Worm Tower Calculations
Hint: Basic numeracy: 1 kg worms processes 1 kg waste
Problem Statement
Using Aquaponic Towers such as in the Aquaponic Greenhouse - how many of these towers - functioning as worm towers - would be required to process household blackwater? The towers were 6-10' tall, and 6" diameter. Volume Calculator shows a 10' tower is 1/20 of a cubic meter.
Chemical Oxygen Demand per day per person is 100g - from Biodigester#Technical_Design_.2B_Calculations. About 1 lb wet feces per day.
Feces is 75% water. [1]. It requires only 100 Whr to evaporate the water in feces. But, feces will be in a larger volume of water, such as 1 gallon - making it 0.6 kWhr for evaporation. Not bad. This would be an incinerating toilet.
For worms - vermiposting works at approximately 1kg worm biomass per 1 kg feedstock per day - [2]. For 1 lb - that is 1/2 kg of worms - to process human waste per person. About 4000 worms to a kg of worms. [3]
Worms consume 25% of their body weight easily per day - [4]
This [5] implies easily 1/2 lb worms per cubic foot.
500 worms, 1/2 lb, cubic foot.
Thus, one tower at 2 cubic feet (10' long, 4" round) has 1 lb of worms. Thus, a beginner's tower - 4 towers are required per person..
Thus - 8 cubic feet - about 1/4 of a cubic meter - are reqiured.
