Impact of Different Livestock Manures on the Compost Quality and Greenhouse Gas Emissions during Food Waste Composting

Abstract

Although livestock manure and food waste have emerged to be main issues to cause environmental problems, at the same time, and recycle natural resources, the simultaneous treatment method and impact of two organic wastes are not well understood. In this research, the influence of different types of livestock manures combination on compost maturity, greenhouse gas (GHG) and NH 3 emission was evaluated during food waste composting. Apart from a control treatment (only food waste, OF), three co-composting treatments were conducted: (1) food waste + cow manure (FCM); (2) food waste + swine manure (FSM); and (3) food waste + poultry manure (FPM). An 84-day composting experiment was conducted in 62 L composting chamber. During composting process, changes of methane (CH 4), nitrous oxide (N 2 O), ammonia (NH 3) emissions and compost pile; temperature, pH, nutrient content, etc., were periodically investigated. The co-composting with livestock manures significantly reduced nitrogen losses by NH 3 (11.5-44.2%) and N 2 O (39.1-49.7%) emissions. The lowest NH 3 emission were observed in FSM treatment. The highest CH 4 and N 2 O production was detected in FCM and OF treatment, respectively. The global warming potential (GWP) value was calculated to evaluate overall GHG impact, then FSM showed the lowest GWP value (7.0 kg CO 2 eq. kg-1), which is 109% reduction rate compared to FC (highest GWP, 14.7 kg CO 2 eq. kg-1). Nutrients content such as Ca, Mg, and K of final compost product were increased by 33-76%, 17-76%, 60-90% in livestock manure combination treatments. Germination index was increased in FSM and FPM, compared to OF during composting, and then they could accelerate maturation rate. These results suggested that co-composting with food waste and livestock manures is recommendable to improve compost quality, especially, swine manure was an efficient material to reduce GHG and nitrogen loss by NH 3 for food waste composting.