"Recycling: yes or not?"

Final post.

Hi everyone!

It is definitely time to give an end to the “Recycling: yes or not?” discussion. I closed the last post shortly introducing the food waste and its related disposal methods. Hence, today I get start from there and afterwards I will briefly write about glass and textile treatment. Also this post will be principally based on the WRAP report “Environmental benefits of recycling – 2010 update”.

So: food waste. Anaerobic digestion (AD) and composting are the two most common ways to treat organic food waste. Basically, there is no chance to literally recycle food waste. The most favored procedure is probably the AD: a study conducted by Finnveden et al. (2005) listed the advantages as the production of biogas, used for both electricity and heat, as well as fuel for vehicles. Moreover, the WRAP report explains that AD is a powerful option also in terms of global warming impact: the biogas produced is mainly composed by CO2 and CH4 and, rather than being released in the atmosphere, they are exactly collected and used for energy purposes. Precisely, the less global warming impact marks the difference between composting and AD: in fact, the former shows here more influence compared to AD. Moreover, AD allows also a higher energy recovery than composing (Mata-Alvarez et al. 2000). A confirm comes also from the WRAP report, which exactly list composting as second preferred option after AD. However, composting represents, for instance, one of the easiest and most immediate techniques to domestically well treat our food waste. Finally, WRAP shows also that incineration (with energy recovery) could give good results when organic waste is involved: this is the specific case of garden waste, which obviously guarantees a remarkable heating value.

Chynoweth et al. (2001) edited another significant AD-related work: here, the authors strongly emphasized the key role of the AD, explaining how the society would gain considerable advantages using natural-methane instead of the traditional fossil fuel and, at the same time, that would mean a further action against global warming and acid rains.

Glass. Finding scientific and complete information about glass treatment has not been that accessible. However, I managed to find few useful papers about recycling and landfilling glass waste. The main disposal methods about glass waste are exactly the two just listed (Sahyan and Xu 2004). Moreover, this paper explains also what the main “second-live” of the glass is. In fact, the authors give evidence that the glass is an important ingredient for the formation of concrete aggregate and, noticeably, they explain this reusing technique as a key tool to reduce landfilling. Shao et al. (2000) have been even more specific: indeed, they assert how glass is non-biodegradable and, therefore, totally non-adapts to landfilling. In addiction, this paper shows again the important role that glass covers concerning concrete production as well as mention recycling as other alternative destiny for glass waste.

Concluding as the WRAP report does, I wish to say something about textiles, a quite common component of MSW. The document displays the end-of-life of clothes as second-hand stuff, recycling (mainly referred to a reusing concept) and waste, which ends up in incineration or landfilling. Predictably, there are a lot of ways to prevent the incineration/landfilling of textile waste and this is exactly the main evidence of the report, which lists a quite long series of second-life possibility for this kind of rubbish. More specifically, Woolridge et al. gave, in terms of energy saved, some precise number when analysing donated clothes: “for every kilogram of virgin cotton displaced by second hand clothing approximately 65 kWh is saved, and for every kilogram of polyester around 90 kWh is saved. Therefore, the reuse and recycling of the donated clothing results in a reduction in the environmental burden compared to purchasing new clothing made from virgin materials” (Woolridge et al. 2006: 94).

Obviously our homes and flats are not well equipped for collecting textile but, in London as anywhere else, there is a bunch of Oxfam and similar charity shops.

Briefly concluding with gasification, not mentioned so far. As explained in this post, we can consider gasification as a well-improved incineration. Malkow (2004) developed a very articulated work about the different kinds of gasification (and pyrolysis), explaining how it leads the way to a high energy saving and less environmental impact compared to incineration. Moreover he pointed out the benefits considering the less amount of emissions released in the atmosphere. Its position in the Waste Hierarchy is thus quite well positioned.

Well, it ended up a massive post. I tried to summarize the big amount of information of the remaining issues and I am aware that there would be a lot more bits to talk about. Anyway, I hope that I gave a quite fair and scientific idea about why recycling is up there in the Waste Hierarchy: it generally represents the best compromise between energy demand, environmental and healthy impacts. Moreover, leaving the science for a moment, I personally find so ridiculous just bin our waste when it could have such a considerable number of second uses and second life.

Importantly, recycling is not the highest position in the Waste Hierarchy. The following posts will be thus dealing with the remaining two RE: reusing and reducing. Finally there will be space for some more posts regarding recycling@UCL, few initiatives and a future work discussion.

See you soon on RE-cycling!

"Recycling: yes or not?"

Hi bloggers!

After a while, it is now time to complete the “Recycling: yes or not?” discussion. That will roughly take two more posts, I promise.

The conclusion of the last post introduces what I am going to talk about today: in the next paragraphs, I will analyze the remaining disposal methods. In order to do that, these posts will be mainly based on the “Environmental benefits of recycling – update 2010“ report, edited by the Waste & Resource Action Program (WRAP – www.wrap.org.uk). This document runs a clear excursus across all the waste treatment methods, highlighting the best disposal solution for every different type of waste. Moreover, it is focused on the Municipal Solid Waste and, obviously, it analyzes also landfilling and incineration. Considering that these two disposal options have been already discussed, I will be mostly talking about Composting, Anaerobic Digestion and Pyrolysis in comparison to recycling.

Before analyzing in detail the contents of this report, I would like to get started with a significant sentences available in the summary (page 1):

“The conclusion was clear – most studies show that recycling offers more environmental benefits and lower environmental impacts than the other waste management options”.

Right, the scheme followed by the report is structured according to the different type of waste. For the first one, cardboard, it is shown that landfilling, incineration and recycling are the most common treatment. Same consideration can be found in other works like Arena et al. (2004). As well as WRAP report, the authors actually note that for paper, incineration could be sometimes better that recycling because it allows higher ratios in terms of energy recovery. Considering instead both the water usage (quite high for incineration) and energy request, recycling seems to be the best option. In 2014, Bajpai totally promoted paper recycling instead: indeed, his work points out how paper produced from recycled material requires less energy, prevent virgin material employment and reduce environmental pollution (Bajpai 2004). 

Same conclusions have been traced by a Swedish study. Herein, the authors show how "the potential saving that can be made when going from incineration to recycling is 1.2 million ton CO2 -equivalents" (Finnveden et al. 2005: 225).

Concerning plastics, recycling is overall ranked as the best option in terms of climate change (low impact), energy demand as well as water request (low as for paper). Pyrolysis is also considered as a preferred disposal methods because it is the treatment that shows the lowest toxics effects on human health.

Also Quian et al. (2014) promoted the pyrolysis process: considering before the advantages of recycling, as it helps to protect the environment and reduce the use of natural resources, they illustrated that, with its considerable heating value (Kiran et al. 2000), plastic represents the right ingredient to produce a more calorific fuel.

The problem of recycling plastic consists in its costs: how explained by Eriksson et al. (2005), recycling plastics presents the lowest consequences but, at the same time, the highest outlay. However, the same study explains how the general term “recycling” means reducing the environmental impact as well as softening the demand of energy resources and also limiting the economic expenses.

Anaerobic digestion (AD) and composting are taken into account especially when food and organic waste are involved but this, with few more important bits, will be the topic of the last "Recycling: yes or not" post.

See you soon on RE-cycling!

Recycling: yes or not?

Incineration

Back again on RE-cycling!
Let's restart the debate that I started few posts ago. Today it is time to talk about the incinerations’ impact.

Incineration consequences are involved in two main fields: global warming and human health. In both cases, the original factor that needs an accurate analysis is the gas emissions. Despite the combustion of waste does not release methane, in terms of global warming incineration is problematic because of the amount of CO2, N2O and NH3 emitted ("Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories" IPCC 2000, page 455). Instead, considering humankind health, Daskalopoulos et al. (1997) explain how municipal waste combustion released "polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF)" (Daskalopoulos et al. 1997: 226). These are generally known as toxins and they are considered causes of skin and liver diseases as well as cancer. Moreover, the same authors say that also metal compounds, heavy metals and acids gases are a result of waste incineration and also involved in the human health concerns.

However, comparing incineration to landfilling, it is easily noticeable that:
1. gaining and using energy from incineration is easier rather that from landfilling. Indeed, as highlighted in “Incineration of Municipal Solid Waste” report (DEFRA 2013), from incineration there is a substantial gain of usable energy in terms of heat and electricity.
Even though successful attempts have been done, energy recovery from landfilling is in fact a quite expensive procedure and it is mainly discussed as a possibility rather than a convenient and actual opportunity (Lombardi et al. 2006).
2. intuitively, incineration reduces the volume of waste. This means that less rubbish is thus dispatched to the land. Moreover, the residual bottom ash can also be reused in other engineering fields like road building (Incineration of Municipal Solid Waste, DEFRA 2013).
3. as explained in the UK Government report “Waste GHG Inventory Summary Factsheet”, the emissions from landfill represent the biggest amount of Green House Gases concerning the waste management (incineration does not produce CH4). In 2010, 89% of UK waste disposal gases came from land and just a minor part from incineration.
4. finally, another evidence is that water and soil pollution are mainly related to the leachate derived from the landfilled waste. Water contamination coming from incineration is minimal (Daskalopoulos et al. 1997).

Keeping in mind the energy recovery concept, I would say that with this post we have learnt why landfilling is at the bottom of the “Waste Hierarchy” and why the incineration is located in a slightly better position.
At this stage, we have to keep climbing the hierarchy as well as keep comparing the different disposal method each other. In the next few posts I should be able to conclude the current discussion and hopefully I will have fully explained the RE-RE-RE importance.

So...see you soon on RE-cycling!