**2. The province of Pontevedra**

Spain is made up of 50 provinces, one of which is Pontevedra. The province of Pontevedra lies in the northwest of the Iberian Peninsula. It is bordered to the south by Portugal and to the west by Atlantic Ocean (**Figure 1**).

The province has an area of 4495 km2 . It has a population of 942,731 inhabitants in 61 municipalities. With a population density of 209 inhabitants km<sup>−</sup><sup>2</sup> , Pontevedra is considered as an intermediate region according to the rurality indexes [8]. However, the population is more intensively concentrated in the metropolitan areas of the capital, Pontevedra, and the city of Vigo and along the coastal area. The eastern area of the province is a rural zone, with less densely populated municipalities, some of them with densities less than 50 inhabitants km<sup>−</sup><sup>2</sup> . **Table 1** shows the analysis of population dispersion data in the province. The population nuclei are distinguished according to the number of inhabitants in the settlement. A population nucleus, in its broadest sense, is considered to be a set of at least 10 buildings


#### **Table 1.**

*Dispersion data of the population of Pontevedra according to the size of the population nuclei. Source: prepared from the data of the Spanish Statistical Office [9].* 

that are made up of streets, squares and other urban roads; otherwise, the population is understood as disseminated. Around 30% of the population lives in small nuclei or scattered.

The dispersion of the population along with a complicated orography and a high rainfall involve a significant cost overrun in the public services, in general, and the municipal waste management in particular. In the waste management model of the province of Pontevedra, different waste streams are collected and managed separately: paper and cardboard, glass packaging and light packaging. Bio-waste is not source-segregated and it is collected in the mixed fraction, that is, all unsorted waste: bio-waste, sanitary textiles, ceramic waste, household cleaning waste, etc. The collection of these fractions takes place mainly in containers on public roads. Mixed fraction is managed in a centralized way in an incineration plant located at an average of 120 km from the municipalities of the province [7].

The services of collection, transport and treatment of the waste generated in the household, and similar sources such as commerce, offices and services, correspond to the municipalities. Each municipality decides how to provide and finance these services. These services suppose a high economic cost for the small and medium municipalities due to the difficulty in reaching a critical mass that optimizes the resources (containers, vehicles, staff, etc.) and the gap between the real cost of the services and the taxes applied to the citizens. Municipal waste generation in the province of Pontevedra accounted for 348,326 tonnes in 2017, but only 9.04% corresponded to separate waste collection, which led the municipalities far from the recycling objectives imposed by the EU.

The Provincial Council of Pontevedra is a supra-municipal authority, which provides direct services to citizens and technical, economic and technological support to the municipalities of the province of Pontevedra. The Provincial Council of Pontevedra has been promoting the composting plan called REVITALIZA since 2015.

## **3. Composting plan: 'REVITALIZA'**

 REVITALIZA establishes a new municipal waste management model focused on the segregation and treatment of the organic fraction as close as possible to its point of generation. It includes three fundamental bases or lines of action depending on the population distribution of the province and the particularities of each housing: individual or home composting, community composting and small composting facilities. The first two lines are considered as local composting, that is, composting near the area where the waste producers live. Small composting facilities should be located in the municipality or in a municipality near the places where the bio-waste is produced, and the waste will require collection and transport. **Table 2** presents a study of the theoretical requirements calculated for each one of the bio-waste treatment lines according to the population distribution of the province (**Table 1**). This study identifies what part of the bio-waste could be treated by local composting (home and community composting), while everything that could not be treated


*CCC: community composting centre.* 

*Calculated following the assumptions: community composting centre of six units and small composting facilities of 3000 tonnes year<sup>−</sup><sup>1</sup> except one facility of 25,000 tonnes year<sup>−</sup><sup>1</sup> that would provide service to the city of Vigo.* 

#### **Table 2.**

*Theoretical requirements of equipment and/or facilities for the implementation of the three lines of action (home composting, community composting and small composting facilities) of REVITALIZA based on population distribution data of the province of Pontevedra.* 

from a technical point of view through this priority path would be diverted to industrial composting at small and medium scale called small composting facilities.

 As mentioned in the previous section, the population distribution of the province increases the cost of treatment of the waste, as there are small-sized nuclei and scattered population in dispersed areas. Based on the data in the table, most of the population of the province of Pontevedra can be served by local composting; the small facilities are restricted, especially for urban centres. Home composting is considered an interesting alternative to central composting, especially in areas with low population density [10]. According to REVITALIZA, the municipalities with scattered population would advance towards the sustainable management of the resources by means of local or in situ treatment of the bio-waste, so that municipalities would reduce the costs and environmental impacts of the collection and management of the mixed fraction of the municipal waste. REVITALIZA promotes the following actions:


Initiatives to improve waste management services and the overall sustainability environmental policy chosen by local authorities require participation of all involved stakeholders (citizens, NGOs, state authorities, etc.). In order to be successful, all actions have to be credible, transparent, socially sustainable and, as far as possible, convenient and practical to participants [11]. Thus, consciousness-raising and training capacity for citizens are fundamental for the success of the composting plan. Therefore, experts on municipal waste management and composting process are required. The Provincial Council of Pontevedra has organized selection processes and specialized courses for the selection and training of staff called master composter. The courses had counted on the participation of expert teachers with recognized experience in the sector, both state and international. Master composters have as functions advising local governments on the composting plan and carrying out the actions, following the particularities of each municipality, for the implementation of REVITALIZA. In addition to the master composters, REVITALIZA has external collaboration from specialized associations: NGOs Amigos da Terra and ADEGA. These groups advise neighbours and control the operation of home composters. Likewise, personnel of the municipalities adhering to the plan will be trained so that they can take responsibility for the composting work in successive years. The Provincial Council of Pontevedra also carries out training actions addressed to the educational community, both teachers and students, through an agreement with the Center of University Extension and Environmental Outreach of Galicia, Spain (CEIDA).

#### **3.1 Home composting**

In accordance with the priority of minimizing the collection and transport of organic matter, the first level of REVITALIZA is local composting and, within it, individual or home composting.

 The Provincial Council of Pontevedra transfers composters with capacity of 300 L to the houses with a plot of land (garden and orchard) (**Figure 2**). In this way, selfmanagement of the bio-waste generated by the family nucleus can be carried out on site. In home composting, the participants segregate the bio-waste and deposit it in the composter, they are responsible for the composting process and they benefit from the obtained compost. Organic materials used for compost should include a mixture of food and kitchen waste and green organic material such as grass clippings, pruning remains, leaf litter, etc. Bulking agent is a carbon-based material such as chip or shredded pruning waste that creates necessary aeration structure for the composting process. The methodology used in home composters consists of alternating layers of food and kitchen waste with bulking agent that can be obtained in the garden of the participants themselves. REVITALIZA contemplates either the provision of bulking agent or the loan of crushers to process the garden waste from participants who require it.

The neighbours receive training and guidance from the associations that assist the Provincial Council. These associations carry out initial training and follow-up of the process through visits to each home composter. In the first year, at least three visits are made to check the development of the process: taking measurements of temperature, moisture control, filling level, incidents, etc. In addition, follow-up actions through telephone calls, emails, etc. are included.

#### **3.2 Community composting**

 Community composting is a fundamental basis and strategic priority of REVITALIZA. Following the criterion of bio-waste management in areas close to the point of generation, composting at a community level consists in managing the bio-waste from local residents and/or activities within the same neighbourhood or community. To this end, community-composting centres (CCCs) are set up, either at neighbourhood communities or at small specific producers such as food stores, markets, bars, restaurants, hotels, etc. Community composting is considered an intermediate technique between home composting and composting in small-scale composting facility. In that sense, CCC that accepts more than 30 tonnes year<sup>−</sup>1 will be subject to specific legislation that includes, mainly, installations and environmental permit. A CCC is made up of modular units of 1 m3 that serve around 20 inhabitants each. The minimum and maximum number of modular units per CCC

*Towards the Recycling of Bio-Waste: The Case of Pontevedra, Spain (REVITALIZA) DOI: http://dx.doi.org/10.5772/intechopen.83576* 

#### **Figure 2.**

*(A) Home composter with an aerator on the lid, (B) material in composting process (C) bio-waste feeding to the composter and temperature measurement.* 

is 3 and 10 (**Figure 3**). The area of influence of a neighbourhood CCC is located at a maximum distance of 150 m from the homes it serves. In [12], it is observed that the larger is the distance of waste containers from the houses, the larger is the probability of waste dumping in other places. If the CCC is too far away, the probability that the neighbours deposit their waste in the container of the mixed fraction is greater. In the case of small producers' CCCs, they can be located in the producer's own facilities or in their proximity and must not exceed 30 tonnes year<sup>−</sup><sup>1</sup> of bio-waste.

Master composters evaluate the potential locations of the CCCs in the municipalities and the possible neighbourhood communities or small producers that would contribute bio-waste to the centres. The treatment capacity, the surface requirements and the material resources can be dimensioned according to the data collected by the master composters. An installation protocol has been developed for the placement of the CCC, in which the following criteria must be fulfilled:


As an essential part of an appropriate composting process, food and kitchen waste must be mixed with bulking agent (crushed vegetable waste). This material is supplied by the municipality and comes from gardening activities, which involve pruning, cutting and removing vegetation of gardens, parks and other public spaces. The Provincial Council places at municipalities' disposal the crushing service, in case of lack of shredder equipment, so that they can prepare the remains of gardening to an optimum granulometric size for the community composting process [7]. Crates or bags with bulking agent are arranged in the CCC for use by the participants and master composters (**Figure 3**).

Participants of community composting receive initial training for the correct segregation and deposition of the bio-waste, as well as, information on the development of the composting process. The master composters continue their educational work in CCC on a day-to-day basis where they talk with the participants or interested parties and resolve their doubts and questions.
