"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!

Digging the topic - part 3

From here to there

Hi everyone!

The last post I wrote on RE-cycling had interrupted, in a way, the "Digging the Topic" series that I was writing up. Hence, I think it's time to end the trilogy with the last piece of writing. With "Digging the topic - part 3" I will briefly give an overview on all the destinations of waste once collected from our houses, offices and premises. Therefore, following the guideline purpose of my blog, I will be focusing mainly on the MSW (Municipal Solid Waste).

Once collected, the waste starts a journey that ends up somewhere: the waste disposal methods explain in detail this somewhere taking into account all the possible options for the community to get rid of its scraps. Having a look at Figure 1, the Waste Hierarchy described in the newest Defra report “Waste Management in England” helps us to have a better idea of the term "disposal": the bottom of the arrow defines the disposal as an option with no energy recovery while, other disposal methods such as anaerobic digestion, gasification or pyrolysis, are ranked as other recovery because there is a production of reusable energy from their application.

Figure 1: waste hierarchy according to the "Waste Management in England" report (Defra) 

Recycling could be also considered as a disposal method because it is a (great) method to treat the waste. Anyway, we could generically list the disposal methods as follow:

1. Recycling (…and I don’t need to say what recycling is about)

2. Composting. The most complete definition I found out there was provided by Lau et al. in 1991: “controlled biological process which converts biodegradable solid organic matter into a stable humus-like substance” (Lau et al. 1991: 145). Another interesting paper written by Slater and Frederickson (2001), explains what composting means and involves. At this stage of the discussion, what is relevant among the huge amount of information provided is that composting refers mainly to kitchen and garden waste (more widely, it is a biodegradable-waste related method), it is a biological treatment, its output is used as fertilizers in agriculture or in reclamation projects.

3. Anaerobic digestion (AD). I am talking again about organic waste, yet treated in an oxygen-free environment (Alvarez et al. 2000). The outcomes of this technique are very interesting. In 1995, Braber presented a wide overview of the AD advantages, such as the considerable production of energy, reduction of CO₂ emission and, as well as for the composting, less land requirement.

4. Gasification and Pyrolysis. Here, taking a break in citing papers, I found an extremely useful webpage (www.gasification.org) which deals with this disposal methods. Basically, they both consist in burning waste but the former involves high temperature and an aerobic environment while the latter occurs at lower temperatures, it is anaerobic and it uses an indirect source of heat. The most important thing to say is that these methods allow high energy recovery ratios while the simple…

5. …incineration, an aerobic high-temperature waste combustion, often doesn’t. For fully understand the incineration process and its differences with gasification, I think it is time to link the first video.

6. Landfilling, which is the act of placing waste into specific portion of land. All official reports, environmental organization and, above all, the EU, describe landfilling as the last favourite way to treat waste. The reasons are quite straightforward if we consider all the disadvantages that it brings. In 1995, a number of these consequences have been listed by El-Fadel et al. as "gas and leachate generation, […] the migration of gas and leachate away from the landfill and their release into the environment, […] potential health hazards, vegetation damage, […], ground water pollution, air pollution, global warming" (El-Fadel et al. 1995: 1).

Well, the list above wanted to be an overview of the disposal methods together with a brief description of the relative main features. Therefore, concluding “Digging the topic – part 3”, I would say that this post has the double function to explain what the destiny of the rubbish is and, at the same time, to introduce automatically the following discussion: what are pro and cons for each method? In more generic terms, why is this specific sector of waste management so important? Hence, do we have to care about recycling? If yes, why? Looking back at Figure 1, it is clear how Defra wants to make clear that incineration and landfilling are the last favoured option to treat waste. At the same time, RE-RE-RE are at the top of the arrow so it looks like that a clear trail has been blazed. The following posts will be debating the questions above and I will try to understand what responsibility of the masses is within the waste process.

See you soon on RE-cycling!