Compost cycle at Fraser Richmond featured in ‘Delta Optimist’

In case you missed it, last week the Delta Optimist featured an article on the circle of curbside compost. It’s journey from your house to processing and beyond was detailed by writer Jessica Kerr on Aug. 18. Harvest partner Fraser Richmond Soil and Fibre was included in the story, set in the metro Vancouver area.

If you’ve ever wondered what exactly happens to your organic waste once it’s collected, well, as Kerr writes, it takes on a sort of second life. Food scraps, grass trimmings,  yard and wood waste move on to the organic processing facility. While it seems like a mystery, the process of anaerobic digestion is explained as follows:

Fraser Richmond Soil and Fibre receives organic waste from most municipalities in the Lower Mainland. Packer trucks bring material either directly to the facility or to one of several transfer stations around the Lower Mainland.

The material is composted in large batches. The yard waste, food scraps and wood waste are mixed together in piles with larger pieces of already composted material, which are then covered with carbon activated ash from wood sources, which helps to insulate and reduce odour.

“We’re not in business if we’re producing odour so everything we do revolves around odour control and odour protection and odour mitigation,” Vice President Steve Aujla said.

“We’re trying to create an ideal environment for the organisms for them to thrive off of, so they can multiply quicker so they can ideally break down the stuff in near perfect conditions,” he said.

After seven to nine weeks, the material is ready for the next steps.

The batch of compost is sieved to separate the finer material, which is the marketable compost, from the larger pieces, which are then put into the next batch of compost.

That practice also helps speed up the composting process as the composted matter will bring many microorganisms with it to help jumpstart the new batch.

“They all get recycled, they get re-composted again until they break down smaller and smaller and smaller,” he said.

Once separated, the finished compost is piled in another area of the site. The product is sold as pure compost and also gets combined with sand to make garden, turf and top dressing soils.

The pure compost as well as the different soils are sold in bulk to homeowners, landscapers, municipalities and other companies that bag and sell them.

The entire process takes between 10 and 12 weeks.

“It’s amazing those little creatures what they’re doing,” Aujla said.

Read the full story at www.delta-optimist.com.

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International Compost Awareness Week Kicks Off

The first full week in May (pssst, now!  May 2-8, 2010)  is full of earthy delights via International Compost Awareness Week (ICAW).  This year’s theme: “Compost!…Recycling for a Greener Tomorrow.” We stopped a few international-types on the street and asked them what they thought about compost.  Here’s what we heard:

• “J’aime bien le compost pour le jardin.” -anonomyous person from France [Rough translation: "I like compost for the garden."]
• “Tiako zezika satria afaka maniry tsara ny vary-ko.” -anonymous person from Madagascar  [Rough translation: "I like compost because it allows my rice to grow well."]

The beneficial properties of compost are seemlingly endless.  We invite you  to take a moment and answer, How, where, or why do you like compost?  (All languages welcome!)

Energy or Compost From Green Waste? (We think both.)

A study in Europe compared two approaches for recycling green waste: composting and waste-to-energy (see below).  Harvest Power represents the best of both worlds: its high solids anaerobic digestion (HSAD) technology harnesses renewable energy from green waste, then the remaining digestate gets composted.  The environmental benefits from HSAD and composting provide a powerhouse of CO2 savings.  We hope the next comparative study includes HSAD.  In the meantime, enjoy.

Recycling green waste as compost could match the environmental benefits of converting it into renewable energy, in terms of CO2 savings, according to new German research. It suggests that the two forms of waste management should be seen as complementary and both should receive subsidies.

Green waste is biodegradable waste, usually from gardens and parks, and includes grass, hedge trimmings, leaves and tree trunks. It can be used to produce energy in biomass power stations and receives a renewable energy subsidy in Germany. It can also be recycled as compost, which reduces the extraction of peat – an important sink for CO2. However, composting does not receive financial support in Germany. The EU is currently developing policy to encourage composting and develop standards for composting across the EU.

The research compared the environmental benefits of energy recovery from green waste and of recycling green waste using 81 samples. It analyzed the CO2 balance of each system by estimating the release and savings of CO2 at the different stages of the process chain. For energy recovery this included the transport, shredding, incineration and the CO2 saved from the renewable energy produced. For recycling this included stages such as transport, composting and CO2 saved by replacing peat. Four different types of green waste were considered that differed in their amount of wood, herbaceous/grassy material and soil.

The results demonstrated that waste with a high percentage of wood produced the most CO2 savings for both composting and energy recovery whilst those with only herbaceous and soil components produced the least savings. The CO2 savings from energy recovery varied from 126 to 1040 kg of CO2 saved per tonne of green waste, depending on the type of waste and its composition. The CO2 savings from recycling varied from 259 to 1193 kg of CO2 per tonne of green waste, again depending on the type of waste. This indicates that the environmental gains, in terms of CO2 savings, were similar for both energy recovery and recycling of green waste.

Notably, green waste with a high percentage of herbaceous/grassy content and soil content had twice the CO2 savings from recycling as from energy recovery. This is probably because this type of waste has low heating values, due to high water and ash content, and is therefore better for composting purposes.

The researchers suggested that energy recovery and recycling of green waste should be judged as complementary systems. It is unlikely that one method on its own will achieve the desired reduction in CO2 levels and a combination is more likely to lead to a significant decrease in greenhouse gas emissions. As such they recommend that recycling of green waste be awarded equivalent financial support as the use of green waste to produce renewable energy.

See: http://ec.europa.eu/environment/waste/compost/index.htm

Source: Kranert, M., Gottschall, R., Bruns, C. & Hafner, G. (2010). Energy or compost from green waste? A CO2-based assessment. Waste Management. 30: 697-701.

Contact: martin.kranert@iswa.uni-stuttgart.de

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