Energy and Nutrients from Apple Waste Using Anaerobic Digestion and Membrane Technology

Area of Science:

• Environmental Science
• Biotechnology
• Waste Management

Background:

• Growing food waste necessitates sustainable management strategies.
• Anaerobic digestion (AD) and nutrient recovery offer promising solutions.
• Valorizing food waste like apple pomace (AP) is crucial for circular economy principles.

Purpose of the Study:

• To evaluate the impact of apple pomace (AP) addition on methane production during anaerobic digestion (AD) with swine manure (SM).
• To assess the efficiency of gas-permeable membrane (GPM) technology for nitrogen (N) recovery from digestates.
• To explore the potential of AP valorization through AD and subsequent nutrient recovery.

Main Methods:

• Co-digestion of swine manure (SM) with varying proportions of apple pomace (AP) (0-30% on a volatile solids basis).
• Measurement of methane production and process stability during anaerobic digestion.
• Application of gas-permeable membrane (GPM) technology for nitrogen recovery from digestates.

Main Results:

• Co-digestion with 7.5% and 15% AP yielded methane production comparable to SM alone.
• Nitrogen recovery rates of 33 and 25.8 g N m⁻² d⁻¹ were achieved using GPM technology on digestates from SM and 7.5% AP co-digestion, respectively.
• Optimal AP inclusion levels were identified for efficient methane generation.

Conclusions:

• Co-digestion of AP and SM is a viable strategy for enhancing methane production.
• Gas-permeable membrane technology effectively recovers nitrogen from digestates, creating bio-based fertilizers.
• This integrated approach offers a sustainable solution for food waste management and nutrient recycling.