Taking into account the physical-chemical characteristics of the SC-OFMSW processed at Valorsul's anaerobic digestion plant, the influence of seasonal effects was studied. The waste presents a good quality, with a putrescible content of around 90%. In terms of chemical characteristics, the waste composition is similar to the one referred in the literature. The results show that seasonal variations seem not to affect the SC-OFMSW characteristics. The waste is very soluble and for that reason the solids content in the digester is low (TS in the digestor is 2.8%). The production of biogas is higher than the one predicted in the design operational parameters. Consequently, smaller quantities of compost are produced.

The European Commission is tightening waste laws, and many local authorities, particularly in countries with low recycling rates, face the question of what system to introduce for the sourceseparate collection of food waste from householders. This study provides empirical data in form of fuel consumed and waste yield from four councils that already have source separate organic waste collections in operation. Two systems were compared: (i) door-to-door collection and (ii) bring systems where the householder walks to the bin in her/his street to drop off organic waste. Fuel consumption for the collection operation with the bring system was dramatically lower compared to the door-to-door system. Organic waste yield was constant over the observation year in the door-to-door system employing small 20-to 30-litre bins, but increased notably in the summer with the bring system that used 240-litre bins. The metric used to quantify seasonality was the summer/winter yield ratio. As commercial waste companies do not normally allow the making of data public, this is a rare opportunity to learn from collection systems currently in operation.