Waste is something we would all rather do without. Eliminating waste is key to establishing a circular economy. We are, however, a long way from achieving this. In the meantime, we have a lot of waste to deal with. In the Netherlands it’s about 60.000 kilotons a year, of which over 8.800 kilotons come directly from consumers.1 And while we, the consumers, might think that our stake is relatively small; we still produce an amount of waste weighing more than 1.25 million (African) Elephants. Each year.
We should do all we can to reduce the production of waste, but we should also make better use of it. Separating and then recycling our waste is one option. In 2014 the national average for separating household waste was 52%. We’re doing quite well compared to other countries in Europe, however, the range of these percentages is broad. Some municipalities achieve household waste separation as high as 96%, while others lag far behind.2 Why is this?
Figure 1 shows us a moderate negative association between household waste separation and address density per km2 (which is used as a measure for urbanity in the Netherlands). As the address density increases the total percentage of separation of household waste decreases.
Figure 1: A scatterplot of household waste separation rates and address density per km2 per municipality
It would seem that increasing household separation rates is especially challenging to metropolitan areas, but again we must ask; why? Two often suggested explanations both relate to space. The first may seem obvious; more densely populated areas have more high-rise buildings. There is relatively little indoor space and access to outdoor space is absent or limited. Within the household, storing separate waste fractions may simply seem a waste of space. The second explanation may well be that disposing of household waste takes time. Disposal points are farther away from residents in metropolitan areas than in less densely populated areas where kerbside collection is the norm.
An effective recycling infrastructure relies heavily on effective source separation of household waste. It is therefore important to know what drives certain kinds of behaviour. The most significant indicators of recycling behavior are convenience-based factors. One of the most significant being the accessibility of waste disposal points. Multiple studies have indicated that as the distance from the household to a waste disposal point decreased the recycling rate went up and miss-sorted fractions of recyclables decreased.
You would think that the accessibility of containers to households is thus the most important locating factor for waste disposal facilities, but you would be wrong. Location-allocation models, models simulating the optimal locations for static facilities, have a strong focus on logistics. In waste management practice this means that the models optimise routes for collections services not the users of the facilities. Inclusion of facility users is minimal. Routes are rarely calculated. Euclidean distance (a straight line from A to B) or Network distance (measured over the road network) are often used, but poor, approximations. People can’t walk through walls and the pedestrian environment is different from that of motor vehicles.
Pedestrian route choice does not always correspond to the shortest possible walking distance. Many researchers have tried to explain this seemingly arbitrary phenomenon. For example; environmental psychologists have suggested that we have an inherent preference for uncomplicated routes. This would mean that we might prefer a long straight walk over a shorter walk with more turns. It is one of our aims to discover if any of such factors influence the routes people take in Amsterdam when they dispose of their waste.
Preliminary findings suggest that mixed waste containers are accessible enough, but recyclable containers are not. Interviews and observations revealed that in many cases residents would have a mixed waste container and a single type of recyclable close by. They often admitted to only recycling the fraction of which the container was closest. This illustrates the importance of convenience. It also shows why I personally find ‘Reverse Waste Collection’ such an elegant concept. The underlying idea is that disposing of recyclable fractions of waste is made more convenient than disposing of unsorted waste. The opposite of what is true in Amsterdam. By making all types of recyclable containers more accessible than containers for mixed waste, residents will be triggered to recycle more, since they would prefer having to take waste to the more distant mixed waste container less often. They would attempt to minimize their mixed-waste output to minimize those trips.
Robin Ammerlaan, MSc student Geo-Information Science at Wageningen University, working on the Smart Wasting in Amsterdam project as graduation student.