Grape Skin Composting Process to Recycle Food Waste: Kinetics and Optimization

Area of Science:

• Environmental Science
• Microbiology
• Waste Management

Background:

• Composting is a key aerobic method for valorizing organic waste into compost.
• Maintaining critical factors like moisture, temperature, pH, and C/N ratio is vital for compost quality.
• Grape skins present a viable organic waste stream for composting applications.

Purpose of the Study:

• To optimize grape skin composting by investigating the effects of initial moisture content and airflow rate.
• To monitor physicochemical and microbiological changes during the 30-day composting process.
• To determine the kinetics of organic matter degradation and microbial growth.

Main Methods:

• Nine composting trials were conducted with varying initial moisture and airflow rates.
• Physicochemical variables and microbiological activity were monitored throughout the 30-day period.
• Response surface methodology was employed to identify optimal operating conditions.

Main Results:

• All nine composting processes demonstrated efficiency, with significant decreases in organic carbon content and C/N ratio.
• The germination index for all experiments exceeded 80%, indicating non-toxic end products.
• Experiment 3 showed the highest organic carbon reduction (71.57% to 57.31%) and degradation rate (0.0093 1/day).

Conclusions:

• Grape skin composting is an effective waste valorization strategy.
• Optimal conditions for grape skin composting were determined to be 58.15% initial moisture content and 1.0625 L/min airflow rate.
• The resulting compost is non-toxic and suitable for plant use.