Characterization of food waste from different sources in Hong Kong.

ood waste from different sources or at different generation stages may have different compositional characteristics and is therefore suitable for recycling into different products. To have a better understanding of their chemical composition, five food waste types were collected, namely household kitchen waste (HH), pre-consumption and post-consumption food waste from a hotel (Hpr and Hpo), wet market food waste (WM) and kitchen waste from a Chinese restaurant (CR), and their compositions were assessed monthly for one year. They served as suitable feedstock for various conversion technologies according to their chemical profiles. HH and CR had higher crude protein content (26%) and considerable amount of minerals, making them nutritionally suitable for feeding animals. Pre-consumption food wastes Hpr and WM had more favorable C:N ratios (16.5-17.4) and crude fat contents (4.6-6.5%) as feedstock for composting. Post-consumption food wastes were potential feedstock for the production of biogas and biodiesel because of the higher dry matter (>26%) and fat content (> 13%). The coefficients of variation (CV) in all nutrients analyzed except Ca for post-consumption food wastes ranged 5-37%, which showed lower temporal variability than pre-consumption food wastes (CVs ranged 10-131%). This implies that the composition of post-consumption food waste was relatively less fluctuating and can be considered a more reliable feedstock for food waste conversion.