Recycling our organic waste

Each year in Ireland we produce an incredible 3 million tonnes of household waste. Most of it still ends up in landfill, creating huge environmental problems and only 22% of this domestic waste gets recycled. Clearly this is an unsustainable situation and one that the EPA and Local Authorities are anxious to rectify. The EU Landfill Directive requires each Member State to produce a strategy on biodegradable waste. It also sets targets for diverting biodegradable municipal waste from landfill by 2010, 2013 and 2016. If Ireland doesn’t meet these targets we face potential fines of up to half a million Euro per day so we have a huge task ahead of us. At this sorting centre in Dungarvan the EPA is conducting a waste characterisation survey to evaluate the type and amount of waste we are throwing into our black bins, much of which could be recycled. We actually go out with the bin truck and we go along a normal collection day; we take it all back to the depot here where we take a small subsample of that waste. We put it up on the tables and we sort through it. We take out all the paper and put them into the buckets that are marked paper, if it’s plastic packaging it goes into one bucket if it’s non packaging it goes into another bucket. And we weigh all these buckets and eventually what we do is we get a total weight for the sample and then we know how much of each type of waste, so the percentage that was aluminium, the percentage that was packaging. And at the end of that we get a result that is representative of the national sample. Armed with this information, the EPA can work out what quantity of recyclable material ends up in landfill. It does tell us a bit more about the different types of waste in the black bin. So it helps us identify areas to focus on, like organic waste. By measuring it at regular intervals we can tell if it’s increasing or decreasing. And if any kind of the initiatives that have been implemented are actually having any kind of impact. Tell us about the results of your survey here today. Are you finding a change since say 4 years ago? There was an increase in packaging waste between 2005 and 1998 from 25% to 28%. We also had an increase in terms of biodegradable waste. The EPA conducts these surveys all over the country and it’s not just black bins. Dry recyclable bin and food waste bin material is also broken down to get a clearer picture of what people are throwing away. What we actually do is we survey each bin separately so one week we come along, we survey the recycling waste. This week we are looking at black bin waste and then we would also look at their brown bin waste as well and that gives us a representative sample. We apply the different fractions to the total waste to tell us the amount on a national level. Getting rid of organic waste is one of our biggest challenges and 2 years ago Dublin City Council decided to introduce brown bins for this type of material. All organic waste including all food and garden waste can go into these bins. So far over 60,000 bins have been rolled out in pilot areas and Dublin City Council hopes to double that figure by late Spring 2009. Up until the brown bin was rolled out all of the material would have going into your black bin and so now with the brown bin the collections are every fortnight so you have the potential to leave out your black bin one week and your brown bin the following week. The brown bin, Duncan, as you can see is a 140 litre in size, compared to the green bin which would be a 240 litre or the black bin which is also a 240 litre in size. So it’s much smaller but it’s on wheels the same way. It’s on wheels, it’s the same height as such but it’s slightly narrower. All householders also receive a small kitchen caddy similar to this one here. I’ve one under my sink at home. Yes. Material is fine to be left in your kitchen caddy for maybe 2 to 3 days and it saves people going in and out to the brown bin which would be outside. It’s very handy like that isn’t it? It’s very handy. And also you have the option then of using a compostable bag. So a standard biodegradable bag is not a good idea? It’s not a good idea, it won’t break down in the composting process within the 6 week period. Do these brown bins cause any smells or vermin? Well as you can see there are ventilation holes along this side and the other side as well and this will allow air to circulate in the bin, it will dry out the material and it is then not a very attractive environment for maggots and flies to breathe. And also it will take away water vapour and this limits the formation of gas which would lead then to odours. To ensure against odours, bluebottles or maggots meat and cooked food should be wrapped in newspaper or placed in a compostable bag. Despite some initial hesitation Dublin householders have now enthusiastically embraced the brown bin scheme. Billy McLean from Swords has been using his brown bin for a year now. Well we used to have to throw all our waste into the black bin you would get smells with that which funny enough it doesn’t happen with the brown bin. So all the waste now that you generate in the kitchen like say preparing food or all the waste maybe after a meal does that all now go into your brown bin? Oh, it certainly does and we keep the brown bin here underneath the sink here. The small bin is it? Yes this is the small bin as you can see here a little lid on it here to keep the smells away if there was any smells and all our waste goes into that. You don’t use a liner for it like one of these recyclable liner bags? I don’t, no. All I use is a little piece of newspaper in the bottom that is sufficient. How often now would you take this out? Brown bin goes out once every two weeks whether it’s full or not. Fine from the waste in the house you know you’re not going to fill it in two weeks but certainly if you add the garden waste especially during the summer when you have all the grass cuttings. Is that when you’ve got the most? -That’s when we have the most yes. So that must be saving you quite a bit of money too Saving us a lot of money Duncan, well the black bin is costing us €8 every time you put it out. We used to have to put that out once a week now we’d only have to put it out once every 4 weeks. But more important: I think we are doing our bit for the environment. The introduction of a brown bin collection in some neighbourhoods of Dublin City over the past year has undoubtedly been a great success for householders. Prior to this, all of their organic waste ended up in landfill creating smells, leachate, attracting vermin and emitting methane, a highly potent greenhouse gas. Now a third of their waste is diverted from landfill and this food and garden waste is now converted into a very valuable resource. This indoor composting facility at Kilmainhamwood in North Meath is where Dublin’s organic waste ends up. The material is shredded before being placed in these bays where it begins its aerobic decomposition process. We have to control the moisture content of the material for composting it should be in the range of about 60, 65%. Temperature is very important. The process is thermophilic which means that microbes work in the temperature range of 48 to 60 degrees Celsius. This is controlled by aerating composting bays, in order to supply oxygen to the microbes which they will feed from the food waste and brown bin which will generate heat which will keep the bays at their correct temperature. If you look at the outside of the composting bays you will see white filamentous bacteria called actinomycetes or simple fungi as well. These are the same decomposers that biologically breakdown and decay deadwood in the forest. After 3 weeks in the composting bays the material is screened. Once we finish screening we have our 12 mm compost material which goes on to be our end product. After that then there is about 3% of plastics and waste material that comes out at the end of the screen. The plastic is our highest contaminant and it is mainly made up of conventional plastic bags and wrapping that people maybe used to collect their garden waste and then they’ll throw it into the brown bin. Finally it’s pasteurised at specific high temperatures in controlled tunnels over time to ensure no contaminants make it through to the final product which means it must comply with the Department of Agriculture Regulations and is EPA licensed. This is the product Duncan, our finished product that we bagged for Dublin City Council. As you can see it’s nice. Very nice – that’s good stuff. That’s first class organic. Good for gardens and houses. Mix that now for gardens and soils about 2 to 1 ratio mix, it provides all the macro and micro nutrients for plant growth, lovely material. That material is made in 8 to 10 weeks. The bags of compost are available in 4 recycling centres around Dublin; here at Rathmines, Collins Avenue, Newtown Industrial Estate and Crumlin. This material is a nutrient-rich compost it’s different from a peat based compost so it can be used in your garden and there are instructions on the back of the bag of how you would mix it with your own soil type at home. Brown bins have now been rolled out in 5 Local Authorities across Ireland including here in Dungarvan Co. Waterford. The brown bin itself which we introduced a number of years ago, maybe 4 years ago, it’s taken away on a three weekly collection to an organic processing facility where it is turned into Grade A compost. So everybody is aware of the various issues that are out there on the environmental front and I think people do see the benefits of the brown bin waste going off to a composting facility. You’ve got all the advantages on one side you’re not producing all this harmful greenhouse gas and the other side then that food waste is being converted into compost for gardening and all the other benefits that come with that. It’s clear organic waste is a potential resource that can be turned into high value end uses such as biogas. The Dublin Authorities are now developing this. However the real challenge to us now is to reduce the amount of food waste we produce in the first place.

Leave a Reply

Your email address will not be published. Required fields are marked *