Sewage

Industrial development on Luna should start with remote controlled devices, but eventually the capitol development will make the value of human presence high enough and the expense of supporting people on Luna low enough that there will be people on Luna doing what people do best. Part of the infrastructure to support people will be the sewage treatment facilities. Human waste must be handled very differently than the industrial waste that Luna will need to process from the start of industrial activities.

Begin at the Beginning

A possible procedure of sewage treatment should start at the toilet. Each flush should be an isolated batch of sewage that is subject to automated analysis to insure that it is not contaminated with chemicals or solid foreign objects that would interfere with the recycling process that will be vital to the colony. Pressing the flush button should cause the cause the toilet lid to fasten securely isolating the batch. Scanners would check for the presence of RFID tags which will be incorporated into towelettes that people will use to clean themselves. The towelettes should be disposed of in a separate recycling system specialized for washing them. The presence of a towelette in the toilet bowl will activate an out-of-order signal for maintenance service to unfasten the toilet lid, fix the problem, and return the toilet to service. In case there are no RFID tags in the bowl, automatic machinery will stir the contents and force it through a screen using added water as necessary. Solid objects that do not go through the screen will also activate an out-of-order signal. Automatic chemical analysis will be the last step before automated equipment seals the batch into a barrel for shipment to the central sewage treatment facility. Each barrel will be labeled with the time, date, and location code. The number of flushes packed into a barrel before sealing it will be chosen for minimum cost. The first personnel at a lunar mining colony will all be extraordinarily capable and multitalented. Any one of them could check out a sanitary service tool kit and restore an out-of-order toilet to operating condition, whether or not it was their turn to respond to such out-of-order calls. Why should such people not be trusted to simply not contaminate human waste with things that would interfere with recycling? This is open to consideration, but the idea behind the automated system is making it easier to go along with the program than to get rid of an inconvenient or unauthorized item by simply flushing it. Personnel will have access to a wide variety of chemicals and equipment to do their jobs. Possession of an odd item that is inconvenient to dispose of is a circumstance that might occur. The procedures for living in a moon base established by the first personnel should be suitable for a larger number of people of a less select group who should succeed them as the base expands.

The Lack of Sewer Pipelines

Sewer pipelines connecting each toilet with the sewage treatment facility would be convenient but there needs to be allowance for the air tight emergency isolation doors which will close automatically in case there is a breach in the integrity of the pressure vessel that forms the compartment in which the toilet is located. Fresh air and stale air ducts will need to have their separate air tight isolation doors in case of emergency, but isolation doors for hot and cold water pipes and sewage pipes would be an excessive complication. In case of a breach, affected compartments will need to function on canned oxygen generators, canned CO2 scrubbing units, and emergency sanitary procedures which might, depending upon the nature of the emergency, result in some stored sewage to be processed later. Improved process efficiency of waste treatment occurs with uniform flow conditions. The biological treatment of waste can use a greater or a lesser flow, but transitions should be gradual and managed. So, a temporary storage place for barrels of waste, possibly refrigerated, should be available.

Use of Developed Technology

Sewage treatment on Earth has already resulted in a sewage sludge product which can be used to fertilize agricultural fields. On Luna where the process will need to be more carefully controlled, the process should work more efficiently. The sludge from sewage treatment on Luna should be sent as fertilizer to gardens that are growing food. Most of the pieces of a materially closed recycling life support system are now on hand, but sewage processing systems on Earth are sized to support many thousands of people. Resizing for twenty to a hundred people will make the systems more costly per person. There is considerable room for improvements that will make such life support systems more efficient on a small scale. One development that is technologically related is the Blue Diversion Toilet which facilitates recycling small batches of waste without the toilet being connected to a sewer pipeline. The commercial offering of a sealed underwater habitat for shrimp suggests some directions in which research might proceed. The potential biological hazard that sewage constitutes will be handled with procedures similar to those used on Earth.

Various Thoughts

• Sewage Treatment is done on most ships. Packaged systems are available.
• How do they handle the problem for Biosphere II?
• How is the problem handled at the South Pole Station? Adapt it for the moon?
• Medications aren't always completely absorbed and will be excreted into the sewage system. A solution for handling them there is required.