Biocrude Yield Research Articles

Hydrothermal liquefaction of microalga with and without seawater: Effects of reaction temperature on yield and hydrocarbon species distribution in biocrude

AbstractA halophytic microalga Tetraselmis sp. biomass diluted with deionized water and seawater was converted to biocrude with the hydrothermal liquefaction (HTL) process in a batch reactor at 310, 330, 350, and 370°C, 15 min with %w/w solids. The biocrude yield, carbon, and energy recovery in biocrude and hydrocarbon species distribution from deionized water base HTL (DW HTL) and seawater base HTL (SW HTL) were evaluated. The results revealed that irrespective of reaction medium, the yield in biocrude increased with an increase in temperature, reaching a maximum of 50–56 wt% at 350°C, characterized by a higher heating value of up to 35.6 MJ/kg. The carbon and energy recovery at 350°C were 85% and 89% respectively, for SW HTL, while the DW HTL stream was 10% and 12% lower. Also, the GC MS analysis of biocrude obtained from both streams contains a complex mixture of compounds such as hydrocarbons, phenolics, and large amounts of nitrogenated and oxygenated compounds. The metallic constituents in biocrudes derived from both steams showed no substantial variations. The study showed a marginal increase in biocrude yield and its HHV with a reduction in oxygen and nitrogen contents from the SW HTL stream, suggesting the potential of seawater as a reaction medium.

Hydrothermal liquefaction of composite household waste to biocrude: the effect of liquefaction solvents on product yield and quality.

The hydrothermal liquefaction (HTL) of composite household waste (CHW) was investigated at different temperatures in the range of 240-360 °C, residence times in the range of 30-90 min, and co-solvent ratios of 2-8 ml/g, by utilising ethanol, glycerol, and produced aqueous phase as liquefaction solvents. Maximum biocrude yield of 46.19% was obtained at 340 °C and 75 min, with aqueous phase recirculation ratio (RR) of 5 ml/g. The chemical solvents such as glycerol and ethanol yielded a biocrude percentage of 45.18% and 42.16% at a ratio of 6 ml/g and 8 ml/g, respectively, for 340 °C and 75 min. The usage of co-solvents as hydrothermal medium increased the biocrude yield by 35.30% and decreased the formation of solid residue and gaseous products by 19.82% and 18.74% respectively. Also, the solid residue and biocrude obtained from co-solvent HTL possessed higher carbon and hydrogen content, thus having a H/C ratio and HHV that is 1.01 and 1.23 times higher than that of water as hydrothermal medium. Among the co-solvents, HTL with aqueous phase recirculation resulted in higher carbon and energy recovery percentages of 9.36% and 9.78% for solid residue and 52.09% and 56.75% for biocrude respectively. Further qualitatively, co-solvent HTL in the presence of obtained aqueous phase yielded 33.43% higher fraction of hydrocarbons than the pure water HTL and 7.70-17.01% higher hydrocarbons when compared with ethanol and glycerol HTL respectively. Nitrogen containing compounds, such as phenols and furfurals, for biocrudes obtained from all HTL processes, were found to be present in the range of 8.30-14.40%.

Effect of thermodynamic models on process modelling and techno-economics for biofuel. A case study using fractional distillation of an algae biocrude

This modelling study highlighted the impact of thermodynamic methods on process modelling results and subsequent technical and economic aspects of biofuel production. Fractional distillation of biocrude derived from thermal liquefaction of algae was modelled using three widely used thermodynamic property methods, namely Peng-Robinson, NRTL and PSRK. Process models revealed differences in mass and energy flows when using different thermodynamic models. Most importantly, for different thermodynamic models, significant variations in the separation of key components were found, affecting the proportion of biofuel fractions. One fraction varied in the amount of key components in the range of 100%–600%. These variations subsequently affected financial parameters. The net present value exhibited a difference of between US$7.8 and US$5.8 million when comparing the Peng-Robinson model to the PSRK model in different scenarios, and US$3.4–4.5 million when comparing PSRK and NRTL. The profitability of biofuel production was most dependent on biocrude yield and algae price. A switch-value analysis resulted in an algae feedstock price of $286.20/t, below which biofuel production becomes profitable. By considering two distinct scenarios characterized by different feedstock prices, the minimum fuel selling price was estimated to be competitive with fossil fuels: US$1.1/L when algae was US$474/t and US$0.5/L when algae was cheaper (US$65/t).

Hydrothermal liquefaction of catering wastes towards biofuel intermediates

AbstractThe potential application of the hydrothermal liquefaction process on catering wastes, spent coffee grounds (SCG) and orange peels, towards reducing municipal wastes was examined in this study, targeting to the production of biofuel intermediates. The study was focused on the two main process parameters, temperature (280–350 °C) and residence time (5–60 min) while the other parameters such as biomass/solvent ratio and applied extractant were selected according to literature. The results indicated that spent coffee grounds are a more promising feedstock, rendering higher bio-crude oil yield than orange peels (34 wt% and 22 wt% respectively). The optimal conditions for each feedstock varied due to their different structural properties, which not only affected the products’ yields but also their quality. To better understand the distribution of the process degradation products and a part of the reaction’s pathway, the gas product was analyzed via GC-FID, and the aqueous phase was studied via HPLC analysis. Finally, the bio-crude oil was subjected to elemental, thermogravimetric, and GC-MS analysis to determine its quality and biofuel potential, based on which the bio-crude oil derived from spent coffee grounds showed promising results while orange peel–derived oil is of lower value. According to the study’s findings, the bio-crude oil can be utilized as a fuel substitute after being upgraded via hydrotreatment enabling the heteroatoms removal and enhancing its fuel properties. Graphical abstract

Application of hybrid multi-criteria decision-making approach to analyze wastewater microalgae culture systems for bioenergy production

Bioenergy generation from microalgae can significantly contribute to climate mitigation and renewable energy production. In this regard, several multi-criteria decision-making method were employed to prioritize appropriate microalgae culture system for bioenergy production. Entropy weight, Criteria Importance Through Intercriteria Correlation (CRITIC) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) were the employed MCDA method. Fourteen microalgae culture systems were selected as a case study, which contain teen monoculture and four dual-culture. Initially, through ans in-depth review of the literature and expert views, four categories total eight indicators were selected as the evaluation indices of the study, namely 1) Proliferation: Half growth cycle and Max growth rate,2) Biomass output: Bio-crude yield and Lipid yield, 3) Nutrient utilization: residual concentration of total Nitrogen and total Phosphorus, and, 4) Stability: coefficient of variation of Bio-crude yield and Lipid yield. The result indicated that "Pediastrum sp. &Micractinium sp." was identified as the most bioenergy potential microalgae culture system, and the evaluation results of entropy weight method and CRITIC method are similar. It is pertinent to note that 1)the entropy weight method exhibits lower sample size requirements, 2) the critic method excels when dealing with larger sample sizes, and 3) the TOPSIS method necessitates the incorporation of appropriate weighting methods to ensure credible results. In the application stage, the key indicators related to cost can be further included in the evaluation indices.

Influence of catalysts on the hydrothermal liquefaction of municipal primary sludge: Upgrading to a higher quality biocrude

Effect of homogeneous and heterogeneous catalysts on hydrothermal liquefaction of primary sludge was studied. Biocrude, biochar, aqueous phase and biogas were all affected, in terms of quantity and quality. HTL without any catalyst attained a biocrude yield of 37.7 % (w/wVS). The best improvements in biocrude yield are observed with CuSO4 (10 %), 42.20 % (w/wVS) and TiO2 (20 %), 41.90 % (w/wVS). All experiments with catalyst produced a biocrude with HHV higher than 30 MJ/kg and with carbon content higher than 60 %. The analysis demonstrated that the major fraction of biocrude were asphaltenes, the heavier phase. While, the light phase, oils, in most of the cases, contained more saturates than polars. Biochar and aqueous phase were recuperated with high organic contents, that enables their usages in further applications. Even though gas fractions were small, their compositions varied between CO, CO2 and hydrocarbons. Catalysts were normally recuperated with the solid phase, except some cases due to their particle sizes. Most of the ashes of primary sludge were transferred to biochar. Some parts of them went to the aqueous phase and biocrude during separation process.

Industrial waste to diesel engines: A novel hydrothermal co-liquefaction approach to produce diesel blendstocks

A mixture of industrial rejects containing textile and chemical wastes were co-liquefied using industrial wastewater at different mixture compositions and temperatures to produce bio-crude. The bio-crude yield from a 75:25 w/w textile:chemical waste was 64.5 wt.% at 325 °C and 30 min, and it was further distilled in 150–350 °C range for diesel blending. The distillate was rich in C13–C24 aliphatic hydrocarbons with H/C mole ratio of 1.86. The bio-crude-diesel blends were tested for their compatibility and efficiency in diesel engines, thus presenting an end-to-end approach from wastes to diesel-range fuels. The blends exhibited similar properties to that of commercial diesel. The 5 vol.% blend of the distillate with commercial diesel exhibited performance and emission characteristics similar to diesel when used in an internal combustion engine. The hydrochars exhibited calorific values between 14 and 32 MJ kg−1, and the aqueous phase contained Na+, K+, Ca2+, Cl–, and SO42– ions.

Effect of the reactor heating rate on bio-crude yield and quality from hydrothermal liquefaction of different sludge

This study scrutinizes the effect of the heating rate obtained in two reactors of different volume (10 mL and 500 mL) on the production of bio-crude during the hydrothermal liquefaction (HTL) process applied to sludges of different nature: a municipal, a paper mill and an agricultural sludge. The effect of the reactor scale on the chemical composition of the bio-crude and the solid residue (co-product of HTL process) is also evaluated by elemental, GC–MS and FT-IR analysis. Results suggest that different heating rates along HTL exert an almost negligible influence on the bio-crude yield and limited effect on the chemical composition when the reaction time under the isothermal conditions is kept at 10 min. In fact, regardless of the heating rate, the bio-crude yields on dry basis from municipal, paper mill and agricultural sludges are equal to 21 %, 21 % and 12 %, respectively. These results could be explained with the different reactive pathway and kinetics of the sludges macro-components.

Influence of reaction parameters on biofuels derived from solvothermal liquefaction of Citrus limetta fruit wastes

Citrus limetta or sweet lime is a widely consumed fruit worldwide. The wastes generated from their processing are enormous and are discarded without any value-addition. Biomass liquefaction in hydrogen-donor solvent is an effective thermochemical conversion technique to produce value added products such as biocrude and biochar from wet biomasses directly. Thus, liquefaction studies of Citrus limetta peel and pulp were conducted using solvent methanol at temperatures of 240 °C–280 °C, 30 min residence time as well as 1:2, 1:3 and 1:4 ratios of biomass to solvent. The impact of temperature as well as biomass to solvent ratio on yield of biocrude and biochar were investigated herein. Biocrude produced from Citrus limetta peel at 240 °C and 1:3 ratio of biomass to solvent is maximum (12.5 wt. %). At reaction parameters of 280 °C and 1:4 ratio of biomass to solvent, biocrude from Citrus limetta pulp showed higher heating value of 27.18 MJ kg−1 which was the maximum obtained in this study. The gas-chromatography mass-spectrometry (GC-MS) indicated presence of alcohols, phenols, alkanes, ketones, ethers, esters and fatty acid methyl esters as major compounds. The characteristics and energy content of biochar demonstrated their potentiality for bioenergy applications.

Hydrothermal co-liquefaction of microalgae, sugarcane bagasse, brewer's spent grain, and sludge from a paper recycling mill: Modeling and evaluation of biocrude and biochar yield

Biomass can be used as an energy source to thermochemical conversion processes to biocrude production. However, the supply and dependence on only one biomass for biocrude production can be an obstacle due to its seasonality, availability, and logistics costs. In this way, biomass waste and agroindustrial residues can be mixture and used as feedstock to the hydrothermal co-liquefaction (co-HTL) process as an alternative to obtaining biocrude. In this sense, the present paper analyzed the biocrude yield influence of the co-HTL from a quaternary unprecedented blend of different biomasses, such as sugarcane bagasse, brewer's spent grain (BSG), sludge from a paper recycling mill (PRM), and microalgae (Chlorella vulgaris). In this way, a simplex lattice design was employed and co-HTL experiments were carried out in a 2000 mL high-pressure stirred autoclave reactor under 275 °C for 60 min, considering 15% of feedstock/water ratio. Significant effects in each feedstock and their blends were analyzed aiming to increase biocrude and biochar yield. It was found that the addition of microalgae is only significant when considered more than 50% into the blend with BSG and PRM sludge to increase biocrude yield.

An integrated energy recovery approach of biohythane-biocrude production from microalgae-sludge through co-digestion and co-liquefaction

Higher energy recovery from wet-waste is a challenging task while considering the waste-to-energy approach to tackle the huge wet-waste biomass generated around the globe. This study took the opportunity to explore the combined approach of biohythane (e.g., bioH2 and bioCH4) and biocrude generation using two-stage anaerobic digestion coupled with hydrothermal liquefaction (TSAD-HTL). The finding of this study suggests that the highest biohythane productivity of 268.7 mL/g-VS with energy recovery of 9.95 MJ/kg-VS was produced from sludge-microalgae co-digestion, which was 17% and 205% higher than mono-digestion of microalgae and sludge, respectively. In addition, the highest biocrude yield of 45.4% was obtained from sludge-microalgae-derived digestate. The lighter fraction (<C20) of biocrude was observed at 91.8 % (20 % naphtha, 58 % jet fuel, and 13 % diesel) with an HHV of 35.85 MJ/kg. The higher energy recovery of 81 % and lower energy consumption ratio of 0.25 suggests that the integrated TSAD-HTL is an innovative energy-positive approach for producing biohythane-biocrude from wet wastes as a sustainable concept of zero waste.

Comparative dynamic optimization study of batch hydrothermal liquefaction of two microalgal strains for economic bio-oil production

This work presents dynamic optimization strategies of batch hydrothermal liquefaction of two microalgal species, Aurantiochytrium sp. KRS101 and Nannochloropsis sp. to optimize the reactor temperature profiles. Three dynamic optimization problems are solved to maximize the endpoint biocrude yield, minimize the final time, and minimize the reactor thermal energy. The biocrude maximization and time minimization problems demonstrated 11% and 6.18% increment in the optimal biocrude yields and reduction of 78.2% and 61.66% in batch times compared to the base cases for the microalgae with higher lipid and protein fractions, respectively. The energy minimization problem revealed a significant reduction in the reactor thermal energies to generate the targeted biocrude yields compared to the biocrude maximization. Therefore, the identified optimal temperature trajectories outperformed the conventional fixed temperature profiles and could improve the overall economics of the batch bio-oil production from the algal-based biorefineries by significantly enhancing the reactor performance.

Exploration of hydrothermal liquefaction of multiple algae to improve bio-crude quality and carbohydrate utilization

With the growing emphasis on biofuels research, enhancing the utilization efficiency of the hydrothermal liquefaction (HTL) process for biomass has emerged as a focal point for researchers. In this study, HTL products from various algae species were analyzed to compare the quality of bio-crude, with a specific focus on the utilization of carbohydrates in biomass. Notably, bio-crude yields from high-lipid algae exhibited less fluctuation with temperature, while the quality showed a significant improvement with increasing temperature, as evidenced by the fatty acids and esters contents in the bio-crude. The results of elemental analysis indicated that bio-crude derived from high-lipid algae had a lower nitrogen content. In the analysis of carbohydrate utilization, it was observed that the aqueous phase products of Chlorella protothecoides demonstrated relatively high yields of furfural and 5-HMF. Similarly, the aqueous phase product of Spirulina exhibited comparatively high yields of levulinic acid. The inclusion of platform compounds in elemental recoveries contributed to an enhancement in the carbon and hydrogen recovery of the product. This study establishes a theoretical foundation for the selection of feedstocks for alternative fuels and highlights the potential of carbohydrates utilization from algal biomass.

Sub-Supercritical Hydrothermal Liquefaction of Lignocellulose and Protein-Containing Biomass

Hydrothermal liquefaction (HTL) is an emerging technology for bio-crude production but faces challenges in determining the optimal temperature for feedstocks depending on the process mode. In this study, three feedstocks—wood, microalgae spirulina (Algae Sp.), and hydrolysis lignin were tested for sub-supercritical HTL at 350 and 400 °C through six batch-scale experiments. An alkali catalyst (K2CO3) was used with wood and hydrolysis lignin, while e (Algae Sp.) was liquefied without catalyst. Further, two experiments were conducted on wood in a Continuous Stirred Tank Reactor (CSTR) at 350 and 400 °C which provided a batch versus continuous comparison. Results showed Algae Sp. had higher bio-crude yields, followed by wood and lignin. The subcritical temperature of 350 °C yielded more biocrude from all feedstocks than the supercritical range. At 400 °C, a significant change occurred in lignin, with the maximum percentage of solids. Additionally, the supercritical state gave higher values for Higher Heating Values (HHVs) and a greater amount of volatile matter in bio-crude. Gas Chromatography and Mass Spectrometry (GCMS) analysis revealed that phenols dominated the composition of bio-crude derived from wood and hydrolysis lignin, whereas Algae Sp. bio-crude exhibited higher percentages of N-heterocycles and amides. The aqueous phase analysis showed a Total Organic Carbon (TOC) range from 7 to 22 g/L, with Algae Sp. displaying a higher Total Nitrogen (TN) content, ranging from 11 to 13 g/L. The pH levels of all samples were consistently within the alkaline range, except for Wood Cont. 350. In a broader perspective, the subcritical temperature range proved to be advantageous for enhancing bio-crude yield, while the supercritical state improved the quality of the bio-crude.

Unravelling the Role of Biochemical Compounds within the Hydrothermal Liquefaction Process of Real Sludge Mixtures

This paper aims to provide a contribution to understanding the role of sludge macro-components (lipids, proteins and carbohydrates) on the yield/quality of bio-crude obtained via hydrothermal liquefaction (HTL). This was pursued by analysing the HTL process of real sludges and the mixtures thereof at different compositions, a topic that has been explored in a very limited way in the pertinent literature. The HTL experiments were run with municipal sludge, tannery sludge and a mixture of them in 25:75, 50:50 and 75:25 weight ratios in a batch reactor at 350 °C and for different residence times. The outcomes for a single sludge showed a greater bio-crude yield for the municipal one (42.5% at 10 min), which is linked to its significant carbohydrate content. The results obtained from the sludge mixtures suggested that a carbohydrate-to-protein mass ratio of 2:1 would maximise the bio-crude yield (average value of about 38%). Moreover, LC-MS and NMR analyses highlighted that the mixed sludges contributed to the formation of a higher number of compounds after the HTL treatment, with respect to the pure municipal or tannery sludge, with an increase in amine, alcohols and aromatic compounds.

Optimization of solvothermal liquefaction of water hyacinth over PTFE-acid mediated kaolin catalyst for enhanced biocrude production

The invasive nature of water hyacinth and the need for renewable energy sources have necessitated this research. Catalyst development through enhanced pore structure and process parameters optimization are requirements for effective mass transport during the biomass valorization and improved biocrude formation during solvothermal liquefaction process. In this present study, the effects of temperature (250–340 °C), residence time (10–20 min) and catalyst loading (10–13 wt%) on biocrude, biochar, gas yield, and biomass conversion were optimized using a Box-Behnken experimental design. The developed catalyst through the application of polytetrafluoroethylene (PTFE) for pore structure enhancement was characterized using SEM, BET and XRD techniques. The process optimization found maximum biocrude yield (32.0 wt%), minimum biochar yield (19.4 wt%) and maximum conversion efficiency (80.6%) at 340 °C, 20 min residence time, and 13 wt% catalyst loading. The GC-MS result of the biocrude produced at the optimum conditions (13 wt% catalyst loading) consists of ketones (32.2%), acids (22.3%) and had 65.2% carbon, 7.3% hydrogen, HHV of 29.4 MJ/kg and H/C ratio of 1.34 while an increment in catalyst loading of 20 wt% enhanced the overall biocrude properties with HHV of 35.50 MJ/kg. This result depicts the suitability of the PTFE modified acid treated kaolin for high quality biocrude production through valorization of water hyacinth into a candidate for renewable energy material.

Integrated biorefinery approach for seaweed Sargassum fusiforme: A step towards green circular economy

This study aims to maximize the utilization of Sargassum fusiforme (SF), embedding the concept of a green circular economy. We developed a green extraction process using water and ultrasound assistance to extract high-value SF polysaccharides (SFPS). A 2k factorial design coupled with center points evaluated the curvature effect in the extraction process. Optimal extraction conditions were identified to be a mass-liquid ratio of 1:59 (w/v), an extraction temperature of 70 °C and time of 88 min, yielding 15.30 wt% SFPS, validated through experiments. SFPS demonstrated significant antioxidant capacity, indicated by their ferric ion reduction ability and superoxide anion scavenging ability. Post-extraction, the waste ethanol solution and SF residue were employed as feedstock for hydrothermal liquefaction (HTL), aiming to produce biocrude oil. We explored various parameters affecting the yield and quality of the resultant biocrude. The optimal HTL conditions for SF residue included a temperature of 280 °C and a reaction time of 45 min. The biocrude obtained using the waste solution exhibited higher carbon content (69.83%) and higher heating value (33.42 MJ/kg) compared to freshwater, indicating enhanced energy recovery (87.65% vs. 15.39%). Also, the presence of ethanol in waste solution facilitated a decrease in fatty acid content from 48.50% to 24.50%, while simultaneously increasing ester content from 6.37% to 35.54%, presumably due to the trans-esterification of fatty acids into esters. Utilizing the waste ethanol solution as HTL processing medium also led to a much lower greenhouse gas emissions (1714.0 kg CO2-eq) compared to that of freshwater (7735.4 kg CO2-eq) as evidenced by the life cycle assessment. This study's innovative approach not only valorizes the waste streams from SFPS extraction but also adds value by generating high-quality biocrude oil, offering practical solutions for waste reduction and resource recovery, fostering sustainable development and circular economy initiatives.

Hydrothermal liquefaction of Chlamydomonas nivalis and Nannochloropsis gaditana microalgae under different operating conditions over copper-exchanged zeolites

In this study, two different green microalgae, Chlamydomonas nivalis (C. nivalis) and Nannochloropsis gaditana (N. gaditana), were cultivated in open ponds and the harvested wet biomass was converted to bio-crude by hydrothermal liquefaction (HTL) with/without catalyst. Catalytic HTL experiments were performed by using copper-exchanged zeolites including Cu-MOR, Cu-ZSM-5, and Cu-SSZ13, synthesized by recently developed supercritical ion exchange method using scCO2. The composition of all bio-crudes was analyzed by elemental analysis and GC/MS. First, the effects of different operating conditions on the yields of the products and the bio-crude composition were determined for non-catalytic process. Temperature, duration, and water/algae biomass ratio in the feed were the process parameters investigated in the ranges of 250–350 ºC, 10–60 min, and 5–20 wt%, respectively. For C. nivalis, 300 ºC, 60 min, and water/algae ratio of 4 were the optimum conditions which led to maximum bio-crude yield of 18.8 wt%, while 300 ºC, 30 min, and water/algae ratio of 9 were the optimum ones for N. gaditana at which the maximum bio-crude yield of 34.0 wt% was observed. Bio-crude yield of N. gaditana was improved using Cu-MOR, while using catalysts for the case of C. nivalis resulted in more gasification with no positive effect on bio-crude yield. Moreover, elemental analysis showed that the fraction of nitrogen and oxygen in biocrude decreased in catalytic HTL runs, in line with the GC/MS results showing that the concentration of hydrocarbons and cyclic compounds increased in the presence of catalysts accompanied by a decrease in concentration of nitrogenous compounds.

Effect of temperature on hydrothermal liquefaction of high lipids and carbohydrates content municipal primary sludge

The study assessed the valorisation of primary sludge through HTL and the influence of temperature on the product distribution. The experiments were conducted at different temperatures, 30 min reaction time, and 100 rpm stirring rate. The maximum yield of biocrude produced was 39.47% at 270 °C. The best yield of oils was 23.96% at 300 °C. The lowest yield of asphaltenes was 12.50% at 240 °C. HHV for biocrude were always between 39 and 41 MJ/kg, close to petroleum. Best energy recovery for biocrude was 82% at 270 °C.

Integration of hydrothermal liquefaction of Cyanophyta and supercritical water oxidation of its aqueous phase products: Biocrude production and nutrient removal

Cyanophyta has the potential to produce biocrude via hydrothermal liquefaction (HTL). However, aqueous phase products (APs), as by-products of HTL, pose a risk of eutrophication for the high levels of carbon, nitrogen, and phosphorus. Supercritical water oxidation (SCWO) can efficiently convert organics into small molecules, offering a technique for the harmless treatment of APs. Effects of holding time, pressure, and moisture content on the biocrude yields from isothermal HTL (300 °C) and fast HTL (salt bath temperature of 500 °C) were comprehensively investigated. Biocrude properties were characterized by elemental analysis, FT-IR and GC–MS. Subsequently, the APs obtained under the conditions producing the highest biocrude yield were subjected to SCWO at 550 °C with different oxidation coefficients (n) from 0 to 2. Removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3−N), and total phosphorus (TP) were further explored. The results show that the highest biocrude yields from isothermal HTL and fast HTL were 24.2 wt% (300 °C, 1800 s, 25 MPa, and 80 wt% moisture content) and 21.9 wt% (500 °C, 40 s, 25 MPa, and 80 wt% moisture content), respectively. The biocrude primarily consisted of N-containing heterocyclic compounds, amides, and acids. SCWO effectively degraded the COD and TP in APs, while the NH3-N required further degradation. At n = 2, the highest removal rates of COD, NH3-N and TP were 98.5 %, 22.6 % and 89.1 %, respectively.