Recycling and reducing CO2 by composting tomato scraps (Introduced to: Iwaki Onahama Saien) - Deodorization and Composting equipment - Miraie

CASE STUDY

Construction example

2021.10.25 EASYJET

Recycling and reducing CO2 by composting tomato scraps (Introduced to: Iwaki Onahama Saien)

In this case, composting of materials with high moisture content had resulted in sludge-like compost, but by improving aeration they were able to raise fermentation temperature and reduce odors

Introduced toFukushima Prefecture
Processed Material and AmountTomato scraps (leaves, stems, fruits) 45 m3/day
OverviewIn this case, composting of materials with high moisture content had resulted in sludge-like compost, but by improving aeration they were able to raise fermentation temperature and reduce odors.

Measures and Effects

Increase processing amount by improving aerationTomato scraps with high moisture content turned to a sludge-like state in the rotary tank. By introducing high pressure aeration, they stabilized fermentation and increased the processing amount of scraps.
Reduce foul odors by eliminating incomplete fermentationBy introducing high pressure aeration, they stabilized processing of compost and drastically reduced foul odors.
Raise fermentation temperature with improved aerationHigh pressure aeration raised the fermentation temperature from the 30 to 40˚ C range to the 60 to 70˚ C range.
Reduce costs by controlling electricity billsBy switching from a normal blower system to a high pressure aeration system, they were able to reduce their electricity bill by 30%.
Improve compost quality by mixing and changing the types of auxiliary materialsBy revising the types and amounts of auxiliary materials, they stabilized the composting process and improved the quality of compost.

Iwaki Onahama Saien Co., Ltd., which has investment from Kagome Co., Ltd., has introduced EasyJet as a system for composting tomato scraps. Here we introduce an overview of their system.

Iwaki Onahama Saien is a high tech vegetable farm with the largest hydroponic tomato farming operation in Japan, boasting an area of 20 hectares (equivalent to 4 Tokyo domes).

This farm grows fresh edible tomatoes branded as “Kokumi Tomato,” producing 3,000 tons annually.

In the tomato cultivation process, they prune as much as 40 cubic meters (5 tons) of leaves and stems per day.

They were already composting these leaves and stems, but the moisture content of tomato scraps can be as high as 90%, so these scraps did not ferment very well, and raised the issue of how to improve the quality of compost.

Previously, they had done composting with a rotary stirring device and blower aeration from the floor. However, blower aeration necessitates cleaning and other maintenance, and fermentation was not stable.

Therefore, they decided to change the aeration part of their system to EasyJet, in order to shorten the fermentation period and raise the fermentation temperature.

Immediately after they started using EasyJet, the fermentation temperature rose above 70˚ C, and composting is now going smoothly.

They also managed to lower the amount of electricity used in the compost production process by 20%, thereby reducing their electricity costs and CO2 emissions.

Tomatoes produce a large volume of scraps (stems, leaves, etc.) compared to other hydroponic crops. We made a proposal for a way to efficiently compost these scraps and reduce processing costs.

In preparation for introduction, we did preliminary composting tests at our in-house test facility, and made a proposal for a plant based on the test data.

In this case, composting materials with high moisture content had resulted in sludge-like compost, but by improving aeration they were able to raise fermentation temperature and reduce odors

PlaceFukushima Prefecture
Processed Material and AmountTomato scraps (leaves, stems, fruits) 45 m3/day
OverviewIn this case, composting materials with high moisture content had resulted in sludge-like compost, but by improving aeration they were able to raise fermentation temperature and reduce odors.

Measures and Effects

Increase processing amount by improving aerationTomato scraps with high moisture content turned to a sludge-like state in the rotary tank. By introducing high pressure aeration, they stabilized fermentation and increased the processing amount of scraps.
Reduce foul odors by eliminating incomplete fermentationBy introducing high pressure aeration, they stabilized processing of compost and drastically reduced foul odors.
Raise fermentation temperature with improved aerationHigh pressure aeration raised the fermentation temperature from the 30 to 40˚ C range to the 60 to 70˚ C range.
Reduce costs by controlling electricity billsBy switching from a normal blower system to a high pressure aeration system, they were able to reduce their electricity bill by 30%.
Improve compost quality by mixing and changing the types of auxiliary materialsBy revising the types and amounts of auxiliary materials, they stabilized the composting process and improved the quality of compost.
Tomato scraps discharged from the farm are transported to the composting plant next to the farm

This is the progress after introduction of EasyJet to Iwaki Onahama Saien.

Iwaki Onahama Saien discharges 40 m3 per day of tomato scraps (primarily pruned stems and leaves, and depending on the season, large amounts of unsellable fruits), and these scraps are composted in 20 days.

Tomato scraps carried in to the composting plant are first cut apart in a shredder, then put in to a rotary stirring tank. EasyJet is installed on the floor of the stirring tank, and it promotes fermentation.

The freshly pruned leaves and stems are decomposed by aerobic microorganisms, reaching temperatures above 70˚ C by the next day, and turning brown within a couple of days.

In this facility, composting is complete in about 20 days, and completed compost is sold to local farmers and general consumers.

Oxygen concentration in compost

Looking at fermentation data, the part with EasyJet shows good oxygen concentration (Photo 6).

They have also recorded fermentation temperature over 70˚ C in winter, so composting is going smoothly.

During stirring

Even after delivering EasyJet, we continue to visit Iwaki Onahama Saien on a regular basis in order to give advice about operation while sharing fermentation data with them.

When it comes to recycling food scraps, the know-how for composting them is very different from the know-how for composting livestock manure.

This makes operation management after installation is very important, and we are making great efforts in this area.

At Iwaki Onahama Saien, fermentation temperature was maintained above 70˚ C even when we visited them in December, so composting is going smoothly.

Before delivery, fermentation temperature would not rise high enough, causing issues such as odor during fermentation, but those issues have now been solved.

With regard to odors, sulfuric odors peculiar to anaerobic fermentation have been nearly eliminated, which is a great improvement. We plan to maintain stable operations year round while continuing to follow up on introduction.

In this case, high pressure aeration was introduced to a rotary fermentation tank suffering incomplete fermentation, improving both the processing amount and odors (Introduced to: Food Factory Company O)

Processed Material and AmountPlant scraps 40 m3/day
OverviewIn this case, high pressure aeration was introduced to a rotary fermentation tank suffering incomplete fermentation, improving both the processing amount and odors.

Measures and Effects

Increase processing volume by improving aerationBy introducing high pressure aeration, they increased the processing amount 1.5 to 2 times.
Reduce foul odors by eliminating incomplete fermentationBy doing aerobic fermentation, they reduced the generation of hydrogen sulfide and other odorants, and odor complaints practically stopped.
Raise fermentation temperature with improved aerationFermentation temperature was 30˚ C, but was raised to the 60 to 70˚ C range.

Company O used to do composting with a rotary fermentation tank. However, the compost turned to a sludge-like state because of its high moisture content, causing problems such as incomplete fermentation and foul odors.

Therefore, they decided to introduce EasyJet on about half of the floor of the rotary tank, and use high pressure aeration to improve fermentation.

After introducing EasyJet, fermentation temperature was maintained at high temperatures around 70˚ C, deposit height was raised, and the amount of compost processed increased drastically.

Complaints about the foul odor problem also practically stopped.

Currently, it operates stably without impact from seasonal fluctuations.