Waste Management

in

Mars Base Zero

By Ray R. Collins

Introduction

Although Mars Base Zero does not yet have a waste management system set up yet, it is designed. Portions of the system have already been investigated, especially the aspects of input. The system is ready to be implemented, and it is expected to take about a year to achieve a reasonable balance between inputs & outputs (since it will take awhile for the material to decompose). Most of the systems mentioned here will be implemented in the fall of 2000.

System Outline

System Inputs

• Slop bucket
• Contains soap, toothpaste, food scraps
• Quantity: 5 gallons a week
• Urine
• Feces and plants which are used for toilet paper.⁴
• Kitchen waste
• Egg shells, plant scraps, very tiny quantities of meat
• Chicken manure
• Garden waste: above ground
• Primarily high carbon plant remains
• Garden waste: below ground
• Roots

Processes

• Sterilization to 160°F³
• Feces and chicken manure will be sterilized before further processing
• Feces will be added to the earthworm box
• Chicken manure, which is deadly for earthworms, will be added to the compost heap
• Dilute urine with water^{1, 3a}
• Compost heap will be mixed to maintain the proper carbon to nitrogen ration, with air ventilation pulled down through the pile and distributed under a soil bed.^2,5
• Earthworm boxes.
• Soil decomposition. Organic parts (roots, plant stocks dug into the soil) not removed from the soil will be naturally decomposed by organisms living in the soil.

Outputs

• diluted urine¹
• good for non-root crops
• compost
• good for soil
• earthworm casts
• good for soil

Discussion and Conclusions

Waste management in closed ecosystems is critical to maintaining nutrient flow. It is very important to minimize time in the breakdown cycle, so that nutrients do not end up sequestered in the breakdown cycle for prolonged periods of time. Keeping an eye on the chemistry is also important, for if the waste breakdown process results in sequestering of nutrients, the ecosystem will suffer.

Improperly managed wastes will result in imbalances, which could result in reduces soil fertility. Degradation of imported material will result in a gradual shift in the nutrient level of the soil (higher), which could eventually pose problems. This needs to be watched as the soil changes from a natural one to an amended one.

I consider waste management one of the more important aspects of running Mars Base Zero. While we have not yet added these capabilities to the facility, we hope to do so shortly after restarting operation in the fall of 2000.

Brief Composting Notes & references

Future Fertility

1. p32: undiluted urine is toxic to soil organisms. It should be diluted with 5-10 parts h2o/1 pt urine.

2. P61: air is drawn into the compost pile by fans

4. P65: plants which make good toilet paper (footnote 157)

5. P107: to get the proper C:N ratio for composting, add 1 part dry to 1.25 parts green by volume

The Composting Toilet Book by David Porto and Carol Steinfeld

3. a. p61 160° F will kill all pathogens; urine is usually sterile; urine is too strong-dilute with 8 parts water.

3. b. P62 pasteurization 143.6 F for 1 hr