POLICY ISSUES FOR COMPOSTING DEVELOPMENT:
NOTES FROM ITALY

Favoino E., Centemero M., Ragazzi R., Tornavacca A.

1. ABSTRACT

2. INTRODUCTION

Composting in Italy is growing fast. More than 600 Municipalities are running source separation programs for food waste at present.

As a consequence, the number of composting plants for source separated materials is steadily growing: 72 industrial composting sites were recorded in November 1998. This figure does not include those small sites (less than 1000 Mg/y) that compost only yard waste.

The main cause for such a huge growth in quality composting has to be found in recent environmental policy developments. Decree 22/97, the National Waste Management Law (Feb. 1997) claims for a recycling goal of 35 % to be accomplished – on a provincial basis - within 2003. Source separation of the organic waste is not compulsory. Still, food waste source separation gets a need to reach the medium-term material recovery goal of 35 %. In effect, intensive collection of dry recyclables (paper, glass, plastic, etc.) does not allow local authorities – in general – to meet such a goal (it has to be noted that home composting and construction and demolition debris are not included into the total material recovery figure). Thus, most Regions and Provinces are including a broad promotion of food waste source separation in their Waste Management Plans.

Food waste source separation has already allowed some Provinces, Milan Province included (some 190 Municipalities, > 3500000 inhabitants), to meet the 2003 recycling goal (35%), with many municipalities overpassing 60 %. The use of specific tools and systems for door-to-door food waste source separation has shown to be effective with relevance to quantity and quality of food waste collected, and very cost-competitive.

The collection of yard waste is even more developed, above all in some regions such as Lombardia and Piemonte (some 3000 municipalities, 13000000 inhabitants) where it has been made compulsory since 1994, Emilia Romagna and Veneto.

3. LANDFILLING AND NEW WASTE MANAGEMENT PROVISIONS

Waste disposal in Italy - as in general in Southern Europe - still relies largely upon landfilling. Latest statistics (ANPA, 1999) showed that landfilling is still the most used tool in waste disposal. In 1997 source separation and material recycling averaged 9.5 % of national MSW production. As for final disposal, these were the figures:

landfilling for untreated MSW 79.9 % out of total MSW
biological treatment (mixed MSW composting) 9,4 % "
incineration (mostly without thermal recover) 6.6 % "
others (inertisation, mixed MSW sorting, etc.) 4.1 % "

Such percentages describe a situation in which MSW gets substantially landfilled as it is. This means huge volume and area requirements. Furthermore, with waste being landfilled as it is, a troublesome landfill management is to be foreseen due to biogas and leachate production, future settlements in landfill shape and their relevance – in turn – on the effectiveness of environmental management during the after care period.

Nevertheless, some differences among Regions have to be stressed. The average recycling rate in Southern Italy was 1,4 % (1,1% the year before) with Regions as Calabria (pop. 2000000) and Sicily (pop. 5000000) below 1%. Meanwhile, in Northern Italy, recycling rate averaged 17 % (12,71 % in 1996), with Lombardia (9000000 inh.) reaching 26.9 %.

In Lombardia, single Municipalities (up to 100000 and more inhabitants, e.g. Monza, pop. 120000) were recorded in early 1999 at 50% recycling and more; two Provinces (Milan, 3,5 million inh. and Bergamo, 1 million inh.) have been reported to overpass 40%.

In this respect, a turning point has been set by the above mentioned Decree 22/97 , as it claims for new targets in MSW management, recycling and landfilling. Sticking to most relevant topics concerning landfilling, it has to be stressed that:

• as for quantities to be landfilled:
  -  landfilling comes last in the waste management hierarchy. Waste minimisation is to be preferred along with recycling; then comes thermal recovery and, as a final option, landfilling (articles 4 and 5).
  -  a 35% recycling target has to be met within year 2003 (art. 24). This means compelling local authorities to plan and develop – in the middle term - Integrated Waste Management Systems where recycling and namely composting take a central and primary role;
• as for quality of the waste to be landfilled:
  -  only pre-treated waste will be allowed to be landfilled since January, 1^st 2000 (art. 5).
• as for landfilling costs
  -  landfilling costs and tipping fees will have to take into account savings needed to ensure a long after care period (30 years in latest draft technical regulations)
  -  an additional fee has to be applied to those provinces where recycling targets have not been met.

The new legislation has enhanced the will of many Local Authorities to start and develop innovative waste management programs. Actually, even before the issuing of Decree 22/97, in some Municipalities and Provinces integrated programs to maximise recycling were run, especially due to local waste disposal crisis. The first Municipalities to run food waste separation started towards 1990 while first wide territorial programs were implemented in 1995 in Lombardia. Nevertheless, after the Decree was issued, many Authorities responsible for waste management planning have regarded recycling and composting as the main tool in Waste management.

For the time being, the development of recycling programs mainly refers to Northern Italy, even though some programs are starting in central and southern regions, such as Abruzzo (table 1).

Table 1: Municipalities and inhabitants involved in source separation programs for food waste
(update: Jan, 1999)

4. THE CONTRIBUTION OF DIFFERENT WASTE MATERIALS AND THE IMPORTANCE OF SORTING FOOD WASTE

As source separation grows up, we get important hints about items on whose collection efforts have to be concentrated in order to reach high recycling rates. (Consorzio Provinciale della Brianza Milanese, 1997; Legambiente, 1998; Provincia di Lecco, 1997; Provincia di Lodi, 1998; Provincia di Milano, 1998 a).

Traditionally, source separation systems were meant to be simply added to common MSW collection. Sorting of paper, glass and plastics by means of road containers did not imply structural changes in the MSW collection. With such systems, separation rates range between 2-3 and 15%, depending above all on road container frequency of distribution. Table 2 reports the maximum specific contributions of such systems for different waste materials .

More recently, integrated source separation systems have been introduced. "Integrated" source separation means that higher separation rates and above all the segregation of fermentable fractions such as food waste, enable to change also the features of collection systems for Restwaste. In such respect, a central role is played by food waste source separation. The contribution of food waste – when led with "door-to-door" systems - accounts for some 60-80 kg inh-1 y-1 (Consorzio Brianza Milanese, 1998); it has to be added to yard trimmings (see further on for specific collection systems) whose contribution ranges between 30 and 150 kg inh-1 y-1, depending on urbanisation and diffusion of home composting. The overall contribution of compostable fractions therefore enables a 30-40 % separation rate.

Table 2 Maximum specific contribution of different materials (values in kg inh-1 y-1)

Very often, where food waste separation gets applied, it is accompanied by the introduction of door-to-door paper collection. This allows separation of some 40-60 kg inh-1y-1 (Legambiente, 1998), that means 2 to 3 times more than the specific contribution of road container collection. In general, we could say that door-to-door collection is a powerful way to reach high recycling rates; this applies above all to those materials whose contribution is relevant such as paper and food waste (as for yard waste, see further on, § 5.1).

Some Municipalities have tried door-to-door collection for glass and plastics. In general, as for glass it has been recorded almost the same outcome as with road containers (25 to 30 Kg inh^-1 y^-1). As for plastics, the contribution gets almost doubled (some 5-8 kilos); nevertheless it accounts for just 1.5-2 % out of overall MSW production (ibidem). Hence, as in general running a door-to door system is much more costly, it is useful to adopt it only for those fractions whose contribution gets significantly higher (paper, food waste), and that enable us to modify collection of restwaste to save money on that side.

4.1 The importance of sorting food waste

From a quantitative point of view, fermentable material (food waste) accounts for a major percentage of MSW; and this is particularly true in Southern Europe. In Northern Italy food waste percentages ranges between 27 and 40% of total MSW; in Southern Regions they range between 35 and 50%, mainly due to lower presence of packaging in a poorer economy and the custom to have meals at home with a lower use of pre-cooked and/or frozen products (that produce less food waste). We found such a situation to be quite common across the Mediterranean sea. Some colleagues of ours, for instance, in a recent meeting in Turkey reported 60% of food waste reached in some Regions.

From a qualitative point of view, the more fermentable material gets source separated and recycled, the less overall production for biogas and leachate is to be expected in landfilling and/or the best thermal valorisation of "restwaste" can be envisaged .

On the other side, we have to remind that the recycling of dry fractions and packaging materials (paper, glass, plastics, etc…) determines – as an undesired side-effect – the concentration of the fermentable material inside "restwaste", if food stuff is not effectively recycled. This is what actually occurs even in those Countries where biowaste source separation has already gone a long way; that means, separation of dry recyclables is likely to be more effective than that of food waste.for instance, in The Netherlands and Germany, food waste percentage inside "restwaste" is often reported to be at 40-50% (Wiemer, Kern, 1995; Baden Baden Amt für Umweltschutz, 1996).

4.2 "Biowaste", "VGF" and "Food waste": relevance of a definition to waste management performances

In Germany, Austria, etc. the fraction targeted by the source separation system is referred to as "Bioabfall" (biowaste), that means a mixture of food scraps and yard waste; in the Netherlands, in Belgium (Flanders) and in many sites in Germany and Austria, the definition "GFT" or "VGF" (vegetable, garden, fruit) is used, that is meant to be a mixture of yard waste and the food waste portion before cooking (not including pasta, meat, fish…). This choice is due to the troublesome, highly fermentable nature of cooked scraps; it in turn leads to low diversion rates of food waste from the "restwaste" (as already metioned, it is not unusual to find 40% and more food stuff inside it). When transferred to warmer climates – as in the Mediterranean Area – this system would for instance keep the need of high collection frequencies for restwaste.

Moreover, in central Europe in the "biobin", a large proportion of garden waste can be found (up to 80-90% w/w out of the total bin content) in addition to food waste. The delivery of garden waste is much stimulated as households – even in single-family dwellings with gardens – are provided with bins allowing large-volume deliveries.

In Italy, the source separation system for compostable organics is different since the collection of food waste and that of yard waste are kept separated. The first targets only "food waste" on the whole (including cooked scraps as meat and fish), often referred to as the "wet" fraction, by means of small volume bins and buckets; the second targets yard waste only.

This distinction between the two collection rounds takes into account:

• the different biochemical and seasonal feature of the food scraps as compared to the yard waste. In Italy - in contrast with what is generally being done in Central Europe - the collection round for the garden waste, that does not stink, and does not produce leachate, uses different tools and a lower frequency as compared to that for food waste. It is also possible to make the total bin/vehicles volume fit to the specific production of food waste, that does not show seasonal fluctuations as for yard trimmings; vehicles and systems used for yard waste, on the other side, can be seasonally adapted;
• the different bulk density of yard and food waste. In case of yard waste, it compels to use compacting vehicles while in case of food waste compacting vehicles can be replaced by bulk lorries that are much cheaper at an equivalent working capacity. This is one of the most powerful means to optimise operational features and cost figures related to source separation systems.
• the troublesome features of food scraps (high putrescence and moisture content). This asks for the adoption of specific tools, systems and collection frequencies in order to have the system clean and ‘easy-to-use’. When you let people feel comfortable, you enhance the overall participation. This leads to better quality and higher quantity collected; lowers the percentage of fermentable material inside the restwaste, making it possible to collect it less frequently. In effect, analytical measurements report the content of food stuffs inside Restwaste at an average 20% (Provincia di Milano, 1998 b), that is, much lower than in previous source separation programs across Europe.

Nevertheless, "easiness must have a borderline". A comfortable system that does not make any difference between food and yard waste is a system where a huge delivery of garden waste is to be expected. It is noteworthy that in Central Europe it has often been recorded an overall organic waste collection of some 150-200 kg inh-1 y-1 and more. This is due, above all, to the easiness of delivering yard waste to the collection service (households are allowed to deliver it in the same bins adopted for food waste collection). The general outcome is a high recycling rate, but the overall MSW production figure gets much higher, as well. In such situations, it is likely to record an overall MSW production of some 600-650 kg inh-1 y-1. The same has been already recorded in a few situations in Italy with similar collection systems adopted (Legambiente, 1997; Legambiente, 1998)

5. FOOD AND YARD WASTE SOURCE SEPARATION SYSTEMS

5.1 Yard trimmings collection systems and their relevance to home composting

In normal weather and cropping conditions, lawn mowings from public and private areas yield 2 to 6 kg y^-1 grass clippings per square meter; these are roughly doubled by trees and brush pruning and leaves.

The average (per person) recovery rate of garden waste collected in Italy (in those areas where the systems are well established) is often 30-70 kg inh-1 y-1. Where garden waste is collected together with kitchen waste (in a single bin as for instance the German and Dutch model), it is usual to see recovery rates as high as 150 and more kg inh-1y-1. We have already underlined that such a situation makes material recovery rates rise, but also increases the overall quantity of waste to be collected and treated. Hence, efforts have to be made to find suitable systems that enable high recycling rates, without implying a rise in the overall MSW production.

It is important to note that "where there are yard trimmings, there is a garden in which home composting could be performed". Our aim is to adopt a collection system which does not excessively promote the easiness for the households to ‘get rid of yard trimmings’; nevertheless, we have to ensure the collection of yard waste by households who have not time or conditions to run an home composting experience. Therefore in Italy, the collection of garden waste is generally kept separated from the collection of kitchen waste.

The collection system for yard waste can be centralised or door-to-door, with a specific round (‘green circuit’) and a lower frequency of collection than kitchen waste (i.e. fortnightly to monthly). Separate garden waste collection enables waste managers to plan and run a system:

• that does not involve seasonal fluctuations for the collection of food waste
• that is kept separated from the specific collection systems for kitchen waste, as they are fermentable, wet and with higher bulk density
• with overall low collection costs for the yard waste itself, thanks to simplified collection and cheaper tipping fees by composting plants
• that makes it possible to enhance home composting; as households are not provided with a specific bin, they seldom find it too easy to give off yard waste.

5.2 Food waste collection systems: optimisation and outcomes

Running source separation for food waste, above all by households, means to find out the best way to face the specific troublesome features of such a material: its fermentable nature and its high moisture content. In this respect, a comfortable feature of the service, where households are provided with devices to avoid nuisance, will result in an enhanced participation and will thus determine higher collection quantity/quality (Favoino, 1999).

In Italy, the answer to this problematic issue – above all where a "door-to-door" collection system is adopted – has been, tipically:

• a relatively "intensive" collection schedule as compared to Countries in Central Europe (once to three times a week; it has to be noted that in Southern Italy, as in Spain, Portugal, etc. collection is scheduled up to 5-6 times a week due to weather conditions; in Northern Italy the collection for MSW is usually 3 times a week)
• the use of "door to door" collection systems so as to have them get more "user-friend" and enhance participation
• the use of watertight, transparent tools to hold the waste ("Biobags")

The use of the bags:

• prevents pest attraction (insects) and leachate production and keeps the bins clean. This, in turn, makes it possible to lower the frequency for washing rounds. Actually, in most cases, bins are personal and are washed by households themselves once to twice a year.
• Avoids nuisances generally related to delivery of "loose" material inside the bin, makes it possible to collect even meat and fish scraps along with vegetables and fruit residues.
• Increases collection outcomes that, in turn, allow a significant reduction in collection frequency for "restwaste"
• their small bag size prevents bulky materials (e.g. bottles, cans) from being included into the collection, allowing higher biowaste cleanness.

The ‘bio-bag’ is placed:

• directly on the roadside on the collection day, either as it is or inside the family small bin (6.5 to 10 litres) or inside "buckets" (20 to 30 litres). This system is often under adoption in small towns and villages to reduce collection time for each dwelling (loading is manual) and to prevent households from delivering garden waste inside the bins
• or in a bigger bin whose capacity usually ranges from 80 to 240 litres for 10 to 20 families depending on the collection frequency. This system is under adoption where dwellings are in high-rise buildings.

Lately, a national regulation about tests to be used to certify the biodegradability has been issued. It relies upon ASTM methods. This provides a sound basis to choose bags for source separation of food waste. Actually, most composting plants are now adopting flow-sheets that comply with the use of degradable materials.

Table 3 . Source separated food waste purity in some Italian areas and municipalities
(sources: Provincia di Milano, 1998; Favoino, 1999; Bigliardi, 1998)

As for quality (table 3), the material collected shows on average a 97-98% purity, well beyond a suitable aim that could be set at a 93-95% purity, depending on the plant sorting equipment; it has to be noted that with a 97% purity and more it is possible to tip the material directly to the composting section, without any pre-sorting step.

Thanks to the optimisation tools already described (lower collection frequencies for restwaste, use of bulk lorries for food waste collection, etc.), the collection system has proven to be cost-competitive. In general, it could be said that where optimised door-to-door collection systems are run, the overall waste collection costs equal the previous mixed MSW collection cost.  

6. COMPOSTING TO SUPPLY ORGANIC MATTER: AGRICULTURAL MODELS AND COMPOST USE IN A MEDITERRANEAN COUNTRY

Actual compost production in Italy equals some 450000 Mg. y^-1. Most of it is actually sold to growing media producers, who mix it with other materials and bag it. In such marketing conditions, actual prices range between 7 and 12 Euro/mc (screened at 10-15 mm mesh size, in bulk) (Centemero, 1999).

Market conditions are favourable and provide sound elements for the needed confidence on the operators’ side. Moreover, Decree 22/97 allows stakeholders, categories and institutions to set out and sign "Accordi di Programma" (Program Agreements) to promote the use of products from recycled waste materials. An agreement that specifically targets the use of composted products is already on draft and is expected to be issued in next months. Its main provisions are:

• the preference for composted products in Tenders for public green areas
• funding farmers for replacement of old machinery when the new equipment is mechanically suitable to spread compost as an organic fertiliser (see further on).

There is a great awareness, among composting plant managers and research centres, that in next future the use of compost in field crops has to back up the growth of compost production, that is forecast to get 3 to 5 times more as a mere consequence of Decree 22/97 provisions.

It has to be underlined that specific weather and cropping conditions determine – in general - a huge request for organic matter in Mediterranean agricultural models. Warm and dry climates and the intensive, humus-consuming crops (e.g. horticulture, fruit culture) make soils hungry for organic matter; decades of chemical fertilisation as a complete substitute for organic fertilisation have worsened the overall situation. We record many soils, not only in Southern Regions, but even in Northern flatlands, below 1.5 % organic matter content. Moreover, the recent Dakar Conference has pointed out that Italy, as many other Mediterranean Countries is under a desertification threat.

This picture leads, on the whole, to a favourable situation to promote the use of composted materials. Many Farmers’ Associations are now addressing compost as a suitable tool to restore fertility and settle for those crops that best fit Mediterranean climate (e.g. horticulture, peach, apricot, etc.) in place of animal breeding. A major challenge is still represented by the need to find suitable equipment for mechanical spreading, as old machinery was fitting the features (moisture content, consistence, granulometry) of either manure or chemical fertilisers. In some recent trials (Bisaglia, Centemero, 1998) the Scuola Agraria del Parco di Monza addressed such a need finding suitable solutions.

From a "strategic" viewpoint, anyway, there’s a great awareness – by some central institutions - of the importance of this topic. For instance, ANPA, the National Environmental Protection Agency has in mind to promote the launch of a National Plan for Organic Matter to the Soil, in which the overall needs, calculated by fertility restoration programs, have to be supplied by organic fertilisers, among which composted products are forecast to play a key role.

In such respect, some local initiatives have to be quoted, meant to promote the use of organic fertilisation, and in specific of composted products. We already record the proposal of a regional law (in Emilia-Romagna) aiming at funding the use of composted amendments.

Supporting the strategy on the agronomic side has to be foreseen in next future as one of the key elements in a general strategy that targets full recovery of the role of organic matter in agriculture from waste materials. Specific needs in Mediterranean conditions provide a reasonable right to do it.

7. THE ITALIAN COMPOSTING CAPACITY IN COMPARISON TO EU COUNTRIES

Table 4 shows the situation in Italy as for number, overall and average capacity of composting plants (update: November, 1998).

The overall capacity was then some 1000000 Mg. y-1, with a forecast increase in the short-term (plants then under construction, now likely to be under operation) up to 1500000 Mg.y-1. Bare values are likely to put Italy at second place in EU Countries (after Germany, at the same level as The Netherlands), but the average capacity (per inhabitant) has to be evaluated in order to make a comparison among more and less populated Countries.

Though concentrated in Northern and Central regions, the Italian "composting capacity", will average in the short time some 30 kg inh-1y-1 for each of the 55 Million inhabitants. This has to be compared – for instance - with the estimated total German composting capacity, put in most recent surveys at some 6-8000000 Mg.y^-1. This means an average capacity of 65-85 kg inh-1.y-1 for each German citizen. We must underline that in some EU Countries, namely The Netherlands, Austria, Denmark, the average capacity has already overcome 100 kg inh-1.y-1. This value is noteworthy as it could be referred to as the "one hundred kilos target"; we mean, the medium-term goal for collection of compostable waste, comprising both food and yard waste without an uncontrolled growth in yard waste collection (see § 3 and 4).

Table 4: Quality composting plants in Italy

8. THE ULTIMATE STEP: BIOLOGICAL TREATMENT BEFORE LANDFILLING

Since a long time, studies on the environmetal side-effects of landfilling have focused on the importance to lower to the maximum extent the fermentability of the waste to be disposed. As fermentable waste undergoes anaerobic conditions, it produces biogas, heightens the chemical "strength" of leachate, causes settlements in the shape of the landfill. All this, means in turn, a long-term threat to groundwater and air, or at least a hurdle towards site reclamation; in any case it is a bothering issue for land managers and population dwelling around landfill sites.

Two ways are available to lower fermentability: the first is source separation of food waste; the second is any pre-treatment (biological or thermal treatment) meant to degrade fermentable volatile solids before "burying" the waste.

In general, source separation and pre-treatment have to be combined on the way to a sustainable landfill management; even in those Italian experiences were the most effective collection of food waste is accomplished, still we record percentages ranging from 10 to 20 % food stuffs inside restwaste (see above what has been mentioned as being the "concentration effect" inside restwaste, § 4.1).

Hence, pre-treatment is in general a must. How should pre-treatment be managed? The question has to focus on methods to measure the stability (that is, the loss of fermentability) of the waste to be landfilled. In order to have objective measurements some methods have already been proposed and used in the past.

The first noteworthy attempt to regulate this issue has been made by Germany, that in TASi (Technische Anleitungen – Siedlungsabfall) claimed for a 3% TOC (or 5% VS) content to be accomplished in order to have a landfillable waste. We have to be aware that this means to endorse incineration as the only possible pretreatment. Is it a suitable approach?

First, many studies focus on the substantial equivalence ("gleichwertigkeit") of biological pre-treatment – the so called "cold" pre-treatment – in order to lower to the maximum extent fermentability (Leikam, Stegmann, 1997). This refers both to biogas-production attitude and to the chemical "strength" of the resulting leachate, provide the biological treatment is long enough – and properly managed - to allow an effective microbial activity (Table 5).

Table 5: effects of biological pre-treatment (source: Leikam, Stegmann, 1997)

Then again, if we endorse a test method – such as TOC or VS content - that could be accomplished only through incineration, we would experience a much less "flexible" system for Integrated Waste Management, especially where it is at starting point. Incinerators – above all with BAT and Energy Recovery – are a suitable option in the "waste management chain"; still, be their adoption obliged, we would loose a main road towards the growth of recycling. We know that incinerators have to work at a certain throughput. If built before full development of recycling, this would hinder, for sure, a further growth of source separation and material recycling above all where they are still low and are forecast to undergo a long, slow growth: namely, many Mediterranean Regions.

Moreover, a biological treatment plant is a quality composting plant in pectore; we mean, a plant that could be converted – in the future – to quality composting. This can be done even progressively – following the growth of source separation - provide the biological section is modular enough, in order to use different bays, or lanes, or containers, or areas for quality composting, respectively for biological treatment of restwaste.

Then again, biological treatment seems to be a much more suitable option in areas less populated, with lower MSW production, that would not meet the capacities needed for an effective incineration, or should face high transportation costs.

Lately some new methods have been proposed in order to understand better the positive effects of biological treatment before landfilling. In general, they enable to describe more sharply – as compared to VS content - the environmental attitude of waste to be landfilled.

In particular, most test methods are focusing on :

• the respiration rate (e.g. "Respirometric Index")
• the biogas production attitude (e.g. "Gar-test")
• the chemical strength of the leachate (e.g. COD, BOD/COD rate, etc.)

New draft regulations to be issued in Italy, substantially set a certain IR (respirometric index) and BVS content (biodegradable volatile solids) to be attained. To focus only on biodegradable volatile solids instead of total VS enables to avoid any interference on VS by undegradable or not easily degradable organic compounds (e.g. plastics, polyethylene, wood). Such an approach is much more reliable than VS measurement to have a "true" description of undesired side-effects related to landfilling.

9. MIXED MSW COMPOSTING AND BIOLOGICAL TREATMENT IN ITALY

Biological treatment of residual waste is under development as Decree 22/97 asks for waste to be pre-treated before being landfilled within January, 1^st 2000. In the past, many mixed MSW composting plants aimed at producing compost for field crops. Some 30 plants under operation have been recently recorded (ANPA, 1999). In 1997 the overall capacity for mixed MSW or Restwaste topped some 1650000 Mg y^-1. Referring to 1995, some reported 65 mixed MSW composting plants (with an overall capacity of some 3000000 Mg y^-1), only 23 of which in operation (some 850000 Mg y^-1), 16 shut down and 25 under construction or upgrading (Merzagora, Ferrari, 1996). Many of those plants have been shut down in past years; subsequently many others have not been fully completed. Such shortcomings were due to:

• poor environmental conditions (lack of air-treatment systems),
• poor process management (with production of immature compost) or, most of times
• the unsuitability of the targeted end use, as farmers never have trusted mixed MSW compost use in farmland applications, with a few exceptions.

The strategy has thus changed; more and more often old composting plants get fully or partially converted to quality composting and/or used for biological treatment of Restwaste. Moreover, new ones have been recently opened. In particular, Milan biological treatment plant has probably to be considered as the biggest one across the world: its capacity tops 2000 Mg y^-1of Restwaste.

Nowadays, biological treatment for Restwaste targets different possible aims:

• stabilisation prior to landfilling,
• increase of the calorific value of Restwaste before thermal valorisation, as in Trockenstabilat method much developed in Germany
• use of earthy materials ("Grey compost" or "Stabilised Organic Fraction", S.O.F.) for land reclamation. It has to be mentioned that the huge need of organic matter in Mediterranean weather and cropping conditions (see above, § 6), leads to the need of quality composts only for land farming and gardening.

Some Regions and Provinces have already issued guidelines and/or technical regulations to allow the use of MSW compost for land reclamation (Favoino, 1998). Such regulations rely upon the hypothesis of single applications ("una tantum" , only once) with massive quantities in order to promote biological activities in surface soil layers on exploited mines, slopes to be consolidated, anti-noise barriers, etc. As for use constrictions, regulations address above all the need to check both:

• heavy metals load
• nitrogen load.

Limit values are set out in order to aim at accomplishing maximum concentration of PTE in the soil and at preventing nitrogen transfer to the groundwater.

10. CONCLUSIONS

Recent developments in waste management show the evidence that Italy is moving fast towards those strategies already under adoption in Central Europe. Food and yard waste source separation, their recovery through composting, play a key role in that. In fact, they are envisaged as the only tool that enables Local Authorities to accomplish the target set out by Decree 22/97 for year 2003 (35% recycling rate). Source separation programs have widely shown the possibility to effectively apply to the Mediterranean area strategies already widespread across Europe.

Moreover, systems run for food waste separation have shown to be effective and improve some performances as compared to previous systems run in Europe. To summarise, it has to be stressed that:

• There is a much bigger diversion of food waste from MSW
• Hence, we record a lower tendency of "residual waste" to be fermentable, to produce leachate and attract insects; this allows in turn a lower collection frequency for "restwaste"
• In general, there is a much lower collection of yard waste, targeted as a home-compostable material to the largest possible extent; this helps keeping low the overall MSW production figure.
• Collection costs can be kept at a lower level by means of reducing collection frequency for restwaste and using bulk lorries instead of compacting vehicles for food waste, as its bulk density without yard waste gets much higher;

Great differences in source separation are still to be seen between Northern and Southern Regions. Some Provinces in Lombardia reached 40% recycling rates in 1998, while most Southern ones averaged 1 to 2 %. In next months, effects have to be expected there by means of compulsory actions: the institution of special powers is committed to realising waste management programs in order to comply with law provisions. The development of Integrated Waste Management strategies in Southern Regions is foreseen to be a major environmental challenge for Italy in next years.

Specific features of agricultural and cropping conditions in Mediterranean Countries set out the need for huge quantities of composted materials. Central Institutions mean to support the promotion of organic waste recovery; the risks for desertification provide further powerful meanings to do that.

Decree 22/97, Art. 5, claims for restwaste to be treated prior to landfilling. Biological treatment is forecast to be an effective tool, and treatment sites are growing by number and overall capacity. In technical regulations related to landfilling, Italy is choosing a flexible approach to pre-treatment endorsing biological treatment as a suitable way to manage restwaste, beside thermal treatment. Treatment plants target different end use, leading to three major goals:

• Pre-landfilling stabilisation
• Thermal valorisation ("dry stabilate" method)
• Use in land reclamation

Regulations to be issued, now on draft release, will allow the use of mixed MSW compost (a.k.a. SOF, "Stabilised Organic Fraction") in land reclamation. The use of SOF (in land reclamation) should help that of quality compost (in cropping, gardening and nursery) to accomplish the huge need for organic matter, that is a main feature of the Mediterranean agronomic framework. We know that the capability of:

• defining the use in land reclamation on a sound scientific basis and of
• keeping separated goals for quality composting and SOF production

will be one of the major challenges in next future.

Draft regulations seem to win the challenge.

11. REFERENCES

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