A Recycling Approach for Solid Waste Management in Rhiannon

     In space-based communities such as Rhiannon, any non-recycled waste product represents a loss of raw materials. Rhiannon recognized the huge task…and opportunity… presented by solid waste management in its boundaries. Typically, on Earth, dehydrated solid waste product is transported to landfills (in Rhiannon, this could result in over 120,000,000 pounds of landfill contents annually). Rhiannon, concerned with expanding population and limited water and nutrient resources, engineered an innovation for its water pollution and solid waste management industries.

     Construction and materials engineers in Rhiannon devised systems of sloped, winding, glass channels through which previously-screened wastewater flows. Centrifugal force settles out the sand and grit, which are removed to wastewater treatment facilities for further treatment.After entering lagoons, where oil-based pollutants are skimmed, the waste is aerated and inoculated with water from previous "runs." Microbiologists and chemical engineers have formulated a microbiological flora that aerobically breaks down the organic matter. A biomass conversion takes place, as human waste is transformed into ever-increasing volumes of microorganisms. After the waste is consumed, the lagoon contents enter holding tanks where oxygen is removed, killing the microorganisms.

     Meanwhile, the oil-based pollutants have been treated aerobically with special strains of Pseudomonas and Bacillus that rapidly degrade these hydrocarbons. When the oil has depleted, the bacteria population declines and settles out. The biomass slurry from the bottom of the lagoons is pumped into dehydrating facilities. Construction engineers designed them to resemble "giant salad spinners," where centrifugal force concentrates the slurry by slinging away most of the water. Subsequently, the biomass is squeezed at intense pressure resulting in damp "cakes." Materials engineers and ceramics engineers designed the kilns to withstand intense temperatures and rotational forces. Inside these kilns, the "cakes" are cooked and churned at temperatures approaching 800°F.

     Electrical engineers devised a use for the heat formed by the generators that provide energy to the waste treatment plant. The heat is applied to the rotating kilns. After an hour, the material is removed from the kilns; the intense heat has removed any potential pathogens from the product.

     Unfortunately, the "fertilizer" may not be safe at this point. Chlorine pollutants in the waste may have been transformed into dioxins by the heat used during pasteurization/dehydration. The product is mixed with water and treated with Dechloromonas, genetically-engineered dehalogenating bacteria that break down dioxins; the resulting hydrochloric acid product is removed with excess water by centrifugal motion and compression techniques. The nutrient-rich water is UV sterilized, filtered, and used in Rhiannon's hydroponic flow grid. The biomass cakes are reheated for an hour, then screened to create granular fertilizer. This organic fertilizer facilitates establishment of topsoil on the lunar surface.

     The solid waste management system engineered for Rhiannon is a marvel. Engineers found ways to maximize efficiency, using product overruns as inoculants, and even capturing "waste heat" for use in pasteurization. By using microbial solutions for eliminating human waste, grease, and potential dioxins, the treatment center ensures that the recycling of nutrients is risk-free to the Rhiannon population and its water supply.

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