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This study investigated the torrefaction of de-oiled Jatropha seed residue after a two-stage sequential process consisting of mechanical screw pressing and solvent extraction using n-hexane (denoted as JMS). The optimal torrefaction temperature (Tr) and torrefaction time (tr) were determined in the ranges of 260–300 °C and 10–60 min, respectively, so to achieve a better heating value and satisfactory energy densification (ED) with acceptable mass loss. Thermogravimetric analysis was employed to elucidate the thermal decomposition behaviors of JMS. By comparison with the torrefaction of Jatropha seed residue after mechanical oil extraction by screw pressing only (namely, JMET), the results indicated that the ED of the torrefaction of JMS yielding the torrefied product JMST (two-stage product) was higher than that of the torrefaction of JME giving the torrefied product JMET (single-stage product). Further, it was found that JMET contained some tar, which was attributed to a thermal reaction in the residual oil in JME during torrefaction. The tar/oil content of JMET was about 1.0–1.8 wt.% in the determined optimal conditions. Thus, the enhanced recovery of the residual oil is advantageous not only because it allows obtaining more oil from Jatropha seed residue with a positive net energy gain but also because it prevents the formation of tar in torrefied biomass products.

Combined heat and power production from biogas is now playing an important role in energy and resource utilization as well as pollution control in waste water treatment. This research used biogas from the Bali Sewage Treatment Plant in New Taipei City, Taiwan, as a major source of fuel for the electricity generation. A micro gas turbine electricity generator, Capstone CR-30, which possesses a maximum rated power load (PWL) of 30 kW, was equipped to convert biogas into electricity. The biogas is mainly composed of CH4 (56.1 ± 8.0 vol.%), CO2 (25.5 ± 9.8 vol.%), H2 (0.5 vol.%), and H2S (0.99 ± 0.07 ppmv). During the test operation period of the generator, it was found that the thermal efficiency increases from 19.8% to 23.4% kWhe/kWhth, while the electricity generation efficiency (ηEB) also rises from 0.93 to 1.09 kWhe/m3 biogas as the PWL increases from 10 kW to 30 kW. The results indicated that the generator has a better performance with higher PWL. At PWL = 30 kW, the average adjusted concentrations of CO and NOx (adjusted to 15 vol.% O2) emitted from the generator are 86 ppmv and 17 ppmv, respectively. Both are much lower than the emission standards of stationary sources in Taiwan of 2000 ppmv and 150 ppmv, respectively. Thus, PWL of 30 kW was selected in cooperation with biogas inflow = 0.412 m3/min and air/fuel ratio (i.e., air/biogas ratio) = 76.0 vol./vol. for the long-term regular operation. At the above setting conditions for long-term operation, the generator continuously consumed the biogas and provided stable electricity generation at a rate of 19.64 kWhe/h for a 2-year running period. Moreover, the greenhouse gas can be cut off with a rate of 10.78 kg CO2e/h when using biogas as fuel for electricity generation. Overall, this research proves that the application of a micro gas turbine electricity generator not only has promising performance for using biogas but also gives a significant reduction of greenhouse gas emission, which fits the concepts of the circular economy and environmental protection.

This study used the subcritical hydrothermal liquefaction technique (SHLT) in the co- liquefaction of process rejects at a wastepaper-based paper mill (PRWPM) and waste soybean oil (WSO) for the production of biofuels and bio-char material. PRWPM emits complicated waste composed of cellulose, hemicellulose, lignin, and plastic from sealing film. The waste is produced from the recycled paper process of a mill plant located in central Taiwan. The source of WSO is the rejected organic waste from a cooking oil factory located in north Taiwan. PRWPM and WSO are suitable for use as fuels, but due to their high oxygen content, their use as commercial liquid fuels is not frequent, thus making deoxygenation and hydrogenation necessary. The temperature and pressure of SHLT were set at 523–643 K and 40–250 bar, respectively. The experimental conditions included solvent ratios of oil–water, temperature, reaction time, and ratios of solvent to PRWPM. The analysis results contained approximated components, heating values, elements, surface features, simulated distillations, product compositions, and recovery yields. The HHV of the product occurred at an oil–water ratio of 75:25, with a value of 38.04 MJ kg−1. At an oil–water ratio of 25:75, the liquid oil-phase product of SHTL has the highest heating value 42.02 MJ kg−1. Higher WSO content implies a lower heating value of the oil-phase product. The simulated distillation result of the oil-phase product with higher content of alcohol and alkanes obtained at the oil–water ratio of 25:75 is better than the other ratios. Here, the carbon number of the oil product is between C8–C36. The product conversion rate rises with an increase of the WSO ratio. It is proved that blending soybean oil with water can significantly enhance the quality of liquefied oil and the conversion rate of PRWPM. Therefore, the solid and liquid biomass wastes co-liquefaction to produce gas and liquid biofuels under SHLT are quite feasible.

The reduction of high acid value (AV) of inedible jatropha oil (JO) by esterification with isopropanol (IPA), which is a common alcohol solvent waste in Taiwan’s high-tech industry, was studied. The decrease of AV is beneficial for the subsequent transesterification to produce JO biodiesel (i.e., biodiesel of fatty acid isopropyl ester (FAIE)). Acid catalyst (H2SO4) and a novel mixing/emulsion technique using ultrasound irradiation (UI) were applied to promote and facilitate the esterification process. The results showed that increased IPA/oil molar ratio (MIOE) can significantly reduce the AV, kinematic viscosity (KV), density (ρLO), and water content (MW) of esterified JO, while also providing the benefit of enhancing the yield (YF) of biodiesel of FAIE. For example, with MIOE = 5 at esterification temperature (TE) = 394.2 K (393.8–394.7 K), a reduction of AV of 99.25% with YF of 67.15% can be achieved. Free fatty acid (FFA) was reduced from 18.06 wt.% to 0.14 wt.%, indicating 17.92 wt.% out of 18.06 wt.% of FFA was esterified to FAIE. As a result, among the YF of 67.15%, 49.23% (= 67.15 wt.% deducting 17.92 wt.%) was contributed by the transesterification of triglycerides. By esterification of high FFA-containing raw JO with acid catalyst, one can not only avoid saponification, but also reduce the loading of the subsequent alkali-catalyzed transesterification. Moreover, increasing TE from 394.2 to 454.4 K further reduced AV (from 0.27 to 0.084 mg KOH/g) and MW (from 0.27 to 0.043 wt.%), but, on the other hand, it increased KV (from 14.62 to 25.2 mm2/s) and ρLO (from 901.6 to 913.3 kg/m3), while it decreased YF (from 67.15 to 25.84%). In sum, IPA was successfully used as a replacement for methanol in the esterification of JO while UI provided mixing/emulsion along with heating resulting from cavitation for the system.

The pulp industry in Taiwan discharges tons of wood waste and pulp sludge (i.e., wastewater-derived secondary sludge) per year. The mixture of these two bio-wastes, denoted as wood waste with pulp sludge (WPS), has been commonly converted to organic fertilizers for agriculture application or to soil conditioners. However, due to energy demand, the WPS can be utilized in a beneficial way to mitigate an energy shortage. This study elucidated the performance of applying torrefaction, a bio-waste to energy method, to transform the WPS into solid bio-fuel. Two batches of the tested WPS (i.e., WPS1 and WPS2) were generated from a virgin pulp factory in eastern Taiwan. The WPS1 and WPS2 samples contained a large amount of organics and had high heating values (HHV) on a dry-basis (HHD) of 18.30 and 15.72 MJ/kg, respectively, exhibiting a potential for their use as a solid bio-fuel. However, the wet WPS as received bears high water and volatile matter content and required de-watering, drying, and upgrading. After a 20 min torrefaction time (tT), the HHD of torrefied WPS1 (WPST1) can be enhanced to 27.49 MJ/kg at a torrefaction temperature (TT) of 573 K, while that of torrefied WPS2 (WPST2) increased to 19.74 MJ/kg at a TT of 593 K. The corresponding values of the energy densification ratio of torrefied solid bio-fuels of WPST1 and WPST2 can respectively rise to 1.50 and 1.25 times that of the raw bio-waste. The HHD of WPST1 of 27.49 MJ/kg is within the range of 24–35 MJ/kg for bituminous coal. In addition, the wet-basis HHV of WPST1 with an equilibrium moisture content of 5.91 wt % is 25.87 MJ/kg, which satisfies the Quality D coal specification of the Taiwan Power Co. requiring a value of above 20.92 MJ/kg.

Although the main purpose of the torrefaction of biomass is to produce high quality solid bio-fuel, the by-products, including liquid and gas products, are worth investigating to know their effects on the environment and the reusable possibility. Consequently, after torrefying waste bamboo chopsticks (WBCs) for producing solid bio-fuel, the liquid and gas products were examined in this study. The torrefaction target was set to produce torrefied waste bamboo chopsticks (WBCT) retaining about 70 wt %. A proper torrefaction temperature (Tr) and torrefaction time (tr) were found at 563 K and 40 min, respectively, for carrying out the torrefaction in a tubular furnace with carrier nitrogen. These conditions gave a solid yield (YS) of 69 wt % of WBCT relative to the original WBC, and 31 wt % of by-products were produced. The liquid products were composed of water as high as 62 wt %, along with some organic acids. Some medicine components were also found in the liquid products, representing potential medicine applications. During torrefaction, CO, NOx, SO2, and CO2 emissions were largely discharged from 10 to 20 min of torrefaction time. O2, CO2, and H2O are the major compounds in the total gas products collected. Some combustible gases of C1 to C6 hydrocarbons were also produced. Moreover, the gas volume balances were computed and evaluated. The information obtained in this study is useful for the proper design, operation, pollution control, and utilization of the products.

The purpose of this study is to co-sinter washed-fly ash, limestone sludge, stone sludge, and iron-oxide sludge to fabricate 4 types of eco-cement clinkers. The compound raw materials were burned for 2 h at 1400°C to form the eco-cement clinkers, all of which met the toxicity characteristic leaching procedure requirements. The results show that the major components of ordinary Portland cement (OPC), C3S, C2S, C3A, and C4AF, were present in the eco-cement clinkers. The compressive strength development indicated that the EcoA pastes were similar to those of commercial OPC products. The compressive strength in the EcoG pastes decreased because of the amount the α-C2S increased. The mercury intrusion porosimetry results showed that the pore volume in the pastes gradually decreased when the curing time increased. Additionally, from the X-ray diffraction results, all the eco-cements produced Ca(OH)2 during hydration, which also increased with curing age. The scanning electron microscopy images of OPC and EcoA pastes showed that the pore volume decreased and the denser structural increased with the curing time increased. In addition, adding higher amounts of 1% washed-fly ash caused to increase the content of α-C2S. The result show that this co-sintered process from 1% washed-fly ash and 99% waste sludge (77% limestone sludge, 19.51% stone sludge and 2.49% iron-oxide sludge) to produce eco-cement with excellent mechanical characteristics. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 964–972, 2015

This study uses different scenarios to evaluate, by means of energy life-cycle assessments (ELCAs), the energy balance of potential gasification technology and limitation boundaries in Taiwan. Rice straw is chosen as the target material in this study because it is the most significant agriculture waste in Taiwan. Energy products include syngas (CO + H2), methane, carbon dioxide and carbon black residue. The scenarios simulate capacities of 50,000–200,000 tons/year. The distances of collection and transportation are calculated by a circular area 50–100 km in diameter. Also, the on-site and off-site pretreatments of rice straw are evaluated. For this optimum scenario case, the average of the total input energy for the assessed systems is about 15.9% of the average output energy; the value of the net energy balance (NEB) is 0.841. Every technological process has positive energy benefits at all on-site scenario cases. As the capacity is increased, the energy consumption required for transportation increases and the values of the energy indicators decrease. According to the limitation boundaries from the tendency model at on-site cases, the suggested transportation distance and treatment capacity are below 114.72 km and 251,533 tons/year, respectively, while the energy return on investment (EROI) value is greater than 1.

This investigation examines the chemical and physical behaviors of waste catalyst (WC), a byproduct of the petroleum refining industry, used as a component of cement-based materials. WC was recycled as a pozzolanic material partially to replace cement to enhance the pozzolanic activity of pastes contained WC. Fourier transformation infrared spectroscopy (FTIR), differential thermal and thermogravimetric analysis (DTA/TGA) and 29Si magnetic angle spinning/nuclear magnetic resonance (29Si MAS/NMR) approaches were adopted to relate both the hydration products of pastes contained WC and the structural features to its cementitious activity. The cementitious activity of WC was evaluated by testing the compressive strength of blended cement pastes. The results demonstrate that the blended cements that contained 10% WC exhibited favorable cementitious activity owing to the formation of C-S-H C-A-H and C-A-S-H materials in the hydration products, and an increase in densification. The substitution of cement by WC would have an additional positive environmental impact because it would permit the recycling of a byproduct of the refinery industry in Taiwan that otherwise would remain in the environment as a waste product. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 353–358, 2014

This study used thermal cracking with hydrogen (HTC) to produce bio-fuel oil (BFO) from jatropha oil (JO) and to improve its quality. We conducted HTC with different hydrogen pressures (PH2; 0–2.07 MPa or 0–300 psig), retention times (tr; 40–780 min), and set temperatures (TC; 623–683 K). By applying HTC, the oil molecules can be hydrogenated and broken down into smaller molecules. The acid value (AV), iodine value, kinematic viscosity (KV), density, and heating value (HV) of the BFO produced were measured and compared with the prevailing standards for oil to assess its suitability as a substitute for fossil fuels or biofuels. The results indicate that an increase in PH2 tends to increase the AV and KV while decreasing the HV of the BFO. The BFO yield (YBFO) increases with PH2 and tr. The above properties decrease with increasing TC. Upon HTC at 0.69 MPa (100 psig) H2 pressure, 60 min time, and 683 K temperature, the YBFO was found to be 86 wt%. The resulting BFO possesses simulated distillation characteristics superior to those of boat oil and heavy oil while being similar to those of diesel oil. The BFO contains 15.48% light naphtha, 35.73% heavy naphtha, 21.79% light gas oil, and 27% heavy gas oil and vacuum residue. These constituents can be further refined to produce gasoline, diesel, lubricants, and other fuel products.

Effects of reaction conditions on the production of alcohols (AOHs) and alkanes (Alk) from CO and H2, which can be obtained from the gasification of biomass, using a molybdenum sulfide (MoS2)-based catalyst of MoS2/γ-Al2O3 were studied. A high-pressure fixed packed bed (HPFPB) was employed to carry out the reaction. The results indicate that the conversion of CO (XCO) and specific production rates of alcohol (SPRAOH) and alkane (SPRAlk) are highly depended on temperature (T). In T = 423–573 K, maximum yield of alcohols (YAOH) and SPRAOH occur at T = 523 K. In the meantime, well performance gives the selectivity of ethanol (SEtOH) of 52.0 C%. For the studies on varying H2/CO mole ratio (MH/C) from 1 to 4 at 523 K, the appropriate MH/C to produce EtOH is 2, giving higher ratios of SPRAOH/SPRAlk and YAOH/YAlk than those with other MH/C. As for varying the total gas flow rates (QG) of 300, 450, 600 to 900 cm3 min−1 tested at T = 523 K and MH/C = 2, the lower QG provides longer reaction time (or gaseous retention time, tR) thus offering higher XCO, however lower productivity. For setting pressure (PST) = 225–540 psi, a supply of higher pressure is equivalent to providing a larger amount of reactants into the reaction system, this thus suggests the use of higher PST should give both higher XCO and productivity. The assessment of the above results indicates that the MoS2/γ-Al2O3 catalyst favors the production of alcohols over alkanes, especially for ethanol. The information obtained is useful for the proper utilization of biomass derived gases of CO and H2.

Blends of biodiesels produced from soapnut oil and high-oleic free fatty acids (FFAs), which are potential non-edible oil feedstocks, were investigated with respect to their fuel properties. The soapnut oil methyl esters (SNME) had satisfactory fuel properties with the exception of its high cold filter plugging point. In contrast, the biodiesel from the FFAs had favorable fuel properties such as a low cold filter plugging point of −6 °C; however, it exhibits poor oxidation stability with an induction period (IP) of 0.2 h. The complementary blend of the SNME and the FFA-based biodiesel at various weight ratios was studied to improve the fuel properties. As a result, the biodiesel blend at a weight ratio of 70:30 can successfully meet all the biodiesel specifications, except the marginal oxidation stability. Furthermore, the effectiveness of N,N’-di-sec-butyl-p-phenylenediamine at the concentration between 100 and 500 ppm on the improvement in the oxidation stability of the biodiesel blend was examined. The relationship between the IP values associated with the consumption of antioxidants in the biodiesel blends was described by first-order reaction rate kinetics. In addition, the natural logarithm of IP (ln IP) at various concentrations of antioxidant presented a linear relation with the test temperature. The IP at ambient temperature can be predicted based on the extrapolation of the temperature dependence relation.

This study examined the effects of additives of potassium carbonate (K2CO3) and zinc oxide (ZnO) on the pyrolysis of waste sunflower-oil cake using a 60 kW pilot-scale plasma torch reactor. The major gaseous products were CO and H2. The productions of CO and CH4 increased while that of H2 decreased with the addition of K2CO3. The use of ZnO reduced while enhanced the formation of CO and H2, respectively. In order to match the appeal of resource reutilization, one can use the waste K2CO3 resulted from the sorption of CO2 with KOH in greenhouse gas control and the waste ZnO obtained from the melting process as additives for the co-pyrolysis of sunflower-oil cake, yielding fuels rich in CO and H2, respectively.

To be a viable alternative, a biofuel should provide a net energy gain and be capable of being produced in large quantities without reducing food supplies. Amounts of agricultural waste are produced and require treatment, with rice straw contributing the greatest source of such potential bio-fuel in Taiwan. Through life-cycle accounting, several energy indicators and four potential gasification technologies (PGT) were evaluated. The input energy steps for the energy life cycle assessment (ELCA) include collection, generator, torrefaction, crushing, briquetting, transportation, energy production, condensation, air pollution control and distribution of biofuels to the point of end use. Every PGT has a positive energy benefit. The input of energy required for the transportation and pre-treatment are major steps in the ELCA. On-site briquetting of refused-derived fuel (RDF) provides an alternative means of reducing transportation energy requirements. Bio-energy sources, such as waste rice straw, provide an ideal material for the bio-fuel plant.

Autoclaving of food wastes (FW) for the resource recovery and reutilization was studied using the pilot plant scale. Experiments were conducted at various temperatures of 408, 428, and 438 K and times of 15 and 60 min. The in-filled steam to the autoclave was supplied by the incineration plant with a gauge pressure of 7 kg/cm2 and a temperature of 443 K or above. The results obtained from the experiments show that the less energy- and time-consuming autoclaving conditions (408 K and 15 min, denoted as Case A408-15) are effective. Comparisons of the properties and characteristics of autoclaved FW (FWA) of Case A408-15 with those of FW are made. The wet bulk volume and wet bulk density of FW A are dramatically reduced to 15.64% and increased to 313.37% relative to those of FW, respectively. This makes the subsequent processing and reuse for FWA more convenient than FW. The autoclaving results in an increase of carbon content and a decrease of nitrogen content, and thus an increase of the C/N ratio of FWA. The contents of sulfur, hemi-cellulose, and cellulose of FWA are also reduced. All these fluctuations are beneficial for making compost or other usages from FWA than FW. The autoclaved liquid product (LA) separated from FWA and liquid condensate (LC) from the released gas possess high COD and TOC. These two liquids can be mixed for use as liquid fertilizers with proper conditioning. Alternatively, further anaerobic digestion of the mixture of FWA, LA, and LC can offer enhanced biogas production for power generation. All these thus match the appeal of sustainable materials management and circular economy. The emitted gas from autoclaving contains no CO and some hydrocarbons. Suitable air pollution control is needed. The results and information obtained are useful for the proper recovery and reuse of abundant food wastes from domestic households and food industries.

In this study, a plasmatron reactor was used for gasifying the waste of distillers grains at different temperatures (773, 873, 973 K) and water flow rates (1, 2, 3 mL min(-1)), which were heated to produce steam. Among all the gas products, syngas was the major component (88.5 wt.% or 94.66 vol.%) with temperatures yielding maximum concentrations at 873 K with a relatively high reaction rate. The maximum concentrations regarding gaseous production occurring times are all below 1 min. With the increase of steam, the recovery mass yield of syngas also increases from 34.14 to 45.47 approximately 54.66 wt.% at 873 K. Water-gas reactions and steam-methane reforming reactions advance the production of syngas with the increase of steam. Furthermore, the water-shift reaction also increases in the context of steam gasification which leads to the decrease of CO(2) at the same time.

This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off-gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas-liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas-liquid contactor. Therefore, the results suggest employing RPBs as ozone-contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs.  2004 Society of Chemical Industry

Oil sludge, if unused, is one of the major industrial wastes requiring treatment from petroleum refinery plants or the petrochemical industry. It contains a large amount of combustibles with high heating values. The treatment of waste oil sludge by burning has certain benefits; however, it cannot provide the useful resource efficiently. On the other hand, the conversion of oil sludge to lower molecular weight organic compounds by pyrolysis not only solves the disposal problem but also has the appeal of resource utilization. The major sources of oil sludge include the oil storage tank sludge, the biological sludge, the dissolve air flotation (DAF) scum, the American Petroleum Institute (API) separator sludge and the chemical sludge. In this study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in northern Taiwan is used as the raw material of pyrolysis. Its heating value of dry basis and low heating value of wet basis are about 10681 kcal kg−1 and 5870 kcal kg−1, respectively. The removal of the moisture from oil sludge significantly increases its heating value. The pyrolysis of oil sludge is conducted by the use of nitrogen as the carrier gas in the temperature range of 380–1073 K and at various constant heating rates of 5.2, 12.8 and 21.8 K min−1. The pyrolytic reaction is significant at 450–800 K and complex. For the sake of simplicity and engineering use, a one-reaction kinetic model is proposed for the pyrolysis of oil sludge, and is found to satisfactorily fit the experimental data. The activation energy, reaction order and frequency factor of the corresponding pyrolysis reaction in nitrogen for oil sludge are 78.22 kJ mol−1, 2.92 and 9.48 × 105 min−1, respectively. For precise use, the two- and three-reaction models are proposed to describe the pyrolysis results. Among the three models proposed, the three-reaction model gives the best fit. These results are very useful for the proper design of the pyrolysis system of the oil sludge under investigation. © 2000 Society of Chemical Industry

Hydrothermal liquefaction (HTL) was employed to transform biomass into bio-oil. Waste bamboo chopsticks (WBC) were utilized as the raw materials of HTL reaction for resolving excessive WBC problem. Effects of temperatures (TC) from 563 to 653 K and K2CO3 catalyst on the yield (YBOAS) of bio-oil (BOAS) obtained as acetone soluble were assessed. As illustrations, for WBC without catalyst at TC of 593 K with reaction time of 30 min, the yield YBOAS reaches only 3.8 wt% with heating value (HBOAS) of 30.9 MJ kg−1, while the addition of catalyst (catalytic HTL, CHTL) with TC at 563 K can lead to evident enhancement of YBOAS to 21.2 wt% with HBOAS of 31.6 MJ kg−1. The yield (YBOCC) of organic C of BOAS with respect to C of dry-ash-free raw WBC for CHTL corresponding to 21.2 wt% of YBOAS is 33.1 wt%. Higher YBOAS and carbon content of BOAS give higher YBOCC and HBOAS, respectively. The results indicate that K2CO3 is an effective catalyst for HTL of biomass of WBC with significant lignin content of 25.5 wt% in dry-basis. Furthermore, the BOAS shows simulated distillation characteristic close to diesel, while is superior to heavy oil and boat oil.