Beneficial synergetic effect of feedstock characteristics and reaction conditions on bio crude production from hydrothermal liquefaction of mixed residential waste

Hydrothermal liquefaction(HTL)is a promising method for sustainable waste management and renewable energy production,converting mixed feedstocks into bio-crude,a precursor to various biofuels.A study focused on mixed residential waste(MRW)as an HTL feedstock investigated temperature ranges(280e360℃)and residence times(30e90 min),achieving a maximum bio-crude yield of 39.16%at 340℃and 75 min.Also,a thorough investigation of the synergistic relationships between all subcomponents of the MRW feedstock was conducted and concluded that the mixed waste(MW)feedstock samples containing a higher proportion of food and plastic wastes and MRW sample presented with a coliquefaction percentage(CE)of around 60%and 107%respectively for production of bio crude.Also,solvents such as ethanol,glycerol and aqueous phase(AQ)were tested for their potential as hydrothermal mediums and found that bio crude yield of 46.19%was obtained in case of AQ phase recirculation.Further,the quantitative and qualitative effect of usage of four different catalysts were tested individually and in combination with AQ phase recirculation and found that,although individually nanoporous ZnO and diatomaceous earth(DE)yielded bio crude in the range of 46.86%and 42.68%respectively,when used in combination,DE cateHTL with AQ resulted in maximum bio crude yield of 54.35%.Furthermore,qualitatively,the bio crude from DE cateHTL with AQ presented with a high carbon and energy recovery percentage of 62.20%and 72.95%respectively and a high hydrocarbon content of 58.98%.

Preparation and Characterization of Hydrogel Materials Based on the Hydrothermal Liquefaction of Enteromorpha prolifera

Seaweed,as a third generation of biomass energy,has significant potential to replace non-renewable fossil fuels.Among various conversion technologies,hydrothermal liquefaction can effectively convert seaweed into bio-oil.However,most current research on hydrothermal liquefaction products focuses on the oil phase and solid phase,with little attention given to the utilization of the aqueous phase by-product.In this study,the large seaweed Enteromorpha prolifera was selected as the raw material.The aqueous phase containing organic components was prepared through hydrothermal liquefaction at different temperatures,which was then mixed with the polymer polyvinyl alcohol to produce high-value chemical hydrogels.Furthermore,the hydrogels were salted out with Fe3+to explore its influence on the degree of crosslinking.The results show that the mechanical properties of the hydrogel are optimal when the hydrothermal temperature is 160℃,with a maximum fracture stress of 0.55 MPa.After salting-out treatment,the mechanical strength of the hydrogel was further enhanced,with the maximum breaking stress increment by 1.3 times(1.26 MPa).This indicates that the process of adding the aqueous phase to the hydrogel has research potential,and Fe3+can further strengthen the crosslinking process.The results of the present study will provide new insights and methods for aqueous phase valorization.

Catalytic Hydrothermal Liquefaction of Algae for Production of Bio-oil with Solid Superacid Catalyst SO_(4)^(2−)/ZrO_(2)

Solid superacid SO_(4)^(2−)/ZrO_(2)as heterogeneous catalyst was prepared to upgrade the bio-oil in the progress of hydrother-mal liquefaction(HTL)for the represented algae of Chlorella vulgaris and Enteromorpha prolifera.The solid superacid catalyst could obviously adjust the composition of the bio-oil and improve the higher heating values(HHVs).The catalytic performance could be regulated by adjusting the acid amount and acid strength of SO_(4)^(2−)/ZrO_(2).Furthermore,it was explored the catalytic effects of SO_(4)^(2−)/ZrO_(2)by the HTL for algae major model components,including polysaccharides,proteins,lipids,binary mixture and ternary mixture.The results showed that the introducing of SO_(4)^(2−)/ZrO_(2)catalyst could increase the yields of bio-oil from proteins and lipids,and avoid the Maillard reaction between polysaccharides and proteins.Moreover,a possible reaction pathway and mechanisms has proposed for the formation of bio-oils from HTL of algae catalyzed by SO_(4)^(2−)/ZrO_(2)based on the systematic research of the producing bio-oil from major model components.

Catalytic Hydrothermal Liquefaction of Water Hyacinth Using Fe3O4/NiO Nanocomposite: Optimization of Reaction Conditions by Response Surface Methodology

This research aimed at optimizing the reaction conditions for the catalytic hydrothermal liquefaction (HTL) of water hyacinth using iron oxide/nickel oxide nanocomposite as catalysts. The iron oxide/nickel oxide nanocomposite was synthesized by the co-precipitation method and used in the hydrothermal liquefaction of water hyacinth. The composition and structural morphology of the synthesized catalysts were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic absorption spectroscopy (AAS). The particle size distribution of the catalyst nanoparticles was determined by the Image J software. Three reaction parameters were optimized using the response surface methodology (RSM). These were: temperature, residence time, and catalyst dosage. A maximum bio-oil yield of 59.4 wt% was obtained using iron oxide/nickel oxide nanocomposite compared to 50.7 wt% obtained in absence of the catalyst. The maximum bio-oil yield was obtained at a temperature of 320°C, 1.5 g of catalyst dosage, and 60 min of residence time. The composition of bio-oil was analyzed using gas chromatography-mass spectroscopy (GC-MS) and elemental analysis. The GC-MS results showed an increase of hydrocarbons from 58.3% for uncatalyzed hydrothermal liquefaction to 88.66% using iron oxide/nickel oxide nanocomposite. Elemental analysis results revealed an increase in the hydrogen and carbon content and a reduction in the Nitrogen, Oxygen, and Sulphur content of the bio-oil during catalytic HTL compared to HTL in absence of catalyst nanoparticles. The high heating value increased from 33.5 MJ/Kg for uncatalyzed hydrothermal liquefaction to 38.6 MJ/Kg during the catalytic HTL. The catalyst nanoparticles were recovered from the solid residue by sonication and magnetic separation and recycled. The recycled catalyst nanoparticles were still efficient as hydrothermal liquefaction (HTL) catalysts and were recycled four times. The application of iron oxide/ nickel oxide nanocomposites in the HTL of water hyacinth increases the yield of bio-oil and improves its quality by reducing hetero atoms thus increasing its energy performance as fuel. Iron oxide/nickel oxide nanocomposites used in this study are widely available and can be easily recovered magnetically and recycled. This will potentially lead to an economical, environmentally friendly, and sustainable way of converting biomass into biofuel.

Hydrothermal Liquefaction of Water Hyacinth: Effect of Process Conditions and Magnetite Nanoparticles on Biocrude Yield and Composition

In this work, an efficient way of converting the water hyacinth to biocrude oil using magnetite nanoparticles (MNPs) as potential catalysts was demonstrated for the first time. MNPs were synthesised by co-precipitation and used in the hydrothermal liquefaction (HTL) of water hyacinth at different reaction conditions (temperature, reaction time, MNPs to biomass ratio and biomass to water ratio). The best reaction conditions were as follows: temperature— 320, reaction time—60 minutes, MNPs to biomass ratio – 0.2 g/g and biomass to water ratio – 0.06 g/g. HTL in presence of MNPs gave higher biocrude yields compared to HTL in absence of MNPs. The highest biocrude yield was 58.3 wt% compared to 52.3 wt% in absence of MNPs at similar reaction conditions. The composition of biocrude oil was analysed using GC-MS and elemental analysis. GC-MS results revealed that HTL in presence of MNPs led to an increase in the percentage area corresponding to hydrocarbons and a reduction in the percentage area corresponding to oxygenated compounds, nitrogenated compounds and sulphur compounds. Elemental analysis revealed an increase in the hydrogen and carbon content and a reduction in the nitrogen, oxygen and sulphur content of the biocrude when HTL was done in presence of MNPs compared to HTL in absence of MNPs. The nanoparticles were recovered from the biochar by sonication and magnetic separation and recycled. The recycled MNPs were still efficient as HTL catalysts and were recycled five times. The application of MNPs in the HTL of water hyacinth increases the yield of biocrude oil, improves the quality of biocrude through removal of hetero atoms, oxygen and sulphur compounds and is a potentially economical alternative to the traditional petroleum catalysts since MNPs are cheaper, widely available and can be easily recovered magnetically and recycled. This will potentially lead to an economical, environmentally friendly and sustainable way of producing biofuels from biomass.

Hydrothermal liquefaction of biomass for jet fuel precursors:A review

Climate change is an important issue facing the world today and carbon reduction has become the fo-cus of attention for all countries.Alternative bio-fuels are an important means to achieve carbon emis-sion reduction.The production of jet fuel precursors from biomass by hydrothermal liquefaction(HTL)has received a lot of attention due to its mild conditions and environmental friendliness.Lignocellulosic biomass and algal biomass are considered as the second and the third generation biomasses as promising raw materials for alternative fuel preparation.Among them,lignocellulosic biomass has been extensively studied due to its wide range of sources and can be divided into one-step HTL and stepwise HTL accord-ing to the process method.Algal biomass has been extensively studied experimentally due to its short growth cycle and the fact that it can sequester large amounts of carbon without taking up arable land.In this paper,the feedstock composition of different biomasses is reviewed for the HTL of biomass.A detailed review of the process characteristics,reaction pathways and influencing factors for the HTL pro-duction of jet fuel precursors from lignocellulosic biomass and algal biomass is also presented.Theoretical references are provided for further process optimization and bio-crude quality upgrading.

Effects of strain,nutrients concentration and inoculum size on microalgae culture for bioenergy from post hydrothermal liquefaction wastewater

Cultivating microalgae in post hydrothermal liquefaction wastewater(PHWW)offers many benefits,including nutrients recovery and reuse,wastewater purification and biomass production.However,the high nutrients concentration and toxic substances in PHWW undermine the efficiency of biomass production and nutrient recovery.This study aimed to investigate the effects of the microalgae strains,initial nutrients concentrations and inoculum sizes on biomass production and nutrient recovery using PHWW as the cultivation medium.Results indicated that both biomass production and nutrients recovery were successfully improved by using the screened microalgae strain at the desirable initial nutrient concentration with the suggested algae inoculum size.Chlorella vulgaris 1067 probably demonstrated the strongest tolerance ability among the five microalgae strains screened,and performed well in the diluted PHWW,of which initial TN concentration was approximately 500 mg/L.The desirable inoculum size was determined to be 0.103-0.135 g/L.The biomass daily productivity was increased by 15.67-fold(reached 0.13 g/(L·d)).With the above optimal conditions,high biomass production and nutrient recovery from the PHWW to produce microalgae biomass for bioenergy production were achieved.

Value-addition of water hyacinth and para grass through pyrolysis and hydrothermal liquefaction

Hydrothermal liquefaction(HTL)and pyrolysis(Py)of Loktak lake biomass mixture of water hyacinth(WH)and para grass(PG)were carried out at 260-300℃ and 300-500℃ to compare the products yield and chemical characteristics of the products.In case of HTL,the maximum bio-oil yield was obtained 13.34 wt.%at 280℃ while for Py,the maximum bio-oil yield was observed 38.8 wt.%at 350℃.The obtained bio-oils and bio-chars were analyzed using GC-MS,FT-IR,NMR,TGA,TOC,and SEM.GC-MS analysis of the bio-oils were showed that the HTL bio-oil majorly contains of nitrogen containing compounds whereas the Py bio-oil contains majority of phenolic compounds.Other compounds like ketones,alcohols,acids were also observed in bio-oil.Higher intensity broad band at 3300-3500 cm^(−1) was observed in the Py bio-oil compared to HTL bio-oil.TGA and proximate analysis of bio-char revealed the higher devolatilization occured during the HTL compared to Py process.The surface morphology of the HTL bio-char was found to be rough and fragmented as compared to the pyrolysis bio-char,clearly showing the biomass macromolecules breakdown differently in HTL and Py process.

Nitrogen distribution in the products from the hydrothermal liquefaction of Chlorella sp. and Spirulina sp.

The high contents of nitrogen-containing organic compounds in biocrude obtained from hydrothermal liquefaction of microalgae are one of the most concerned issues on the applications and environment.In the project,Chlorella sp.and Spirulina sp.were selected as raw materials to investigate the influence of different reaction conditions(i.e.,reaction temperature,residence time,solid loading rate)on the distribution of nitrogen in the oil phase and aqueous phase.Three main forms of nitrogen-containing organic compounds including nitrogen-heterocyclic compounds,amide,and amine were detected in biocrudes.The contents of nitrogen-heterocyclic compounds decreased with temperature while amide kept increasing.The effect of residence time on the components of nitrogen-containing organic compounds was similar with that of temperature.However,the influence of solid loading rate was insignificant.Moreover,it was also found that the differences of amino acids in the protein components in the two microalgae might affect the nitrogen distribution in products.For example,nitrogen in basic amino acids of Spirulina sp.preferred to go into the aqueous phase comparing with the nitrogen in neutral amino acids of Chlorella sp.In summary,a brief reaction map was proposed to describe the nitrogen pathway during microalgae hydrothermal liquefaction.

High yield bio-oil production by hydrothermal liquefaction of a hydrocarbon-rich microalgae and biocrude upgrading

A green colonial microalgae Botryococcus braunii was hydrothermally processed under subcritical water conditions without the addition of catalysts,obtaining an oil yield as high as 68%.The higher heating value of liquefaction products is close to that of petroleum crude oil.The oil fraction from Botryococcus braunii liquefaction was specified for the first time,and the liquefaction mechanism was proposed.Due to the high lipid content of Botryococcus braunii,the liquefaction product distribution is quite distinct from other microalgae.The produced biocrudes contain
9%oxygen,with oleic acid as the main source.Amides derived from oleic acid and proteins are the major nitrogenates in the biocrudes.The biocrude was processed using catalytic cracking and hydrotreating.Catalytic cracking mostly produces aromatics,while the majority of hydrotreating products are straight and branched hydrocarbons.The oxygen content in the catalytic cracking products was very low.The presence of amides in the hydrotreating feed changes the reaction pathway from hydrodecarboxylation to hydrodeoxygenation as a result of the competitive adsorption of amides on the active sites for hydrodecarboxylation.Both processes show satisfactory denitrogenation performance.Catalytic cracking displays superior ability than hydrotreating with regards to the removal of oxygen.

Effects of organic strength on performance of microbial electrolysis cell fed with hydrothermal liquefied wastewater

Microbial electrochemical technology has drawn increasing attention for the treatment of recalcitrant wastewater as well as production of energy or value-added chemicals recently.However,the study on the treatment of hydrothermal liquefied wastewater(HTL-WW)using microbial electrolysis cell(MEC)is still in its infancy.This study focused on the effects of organic loading rates(OLRs)on the treatment efficiency of recalcitrant HTL-WW and hydrogen production via the MEC.In general,the chemical oxygen demand(COD)removal rate was more than 71.74%at different initial OLRs.Specially,up to 83.84%of COD removal rate was achieved and the volatile fatty acids were almost degraded at the initial OLR of 2 g COD/L·d in the anode of MEC.The maximum hydrogen production rate was 3.92 mL/L·d in MEC cathode,corresponding to a hydrogen content of 7.10%at the initial OLR of 2 g COD/L·d.And in the anode,the maximum methane production rate of 826.87 mL/L·d was reached with its content of 54.75%at the initial OLR of 10 g COD/L·d.Analysis of electrochemical properties showed that the highest open circuit voltage of 0.48 V was obtained at the initial OLR of 10 g COD/L·d,and the maximum power density(1546.22 mW/m3)as well as the maximum coulombic efficiency(6.01%)were obtained at the initial OLR of 8 g COD/L·d.GC-MS analysis revealed the existence of phenols and heterocyclic matters in the HTL-WW,such as 1-acetoxynonadecane and 2,4-bis(1-phenylethyl)-phenol.These recalcitrant compounds in HTL-WW were efficiently removed via MEC,which was probably due to the combination effect of microbial community and electrochemistry in MEC anode.

Review of the biological and engineering aspects of algae to fuels approach

Current biofuel production relies on limited arable lands on the earth,and is impossible to meet the biofuel demands.Oil producing algae are alternative biofuel feedstock with potential to meet the world’s ambitious goal to replace fossil fuels.This review provides an overview of the biological and engineering aspects in the production and processing technologies and recent advances in research and development in the algae to fuels approach.The article covers biology,selection and genetic modification of algae species and strains,production systems design,culture media and light management,harvest and dewatering,downstream processing,and environment and economic assessment.Despite the many advances made over several decades,commercialization of algal fuels remains challenging chiefly because of the techno-economic constraints.Technological breakthroughs in all major aspects must take place before commercial production of algal fuels becomes economically viable.

Biocrude oil production from Chlorella sp.cultivated in anaerobic digestate after UF membrane treatment

Algae cultivation in animal wastewater could recover nutrient resources,and harvest considerable amount of algae biomass for biofuel conversion.In this study,Chlorella sp.cultivated in ultrafiltration(UF)membrane treated anaerobic digestion effluent of chicken manure was converted into biocrude oil through hydrothermal liquefaction(HTL).The potential of biocrude production from grown Chlorella sp.was studied through changing the operational conditions of HTL,i.e.,holding temperature(HT,250℃-330℃),retention time(RT,0.5-1.5 h),and total solid(TS)(15 wt%-25 wt%)of the feedstock.The highest biocrude oil yield was 32.9%at 330℃,1.5 h and 20 wt%TS.The single factor experiments of HT also suggested that the biocrude oil yield decreased when the temperature was higher than 330℃.There were no significant differences of elemental contents in biocrude samples.The maximum higher heating values(HHV)of Chlorella sp.biocrude was 40.04 MJ/kg at HT of 330℃,RT of 1 h and TS of 15 wt%.This study suggests the great potential for energy recovery from Chlorella sp.cultivated in UF membrane treated anaerobic digestion effluent via HTL.

Temporal changes in the characteristics of algae in Dianchi Lake,Yunnan Province,China

Algal blooms have become a worldwide environmental concern due to water eutrophication.Dianchi Lake in Yunnan Province,China is suffering from severe eutrophication and is listed in the Three Important Lakes Restoration Act of China.Hydrothermal liquefaction allows a promising and direct conversion of algal biomass into biocrude oil.In this study,algal samples were collected from Dianchi Lake after a separation procedure including dissolved air flotation with polyaluminum chloride and centrifugation during four months,April,June,August and October.The algal biochemical components varied over the period;lipids from 0.7%to 2.1%ash-free dry weight(afdw),protein from 20.9%to 33.4%afdw and ash from 36.6%to 45.2%dry weight.The algae in June had the highest lipid and protein concentrations,leading to a maximum biocrude oil yield of 24.3%afdw.Biodiversity analysis using pyrosequencing revealed different distributions of microbial communities,specifically Microcystis in April(89.0%),June(63.7%)and August(84.0%),and Synechococcus in April(2.2%),June(12.0%)and August(1.0%).This study demonstrated remarkable temporal changes in the biochemical composition and biodiversity of algae harvested from Dianchi Lake and changes in biocrude oil production potential.