are vital for best outcome of the process.•Pyrolytic liquids have the potential to be used as transportation fuel.
•Co-processing biogenic feedstocks can effectively reduce the carbon intensity of refinery operation and its products.•In the short term, oleochemical feedstocks will allow refiners to gain ...experience.•In the longer term biocrudes will be required, influencing aspects such as the choice of insertion points, metallurgy, etc.
Co-processing biogenic feedstocks within petroleum refineries has gained increasing attention with many refineries producing lower-carbon-intensive (CI) diesel and aviation fuels. Although co-processing has proven to be commercially viable and an effective way to produce low CI transportation fuels, it can present some operational challenges. However, various strategies have been used to reduce and mitigate impacts and potential risks. These include, pretreating the biogenic feedstock, infrastructure modifications based on specific refinery configurations, modifying the nature of the desired products as well as modifying the characteristics and percentage blend of the biogenic feed. Other options include the use of different feedstocks, such as lipids or biocrudes, or using different refinery insertion points, such as the fluid catalytic cracker or diesel hydrotreater. Although lipid feedstocks have a relatively simple chemistry and are used at a commercial scale, in contrast, biomass-derived-biocrudes constitute very complex mixtures and co-processing of biocrudes is not currently carried out at a commercial scale. As limited information and data on co-processing is available, this review highlights the potential and challenges of using co-processing as one way of reducing the carbon intensities of refineries and the low-CI drop-in transportation fuels they produce.
To decrease the environmental risks caused by heavy metals (HMs) in red mud (RM) and improve the quality of pyrolysis oil from biomass, high–temperature pretreated RM and cow dung (CD) were microwave ...co–pyrolyzed. Then, the optimization potential of energy consumption was evaluated and the interaction mechanism between RM and CD was explored. The results showed that the increase in transition metal oxides and specific surface area improved the microwave–absorption and catalytic capacity of the pretreated RM. By optimizing the parameters, a pretreatment temperature of 650 °C resulted in a 21.65% reduction in acid content of bio–oil, higher HMs immobilization rates (>91%) and a 7.44% reduction in energy consumption. The synergistic optimization of bio–oil quality, HMs immobilization and energy consumption was achieved. After microwave co–pyrolysis with cow dung, the larger specific surface area (92.90 m2 g−1) and higher carbon crystallinity (ID/IG = 1.02) of pyrolysis residues enhanced the physical adsorption to HMs. The complexation of HMs with –OH could further enhance the solidification of HMs. This work will provide support to efficient resource utilization of solid waste, and demonstrate the great potential of microwave co–pyrolysis in HMs immobilization.
Display omitted
•Pre–treated red mud (RM) reduced energy consumption of co–pyrolysis by 12.15%.•Alkaline sites of pre–treated RM reduced the acidity of bio–oil by 51.09%.•Microwave co–pyrolysis with cow dung promoted fixation of heavy metals in RM (>90%).•Fixation of heavy metals in RM through physical adsorption–chemical complexation.•Resource utilization and environmentally friendly treatment of wastes were achieved.
•Methanol addition can effectively reduce the aging rate of bio-oil.•Carbon steel accelerates the viscosity increase rate of bio-oil.•Corrosion of carbon steel in bio-oil increases with methanol ...concentration.•Abnormally high C, O, and N contents are identified on corroded metal surfaces.•Chelation plays a significant role in metal corrosion in bio-oil.
Bio-oil has been considered to be upgraded via co-processing with petroleum intermediates in existing fluid catalytic cracking (FCC) units to produce drop-in fuels. However, the low stability and high corrosivity of bio-oil are two major obstacles preventing further advances in bio-oil upgrading processes. Previously, efforts have been made to improve bio-oil stability through the use of additives, with methanol as a promising candidate. Yet, the effect of these additives on bio-oil corrosivity has not been fully understood. In this study, both the stability and corrosivity of bio-oil with methanol addition are analyzed. Bio-oil was blended with methanol at concentrations of 5–20 wt%. These mixtures were subject to accelerated aging at 50 and 80 °C for up to 168 hours. Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry, and thermogravimetric analysis were conducted to identify functional groups, chemical compounds, and thermal behaviors of bio-oil, respectively. Viscosity, density, water content, and pH were also measured to track the physical and chemical property changes of bio-oil and bio-oil/methanol mixtures during aging. Alongside, immersion experiments with common FCC structural materials such as carbon steel (CS) and stainless steels (SS) 304L and 316L were conducted in bio-oil and bio-oil/methanol mixtures, at 50 and 80 °C for 168 hours. The result of aging experiments showed that the viscosity increasing rate of bio-oil was dramatically lowered by adding methanol, especially at 80 °C, indicating that adding methanol was effective in stabilizing bio-oil. For corrosivity investigation, CS corroded severely in tested bio-oil mixtures. At 50 °C, it was found that CS immersed in bio-oil mixtures with higher methanol concentration corroded at a more significant rate; whereas at 80 °C, the corrosion rate of CS initially increased with methanol concentration in bio-oil and then declined. 304L SS exhibited moderate corrosion rates at 80 °C, while 316L SS showed minimal corrosion at the tested conditions. It has also been observed that CS accelerated the viscosity increasing rate of bio-oil, especially after being aged at 80 °C for 168 hours. After immersion experiments, abnormally high carbon, oxygen, and nitrogen contents were identified on rigorously cleaned metal coupon surfaces. A combination of viscosity measurements and surface characterization suggested that chelation between organic compounds and metal atoms/ions played a significant role in the corrosion of steels in bio-oil. A mechanism was proposed to justify the corrosion behavior of steels in bio-oil/methanol mixtures.
The current study explores the hydrodeoxygenation (HDO) of pine sawdust derived pyrolysis bio-oil and co-processing of raw bio-oil with Vacuum Gas Oil (VGO) in a micro-activity testing (MAT) unit. ...The catalytic performance of mono- and bi-metallic catalysts were tested for bio-oil upgrading. Notably, FeCo (2:1)/Al2O3 catalysts exhibited superior HDO activity compared to their mono-metallic counterparts. Co-processing of raw bio-oil (2–10 wt%) with VGO led to a notable increase in gasoline yield of ∼48% with a 6 wt% blend. Maximum conversion was achieved with 8 wt% blend, further increasing the proportion, conversion decreased significantly affecting the product distribution.
Display omitted
•Pyrolysis of pine sawdust was carried out in a batch reactor.•HDO of pine sawdust bio-oil was carried out with mono- and bi-metallic catalysts.•FeCo (2:1)/Al2O3 exhibited superior HDO of pyrolysis bio-oil.•Co-processing with VGO resulted in high gasoline yield with 6 wt% bio-oil blend.
Display omitted
•The valorization of wood pyrolysis oils in bio-oil-in-oil emulsions is presented.•The interfacial layer in bio-oil-in-oil interfaces formed a solid-like film or “skin”.•The lifetime ...of the emulsion increases due to the evolution of the interfacial layers.•Changes in the dilational elasticity depend on the asphaltenes aggregation behaviour.•Novel applications in marine fuels and for refinery co-processing are envisioned.
This work presents a novel methodology to obtain stable bio-oil-in-oil emulsions using crude oil endogenous asphaltenes as emulsifiers. This approach provides new insights into the valorization of wood pyrolysis bio-oils through co-processing with crude oils or by direct incorporation in fuels for marine transportation, contributing to a significant reduction of the carbon footprint of these products. Similar to water-crude oil systems, asphaltenes can form a rigid film at the bio-oil / petroleum-derived oil interface, thus limiting droplets coalescence and increasing the emulsion lifetime without requiring additional emulsifier. The evolution of the interfacial layers with the asphaltene content and the nature of the petroleum-derived oil phase were investigated by interfacial rheology. The results show the consolidation of the interfacial layer and the formation of a solid-like film, referred to as “skin” with appropriate asphaltene content and polarity of the oil phase. Changes in the dilational elasticity depend on the asphaltenes aggregation behaviour according to the Yen-Mullins model, and the mechanisms that account for these phenomena are discussed.
Display omitted
•The suppression of thermal cracking of wax by bitumen is explained.•No synergy due to thermal co-processing bitumen and wax beyond dilution effects.•To integrate bitumen and wax ...visbreaking, use separate coils in a common furnace.
Thermal conversion of bitumen and wax is a specific instance of visbreaking paraffinic (waxy) petroleum residua and comparable to co-pyrolysis of polyolefin plastic with petroleum. Despite the lower thermal cracking rate of wax, the topic remained of interest due to potential benefits for bitumen upgrading to enable pipeline transport, such as the self-generation of diluent to reduce viscosity and density, as well as suppression of coking. Visbreaking was investigated at 400 and 450 °C and at severity before and after onset of coking. Wax conversion was expressed in terms solidified wax remaining at ambient conditions and wax conversion was incomplete at the most severe conditions evaluated, 450 °C and 30 min. The suppression of n-alkane thermal cracking by alkyl aromatics and naphtenoaromatics takes place due to increased probability of free radical chain transfer during propagation by hydrogen transfer to the alkyl radical. This caused thermal conversion of wax to be inhibited by bitumen. At the same time there was no observable benefit related to hydrogen abstraction from the wax by persistent free radicals in the bitumen for the same reason. Despite the high hydrogen-to-carbon ratio of wax, bitumen becomes the hydrogen donor for the cracked products from the wax. Cracked wax reduced the viscosity and density of the thermally converted oil product to lower values than could be obtained with visbreaking bitumen on its own. Little evidence was found that wax suppressed coking or the coking propensity of the thermally converted product. In conclusion, there was no synergy from the co-processing of bitumen and wax, in fact, the opposite was found. The recommended way to integrate an n-alkane-rich co-feed with petroleum in a visbreaker is to make use of separate coils in a common furnace.
•Co-processing is a suitable way to upgrade aldol condensation adducts into biofuels.•Commercial sulfide catalysts can totally deoxygenate up to 10 wt% of aldol condensation adducts.•No significant ...detriment of HDS and HDN efficiencies was observed during co-processing.•Adducts co-processing products (C8 and C13) decreases hydrotreated gas oil density.
Nowadays, supported sulfide transition-metal-based catalysts (Mo, CoMo and NiMo) are the most used hydrotreating catalysts. However, hydrotreating oxygen compounds derived from biomass means a challenge due to their deactivation by sulfur leaching. The co-processing approach could be a compromise solution, as it was for the hydrotreating of other oxygen compounds, such as triglycerides. The present work reports the use of four types of commercial sulfide catalysts (Mo/Al2O3, NiMo/Al2O3, CoMo/Al2O3 and CoMo/TiO2) for the co-processing of furfural-acetone aldol condensation adducts (FAA: 5–10 wt%) with atmospheric gas oil and isopropanol as co-solvent. The experimental tests were carried out in a fixed bed reactor at industrial operating conditions (T = 320 °C, WHSV = 0.5 h−1, P = 5.5 MPa). The conversion of FAA to alkanes did not significantly affect catalyst hydrodesulfurization and hydrodenitrogenation effectiveness (<1.0%). Moreover, C8 and C13 alkanes from FAA co-processing decreased hydrotreated gas oil density. Overall, our results point to the suitability of commercial sulfide hydrotreating catalysts for upgrading biomass-derived compounds to decarbonize current fuels using the existing refinery units.
PDF
