Renewable Diesel Pretreatment

Fat, Oil, and Grease Cleanup

ARA’s HCU Pretreat has Launched at Montana Renewables

Hydrothermal Cleanup (HCU), US Patent 10,071,322 B2, is ARA’s novel and patented pretreatment process that offers several key advantages over traditional pretreatment processes, producing a clean stream of glycerides and free fatty acid products from lower cost waste feedstocks. HCU consists of a continuous, refinery-friendly, single-step process that utilizes common refinery equipment such as pumps, heat exchangers, and a hot oil furnace or refinery high-pressure steam. The HCU process requires only water, heat, and pressure to remove metals and other inorganics from most common feedstocks.

Utilizing turbulent flow at high temperature and pressure, HCU provides thorough mixing of fats, oils, and greases and water and close contact of the molecules during its short residence time. The single step, continuous process removes metals (including organically bound metals) and other inorganic contaminants while acidulating soaps and hydrolyzing phospholipids into diglycerides and phosphate salts.

The first commercial HCU Pretreat unit has begun production with the pretreated product consistently meeting specifications. Two additional commercial units are scheduled to start up this year which will bring total installed capacity to 60,000 BPD.



HCU is a Pretreatment Process that Utilizes Conventional Refining Process Equipment and Generates No Solid Wastes

  • HCU uses pumps and heat exchangers typical to petroleum refineries
  • HCU is a continuous flow process
  • Feed stock particulate filtering is only necessary to protect pumps
  • Centrifuges are not required for separation of the clean lipid product and water
  • Diatomaceous earth and bleaching clay filtering are not required
  • Activated carbon filtering is not required
  • Effluent water can be treated by conventional wastewater treatment processes

No Mass Loss

  • HCU preserves nearly 100% of the feedstock – including the lipid portion of phospholipids and organically bound chlorides
  • Conventional cleanup technologies lose up to 5% of the feedstock:
    • phospholipids and gums are removed as wastes
    • lipids are lost in spent bleaching clay
    • lipids are lost in spent activated carbon
    • lipids are lost in wastewater emulsions

No equipment modifications required for highly-contaminated feedstocks

  • HCU uses the same process regardless of the level of inorganic content in the feedstock.
  • Operating costs are similar for RBD soybean oil (20ppm inorganics), DCO (50 ppm inorganics), UCO (200-500 ppm inorganics), and brown grease (>1000 ppm inorganics).
  • Conventional technologies require more frequent changes of filter media for higher inorganic content feedstocks.
  • HCU performance has been successfully demonstrated on many challenging feedstocks
    • Distiller’s Corn Oil
    • Used Cooking Oil
    • Animal Fats
    • Non-degummed and Crude Degummed Seed Oils
    • Brown Grease
    • Soapstock
    • Fatty Acid Distillate
    • Phosphatide Gums
    • Algal Oils (up to 70% phospholipids)
    • Blends of the feedstocks above

HCU can be used as a degumming process as it hydrolyzes phospholipids. It can also be used as an acidulation process for converting soaps to clean free fatty acids.

HCU Process Details

The HCU process consists of the following steps:

  1. The renewable feedstock and water are pumped separately at system pressure and then mixed in a static mixer.
  2. The mixture is heated by a feed-effluent heat exchanger and hot oil heater or refinery high-pressure steam.
  3. The mixture is maintained the desired cleanup temperature for about 2 minutes in turbulent flow conditions.
  4. The clean product is then cooled via a feed-effluent heat exchanger and trim cooler.
  5. Pressure is reduced to near ambient.
  6. The clean organic phase and the aqueous phase readily separate using traditional oil-water separation techniques.

HCU Pretreat – Test Results

Crude Soybean Oil
Crude Degummed Soybean Oil
Used Cooking Oil
Distillers Corn Oil
Brown Grease
Brown Grease/Yellow Grease Blend
DCO – UCO – Brown Grease Blend
Carinata Oil, UCO, DCO, Tung Oil, Pongamia Oil, Peanut Oil, Brown Grease Blend
Packers Tallow
Choice White Grease
Poultry Fat

Cutting Edge Renewable Diesel and Biodiesel Pretreatment

Compare to: Crown Iron Works Renewable Diesel Pretreatment • Alfa Laval Biodiesel Pretreatment

For more information, contact Chuck Red at