di Giuseppe Miccoli (traduzione di Laura Tajoli)
From an environmental point of view, is it more sustainable to have an anaerobic digestion plant that produces biogas or to run a typical compost plant conceived exclusively to produce and sell compost and natural fertilizers? What are the first, good and lasting decisions that municipal administrations and citizens should follow in the organic waste management? The awaited ISDE Position Paper on “FORSU “(Organic Portion of Urban Wastes) treatment answers these questions. “This document – Agostino Di Ciaula, Pugliese doctor and ISDE representative, pointed out – should guide political choices so that they will be directed towards compost heap or, alternatively, towards anaerobic digestion, without paying attention to the economic “distortions” imposed by some lobbies keeping in mind only the citizen’s interest”.

This text has been created by Agostino Di Ciaula, Patrizia Gentilini, Ferdinando Laghi, Gianni Tamino, Mauro Mocci, Vincenzo Migaleddu. It analyzes in depth the different options regarding the biological treatment of the Organic Urban Wastes. The prerequisite is that this part of the wastes will be managed according the EU priority hierarchy (2008/98/CE directive). It’s a crime to send this kind of waste to the dump. Compost heap can contrast the desertification processes that involve our country as well.

The document examines the different ways in which Organic Uban Wastes could be disposed, on scientific, distinguished and most updated basis, highlighting positive and negative aspects. In its conclusive recommendations regarding Urban Organic Wastes (FORSU) ISDE places as top priorities waste reduction and food waste combat “by publicizing experiences such as Last minute markets, Bank networks, Doggy Bags (restaurant services that allow customers to take home the food they did not eat) which permit to save food”.

The ISDE document then indicates domestic compost heap as a priority and it refers to the indications given by professor Federico Valerio, author of a textbook published by Italia Nostra on compost heap that illustrates in detail the ways in which you may obtain a good compost whether you’ve got a big garden or a small balcony (http://www.italianostra.org/wp-content/uploads/compostaggio.pdf).

Before taking into consideration the different plants, ISDE clarifies that “the organic portion that has to be biologically treated needs to come from quality domestic waste sorting” and states that “compost heap is the best treatment of the organic portion of urban wastes since it’s the only one that guarantees the observance of the European waste disposal hierarchy, the most adequate material recovery and the major share of organic carbon in the soil”. That is why ISDE hopes that the “incentive policy” will ban the “actual market distortion which supports energy recovery (incineration and energy production through biomass and biogas combustion) and excludes material recovery”.

As a third point, ISDE document indicates that “compost heap should always be supported by anaerobic digestion, even more so if the spaces and the “green” waste quantities needed to structure the heaps are easy to find. These conditions should be supported during the planning phase”. So it would be better to open compost plants where “the biological treatment of the organic portion aims to produce and sell quality compost to be used in agriculture and gardening”. Key words: quality compost, pulling down of the smelling emissions, no houses in a 250 metre range in order to exclude the bioaerosol inhalation risks.

The last step on this value scale is made up of the anaerobic digestion plants for the organic portion designed for biogas production. It is recommended not to allow the entrance of “any kind of material” and that the “digested compost produced in order to avoid the possible negative consequences of the direct application on the soil (nitrogen mixture losses, ammonia releases, etc.) is provided.

For what the energy aspect is concerned, ISDE advices to avoid “biogas on-place combustion or any other kind of biogas combustion. In order to be used as a fuel, the biogas that has been produced should be refined as biomethane. Biomethane production, if not used on-place, should be addressed to the traction or it should enter the natural gas network. The Italian Government should adopt the most restrictive values that are in force in Europe to define the characteristics of the biomethane that will enter the network, paying attention to the potentially dangerous contaminants, mercury and halogenated compounds in particular”.

To sum up, ISDE says ‘yes’ to the anaerobic digestion plants if, to minimize the local impact, they are “integrated biogas biomethane refinement plants with purification and compost plants for liquid and solid leftovers and that, in particular, the liquid digestate purification takes place in the same place where the digestate is produced, better if coupled with a wastewater treatment plant”. Finally, these plants should “be properly sized in order that the biomethane produced will be used to give the necessary heat and electricity to make the plant work and to satisfy the energetic needs of buildings and companies nearby in a tri-generative configuration (electricity, heat, frigories). Should the biomethane produced be superior to self consumption and to teleheating or telecooling, the amount that exceeds should enter the network or used as fuel for the public transport and waste collection motorized vehicles”.