**4. Separate collection systems in Europe**

Since there are new European standards that must be complied with in terms of recycling targets, local authorities in countries belonging to the European Union have hastened to develop new collection models. As a result, a wide variety of separate collection systems can be found throughout Europe. This has given rise to their study and comparison in the different countries where they have been implemented. For example, in Sweden, Dahlén *et al*. (2007) conducted a study that compared 3 systems. The first consists of kerbside collection of recyclables and organic waste, including a specific case in which fees are paid for the collection of mixed waste. The second involves kerbside collection of recyclables, and the third the collection of recyclables at drop-off points. After the study, it was concluded that in municipalities with a kerbside collection system for recyclables, the mixed waste container has a higher *QCR* due to the proximity of the containers to the public. The introduction of the fee payment system for the collection of mixed waste led to this waste from many homes being burnt or dumped in the wrong place. In fact, in the municipality where this system was in place, the level of improper materials was 12% compared to 4% in one of the municipalities where this model was not implemented.

Mattsson *et al*. (2003) produced a study that compared separate collection systems in both single family and multifamily property close areas in Sweden and England. They used 6 Swedish examples and one recently introduced case in the United Kingdom as examples. The cases analysed showed that although the technical details were almost identical, they differed in terms of how they had been developed. The aspects taken into account for their different developments were: cooperation between the municipality and producers, the efficiency in collection using appropriate vehicles, the quality of the materials collected, Agenda 21 and environmental awareness.

In the United Kingdom, Woodard *et al*. (2001) analysed waste collection in a district before and after the introduction of a new plan. Under the old system, mixed waste was collected in black bins and recyclables (paper, cardboard and metal) in a box, every week in both cases. The new plan (CROWN: Composting and Recycling our Waste Now) added a green container for the collection of biowaste every two weeks. The frequency of mixed waste collection declined and became fortnightly, like biowaste. The container volumes and satisfaction of citizens was noted in a sample of households in a residential area. The result was a 55% reduction in waste sent to landfill sites, an increase from 5.5 to 17.7 liters in the average amount of deposited recyclables per household per week, and a rise in participation from 40% to 78%. Wilson and Williams (2007) subsequently analysed the implementation of a new collection system in a northern town in the United Kingdom. Two samples with different collection frequencies were used to see which system worked better: in one the mixed waste and recyclables were collected in alternate weeks, and in the other the mixed waste was collected weekly and the recyclables fortnightly. The proportion of containers brought to the street for collection compared to the total number of containers available was analysed in each sample, as was the level of material recovery in each sample. Both calculations produced better results in the first sample.

Separate Collection Systems for Urban Waste (UW) 125

index is greater when lightweight packaging is deposited in kerbside bins (System 2), due to the fact that citizens have to travel a shorter distance to dump it. Furthermore, the materials left in System 2 contain a higher percentage of unwanted materials than when they are collected at drop-off points (System 1 and System 4), i.e. the *QCRlp* is lower. This is due to the proximity to the mixed waste bin and to the fact that when it is filled to overflowing, citizens leave their waste in the lightweight packaging bin. In addition, in the collection of paper/cardboard, glass and lightweight packaging at drop-off points (System 1 and System 4), the *SR* of these fractions varied depending on the distance that people had to travel to

An average of 520 kg of urban waste was generated *per capita* in the European Union in 2005 (Blumenthal, 2011) and this figure is expected to rise to 562 kg by 2020 (EU, 2011). If we consider this prediction to be correct, 290 million tons will be generated in 2020, of which 36% will be organic waste, and as such the amount would rise to 104.4 million tons. This is a very significant amount, and as such one would expect that the technology and the number

The organic fraction of urban waste consists of biodegradable materials (food scraps, spoiled food, gardening waste, etc.). European Union legislation, in the Framework Directive on Waste (Directive 2008/98/EC) defines "biowaste" as "biodegradable garden and park waste, food and kitchen waste from households, restaurants, caterers and retail premises and comparable waste from food processing plants", meaning that the organic fraction can be classified as biowaste, like wood, sewage sludge, and agricultural and forestry waste. This is very important from a legal standpoint, since this Directive requires EU member countries to implement separate collection and recovery, thereby reducing greenhouse gas emissions, the recovery of biowaste as biogas and compost, and a reduction in the amount of waste

The main objective of the separate collection of the organic fraction of urban waste is to convert it into high quality compost. This material can be used as fertilizer for agriculture, gardening or landscape restoration work. The critical factor is the percentage of improper materials accompanying the organic fraction of urban waste. It is therefore essential that this

The greatest difficulty in establishing a separate collection system is designing the precollection, to make it as convenient as possible for citizens and not unduly expensive for the Council. Two aspects depend on public participation: the amount of waste collected and its quality. The former justifies the system's existence and the latter prevents composting centres from receiving waste that is more similar to the mixed waste fraction than the organic fraction, as occurs in some cases. Another important external factor that can affect the system is the existence of a potential market which guarantees the destination of the compost in the territory of the composting plant. If this market does not exist, alternatives such as biomethanation or incineration after drying can be considered. In order to minimize the energy costs of drying, biological drying systems (biodrying), solar drying or a combination of both can be used (Adani *et al*., 2002, Velis *et al*., 2009,

deposit their waste; in specific terms, the greater the distance the lower the *SR*.

**5. Separate collection systems for biowaste** 

dumped at landfill sites.

Zhang *et al*., 2009).

of facilities for the use of this material would be greatly enhanced.

operation is carried out under the best possible conditions.

In Cappanori (Italy) four fractions are collected door to door: organic, multi-material, papercardboard and mixed waste. All the fractions are collected by the same truck on different days, so that each time one fraction is collected. In this way, you save considerably on transport (Connett, 2011).

In Portugal, Gomes *et al*. (2008) produced an economic comparison of three alternatives in terms of the collection of biowaste. The alternatives were: collection of biowaste without separation, separation of biowaste in the whole municipality and the separation of biowaste in the main urban centres and home composting in the rest. The costs of collection and transportation in the three stages were quantified and it was found that compared to the first, which was the one used in the study area, in the second the costs would not necessarily be higher, and costs could even be lower with the third.

In Spain, Ayerbe and Pérez (2005) analysed three lightweight packaging collection systems. The first consisted of collection from drop-off points. The second consisted of kerbside collection, next to the mixed waste container, using open top containers. The third was the same as the second but used closed lid containers (The closed lid has a hole with the size of a rubbish bag). A comparative analysis was performed of *QCR*, the yield of the packaging selection plant (the ratio between packaging material entering and leaving the plant). As for the *QCR*, the worst system was the open top, which obtained a proportion of improper materials of over 50%. In terms of performance on the ground, the best system was the first (73.4%) followed closely by the closed lid system (68.7%). Berbel *et al*. (2001) carried out a similar study in Cordoba. They compared two types of collection of lightweight packaging: with a container exclusively for this type of waste and a container for inert waste (packaging and other inert materials). The results showed that more mixed waste was collected from containers with the second system. Gallardo *et al*. (2010) conducted a study to determine the separate collection systems in place in Spanish towns with over 50,000 inhabitants, and their efficiency. They found that there are four different systems (Figure 5) and the most common is separation into four fractions: paper-cardboard, glass, lightweight packaging (plastic, metal and liquid packaging board) and mixed waste: mixed waste is collected at kerbside, while the paper-cardboard, glass and packaging are collected at drop-off points. They also found the *FR* for the four models. The main difference was that in the *FR* for packaging, this


Fig. 5. Pre-collection models implemented in Spanish cities.

In Cappanori (Italy) four fractions are collected door to door: organic, multi-material, papercardboard and mixed waste. All the fractions are collected by the same truck on different days, so that each time one fraction is collected. In this way, you save considerably on

In Portugal, Gomes *et al*. (2008) produced an economic comparison of three alternatives in terms of the collection of biowaste. The alternatives were: collection of biowaste without separation, separation of biowaste in the whole municipality and the separation of biowaste in the main urban centres and home composting in the rest. The costs of collection and transportation in the three stages were quantified and it was found that compared to the first, which was the one used in the study area, in the second the costs would not necessarily

In Spain, Ayerbe and Pérez (2005) analysed three lightweight packaging collection systems. The first consisted of collection from drop-off points. The second consisted of kerbside collection, next to the mixed waste container, using open top containers. The third was the same as the second but used closed lid containers (The closed lid has a hole with the size of a rubbish bag). A comparative analysis was performed of *QCR*, the yield of the packaging selection plant (the ratio between packaging material entering and leaving the plant). As for the *QCR*, the worst system was the open top, which obtained a proportion of improper materials of over 50%. In terms of performance on the ground, the best system was the first (73.4%) followed closely by the closed lid system (68.7%). Berbel *et al*. (2001) carried out a similar study in Cordoba. They compared two types of collection of lightweight packaging: with a container exclusively for this type of waste and a container for inert waste (packaging and other inert materials). The results showed that more mixed waste was collected from containers with the second system. Gallardo *et al*. (2010) conducted a study to determine the separate collection systems in place in Spanish towns with over 50,000 inhabitants, and their efficiency. They found that there are four different systems (Figure 5) and the most common is separation into four fractions: paper-cardboard, glass, lightweight packaging (plastic, metal and liquid packaging board) and mixed waste: mixed waste is collected at kerbside, while the paper-cardboard, glass and packaging are collected at drop-off points. They also found the *FR* for the four models. The main difference was that in the *FR* for packaging, this

transport (Connett, 2011).

be higher, and costs could even be lower with the third.

Fig. 5. Pre-collection models implemented in Spanish cities.

index is greater when lightweight packaging is deposited in kerbside bins (System 2), due to the fact that citizens have to travel a shorter distance to dump it. Furthermore, the materials left in System 2 contain a higher percentage of unwanted materials than when they are collected at drop-off points (System 1 and System 4), i.e. the *QCRlp* is lower. This is due to the proximity to the mixed waste bin and to the fact that when it is filled to overflowing, citizens leave their waste in the lightweight packaging bin. In addition, in the collection of paper/cardboard, glass and lightweight packaging at drop-off points (System 1 and System 4), the *SR* of these fractions varied depending on the distance that people had to travel to deposit their waste; in specific terms, the greater the distance the lower the *SR*.
