The fermentation and drying of manure are essential processes for transforming it into a stable organic fertilizer, free of unpleasant odors and with a high nutrient content.

1. Manure fermentation

Fermentation methods

1.1 Aerobic fermentation (composting)

Description: Takes place in the presence of oxygen through the activity of aerobic bacteria.

Process:

• Manure is placed in piles, platforms, or composting tunnels.
• Aeration is ensured by periodically turning the material.
• The temperature reaches 50–70°C, destroying pathogens and weed seeds.
• The duration is 4–8 weeks.

Advantages:

• ✅ Destroys pathogens and unpleasant odors.
• ✅ Fast and efficient process.
• ✅ Improves soil structure and fertility.

1.2 Anaerobic fermentation (anaerobic digestion)

Description: Occurs in the absence of oxygen and is used for biogas production.

Process:

• Carried out in closed biodigesters.
• The material is decomposed by methanogenic bacteria, producing biogas (CH₄ + CO₂) and digestate (liquid or solid fertilizer).
• The optimal temperature is 35–55°C (mesophilic or thermophilic).
• The duration is 30–90 days.

Advantages:

• ✅ Produces biogas usable for energy.
• ✅ Reduces greenhouse gas emissions.
• ✅ The resulting digestate is a valuable fertilizer.

1.3 Controlled fermentation with effective bacteria (EM – Effective Microorganisms)

Description: Beneficial bacteria are used for rapid and odor-free fermentation.

Process:

• Solutions containing lactobacilli, yeasts, and photosynthetic bacteria are added to the manure.
• Optimal moisture and controlled temperature are maintained.
• A mature compost is obtained in 2–4 weeks.

Advantages:

• ✅ Faster process than classic composting.
• ✅ Reduces ammonia and hydrogen sulfide emissions.
• ✅ Enriches the soil with beneficial microorganisms.

1.4 Thermophilic fermentation

Description: Takes place at high temperatures (50–70°C), rapidly destroying pathogens.

Process:

• Manure is maintained at high temperatures for 7–14 days.
• Requires strict control of aeration and moisture.

Advantages:

• ✅ Very fast process.
• ✅ Eliminates odors and pathogens.
• ✅ Ideal for the production of certified organic compost.

1.5 Cold fermentation (slow decomposition)

Description: A natural process without intervention, carried out at low temperatures.

Process:

• Manure is left to decompose naturally over a long period (6–12 months).
• Aeration is minimal, and the temperature does not exceed 30–40°C.

Advantages:

• ✅ Simple process, with no costs.
• ✅ Better preserves soluble nutrients.
• ✅ Does not require special equipment.

Disadvantages:

• ❌ Long duration.
• ❌ Risk of nitrogen loss through volatilization.

2. Manure drying

Drying is necessary to reduce moisture content and prevent rapid material degradation.

Drying methods

2.1 Natural drying

• Performed by exposure to sunlight on specially designed platforms.
• Requires periodic turning for uniform drying.
• Slower process, affected by weather conditions.

2.2 Mechanical drying

• Uses rotary dryers, conveyor belts with hot air, or fluidized bed dryers.
• Reduces moisture to 10–15%, accelerating the process compared to natural drying.
• Allows production of fertilizer in powder, granule, or pellet form.

Advantages of manure fermentation and drying

• ✅ Eliminates unpleasant odors and pathogens.
• ✅ Reduces volume and weight, facilitating transport and storage.
• ✅ Improves nutritional value, providing a stable and efficient fertilizer.
• ✅ Allows the use of biogas as an energy source in the case of anaerobic fermentation.