Development of Nitrogen Recycling Strategies for Bioregenerative Life Support Systems in Space

Abstract

To enable long-distance space travel, the development of a highly efficient and robust system to recover nutrients from waste streams is imperative. The inability of the current physicochemical-based environmental control and life support system (ECLSS) on the ISS to produce food in situ and to recover water and oxygen at high enough efficiencies results in the need for frequent resupply missions from Earth. Therefore, alternative strategies like biologically-based technologies called bioregenerative life support systems (BLSSs) are in development. These systems aim to combine biological and physicochemical processes, which enable in situ water, oxygen, and food production (through the highly efficient recovery of minerals from waste streams). Hence, minimalizing the need for external consumables. One of the BLSS initiatives is the European Space Agency’s (ESA) Micro-Ecological Life Support System Alternative (MELiSSA). It has been designed as a five-compartment bioengineered system able to produce fresh food and oxygen and to recycle water. As such, it could sustain the needs of a human crew for long-term space exploration missions. A prerequisite for the self-sufficient nature of MELiSSA is the highly efficient recovery of valuable minerals from waste streams. The produced nutrients can be used as a fertilizer for food production. In this review, we discuss the need to shift from the ECLSS to a BLSS, provide a summary of past and current BLSS programs and their unique approaches to nitrogen recovery and processing of urine waste streams. In addition, compartment III of the MELiSSA loop, which is responsible for nitrogen recovery, is reviewed in-depth. Finally, past, current, and future related ground and space demonstration and the space-related challenges for this technology are considered.

Sustainability and environmental impact of on‐line hemodiafiltration

“…This is also possible for spent dialysate . The experience of manned space flights could be adapted to dialysis when research is able to provide affordable devices 10 . Last but not the least, sorbent technology is part of the solution currently developed for the wearable artificial kidney, 11 but it is out of the scope of this topic.…”

Nitrous Oxide Emissions and Carbon Footprint of Decentralized Urine Fertilizer Production by Nitrification and Distillation

“…6 In addition, urine source separation is the primary approach in regenerative life support systems for space application such as the Micro-Ecological Life Support System Alternative (MELiSSA). 7,8 One well-studied treatment chain to convert urine into a liquid ammonium nitrate fertilizer is through partial nitrification, granular activated carbon (GAC) filtration, and distillation. In the system, urea is hydrolyzed to ammonia and then partially oxidized to nitrate.…”

“…This direct recovery and local shortcut of the nitrogen cycle can potentially reduce nutrient emissions to the environment, , which is important as the global nitrogen and phosphorus cycles have exceeded their safe planetary boundaries . In addition, urine source separation is the primary approach in regenerative life support systems for space application such as the Micro-Ecological Life Support System Alternative (MELiSSA). , …”

Metaproteomics, Heterotrophic Growth, and Distribution of Nitrosomonas europaea and Nitrobacter winogradskyi after Long-Term Operation of an Autotrophic Nitrifying Biofilm Reactor

“…Regenerative Life Support Systems (RLSS) are currently in development to tackle low recovery efficiencies, high energy demands, as well as food, water, and oxygen production challenges through regeneration of nutrients from waste streams. In these systems, biological and physicochemical processes are combined in a closed-loop configuration to produce food, water, and oxygen that meet the metabolic needs of the crew [5]. The longest running program that is developing a RLSS is the MELiSSA (Micro-Ecological Life Support System Alternative) program.…”

“…Production of gaseous nitrogen species result in a loss of nitrogen in the bioreactor and production of potentially toxic volatile compounds that have to be avoided in a space environment. Hence, anaerobic conditions should be prevented during CIII operation [5].…”