Food Waste Maceration and Thermal Stabilization System

a) Waste Collection and Mechanical Size Reduction

Food waste from galley and catering operations is collected and introduced into a stainless-steel feed hopper. The material is then processed through a twin-shaft low-speed, high-torque macerator.

This stage performs the following critical functions:

• • Reduces particle size to ≤12 mm to improve thermal penetration.
  • Homogenizes heterogeneous food residues.
  • Prevents downstream pump blockages.
  • Improves heat transfer efficiency during pasteurization.
  • Enhances surface area for subsequent biological stabilization.

The maceration stage transforms bulk solid food waste into a pumpable slurry, enabling closed-system handling and minimizing manual intervention.

b) Thermal Pasteurization (Pathogen Reduction Stage)

The macerated slurry is transferred to a jacketed pasteurization vessel equipped with controlled agitation and thermal oil heating.

The thermal treatment cycle is designed to:

• • Raise slurry temperature to ≥70 °C.
  • Maintain minimum hold time of 30 minutes.
  • Ensure temperature uniformity throughout the vessel.
  • Achieve high-level vegetative pathogen inactivation (≥6-log reduction).

Continuous temperature monitoring and automatic timer interlocks ensure regulatory-compliant thermal lethality.

If the temperature drops below the setpoint, the holding timer automatically resets to guarantee treatment integrity.

This stage reduces biological risk and enhances downstream stability while maintaining a controlled and energy-optimized heating profile compatible with marine power systems.

c) Acid-Phase Biological Stabilization

Following pasteurization, the treated slurry is transferred to a dedicated hydrolysis tank maintained at 45–50 °C under controlled mixing conditions.

During this stage:

• Naturally occurring acidogenic microorganisms convert complex organics into simpler soluble compounds.
• Volatile fatty acids (VFAs) are formed.
• Odor-causing compounds are reduced.
• The waste stream becomes more chemically and biologically stable.

This phase does not constitute full anaerobic digestion but provides partial biological conversion sufficient to reduce instability and improve handling characteristics.

d) Effluent Management and Regulatory Handling

Upon completion of stabilization:

• The treated effluent may be transferred to a holding tank for shore reception disposal, or
• Discharged overboard where permitted and certified compliant with applicable discharge standards.