Co-treatment of organic fractions of urban waste for energy recovery: a case study from Hanoi city, Vietnam

The authors have quantified material and energy flows in two options of co-treatment of organic fractions of wastes by composting, and by anaerobic digestion. The results shown thermophilic anaerobic co-digestion of septic tank sludge, sewage sludge and organic municipal solid waste has provided the biogas yield of 19.6 m3 per ton of mixed waste, equal to 114 kWh of heat and power. The calculation for the case of Long Bien district, Hanoi city has shown anaerobic co-digestion of waste fractions could generate 111,220 kWh of heat and power per day, helping the waste treatment complex to be selfsufficient in terms of energy. Besides, 32.2 MWh/day of surplus energy could be sold to the grid. This option also reduced emission of greenhouse gases versus composting. The study can be used as basis for cost-benefit analyses in selection of appropriate urban waste management options aiming at efficient utilization of engineering infrastructure systems, waste treatment and resource recovery.