Nitrogen Conservation in Simulated Food Waste Aerobic Composting Process with Different Mg and P Salt Mixtures: Fid-Bau Portal

Nitrogen Conservation in Simulated Food Waste Aerobic Composting Process with Different Mg and P Salt Mixtures

Li, Yu / Su, Bensheng / Liu, Jianlin / Du, Xianyuan / Huang, Guohe

To assess the effects of three types of Mg and P salt mixtures (potassium phosphate [K₃PO₄]/magnesium sulfate [MgSO₄], potassium dihydrogen phosphate [K₂HPO₄]/MgSO₄, KH₂PO₄/MgSO₄) on the conservation of N and the biodegradation of organic materials in an aerobic food waste composting process, batch experiments were undertaken in four reactors (each with an effective volume of 30 L). The synthetic food waste was composted of potatoes, rice, carrots, leaves, meat, soybeans, and seed soil, and the ratio of C and N was 17:1. Runs R₁–R₃ were conducted with the addition of K₃PO₄/MgSO₄, K₂HPO₄/MgSO₄, and KH₂PO₄/MgSO₄ mixtures, respectively; run R₀ was a blank performed without the addition of Mg and P salts. After composting for 25 days, the degrees of degradation of the organic materials in runs R₀–R₃ were 53.87, 62.58, 59.14, and 49.13%, respectively. X-ray diffraction indicated that struvite crystals were formed in runs R₁–R₃ but not in run R₀; the gaseous ammonia nitrogen (NH₃-N) losses in runs R₀–R₃ were 21.2, 32.8, 12.6, and 3.5% of the initial total N, respectively. Of the tested Mg/P salt mixtures, the K₂HPO₄/MgSO₄ system provided the best combination of conservation of N and biodegradation of organic materials in this food waste composting process.

This environmental technology study is a quick and easy way to reduce solid waste, conserve N, and enhance resource recovery. Moreover, the composting system does not take up much space. Hence, the aerobic composting could be applied to home composting, and the fertile and nutrient composting product will kick-start flower plant, fruit, and vegetable growing to help create a beautiful garden. Additionally, this study could provide a primary experiment for community composting projects that avoids the transport costs and the C emissions involved in hauling away waste and then bringing new compost back from the garden center.