Thirty days of sample intake should describe routine plant operation, not a one-off sludge snapshot.
Sample Intake
Feedstock Intake
A sample intake workspace for deciding whether a wastewater site can provide stable sludge for sewage-to-fuel experiments.
Acceptance window
What must be true before bench testing starts
Solids, volatile solids, ash, COD, nutrients, metals, and inhibitor screens must move together.
Results must map into low, base, and favorable model cases before HTL or AD comparisons are promoted.
Total and volatile solids
Define how much convertible organic material enters the process.
- Target window
- Thirty-day variation should remain inside the modeled feed envelope.
- Method note
- Measure total solids, volatile solids, fixed solids, and moisture on every intake batch.
- Decision use
- Controls HTL reactor loading, heat balance, and conversion-yield normalization.
Ash and metals
Expose inorganic load that can affect fouling, catalyst exposure, residuals, and disposal.
- Target window
- No single metals result should exceed the pilot safety and disposal screen.
- Method note
- Track ash fraction plus iron, aluminum, calcium, phosphorus, sulfur, and priority trace metals.
- Decision use
- Determines solids handling, nutrient recovery potential, and hydrotreating risk.
COD and nutrient profile
Quantify aqueous phase burden before sidestreams return to the wastewater plant.
- Target window
- COD, ammonia, and phosphorus loads must fit the receiving plant return-stream limit.
- Method note
- Measure soluble COD, total COD, ammonia, total nitrogen, orthophosphate, and alkalinity.
- Decision use
- Sets aqueous phase treatment, anaerobic polishing, and permit boundary assumptions.
Biochemical methane potential
Keep anaerobic digestion as a credible reference and hybrid option.
- Target window
- BMP results should be stable enough to compare AD-only, HTL-only, and hybrid cases.
- Method note
- Run BMP on raw sludge and selected HTL aqueous phase fractions.
- Decision use
- Informs avoided baseline emissions, methane credit, and hybrid system design.
Inhibitor and contaminant screen
Identify compounds that could disrupt biology, upgrading, permitting, or product acceptance.
- Target window
- No trigger compound should force unmodeled pretreatment or disposal routing.
- Method note
- Screen for sulfides, chlorine contributors, PFAS indicators, solvent residues, and priority organics.
- Decision use
- Determines risk controls before bench results are promoted into a pilot claim.