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Waste and recycling tracking

I generally try hard to minimise my environmental impact, but it can be a challenge without being aware of the actual effect that daily decisions have. Now that I live in a one-person flat, I'm much more conscious of exactly how much energy I use, how much stuff I consume, how many possessions I accumulate and how much waste all this activity produces.

I've therefore decided to keep track of how much waste I produce much more accurately. My apartment block in Tampere, Finland, provides bins for six types of waste: paper, card, glass, metal, compost and general waste. Everything except the last of these can be recycled (although whether the council does or not, I don't know). In addition, Finland has an exemplary network for financially-incentivised bottle and can returns, with return stations in pretty much every grocery shop. Each week I therefore find myself splitting my waste into eight different categories. It's a fair bit of effort, so taking weight measurements aswell isn't such a big deal.

The following graph shows my daily waste output based on data I collect roughly once per week. I plan to update it weekly. The area under the graph represents my total waste output. Click on the graph for a larger version.

Some brief points to note about the graph:

1. The daily average, calculated since the start, is shown in the vertical bar on the right hand side.
2. All of the green items are recyclable and should be recycled by the council. The general waste in red isn't recycled.
3. There's only me living in my flat, so this is output for a single person.
5. For info about how the graphs are generated, see my Graphs of Waste posts on the topic.

The data is beginning to build up now, allowing a somewhat clear picture to emerge. I'll continue collecting data over time to see how things are progressing, with the aim of reducing my waste output (both recyclable and non-recyclable) over time if I can.

To view histograms showing the actual values recorded for each of the waste types, select one of the graphs below. Be aware that they all have different scales on the y-axis, so they're not visually comparable.

General

Plastic

Compost

Returnables

Metal

Glass

Card

Paper

Waste

10 most recent items

26 Oct 2020 : Glass or plastic. Which is really better for the environment? #
For the last 14 months I’ve been collecting data about how much rubbish I produce, broken down into various categories (paper, card, glass, metal, returnables, compost, plastic and general). I’ve had two aims: first to gather data about how much rubbish I generate and second to try to reduce my overall output for environmental reasons.

One of the encouraging things about this process is that it seems to have worked. If I look at my waste output between mid-August and mid-October 2020 and compare it to the same period last year, my output has reduced from an average of 366 g per day to 126 g per day, a two thirds decrease. Here’s the breakdown of how the two years compare across the categories.

I’ve been using a variety of different techniques to achieve this. For example my tolerance for eating food past it’s best-before date has increased considerably. There’s a sticker above my letter box asking not to receive any junk mail. I also buy food with lighter packaging: cardboard packets of beans instead of tins, cartons of wine instead of bottles. Wherever possible I buy plastic pots and bottles instead of glass.

Glass is really heavy, so cutting it out has been a really easy way to reduce the weight of my waste and as you can see from the graph, this is where I made my biggest decrease. But for many this choice will seem controversial, and many times when I’ve picked a plastic bottle from the shelf at the grocer instead of glass, I’ve wondered whether I was driven more by hitting my weight targets than any real environmental benefits.

So I thought I’d better look into the relative environmental impacts of glass as compared to plastic. Plastic has had a bad rap recently for having a terrible impact on the marine environment. But this is rather emotive, and is only one facet of the environmental impact of a product. Actually figuring out the full life cycle environmental impact of something is fiendishly difficult. You have to consider the production costs, transportation costs, recycling costs and much more besides. Happily Roberta Stefanini, Giulia Borghesi, Anna Ronzano and Giuseppe Vignali from the University of Parma have done all of this hard work already. Their paper “Plastic or glass: a new environmental assessment with a marine litter indicator for the comparison of pasteurized milk bottle”, recently published in the International Journal of Life Cycle Assessment, compares the environmental impact of glass and plastic polyethylene terephthalate (PET) across a range of environmental factors for the full life cycle of the packaging. This includes comparing non-recycled PET with recycled PET (R-PET) bottles, as well as non-returnable glass and returnable glass bottles.

The indicators used for comparison are “global warming (kg CO2 eq), stratospheric ozone depletion (kg CFC11 eq), terrestrial acidification (kg SO2 eq), fossil resource scarcity (kg oil eq), water consumption (m3) and human carcinogenic toxicity (kg 1.4-DCB)”. In addition they also introduce a new marine litter indicator (MLI).

What they find is surprisingly clear-cut. Across all of the indicators apart from MLI the same pattern emerges: R-PET is the least environmentally damaging, followed by PET. Returnable glass bottles follow, with non-returnable glass bottles the worst by a large margin. We can see this in the six graphs below. There’s a lot of detail in them, but I wanted to include them in full because it’s fascinating to see both how complex the results are and also how the different processes contribute to the final environmental cost. But in spite of the detail the overall conclusion from each graph is clear: non returnable glass is worse than the others (in all of the graphs higher is worse).

It’s a surprising definitive set of results. So why is it like this? The authors of the paper put this more clearly and succinctly than I could manage.

"glass bottles have the highest impact on environment, because of their production and transports. In fact, to create a glass bottle a lot of energy is used to reach high temperature. Moreover, plastics can be transported in octabins before the bottle formation in the food companies, while glass bottles are already transported in their final form, that takes up a lot of places and less bottles can be carried at each journey. Finally, glass bottle’s weight is very high, and trucks consume more, emitting more pollutants. For these reasons, glass bottle appears as the most impactful material according to global warming, stratospheric ozone depletion, terrestrial acidification, fossil resource scarcity and water consumption."

It’s worth noting that in the case of returnable glass bottles the authors assume that a bottle is reused eight times before having to be recycled. This is the number of reuses after which a bottle is likely to become broken or too scuffed to be used again. They determine that a bottle would have to be reused thirty times before its global warming potential reaches similar levels to those of a PET bottle, at which point the other criteria would still be worse environmentally.

The remaining criterion, not shown in these graphs, is that of the MLI. Here things change. MLI is proposed in the paper as an approach to comparing the relative impact on the marine ecosystem of the different packaging types. MLI is defined as follows:
$${\rm MLI} = \frac{F_1^{f_1} \times F_4^{f_4}}{F_2^{f_2} \times F_3^{f_3}}$$
where $F_1$ is the number of disbursed containers, $F_2$ is the incentive for returning a bottle (e.g. the cash given for returning it), $F_3$ is the weight of the packaging material and $F_4$ is the material degradation over time (400 years in the case of glass, 100 years for PET). The values $f_1, \ldots, f_4$ are weights used to capture the relative importance of each of the four inputs.

The results for various weightings are given in this table (taken from the paper but amended slightly for clarity). As with the graphs, a higher number is environmentally worse.

MLI weights $f_1, \ldots, f_4$ PET R-PET Non-returnable glass Returnable glass
3, 2, 1, 2 0.56 0.56 19.47 0.78
2, 2, 1, 1 5.56 5.56 21.16 0.85
1, 1, ½, 1 0.75 0.75 4.60 0.92
2, 2, ½, 1 1.24 1.24 21.16 0.85
2, 3, 1, 2 0.93 0.93 105.80 0.85

This table shows that independent of the weights applied, non-returnable glass has the highest environmental impact. However, the comparison between R-PET and returnable glass is more nuanced. The authors conclude the following:

“According to the MLI proposed, the best solution would be using returnable glass bottles, thanks to the low number of bottles needed and therefore dispersed, their weight and return incentives. However, it is important to remember that the environmental dispersion of bottle is strictly related to human’s behaviour: consequently, it is important to raise the consumers’ awareness on this topic.”

The paper is thorough and we’ve covered a lot of detail here, but the conclusion for me is much simpler: from an environmental perspective returnable PET plastic is clearly better than glass across multiple criteria. The only place where this doesn’t apply is for MLI, for which it’s much harder to make definitive judgements.

It seems therefore, that I should carry on choosing plastic packaging over glass whenever possible. That will benefit both my weight targets and the environment.

Comment
24 Oct 2020 : Waste data dump #
My fortnightly(-ish) waste data dump has just gone up. The daily average is 161g/day, which is pretty good for me. What's more, the largest category is compost, which I suspect is the least environmentally damaging out of them all. In related news I've taken the luxury of getting a couple more bins (paper and plastic) to help with this process. So I'm pretty happy with things this weekend.
10 Oct 2020 : Waste data dump #
It's been a good fortnight on the waste front, probably due to the fact I'm now spending my daytimes in the office rather than at home (although, looking at the trends, I may have to change back to home-working in the not-too-distant future). My daily average over the last 13 days has been 120g/day, which is less than half my 300g daily target. I can't say I'm not pleased. Having said that, looking at the details more closely reveals a more regressive trend. The big shift has been a decrease in compostable waste, while my general waste actually increased slightly on my previous readings. General waste being the most damaging, that's not such a good shift. The numbers that make the difference aren't huge, so it's probably just a fluctuation, but maybe I should be thinking more about category-specific targets in future, rather than combined targets.
27 Sep 2020 : Waste data dump #
Another waste data dump, this one just a week after the last. I made a tactical error this week, buying bread and sausages that were reduced and approaching their best-before-dates. Following my mum's teachings, I thought I was being good but on opening the packets discovered them to be peppered with mould. Not so tasty. So my compost waste is right up this week, leaving my average of 188g/day being 14g higher than my 2020 average.
20 Sep 2020 : Waste data dump #
It's been a while since my last waste update, around five weeks in fact. That's because I was travelling, followed by a fortnight in quarantine. That means that while the graphs show a very low output because of the weeks I was away (average 81.5g/day), in practice my real output was higher (209.5g/day). That's a fair bit higher than my 2020 average so far (173.4g/day) and that's because I stacked up well before quarantine, leaving me with a surfeit of things to eat. A bit counterintuitively, but everything is topsy-turvy right now. I've kept my spirits up by enjoying the extravagance. Happily it's still under my 300g/day target either way; let's see what happens next week when things are (somewhat more) back to normal.
15 Aug 2020 : Waste data dump #
Just a small addition to my waste output, adding in some data I missed before. Less than a week of data averaging 188g/day, but which includes some weight I forgot to add previously, so it's kind-of a correction.
11 Aug 2020 : A year of rubbish #
With my latest waste data dump I've now reached a full year of data (366 days to be precise). I actually don't remember what triggered me to start this time last year and I didn't think I'd manage to keep it up. Here are the stats from the full set of data.

Total period:   2019-08-11 - 2020-08-11 (366 days)
Overall daily average:          231.22 g/day
Year 2019 daily average:        304.18 g/day
Year 2020 daily average:        187.57 g/day

So it seems my average daily output of waste is around 230g/day. It'll be interesting to discover whether that goes down as a result of me recording and keeping track of the data, but if you look at the graphs you can see a big chunk happens around Christmas, so my relatively low average for 2020 will inevitably go up.
11 Aug 2020 : Waste data dump #
It's been a bit of a gap - over 3 weeks - since my last waste data dump. And it's a bit of a strange one after a week in the UK and two weeks in quarantine. By necessity I was very frugal while stuck in my flat, especially given poor planning on my part meant that although I bought essentials, I forgot to get any of the little extravagances that I'd usually indulge in (biscuits, drinks, that kind of thing). So, I survived at least and my daily average waste output is way down at 1.17g/per day. That's the lowest its been for a while (it also hides my waste output while I was away).
15 Jul 2020 : Waste data dump #
I've just put another waste data dump up. There's been a bit of an uptick, with my average up to 211g/day from 157g/day last fortnight. That's still okay though (below my target). Plastic and returnables seem to be the issue, probably because it's been so hot and I've been enjoying some cool beverages. At least I managed not to buy anything in a glass bottle.
4 Jul 2020 : Waste data dump #
It's been a pretty good fortnight as far as my waste output is concerned. Plastic and general waste are up slightly, but that's counterbalanced with no metal or glass used this fortnight at all, bringing my daily average to 157g/day over the last two weeks. I'm happy with that.