Plasma Processing of Water and Inedible Biomass for pH Control and Nutrient Recycling

Health Medicine and Biotechnology
Plasma Processing of Water and Inedible Biomass for pH Control and Nutrient Recycling (KSC-TOPS-94)
Plasma Treatment Improves Sanitation and Benefits Plant Growth
Overview
Researchers at Kennedy Space Center have developed a technology that generates plasma activated water in pH ranges that allow for the addition of nitrates and other nutrients to the water while maintaining a healthy pH for plants. A plasma torch is used to treat inedible biomass, generating ash containing nutrients useful for plant growth. The same plasma torch is also used to treat water, which results in the formation of nitric acid that lowers the pH of the water. Adding the plasma generated ash to the plasma treated water can balance the pH of the water to make it suitable for plant growth while simultaneously adding nutrients recycled from the inedible biomass to further enhance plant development. Plasma treatment of water to high and low pH extremes can also be used for sanitation purposes, causing pH shock to undesired organisms. The uniqueness of this process is the adjustability of the pH with one system. The same plasma system can be used to treat both the water and the biomass. Additionally, the technology can be used as an on-demand, point-of-use method for producing nitric acid.

The Technology
Early exploratory research with the plasma treatment of water and inedible biomass revealed problems with both efforts. Plasma treatment of water lowered the pH of the water below acceptable levels for plants. Additionally, inedible biomass treated with plasma for nutrient recovery has to be dissolved in acid to enhance that nutrient recovery, and acid can be difficult and dangerous to handle. The technology described here utilizes a single plasma torch to treat both water and inedible biomass. Plasma treatment of the water creates useful species, such as nitrates, to the water which are beneficial for plant growth. However, plasma treatment of water also forms nitric acid, causing the water to be too acidic for plants. Plasma treatment of inedible biomass breaks down the cellulose inside the plant material and reduces it to ash, liberating nutrients such as potassium, calcium, sodium, and phosphorus. Researchers determined that careful dosage of the appropriate amount of the recycled ash to the plasma treated water balances the water's pH level and also adds nutrients that can further enhance plant growth. This method eliminates the need for acid treatment of the plasma treated biomass. For cleaning applications, water can be treated with plasma to either high or low pH extremes for shock sanitation treatment. The system requires a high voltage power supply and a plasma torch. The torch requires a tube for gas transportation, an electrode inside the tube, and an electrode outside the tube. Air can be used for both treatments. The plasma system can be optimized to condense the system into a lunchbox sized package to generate the treated water and ash.
Benefits
  • Produces nutrient rich, pH balanced water for use on plants to enhance growth.
  • Provides the ability to vary pH with one system.
  • Simple, condensable system design that reduces complexity and footprint.
  • Eliminates the need to handle acid to dissolve plasma treated inedible biomass.
  • Capable of on-demand, point-of-use production of nitric acid.

Applications
  • Vertical farming
  • Hydroponics
  • Greenhouses
  • Irrigation
  • In-situ generation of cleaning agents
  • Space based agriculture
Technology Details

Health Medicine and Biotechnology
KSC-TOPS-94
KSC-14449
Plasma Activated Water: A Study of Gas Type, Electrode Material, and Power Supply Selection and the Impact on the Final Frontier (https://ntrs.nasa.gov/citations/20220016906) Plasma Assisted Acid Leaching of Inedible Biomass for Nutrient Recovery (https://ttu-ir.tdl.org/handle/2346/89730?show=full)
Similar Results
Wastewater Treatment and Remediation
NASA's system was developed for smaller-scale, space-based applications. However, the technology is scalable for larger industrial and municipal water treatment applications. Implementation of the Ammonia Recovery System could significantly reduce nitrogen content from water treatment processes, meaningfully improving the quality of water. This system offers a novel way to reduce nitrogen water pollutants, while allowing for the nitrogen to be collected and reused- reducing environmental and public health risks and providing an environmentally friendly fertilizer option. NASAs environmental solutions work to sustain life on earth through space based technology The adaptable nature of this system gives it potentially broad applications in a wide variety of industries; it is particularly ideal for on-site remediation of wastewater in places like condo complexes, hotels and water parks. Current methods of ammonia recovery could not meet NASAs mission requirements, so a new process was devised to optimize for high ammonia selectivity, simplicity, low volume , low power usage and zero contaminants in the effluent. To do this, NASA designed a novel regenerable struvite-formation system for the capture of ammonia. This system has three primary functions: 1) Removal of ammonia from wastewater using a media that is highly selective for ammonia 2) Capture of the ammonia for later use (e.g., as a fertilizer) 3) Regeneration of the capture media for reuse in the system
Carbon Capture Filter
NASA’s Carbon Capture Filter was designed to trap solid carbon dust through a variety of mechanisms. These include inertial separation, flow recirculation, flow tortuosity, media filtration, and quenching of hot particles or of precursor particles from pyrolysis. The filter uses a custom-designed housing to produce a strong and large recirculating pattern to remove dust through inertial forces and confine it into a large collection cup, which is enshrouded in a cold trap (using a thermoelectric cooler) to thermally induce precipitation of the solid carbon. The flow then passes through a single stage baffle and tube filters before exiting through the outlet at the top of the housing. During operations, gaseous carbon-containing streams enter the filter via an inlet tube at the top of the housing. The inlet tube extends down towards the bottom of the collection cup, where the high-speed stream meets a sudden perpendicular bottom wall, inducing a stagnation flow. Large particles inertially separate from the flow and impinge onto the bottom wall. The partial enclosure of the collection cup (aside from a small slit connecting it to the upper chamber) causes a recirculation bubble to form, increasing the residence time of the stream. The vortical motion of the recirculation bubble causes the large particles to spin outwards towards the walls of the collection cup. The collection cup is cooled to quench the carbon particles, causing them to precipitate out and collect on the walls of the cup. The extended residence time caused by the recirculating flow further quenches the stream. Only small particles that are entrained sufficiently by the flow make it through the slit between the collection cup and upper chamber. On the top wall of the upper chamber, an array of tubular filters collects the remaining particles before the gaseous stream exits the system. NASA’s Carbon Capture Filter has been prototyped and undergone initial testing with simulant dust, yielding promising results. The invention is available for licensing to industry.
Passive Porous Tube Nutrient Delivery System
The Passive Porous Tube Nutrient Delivery System is a plant growth technique that delivers a nutrient solution to the roots of plants via capillary action. The system was designed for use in microgravity. This new system utilizes a ceramic porous tube and water/nutrients bags connected in a loop. No electricity or moving parts are required. Instead, the nutrients are pumped in through a combination of capillary force and evapotranspiration from the plant. The porous tube supplies the plants with the water and nutrients needed to germinate and grow. This system provides an autonomous plant growth apparatus that is simple to assemble, plant and harvest, minimizing the amount of intervention needed in micro-gravity.
front
Passive Nutrient Delivery System (PONDS)
PONDS was developed as a water/nutrient delivery system for the Vegetable Production System, called VEGGIE, on the International Space Station (ISS). PONDS uses an innovative wicking material to passively link a water/nutrient reservoir to a plant cylinder. The system enables higher germination rates and improved growth conditions compared to the VEGGIE water/nutrient delivery system currently used on the ISS. PONDs consists of two primary components: a water/nutrient reservoir (Figure 1), and a detachable plant cylinder containing growth substrate and wicking material (Figure 2). The reservoir includes a viewing window that allows the user to observe and record water-use data. The plant cylinder, which screws into the reservoir system, is made from commercial-off-the-shelf materials and fittings. Both the reservoir and plant cylinder include oxygen-permeable windows to enhance aeration to the root zone. Water is delivered from the reservoir to the substrate contained within the plant cylinder via the wicking material inserted into the growth substrate. The wicking material is intrinsically hydrophilic, providing improved capacity compared to the system previously used with VEGGIE. As a result, PONDS can continuously supply water to the root zone within the plant cylinder on demand.
Glass of purified water
Pre-Treatment Solution for Water Recovery
The pre-treatment solution increases the solubility of calcium in urine brines by reducing the concentration of sulfates. When the solution is properly dosed, it enables biological, physical, and chemical stabilization of flushed urine for storage and distillation up to a steady 87% water recovery, as realized aboard the U.S. segment of the ISS, without precipitation of minerals such as gypsum. Turning wastewater or seawater into potable water requires three important steps shared by the UPA and Water Recovery System (WRS) aboard the ISS: 1) pre-treatment, 2) distillation or membrane filtration, and 3) transport and storage of potable water and brine. Added during the first step, the pre-treatment solution improves the efficiency of the UPA by reducing the formation of solid precipitates caused by urinary calcium, sulfate ions, and sulfuric acid. This reduction in-turn creates less acidic brines which means more water can be recovered along with less surface scaling and clogging, further increasing recovery. As an added benefit, the solution contains a biocide that prevents the growth of bacteria and fungus, thereby increasing storage time of the treated urine. Although the pre-treatment solution was developed for the ISSs UPA , the technology can potentially be used on Earth to pretreat contaminated water from organic-laden, high-salinity wastewaters. Adding the solution is a simple process that can be scaled to fit demand. It has the potential to improve water recovery in many applications such as: desalination plants, brackish water treatment, mining water treatment, hydraulic fracturing operations, and more. The pre-treatment solution may also lend itself for use in the transport and storage of wastewater due to the solution's ability to prevent microbial growth.
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