Thermal Hydrolysis Research Articles

Elucidating the Molecular Mechanisms and Comprehensive Effects of Sludge-Derived Plant Biostimulants on Crop Growth: Insights from Metabolomic Analysis.

The utilization of urban waste for land management plays a crucial role in reshaping material flows between human activities and the environment. Sewage sludge alkaline thermal hydrolysis (ATH) produces sludge-derived plant biostimulants (SPB), which have garnered attention due to the presence of indole-3-acetic acid. However, there remains a gap in understanding SPB's molecular-level effects and its comprehensive impact on crops throughout their growth cycle. In this study, non-targeted and targeted metabolomic approaches are employed to analyze 51 plant hormones and 1,177 metabolites, revealing novel insights. The findings demonstrate that low concentrations of SPB exerted multiple beneficial effects on rice roots, leaves, and the root-soil system, facilitating rapid cell division and enhancing antioxidant defense mechanisms. These results provide a vital foundation for understanding ATH metabolic pathways and advocating for widespread SPB application, offering significant implications for sustainable land management.

Enhanced volatile fatty acids production in thermal hydrolysis pretreatment with constant pH regulation: Effects evaluation and mechanism elucidation

Enhanced volatile fatty acids production in thermal hydrolysis pretreatment with constant pH regulation: Effects evaluation and mechanism elucidation

Optimizing anoxic/oxic intervals in intermittent aeration for STHP-AD filtrate treatment: Restoring partial nitrification and community dynamics in the SPNAD system

Currently, partial nitrification (PN) processes are commonly used to improve efficiency in high ammonia nitrogen wastewaters. However, initiating and restoring damaged PN performance is crucial for optimizing nitrogen removal efficiency without the use of chemical additives. In this study, a simultaneous partial nitrification and denitrification coupled with anammox (SPNAD) sequencing batch biofilm reactor was constructed to treat anaerobic digestion after sludge thermal hydrolysis pretreatment (STHP-AD) filtrate. The PN performance was successfully recovered through optimizing the operation mode of anoxic/oxic alternation within 120 days. Result showed that Nitrosomonas increased from 0.68 % to 3.43 %, while Nitrospira decreased to 0.06 %. The PN recovery also promoted anammox, with the only anammox bacterium of Candidatus Brocadia, detected in the mixing and biofilm sludge of 1.73 % and 1.41 %, respectively. The autotrophic denitrifying bacteria Thermomonas (increasing from 0.47 % to 23.85 %) and Truepera (rising from 2.31 % to 6.54 %) rapidly accumulated. After adjusting to the anoxic/oxic alternation ratio, the hydraulic retention time was shortened from 50 h to 37.5 h, and the oxic time was reduced to half of the initial operation. The PN recovery and anammox enrichment resulted in improving nitrogen removal approximately 20 %. Eventually, the SPNAD system realizes stable and efficient nitrogen removal with the influent nitrogen loading rate of 0.43 kgN/(m3·d), the ammonium removal efficiency of 94.73 ± 3.27 %, and the nitrogen removal efficiency of 72.98 ± 1.27 %. In this study, a new strategy using intermittent aeration while appropriately extending the oxic time was proposed to restore the system’s ability to treat STHP-AD filtrate after PN disruption.

Mechanistic insights into melanoidins-induced hydrophilicity of thermal hydrolyzed sludge and its impact on dewaterability

Although thermal hydrolysis pretreatment enhances disposal efficiency of sludge, it inevitably leads to melanoidins formation, which will negatively impact the subsequent wastewater treatment processes. However, their effect on the dewaterability of thermal hydrolyzed sludge (THS) remains poorly understood. This study aimed to uncover the underlying mechanisms of how melanoidins affecting dewaterability of THS. Using resin-adsorption method to reduce melanoidins content by 50% led to 21% and 6% decreases in capillary suction time and specific resistance to filtration, respectively, and a 14% increase in sludge cake solid content. Conversely, accumulating melanoidins to 200% worsened THS dewaterability, altering surface morphology and reducing floc stability, which increased the content of bound water by 9%. Additionally, a higher melanoidins level increased the hydrophilic components in extracellular polymeric substances while reducing hydrophobic sites and structures. These findings indicate that melanoidins impair THS dewaterability by altering flocs spatial properties and increasing hydrophilic structures and components.

Total Utilization of Components Contained in Coconut Husk by Microwave-Assisted Thermal Hydrolysis and Deep Eutectic Solvent Treatment

Total Utilization of Components Contained in Coconut Husk by Microwave-Assisted Thermal Hydrolysis and Deep Eutectic Solvent Treatment

Correlation between sewage sludge pore structure evolution and water filtration performance: Effect of thermal hydrolysis with or without carbonaceous skeleton-assisted

Municipal sewage sludge contains a high water content and strong hydrophilicity, making mechanical dewatering a critical step in sludge treatment and disposal. To clarify the collapse of filtration channels within the sludge cake under high pressure and to develop more precise targeted conditioning methods, this study focused on the direct correlation between pore structure evolution and sludge dewatering performance. A self-designed online system was used to compare the dewatering processes of raw sludge, thermal hydrolyzed (TH) sludge, and carbonaceous skeleton-assisted thermal hydrolyzed (CSkel-TH) sludge. In-depth analysis was conducted on the structure scanning data of the filter cake at different time intervals and the corresponding filtrate mass data. The results showed that during the press filtration process, the raw sludge gradually transformed into a filter cake, with larger pores trapping the water. In the upper and bottom layers, regions with a porosity higher than 10 % appeared, forming a “water-locking layer” even with continued pressure, it became impossible to remove additional water. After separate hydrolysis, the porosity and pore connectivity of the sludge decreased, and the thickness of the “water-locking layer” increased as press filtration progressed, inhibiting water discharge and making cake formation difficult. Following CSkel-TH treatment, the number of pores with diameters ranging from tens to over a hundred micrometers increased, and the connectivity between pores was enhanced. In this case, the channels formed by interconnected small pores continuously transported the water trapped in the large pores outward, facilitating water discharge. This work provided a basis for further targeted regulation of pore structures to enhance the effectiveness of high-pressure dewatering of sludge.

Sludge-derived biostimulants promote glycosylation of tricin and luteolin in the flavone and flavonol biosynthesis to enhance anti-inflammatory activities of rice

Alkaline thermal hydrolysis of sewage sludge produces nutrients and biostimulants that enhance plant growth, attracting considerable interest in agriculture. However, the metabolic differences and regulatory mechanisms of sewage sludge-derived biostimulants (SS-BS) on the phenotypic traits, nutritional quality, and safety indicators of harvested crops remain unclear. This study investigates the impact of SS-BS on rice quality on an agricultural production scale. The research reveals that rice treated with SS-BS complies with safety standards comparable to premium rice. SS-BS significantly enhances nutrient enrichment in the endosperm, increasing protein, vitamin B1, dietary fiber, and vitamin E content by 7%, 7.2%, 23.2%, and 42.2%, respectively. Furthermore SS-BS upregulates the FG2 gene,leading to increased Nictoflorin content and activation of the gene expression of UGT73C6 and CYP75A, which catalyze O-glycosylation and promot glycosyl transfer. By inhibiting the synthesis of Trifolin, Scolymoside, and Swertiajaponin, SS-BS favors the synthesis of glycosylated derivatives of Tricin and Luteolin, which exhibit higher anti-inflammatory activity. Additionally, two novel genes, novel.2100 and novel.1300, and an uncharacterized gene, LOC9269295, are closely associated with the production of anti-inflammatory and antioxidant compounds. This study provides new evidence for SS-BS application and insights into their regulatory mechanisms affecting crop quality, contributing to the development of functional foods and sustainable agriculture.

Understanding the impact of pre-digestion thermal hydrolysis process on PFAS in anaerobically digested biosolids

Per- and poly-fluoroalkyl substances (PFAS) present in biosolids are influenced by their source, treatment processes, and the dynamics of water resource recovery facilities (WRRF). Understanding these effects is vital for informed decisions in treatment process selection, however, comprehensive studies are sparse. This study examined the impact of anaerobic digestion (AD) and the addition of a thermal hydrolysis process (THP) before AD on PFAS in the solids stream at a WRRF. Targeted analysis of 58 PFAS (linear and branched) and suspect screening of the solid stream before and after AD as well as THP, with the total PFAS (ΣPFAS) concentrations ranging between 244 and 566 μg/kgdw. Precursor and intermediate PFAS, mainly di-substituted polyfluoroalkyl phosphate esters (diPAPs) followed by fluorotelomer carboxylic acids (FTCAs), were the dominant contributors (62–96 mol % ΣPFAS) in all 5 sample types. AD impacts were observed both before and after deploying THP altering the relative contribution of different PFAS classes through biotransformation, with an increase in PFCAs and a decrease in diPAPs. However, we observed that THP reduced the % of precursor conversion as well as conversion of the FTCA intermediates in the AD process as evidenced by a substantial increase in FTCAs post-THP + AD and lower PFCA generation compared to AD only. Total PFAS organofluorine (∑FPFAS) decreased by 28% pre- and post-AD, which on total fluorine (TF) showed a larger reduction to 43%. Fluoride was <3% of the TF in all cases, thus, the greater reduction in TF vs ∑FPFAS could be volatile losses of PFAS and other non-PFAS F-containing molecules. After THP installation, a 32% decrease in (∑FPFAS) was observed in the combined THP-AD system whereas adjusted total organofluorine increased by ∼43%. Overall, achieving higher solids handling capacity and energy neutrality with the THP addition did not lead to a significant difference in quantifiable PFAS concentrations compared to AD-only.

Comprehensive analysis of the relationship between yield stress and dewatering performance in sludge conditioning: Insights from various treatment methods

Understanding the relationship between sludge yield stress (σy) and dewatering performance is essential for optimizing sludge conditioning processes. This study systematically investigates the effects of various conditioning methods—including thermal hydrolysis (TH), freezing/thawing (FT), anaerobic digestion (AD), polyaluminum chloride (PAC), polyacrylamide (PAM), and Fenton treatment (Fenton)—on sludge yield stress and its correlation with dewatering efficiency. Using linear regression, partial least squares regression (PLSR), and correlation heatmap analyses, we reveal significant variations in the correlation between σy and dewatering indexes, including moisture content (Mc), capillary suction time (CST), and bound water proportion (Wb/Wt), depending on the conditioning method and intensity. Under FT and PAM conditioning, σy shows a strong negative linear correlation with dewatering performance, with Pearson's r values exceeding −0.880, indicating that a decrease in σy corresponds to improved dewatering efficiency. Conversely, AD conditioning exhibits a positive linear correlation, with r values up to 0.993, suggesting that an increase in σy correlates with reduced dewatering efficiency. For TH, PAC, and Fenton treatments, the correlation between σy and dewatering metrics is highly sensitive to changes in treatment intensity. In the PLSR analysis, the VIP values, which quantify the importance of each predictor variable, indicate that Wb/Wt in TH conditioning (VIP = 1.649) and CST in PAC (VIP = 1.309) and Fenton (VIP = 1.299) conditioning strongly influence σy. This study highlights the significant impact of conditioning methods and intensities on the correlation between σy and dewatering performance. While σy provides valuable insights as a predictive indicator, its predictive power is limited in more complex conditioning scenarios. Therefore, optimizing conditioning intensity and incorporating multiple rheological parameters are essential for achieving superior sludge dewatering outcomes.

Saccharification of fructans and simultaneous alcoholic fermentation for sustainable production of agave distillates

ABSTRACT In a world where climate change and sustainability are at the forefront, innovative solutions are more pressing than ever. In the production process of distillates, the critical stage is the cooking of agave for thermal hydrolysis of fructans. This stage determines the efficiency of the process, incurs the highest production cost, and has a detrimental impact on the environment. In this study, we investigate the saccharification of agave fructans in fresh juice using fructanases produced in situ by Kluyveromyces marxianus as an alternative to traditional agave cooking. furthermore, we explore both sequential and simultaneous alcoholic fermentation processes using a native mixed culture to improve the overall yield and obtain a distillate with enjoyable sensory characteristics. The results show that saccharification and simultaneous fermentation allow for obtaining a fermented product containing an average of 7% alcohol. Gas chromatography and mass spectrometry analysis shows that the distillate is essentially an ethanol – water mixture with a broad profile and high concentration of volatile compounds. The composition of the distilled product provides a well-balanced sensory experience that is highly valued by consumers. Hence, for the first time, a novel, efficient, low-cost, and sustainable process for producing agave distillates has been successfully designed.

The interaction between sludge and microplastics during thermal hydrolysis of sludge

In municipal wastewater treatment plants (WWTPs), large number of microplastics (MPs) accumulated in wastewater migrated into sludge. Thermal hydrolysis of sludge (THS) was one of the most promising processes for promoting changes in molecular structure of MPs. The physicochemical properties and degradative pathways of polyethylene (PE) and polyethylene terephthalate (PET) in THS under different temperatures were studied in this paper. It was found that there was a mutual promotion relationship between sludge degradation and MPs aging. The presence of PE and PET MPs not only increased organics and nitrogen concentrations of sludge filtrate, but also enhanced the transformation of organics like proteins. Sludge accelerated the aging of PE and PET MPs. The friability of PE and PET MPs was increased with more surface fragmentation and breakage under the temperature of 120 ℃−180 ℃. Moreover, PE and PET MPs occurred thermal oxidation and reduction reactions with significant chemical structure changes at 160 °C and 140 °C, respectively. Pristine PE and PET had multiple carbon and oxygen active sites. During THS reaction, not only PE and PET reacted hydrolysis/decomposition to produce short-chain hydroxyl-terminated compounds, but also hydrothermal shear broke the polymer molecules and formed carboxyl-terminated and olefin-terminated low-carbon chains. This study provided some promising sign for in situ microplastic removal during sludge treatments.

Impact of thermal hydrolysis on VFA-based carbon source production from fermentation of sludge and digestate for denitrification: experimentation and upscaling implications

Stricter nutrient discharge limits at wastewater treatment plants (WWTPs) are increasing the demand for external carbon sources for denitrification, especially at cold temperatures. Production of carbon sources at WWTP by fermentation of sewage sludge often results in low yields of soluble carbon and volatile fatty acids (VFA) and high biogas losses, limiting its feasibility for full-scale application. This study investigated the overall impact of thermal hydrolysis pre-treatment (THP) on the production of VFA for denitrification through the fermentation of municipal sludge and digestate. Fermentation products and yields, denitrification efficiency and potential impacts on methane yield in the downstream process after carbon source separation were evaluated. Fermentation of THP substrates resulted in 37–70 % higher soluble chemical oxygen demand (sCOD) concentrations than fermentation of untreated substrates but did not significantly affect VFA yield after fermentation. Nevertheless, THP had a positive impact on the denitrification rates and on the methane yields of the residual solid fraction in all experiments. Among the different carbon sources tested, the one produced from the fermentation of THP-digestate showed an overall better potential as a carbon source than other substrates (e.g. sludge). It obtained a relatively high carbon solubilisation degree (39 %) and higher concentrations of sCOD (19 g sCOD/L) and VFA (9.8 g VFACOD/L), which resulted in a higher denitrification rate (8.77 mg NOx-N/g VSS∙h). After the separation of the carbon source, the solid phase from this sample produced a methane yield of 101 mL CH4/g VS. Furthermore, fermentation of a 50:50 mixture of THP-substrate and raw sludge produced also resulted in a high VFA yield (283 g VFACOD/kg VSin) and denitrification rate of 8.74 mg NOx-N/g VSS∙h, indicating a potential for reduced treatment volumes. Calculations based on a full-scale WWTP (Käppala, Stockholm) demonstrated that the carbon sources produced could replace fossil-based methanol and meet the nitrogen effluent limit (6 mg/L) despite their ammonium content. Fermentation of 50–63 % of the available sludge at Käppala WWTP in 2028 could produce enough carbon source to replace methanol, with only an 8–20 % reduction in methane production, depending on the production process. Additionally, digestate production would be sufficient to generate 81 % of the required carbon source while also increasing methane production by 5 % if a portion of the solid residues were recirculated to the digester.

The role elucidating of EPS in thermal hydrolysis and nitrogen conversion of sewage sludge during hydrothermal carbonization process, and its effect on hydrochar's properties

Hydrothermal carbonization (HTC) was conducted to observe the effect of extracellular polymeric substances (EPS) structure on the nitrogen migration mechanism during the HTC process. The denitrification efficiency of activated sewage sludge (ASS) decreases with an increase in EPS stripping intensity. Loosely and tightly bound extracellular polymers diminish the denitrification effectiveness by inhibiting the hydrolysis of nitrogen-containing organic compounds and protecting the cell structure, respectively. Intracellular nucleic acids and proteins generate stable N-containing species, such as heterocyclic-N and quaternary-N, which are unfavorable for deep denitrification. In general, nitrogen removal is more effective outside the cell than inside. Deep destruction of EPS eliminated a considerable number of N-containing components, and the N/C value of hydrochar at 180 °C without cell membrane protection was 0.06, which dropped to half that of ASS (0.11). This study revealed the influence of EPS structure on nitrogen migration in hydrothermal environment and provided significant insights for the preparation of clean solid fuels.

Thermodynamics and explainable machine learning assist in interpreting biodegradability of dissolved organic matter in sludge anaerobic digestion with thermal hydrolysis

Dissolved organic matter (DOM) is essential in biological treatment, yet its specific roles remain incompletely understood. This study introduces a machine learning (ML) framework to interpret DOM biodegradability in the anaerobic digestion (AD) of sludge, incorporating a thermodynamic indicator (λ). Ensemble models such as Xgboost and LightGBM achieved high accuracy (training: 0.90–0.98; testing: 0.75–0.85). The explainability of the ML models revealed that the features λ, measured m/z, nitrogen to carbon ratio (N/C), hydrogen to carbon ratio (H/C), and nominal oxidation state of carbon (NOSC) were significant formula features determining biodegradability. Shapley values further indicated that the biodegradable DOM were mostly formulas with λ lower than 0.03, measured m/z value higher than 600 Da, and N/C ratios higher than 0.2. This study suggests that a strategy based on ML and its explainability, considering formula features, particularly thermodynamic indicators, provides a novel approach for understanding and estimating the biodegradation of DOM.

Enhanced biohydrogen production from thermally hydrolysed pulp and paper sludge via Al2O3 and Fe3O4 nanoparticles

The growing demand for sustainable and green energy sources has led to increasing interest in biohydrogen production from renewable biomass feedstocks. In this study, pulp and paper sludge (PPS), a widely available waste residue, was thermally treated at different temperatures (90°C, 130°C, and 165°C) for varying durations (15, 30, and 60 min). Thermal hydrolysis of PPS increased the chemical oxygen demand (COD) solubilization from 11 % to 24.7 %, and volatile suspended solids (VSS) solubilization up to 15 % with increasing both hydrolysis temperature and reaction time. The resulting thermally treated samples were then evaluated for biohydrogen production through a batch assay. Among the different thermal treatment conditions, the sample treated at 165°C for 60 min exhibited the highest biohydrogen production potential and yield (1287 mL-H2 and 201 mL-H2/g volatile solids (VS)), which is 72 % higher the control untreated PPS (747 mL-H2 and 117 mL-H2/gVS). To further enhance the biohydrogen yield, this optimal sample was mixed with two types of chemically synthesized nanoparticles, namely aluminium oxide (Al2O3) and magnetite (Fe3O4), at various concentrations (50, 100, and 200 mg/g VS). The addition of nanoparticles significantly influenced the biohydrogen production from the thermal-treated PPS. Remarkably, the batch assay mixed with 200 mg of Fe3O4 nanoparticles per gram of VS demonstrated the highest biohydrogen production potential, compared to the thermally treated PPS (1577 vs. 1226 mL-H2). This finding suggests that the presence of Fe3O4 nanoparticles enhances the biohydrogen production process, possibly through improved microbial activity and substrate accessibility. The results of this study highlight the potential of utilizing PPS, an abundant waste product, as a valuable feedstock for biohydrogen production. Overall, this study contributes to the advancement of green energy technologies and underscores the potential of biohydrogen as a renewable and sustainable energy source.

Enhancing methane production in anaerobic digestion of waste activated sludge by combined thermal hydrolysis and photocatalysis pretreatment

Thermal hydrolysis (TH) is promising for sludge pretreatment, but the refractory substances generated at high temperatures inhibit anaerobic digestion. In this study, a novel combined TH and photocatalytic pretreatment method was proposed to improve the anaerobic digestion performance of waste activated sludge. The results showed that the combined pretreatment (170 °C, 0.5 g/L TiO2) increased methane yield by 66 % from 111 ± 5 m L/g VS to 185 ± 5 m L/g VS. After TH pretreatment, photocatalysis further promoted sludge solubilization by destroying extracellular polymeric substances, resulting in an increase in released soluble organic matter from 292 ± 16 mg/L to 4,091 ± 85 mg/L. In addition, photocatalysis improved the biodegradability of sludge by reducing the melanoidin and humic acid contents by 26 % and 20 %, respectively. The proposed novel pretreatment method effectively overcomes the bottleneck of TH technology and provides an alternative pretreatment technology for improving sludge resource recovery.

Controllable synthesis of TiO2/graphene composites for human voice recognition in strain sensor.

Low-dimensional materials have demonstrated strong potential for use in diverse flexible strain sensors for wearable electronic device applications. However, the limited contact area in the sensing layer, caused by the low specific surface area of typical nanomaterials, hinders the pursuit of high-performance strain-sensor applications. Herein, we report an efficient method for synthesizing TiO2-based nanocomposite materials by directly using industrial raw materials with ultrahigh specific surface areas that can be used for strain sensors. A kinetic study of the self-seeded thermal hydrolysis sulfate process was conducted for the controllable synthesis of pure TiO2 and related TiO2/graphene composites. The hydrolysis readily modified the crystal form and morphology of the prepared TiO2 nanoparticles, and the prepared composite samples possessed a uniform nanoporous structure. Experiments demonstrated that the TiO2/graphene composite can be used in strain sensors with a maximum Gauge factor of 252. In addition, the TiO2/graphene composite-based strain sensor showed high stability by continuously operating over 1,000 loading cycles and aging tests over three months. It also shows that the fabricated strain sensors have the potential for human voice recognition by characterizing letters, words, and musical tones.

Self‐Assembly of MnS Shell on CdTe Nanoparticles Induced by Thermohydrolysis: Synthesis and Characterization

Herein, CdTe/MnS core/shell nanoparticles dispersed in an aqueous solution have been synthesized. The formation of MnS semiconductor shell occurs by spontaneous self‐assembly. This process is activated by thermal hydrolysis that removes the excess of thiol and releases S2− ions. In this process, Mn2+ ions on the surface of the CdTe nanoparticles bind to S2− ions to produce a fine semiconducting layer of MnS. Measurements of Raman spectroscopy, optical absorption, and electrochemical measurements are performed. The Raman spectrum shows CdTe characteristic bands at 141 and 163 cm−1. Bands at 221 and 444 cm−1 are associated with the MnS structure. Cyclic voltammetry and differential pulse voltammetry are used to estimate the electrochemical gap at ≈2.47 eV. Absorption optical measurements show tree absorption bands. A broad band between 460 and 520 nm is associated with the first transition in CdTe nanoparticle. The absorption spectrum reveals an optical gap in the range of 2.41–2.33 eV for all the refluxed samples. These values are consistent with those obtained with the electrochemical measurements. The results evidence the formation of a core–shell semiconducting nanostructure made of CdTe nanoparticles coated with a spontaneously self‐assembled thin layer of MnS nanoparticles.

Stability indicating RP-HPLC method development and validation for the determination of pyrimethamine in an oral paediatric suspension

The aim of this study is to validate a high-performance liquid chromatography (HPLC) – UV assay method for a stability assay of an oral suspension of PYR developed for newborns. Analyses were performed by HPLC with a Kinetex Coreshell C18 column, thermostated at 40°C, coupled to a diode array (λ=230 nm, 280 nm, scan from 190 to 400 nm) with an acetonitrile/methanol/KH2PO4 buffer gradient (pH 3, 10 mM). A forced degradation study was performed to validate the stability-indicating character. PYR was subjected to acidic (pH 2) and basic (pH 12) hydrolysis stress, thermal hydrolysis stress at native pH (60°C and 4°C), H2O2 oxidation stress (3 % and 15 %) and photolysis stress (UV and natural light) at day 0, 3 and 16. Linearity, specificity, precision, and accuracy of this assay method have been tested. Forced degradation tests demonstrated the stability indicator character of the method and showed that PYR was very sensitive to oxidation, sensitive to light (UV) and insensitive to hydrolysis (thermal and pH). The method of quantification was linear, specific, precise, and accurate according to ICH recommendations. A stability study on the formulation under development will be carried out with this HPLC – UV method.

Position-Specific Oxygen Isotope Analysis in Inositol Phosphates by Using Electrospray Ionization-Quadrupole-Orbitrap Mass Spectrometry.

Conventional isotope-ratio mass spectrometry measurements obscure position-specific isotope distributions in molecular compounds because these measurements require an initial step that converts compounds into simple gases by combustion or pyrolysis. Here, we used electrospray ionization (ESI)-based Orbitrap mass spectrometry to measure oxygen isotope ratios in the phosphate and hydroxyl moieties of inositol phosphates. A thermal hydrolysis experiment was conducted using 18O-labeled water to examine the position-specific oxygen isotope exchange in inositol hexakisphosphate (IP6) as well as its hydrolysis products IP5, IP3, and PO3 fragments. Measurement precisions of the position-specific and molecular-average oxygen isotope values of inositol phosphates were better than ±1.1‰ and ±0.5‰, respectively. Under optimized ionization and Orbitrap parameters, this level of precision was obtained within 30 min of run time at 60 μM initial concentration of inositol phosphate. The ability to measure phosphate-specific oxygen isotopes in inositol phosphate enabled the quantification of isotope exchange, which did not occur in phosphate on IP6, IP5, IP3, and PO3 fragments, meaning that the change in isotopes should have resulted from hydroxyls in the ring. Isotope mass balance calculations corroborated that hydroxyl oxygens are derived from 18O-labeled water. With the observed sensitivity and precision achieved in this study, Orbitrap IRMS proved to be a promising tool for investigating the position-specific oxygen isotopes in organophosphorus compounds. These outcomes open up numerous potential applications that can expand our understanding of phosphorus cycling in the environment.