Solid waste in the lab: where does it go when we throw it 'away'?

Published: 24-Jan-2022

Nikoline Borgermann, an independent green lab consultant, provides a quick overview of six common laboratory waste types and their fate after leaving the lab

Laboratory work consumes huge amounts of energy, water, chemicals and materials – and it produces massive amounts of waste. Not only do we generate waste considered a threat to human health and the environment – the biohazardous waste – in the labs, we also produce an incredible amount of plastic waste. Indeed, academic research labs produce an estimated 5.5 million tonnes of plastic waste every year!

If you work in a lab, you are probably familiar with the classic types of laboratory waste and how to dispose of it. You might also know that the lab waste isn’t necessarily dealt with in the same way as your waste at home. But what happens to the waste after it leaves the lab? Where do the different waste types go – and how many of them can be truly recycled?

Biohazardous waste is hard on the planet – and the money

Let’s start with the waste type that separates labs from most other work spaces: the biohazardous waste.

Biohazardous waste, also known as infectious waste and biomedical waste, includes everything that has been contaminated with potentially infectious agents or other materials that are considered a threat to public health or the environment. Among many other things, biohazardous waste includes waste that is contaminated with recombinant or synthetic nucleic acids and ‘tools’ involved in producing these such as plasmids, viral vectors and bacteria; pathogenic agents such as bacteria, viruses, parasites and fungi; and clinical waste, including blood, tissue and cell lines.

Everything that has been in contact with any of the above, or other biohazardous substances, is collected separately and disposed of using procedures that minimise the risk of exposure for lab users, service workers and the public. The biohazardous waste is loaded into an incineration chamber separately from residual waste and is burned at roughly 1500°C instead of the typical 1100°C used for residual waste.

Importantly, incinerators across countries and regions differ a lot in terms of how clean the smoke is. In Denmark, for example, the emissions from the newest incineration facility, “Copenhill”, are so clean that people can ski on the top of the building with no health consequences. Its carbon emissions are, however, not exactly improving the state of our planet!

Unfortunately, incineration of biohazardous waste leaves behind a larger environmental footprint than incineration of residual waste: not only does biohazardous waste require higher temperatures, and therefore more energy, it is also often transported further away than the residual waste to reach an incinerator that allows for separate loading of biohazardous waste into the chamber.

Therefore, it’s also much more expensive (!) to send biohazardous waste to incineration than residual waste. In one faculty at the University of Copenhagen, the biohazardous waste makes up roughly 20% of the total waste but accounts for almost 40% of the waste expenses. Yikes! So it makes a difference – ecologically and economically – when you pay attention to what goes into your biohazardous waste bin. Don’t put things in the bin that are not considered biohazardous!

Paper & cardboard: the sorting is simple – but they are not endlessly recyclable

Paper and cardboard are relatively easy to sort, and most people are accustomed to separating these materials from residual waste. Unlike what many think, paper and cardboard are, however, not endlessly recyclable; in fact, high quality paper and cardboard can be recycled roughly seven times. Their final recycling outcome is typically toilet paper and egg trays, respectively.

Recycling paper and cardboard reduces how much wood we need for making new products – and in a time of a climate crisis, we need all the living trees we can get (although some paper is of course, sourced sustainably). The recycling doesn’t come without environmental impact, though: chemicals and glues are used to turn used paper into recycled paper products, and the used paper isn’t necessarily sourced locally; sometimes it’s transported over large distances. Nevertheless, the environmental gains are larger than the environmental pains when we recycle paper and cardboard. Now we ‘simply’ need the paper and cardboard industries to take green steps in terms of transportation and chemistry!

Metal & glass: two materials that can be recycled endlessly

Unlike paper and cardboard, metal and glass can be recycled endlessly. But – because unfortunately there is a ‘but’ – that doesn’t go for all glass. Certain items in the lab are not made of normal glass; they are made of glass optimised to withstand thermal and mechanical shock. This borosilicate tempered glass (which you also find in your kitchen, by the way) cannot be recycled with the normal glass – or recycled at all. It’s collected separately and sent to a landfill. So take good care of your tempered glass (and your normal glass!) – and be mindful not to put any broken tempered glass in the glass recycling bin, because this will interfere with the melting and recycling of the normal glass.

Plastic: the complicated one

Plastic is a wonderful material in many ways: it’s light, waterproof, strong and durable. Unfortunately, it pollutes our environment and poses a serious danger to wildlife. This is why many of us care a lot about plastic and sort it meticulously whenever possible. Sadly, sorting the plastic won’t solve the world’s plastic waste problem!

There are several reasons for that. First of all, plastic cannot be truly recycled; just like paper and cardboard, the quality of plastic is reduced every time it’s melted. Therefore, used plastic is often combined with virgin plastic to form ‘recycled’ products. Alternatively, the used plastic is ‘recycled’ into plastic products of a substantially lower quality than the original plastic product. And this is downcycling – not recycling!

Another reason is that most sorted plastic ends up in plastic landfills, plastic storage facilities, the environment or it’s incinerated under environmentally harmful conditions. And it might even be transported half way around the globe before any of these things happen...

One of the reasons why most sorted plastic is neither recycled nor downcycled is that these processes require prior separation of the plastic into plastic types; it’s not enough that the plastic has been separated from paper, cardboard, residual waste etc.

You are most likely familiar with the plastic foil, also known as soft plastic or LDPE. You probably also know of PET, which is the most widely used plastic type for water bottles. There are four other specific plastic types (PP, PVC, PS, HDPE), and then there’s the “trouble” type: the plastic type designated “other” which includes all the hundreds of mixes of the six plastic types in all sorts of combinations. Plastic items of the type “other” can by definition, not be recycled – even though the material pictogram on the back sure does look like a recycling icon!

So “plastic” isn’t just “plastic”. And at this point in time, we are relying on hand sorting (!) to separate the different plastic types from one another. So unless you meticulously separate all seven plastic types into different bins, someone else will have to fine sort your plastic by hand to prep it for recycling or downcycling. Hand sorting is obviously awfully laborious, so it mainly takes place in countries where labor is cheap. This is why a massive amount of plastic waste is transported from the USA and Europe to South East Asian countries. And not only is this associated with large (!) carbon emissions, there’s also no guarantee that the plastic will be recycled/downcycled; it might as well end up in landfills or the environment – or get burned without cleaning the toxic smoke.

So what can you do? Well, plastic is much more likely to be recycled/downcycled if it’s sorted really well. This means: plastic types aren’t mixed, and the plastic isn’t filthy or mixed with paper or residual waste. In principle, when you sort the plastic waste (really) well, it won’t need hand sorting, and therefore it won’t have to be transported half way around the globe. Your well-sorted plastic waste will, however, most likely be mixed with not-so-well sorted plastic waste from others when it’s picked up by the waste hauler. And therefore, your plastic will need hand sorting anyway...

In addition, the well-sorted plastic waste won’t be recycled if there is no demand for this type of used plastic. This is why we need plastic factories to use it in their production – and why we should demand and buy plastic products with recycled plastic contents!

The two most impactful actions you can take

Some of the waste generated in the lab can be recycled – if not endlessly, then at least some times. So it’s great if you sort your waste and send it for recycling – but please don’t stop there!

Recycling isn’t going to fix the climate crisis or make planetary resources infinite.

Reducing is much more impactful than recycling. You can reduce waste by purchasing products with less packaging material and by minimising consumption – for example by reusing whenever possible and by being minimalistic in your lab work. You can read more about this in our previous article: Click here.

Importantly, you can also influence the products of tomorrow by asking the right questions to the manufacturers and vendors. Are their products and packaging optimised to reduce waste? Are their products for multi-use or single-use? Do their products and packaging contain recycled materials – and are they easily recyclable? Are all parts of products and packaging clearly labeled so we know exactly what materials (including plastic types!) they consist of so we can sort them accordingly?

Remember that manufacturers and suppliers will change their products and packaging much more quickly if they know that it’s important to their (potential) customers!

Relevant companies

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