Physical modelling of the composting environment: a review. Part 1: Reactor systems

Area of Science:

• * Environmental Engineering
• * Waste Management
• * Biochemical Engineering

Background:

• * Composting reactors are crucial for waste treatment and resource recovery.
• * Understanding heat flux is key to optimizing composting processes.
• * Various reactor designs exist, each with unique thermal characteristics.

Purpose of the Study:

• * To review and categorize laboratory- and pilot-scale composting reactors.
• * To analyze the characteristics and applications of different reactor types.
• * To discuss factors affecting simulation of full-scale composting.

Main Methods:

• * Categorization of reactors based on heat flux management: fixed-temperature, self-heating, controlled temperature difference, and controlled heat flux.
• * Review of existing literature on reactor performance and thermal behavior.
• * Estimation of surface area to volume ratios for experimental and full-scale systems.

Main Results:

• * Fixed-temperature reactors are useful for studying reaction rates but can self-heat.
• * Self-heating laboratory reactors experience significant heat loss; pilot-scale reactors better simulate full-scale conditions.
• * Controlled temperature difference and heat flux reactors can mimic full-scale spatial temperature differentials and wall losses.

Conclusions:

• * Self-heating reactors at pilot scale are suitable for simulating full-scale composting, with methods for estimating insulation provided.
• * Controlled reactors offer better simulation of full-scale thermal conditions in laboratory settings.
• * Further research is needed on wall effects, temperature profiles, heat production, compression, and natural ventilation in composting reactors.