MJ per tonne dry solids estimated by CoolProp water enthalpy plus dry-solids sensible heat at the modeled HTL condition
Docker-Generated Heat Integration Screen
Heat Integration Lab
A thermal and molecular route screen for checking whether municipal sludge HTL can recover enough heat through slurry recuperation, aqueous oxidation, AD/CHP, SCWO fallback, and aqueous hydrogen routes without hiding fouling, corrosion, oxygen, or electric burden.
top modeled route because direct slurry heat recovery is the first thermal proof for wet HTL
selected routes spanning recuperation, aqueous heat, biological heat, hydrogen offset, and baseline utility integration
top marker because aqueous organics can release heat but also drive COD, inhibition, corrosion, and treatment burden
baseline heat recovery
Recuperative slurry heat exchanger
First heat-integration block because wet HTL is not credible without recovering sensible heat from the hot product slurry.
Measure heat-transfer coefficient decay, salt/char deposition, clean-in-place interval, pressure drop, alloy coupons, and product-side phase behavior.
- Heat credit
- 4801.9 MJ/t
- Net external
- 2267.6 MJ/t
- Electric burden
- 6%
- Corrosion
- 48
Pyomo-formulated heat-route selector with deterministic enumeration, recuperator, biogas baseline, aqueous, biological, hydrogen, corrosion, and electricity constraints. The selected package averages 34.3% heat closure and 55.7 corrosion risk across 6 route categories.
Heat marker molecules
Water; Sodium chloride; n-Dodecane
Heat integration has to recover sensible heat or aqueous energy without double-counting hydrogen, ignoring oxygen/electric burden, or hiding corrosion and fouling.
- Top marker
- Acetic acid
- Experiment
- Gross heat duty and recuperator fouling run
Routes are not additive by default. The portfolio is a bench package for finding compatible heat loops, not a claim that every heat credit can be stacked simultaneously.
Current heat decision
Oil yield is not enough unless the thermal loop closes
The modeled gross duty is 6669.3 MJ/t dry solids for a 20 wt% solids feed. Recuperation is mandatory, wet oxidation and SCWO are aqueous treatment candidates with heat credit, and AD/CHP remains the incumbent benchmark. The package keeps electric demand, oxygen service, corrosion, fouling, and downstream hydrotreating heat in the same decision.
MJ/t dry solids for the water fraction; this is why wet-feed heat recovery dominates the energy story.
MJ/t dry solids across selected routes, shown as a portfolio average rather than an additive heat claim.
MJ/t dry solids remaining after each selected route heat credit and electric burden.
Aqueous hydrogen routes are tracked separately so hydrogen value is not double-counted as simple heat.
Selected heat package
Six routes to test before claiming energy-positive sewage fuel
Recuperative slurry heat exchanger
Score 38.3; heat closure 72%; heat credit 4801.9 MJ/t; net external heat 2267.6 MJ/t; corrosion 48. Measure heat-transfer coefficient decay, salt/char deposition, clean-in-place interval, pressure drop, alloy coupons, and product-side phase behavior.
SCWO destruction and heat recovery fallback
Score 35.6; heat closure 44%; heat credit 2934.5 MJ/t; net external heat 6936.1 MJ/t; corrosion 88. Prove salt management, oxygen service, corrosion, pressure safety, heat recovery, PFAS destruction, and continuous uptime.
Continuous wet air oxidation heat loop
Score 35; heat closure 32%; heat credit 2134.2 MJ/t; net external heat 6002.4 MJ/t; corrosion 72. Close oxygen demand, exotherm control, residual acetic acid/phenols, refractory nitrogen, materials, and AD/WRRF downstream response.
HTL aqueous AD plus CHP
Score 32.4; heat closure 20%; heat credit 1333.9 MJ/t; net external heat 6002.4 MJ/t; corrosion 28. Measure methane yield, ammonia inhibition, phenolic and pyridine inhibition, acclimation time, digestate handling, and CHP heat capture.
Aqueous phase reforming hydrogen branch
Score 28.8; heat closure 14%; heat credit 933.7 MJ/t; net external heat 7736.4 MJ/t; corrosion 64. Measure catalyst life, nitrogen/salt tolerance, H2 yield, carbon gas fate, heat demand, and integration with hydrotreating.
Existing biogas boiler/CHP heat sink
Score 28; heat closure 24%; heat credit 1600.6 MJ/t; net external heat 5602.2 MJ/t; corrosion 34. Close digester gas availability, boiler turndown, H2S polishing, seasonal heat demand, export power, and baseline emissions accounting.
Selected experiment package
Experiments convert heat-credit ideas into measured thermal gates
Gross heat duty and recuperator fouling run
Run continuous hot/cold slurry heat exchange while tracking heat-transfer coefficient, pressure drop, salt/char deposition, and clean-in-place interval.
Sets the minimum heat-recovery proof before any HTL route can claim positive energy return.
Wet oxidation calorimetry and COD closure
Measure COD conversion, exotherm, oxygen demand, residual acetate/phenols/N-heterocycles, corrosion coupons, and downstream AD kinetics.
Decides whether aqueous treatment can be a heat asset rather than only a wastewater cost.
ECO/APR hydrogen offset balance
Close COD-to-H2 yield, stack or catalyst life, gas purity, compression, electricity/heat demand, and hydrotreating H2 offset.
Separates valuable H2 offset from thermal heat closure so the model does not double-count aqueous energy.
Aqueous AD/CHP inhibition and methane test
Compare untreated and WAO-polished aqueous phase for methane yield, lag, ammonia/phenol/pyridine inhibition, H2S polishing, and usable CHP heat.
Shows whether the WRRF can recover heat biologically without destabilizing digestion.
SCWO fallback heat and salt-stability test
Measure destruction, heat recovery, salt deposition, oxygen service, pressure safety, PFAS-sensitive residual behavior, and materials exposure.
Keeps high-destruction fallback visible without treating it as the lowest-risk heat solution.
Route ledger
Every heat route is compared against the load it actually offsets and the burden it introduces
Recuperative slurry heat exchanger
- Score
- 38.3
- Heat
- 72%
- Net
- 2267.6
- Risk
- 48
SCWO destruction and heat recovery fallback
- Score
- 35.6
- Heat
- 44%
- Net
- 6936.1
- Risk
- 88
Continuous wet air oxidation heat loop
- Score
- 35
- Heat
- 32%
- Net
- 6002.4
- Risk
- 72
Electrocatalytic H2 and COD offset
- Score
- 33.4
- Heat
- 4%
- Net
- 11204.4
- Risk
- 40
HTL aqueous AD plus CHP
- Score
- 32.4
- Heat
- 20%
- Net
- 6002.4
- Risk
- 28
Aqueous phase reforming hydrogen branch
- Score
- 28.8
- Heat
- 14%
- Net
- 7736.4
- Risk
- 64
Existing biogas boiler/CHP heat sink
- Score
- 28
- Heat
- 24%
- Net
- 5602.2
- Risk
- 34
Hydrotreating offgas and product heat recovery
- Score
- 24.5
- Heat
- 12%
- Net
- 6669.3
- Risk
- 38
Dewatering and feed preheat control
- Score
- 23.4
- Heat
- 16%
- Net
- 6802.7
- Risk
- 36
Low-grade product cooling heat pump
- Score
- 17.9
- Heat
- 18%
- Net
- 9136.9
- Risk
- 18
Category ledger
Heat recovery, aqueous treatment, hydrogen offset, and utility baselines stay on the same scale
- Routes
- 1
- Heat
- 32%
- Net
- 6002.4
- Electric
- 22%
- Routes
- 1
- Heat
- 18%
- Net
- 9136.9
- Electric
- 55%
- Routes
- 1
- Heat
- 72%
- Net
- 2267.6
- Electric
- 6%
- Routes
- 1
- Heat
- 24%
- Net
- 5602.2
- Electric
- 8%
- Routes
- 1
- Heat
- 20%
- Net
- 6002.4
- Electric
- 10%
- Routes
- 1
- Heat
- 16%
- Net
- 6802.7
- Electric
- 18%
- Routes
- 1
- Heat
- 44%
- Net
- 6936.1
- Electric
- 48%
- Routes
- 2
- Heat
- 9%
- Net
- 9470.4
- Electric
- 51%
- Routes
- 1
- Heat
- 12%
- Net
- 6669.3
- Electric
- 12%
Molecular marker ledger
Molecules used to evaluate heat recovery, aqueous energy, and utility burden
Water H2O
- Priority
- 32.6
- Heat
- 100
- Aq
- 20
- Corr
- 20
Acetic acid C2H4O2
- Priority
- 44.7
- Heat
- 20
- Aq
- 84
- Corr
- 48
Phenol C6H6O
- Priority
- 39.5
- Heat
- 12
- Aq
- 82
- Corr
- 30
Pyridine C5H5N
- Priority
- 37.5
- Heat
- 10
- Aq
- 88
- Corr
- 22
Ammonia H3N
- Priority
- 36.8
- Heat
- 8
- Aq
- 90
- Corr
- 28
Methane CH4
- Priority
- 36.9
- Heat
- 18
- Aq
- 34
- Corr
- 6
Carbon dioxide CO2
- Priority
- 20.4
- Heat
- 10
- Aq
- 60
- Corr
- 24
Oxygen O2
- Priority
- 31.3
- Heat
- 10
- Aq
- 72
- Corr
- 78
Hydrogen H2
- Priority
- 36.6
- Heat
- 4
- Aq
- 40
- Corr
- 4
n-Dodecane C12H26
- Priority
- 16.5
- Heat
- 6
- Aq
- 0
- Corr
- 0
Hydrogen sulfide H2S
- Priority
- 20.7
- Heat
- 4
- Aq
- 12
- Corr
- 88
Sodium chloride ClNa
- Priority
- 31.2
- Heat
- 12
- Aq
- 54
- Corr
- 92
Highest heat priorities
Aqueous organics, water, salts, oxidants, and biogas determine whether heat recovery is credible
Acetic acid
refractory COD and wet-oxidation heat-release marker. Heat carrier signal 20; aqueous relief signal 84; corrosion signal 48; source IDs heat-pnnl-wao-2025; heat-wo-model-2025.
Phenol
slow-oxidizing phenolic COD and AD inhibition marker. Heat carrier signal 12; aqueous relief signal 82; corrosion signal 30; source IDs heat-pnnl-wao-2025.
Pyridine
refractory nitrogen marker that can survive partial oxidation. Heat carrier signal 10; aqueous relief signal 88; corrosion signal 22; source IDs heat-pnnl-wao-2025; heat-water-research-2026-review.
Methane
recoverable heat and power carrier from AD or incumbent digesters. Heat carrier signal 18; aqueous relief signal 34; corrosion signal 6; source IDs heat-sequential-ad-2026.
Ammonia
return-load and stripping/biology burden marker. Heat carrier signal 8; aqueous relief signal 90; corrosion signal 28; source IDs heat-sequential-ad-2026; heat-water-research-2026-review.
Hydrogen
hydrotreating demand offset and high-value energy carrier. Heat carrier signal 4; aqueous relief signal 40; corrosion signal 4; source IDs heat-apr-h2-2025; heat-eco-h2-2025.
Water
dominant sensible-heat load in wet HTL feed. Heat carrier signal 100; aqueous relief signal 20; corrosion signal 20; source IDs heat-water-research-2026-review; heat-pilot-energy-2021.
Oxygen
oxidant supply, oxygen service, and compressor burden marker. Heat carrier signal 10; aqueous relief signal 72; corrosion signal 78; source IDs heat-pnnl-wao-2025; heat-wo-model-2025.
Full experiment ledger
Unselected heat routes remain visible as alternatives, not hidden assumptions
Gross heat duty and recuperator fouling run
Urgency 121; route score 30.8. Sets the minimum heat-recovery proof before any HTL route can claim positive energy return.
Wet oxidation calorimetry and COD closure
Urgency 118.7; route score 35. Decides whether aqueous treatment can be a heat asset rather than only a wastewater cost.
ECO/APR hydrogen offset balance
Urgency 113.1; route score 31.1. Separates valuable H2 offset from thermal heat closure so the model does not double-count aqueous energy.
Aqueous AD/CHP inhibition and methane test
Urgency 110.7; route score 30.2. Shows whether the WRRF can recover heat biologically without destabilizing digestion.
SCWO fallback heat and salt-stability test
Urgency 109; route score 35.6. Keeps high-destruction fallback visible without treating it as the lowest-risk heat solution.
Hydrotreating offgas and product-heat integration
Urgency 92.3; route score 24.5. Links biocrude upgrading utility demand to the upstream HTL heat ledger.
heat-water-research-2026-review
Hydrothermal liquefaction of municipal sludge: biocrude production and fuel quality upgrading
2026 review identifying municipal sludge HTL as promising for energy recovery while highlighting upgrading, byproduct, and pilot integration gaps.
Open sourceheat-energy-tea-2026
Techno-economic and life cycle assessment of liquid biofuels from municipal sewage sludge by HTL
2026 TEA/LCA record for continuous municipal sewage sludge HTL followed by hydrotreatment and circular-economy framing.
Open sourceheat-wo-model-2025
Opportunities of coupling hydrothermal liquefaction with wet oxidation
Process-modeling source describing HTL process-water wet oxidation as exothermic treatment with potential HTL heat integration.
Open sourceheat-pnnl-wao-2025
Continuous wet air oxidation of HTL aqueous product from various wet wastes
PNNL continuous WAO work reporting substantial COD reduction, calculated reaction energy release, and improved anaerobic methane kinetics after partial oxidation.
Open sourceheat-frontiers-aq-2025
Integrated process for catalytic upgrading of HTL aqueous phase in the supercritical state
Integrated aqueous-phase upgrading study showing heat recovery can keep incremental energy demand small for some conditions.
Open sourceheat-sequential-ad-2026
Emerging directions in sequential hydrothermal liquefaction and anaerobic digestion
2026 sequential HTL/AD study framing residual liquid digestion, biogas, and sludge-specific inhibition as resource-recovery variables.
Open sourceheat-pilot-energy-2021
Hydrothermal liquefaction of sewage sludge: energy considerations and fate of micropollutants during pilot scale processing
Continuous pilot-scale sewage sludge HTL source evaluating energy efficiency, biocrude yield, and quality.
Open sourceheat-apr-h2-2025
Renewable hydrogen production from HTL wastewater via aqueous phase reforming
Lab-to-pilot APR source for producing renewable hydrogen from HTL wastewater model mixtures.
Open sourceheat-eco-h2-2025
Electrocatalytic oxidation of HTL-derived aqueous phase for on-site wastewater treatment and H2 production
PNNL ECO source reporting a preliminary sewage-sludge HTL-AP balance where COD could cover bio-oil hydrotreating H2 demand with surplus.
Open sourceheat integration should not be promoted until gross heat duty, heat exchanger fouling, oxygen or electricity burden, aqueous COD/TN, corrosion, pressure safety, and product-upgrading heat are measured together. Modeling basis: heat and energy integration screen for municipal sludge HTL on a one tonne dry solids basis. Selected package: Recuperative slurry heat exchanger; SCWO destruction and heat recovery fallback; Continuous wet air oxidation heat loop; HTL aqueous AD plus CHP; Aqueous phase reforming hydrogen branch; Existing biogas boiler/CHP heat sink.