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 m~3 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.
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