Earth Tub™ Frequently Asked Questions

What is the Earth Tub?

The Earth Tub is a small scale, in-vessel composting system for recycling organic waste materials at the site where they are generated. Complete with a bio-filter for odor processing and control, this system provides a neighborhood friendly efficient composting technology. The Earth Tub has been developed specifically to meet the composting needs of universities/schools, restaurants/cafeterias, commercial food processors, hospitals, multi-unit residential dwellings, camps and other institutional organic waste generators.

What is unique about the Earth Tub? 

The Earth Tub offers the sophistication of large in-vessel composting systems to the small institutional generator at an affordable price.

What are the key features of the Earth Tub?

• Modular and expandable design allows flexibility in application

• Bio-filter processes odors and accelerates the compost process

• High rate composting reduces volume and stabilizes material quickly

• Powered auger is thoroughly effective for mixing and shredding most foods

• Insulated design allows for operation under winter conditions

• Durable, heavy duty plastic construction (double walled rotomolded polyethylene)

• Finished potting soil mixes can be blended within the Earth Tub by adding peat moss etc to compost

How much organic waste must an institution generate to use the Earth Tub? 

For on-site composting, the Earth Tub is capable of processing as little as 40 lbs (20 kg) per day or as much as 500 lbs (250 kg) per day. The modular design of the system allows it to be adapted to a wide variety of applications and configurations.

How long will it take to fill the Earth Tub? 

Assuming a 5-6 day per week operation, it will take 13 weeks to fill an Earth Tub at 40 pounds per day, 5 weeks to fill at 50 pounds per day, and 3.5 weeks to fill at 150 pounds per day. Each unit has a total of 3200 lbs (1500 kg) biomass capacity when full. This data was collected at University of North Carolina, Charlotte installation.

What if your organic waste stream increases?

Expansion capability is one of the key features of the Earth Tub System. By virtue of its modular design, the system is ideally suited to incremental capacity increases. This system is a perfect application for gradually introducing composting to the institutional organic waste generators.

What are acceptable Materials for Composting?

The system is designed to process Kitchen prep waste and plate scrapings. Green garden waste and manures will easily compost in the system. Meats, cheese, and other fatty foods should be kept below 10% of total waste input. Avoid adding large pieces of meat, fats or oils to the system.

How cold can it be and still maintain compost temperatures in the Earth Tub?

The Earth Tub has been installed in some very cold locations. It may need supplemental heat if the temperature remains below 10F for more than 7 days. The aeration system should be shut down during cold weather.

Do I need two Earth Tubs to compost?

If you are composting less than 50 pounds of food per day, a single Earth Tub will provide continuous composting by adding food on one side and removing compost from the opposite side when the unit is full.