Anaerobic digestion of food waste for bio-energy production in China and Southeast Asia: A review

Rapid economic growth in Asia and especially in China, will lead to a huge increase of food waste (FW) production that is expected to increase by 278 - 416 million tonnes. Among various waste management practices, anaerobic digestion (AD) is a useful method to transform food waste, producing renewable energy/biofuel and bio-fertilizers. This review aims to investigate some of the key factors in proposing FW for anaerobic digestion, with particular reference to China and South East Asian countries. Food waste showed variable chemical composition and high content of biodegradable material (carbohydrates, protein and lipid) led to consistent biogas production (as potential) that was reported as average for Chinese FW, of 480 ± 88 LCH4 kg-1 VS (n = 42) being this data higher than those for energy crops (246±36 LCH4 kg-1 VS), makes FW a good candidate to substitute energy crops, avoiding food-energy conflict. FW co-digestion with different substrates improved total bio-methane production (on average), i.e. from 268 ± 199 mL g-1 VS to 406 ± 137 mL g-1 VS. Food waste pretreatment, also, seems to be very useful in increasing total biogas production and physical and thermal treatments were the best increasing biogas of +40 % and + 30 %, respectively. Techno economic evaluation seems to indicate the feasibility in substituting EC with FW for producing biogas and reducing total biomass cost. To achieve this, separate collection sources need to be implemented, assuring high FW quality to promote a Circular Economy approach in FW management.