Positive GHG results obtained from organic waste collection system

By Isabelle Audet, Bc.Sc., M.Env.

Aware of the impact of its activities on global climate, the Quebec’s government adopted, in 2006, a Climate Change Action Plan standing for the 2006-2012 period. This plan, which was recently substitute by the 2013-2020 Climate Change Action Plan, suggests to municipalities and communities to look at opportunities for reducing GHG emissions. Through the Climat municipalités program, several regional county municipalities (RCM) and municipalities followed the government’s lead and produced a GHG inventory as well as a GHG reduction action plan.

Municipal GHG emissions present similar characteristics in term of sources of GHG emissions. In fact, around 80 % of those emissions come from the community transportation while 15 % belong to the municipal waste management activity. Corporative GHG emissions from buildings, motorized equipment and wastewater treatment represent globally less than 5 %.

At the same time, all RCM and municipalities have now started the revision process of their waste management plan (PGMR). In doing so, they are asked to take action in order to achieve Quebec goals set in its 2011-2015 waste management policy (Politique québécoise de gestion des matières résiduelles 2011-2015). This policy aims to valorise more than 60 % of municipal organic waste by 2015 and to ban it from landfill by 2020. Still today, organic waste represents around 41 % of all eliminated waste in Quebec.

It is thus obvious and logical to optimise Quebec organic waste management in order to reduce GHG emissions but also to reduce the production of waste directly at sources. Even though the theory is simple, field application for an efficient organic waste management system is not that easy. In fact, it could be very challenging regarding economic benefits as well as GHG reduction results.

Numerous options are available to municipal manager for reducing the amount of waste sent to landfills. The most popular one is without a doubt the door-to-door organic waste collection. This option usually implies the acquisition and use of more collecting-trucks which result in increase of carburant consumption and GHG emissions. On the other hand, organic waste diversion from landfills helps to balance those emissions by decreasing the production of methane at the elimination site. Any process of organic waste treatment will indeed always produce less GHG emissions than the degradation process occurring in landfills. However, some factors like the use of biogas capture systems can play a role in the time period required to obtain positive GHG results from the new organic waste collection. Actually, an effective biogas capture system can even neutralize the GHG reductions. It is important to note that several different estimations regarding GHG emission factors can easily be found in literature for organic waste treatment processes (composting and anaerobic digestion). The use of one or the other of those factors largely acts upon the GHG reduction results (see «Composting operations: which emission factors should be used?» for more details).

Nevertheless, door-to-door organic waste collection systems should not be overlooked when elaborating a new organic waste disposal strategy. In the opposite: this collecting operation will enhance the population’s awareness to the environmental cause. GHG positive results should instead be inquired through the optimisation of the collection-trucks uses (co-collection) and through optimisation of composting techniques. Domestic composting should also be encouraged.

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