Water is the most essential human need, hence providing enough water for the inhabitants isa fundamental goal. Besides, water plays an important role in almost every agricultural andindustrial process. All of these require huge amounts of water daily, so the water managementhas to be based on reusing and recycling, and to seldom be changed.3.3.1 Water ProductionAs previously mentioned, it is desirable to renew the water aboard our spacecraft from time totime in order to enhance the quality of water which is of such great importance to the citizens.
This action will be performed gradually, as new obtained water arrives to The Iris.The main way to obtain water is by extracting ice from Moon’s crust. This process will becarried out by robots, as explained in detail in Section 5.3.2.
Another way to obtain water is by reducing ilmenite, an ore that lunar soil abounds with.Apart from water, this reaction forms a very useful product (Fe), and an expensive one, namelytitanium oxide:FeTiO3 + H2 TiO2 + Fe + H2O12Water can also be produced aboard our space settlement as a by-product of the air purificationprocesses in the industrial area, like the ones described in the previous section.3.3.2 Water RecyclingWe will use plenty of water purification methods so as to assure that water quality is at highstandards.
The industrial zone will have a water supply system separated from that of the33residential and agricultural areas since they demand different water properties. Additionally,production of drinking water and distilled water (used in the medical field) will contain extrapurification systems.Microfiltration, Ultrafiltration, and NanofiltrationAll of these types of filtration are based on the same principles: water passes through a semipermeablemembrane that removes undissolved particles. The sizes of membrane’s pores vary from0.1µm at microfiltration to almost 0.
001 µm at nanofiltration. However, nanofiltration alsoinvolves the applying of pressure (nearly 7 atmospheres) on one side of the membrane. Thesemethods will be utilized in every water supply system on The Iris.Figure 34: Water filtration system comparisonImage Credit:https://www.eurowater.
com/products/standard products/nanofiltration plants.aspxReverse OsmosisAs the above graph shows, the reverse osmosis almost completely demineralizes water, thus wecan replace the classic and inefficient Ion Exchange method.Osmosis is a naturally occurring phenomenon where a less concentrated solution tends to migrateto a more concentrated solution.
Reverse Osmosis is the process of Osmosis in reverse, andrequires applying of great pressure on the more concentrated solution, as illustrated in thescheme below.34Figure 35: Reverse OsmosisImage Credit: https://puretecwater.com/reverse-osmosis/what-is-reverse-osmosisThis method will not be used in the industrial area, in order not to make water too corrosiveand to enable us to obtain a certain hardness for each factory.DisinfectionAlthough the filtration membranes don’t allow the micro-organisms through, it is mandatoryto also use a disinfection process in every water supply system in order to prevent any watercontamination . The ultraviolet disinfection is very effective, killing any pathogens, but it leavesno residual disinfectant to inactivate the potential micro-organisms that may appear in thedistribution system. To tackle this problem, we will add chloramines during a second disinfectionstep, whose residual disinfectants are long-lasting and don’t readily form trihalomethanes andhaloacetic acids13.
This way, the negative effects of classic chlorine disinfection are avoided.