As we explore the potential to use human waste for growing food or crops, it is essential to not overlook or underestimate the potential health concerns of such an endeavor.
Let us start with u-anthroponics:
The current proposed methodology for using human urine in a sanitary way for an aquaponics/anthroponics application was documented in the master thesis “Aquaponics and its potential aquaculture wastewater treatment and human urine treatment“. There, the methodology used was based on the methodology used by Pradhan et al, in their 2007 research paper “Use of Human Urine Fertilizer in Cultivation of Cabbage (Brassica oleracea)––Impacts on Chemical, Microbial, and Flavor Quality” (Alternative link).
In both cases, the urine is separated at source from a healthy individual, under no type of medication and without any current disease. While this restriction prevents any large-scale application, it ensures a first layer of protection in terms of potential problems. After the urine is collected, it is kept in a sealed container where the process of urea volatilization will occur. That chemical reaction is described in p.12 of the master thesis and also in the wikipedia page about Ammonia volatilization from urea. The urine is generally stored until its pH reaches a value of 9, which according to Pradhan et al achieves a reduction of the bacterial population and therefore its sterelization. Further research such as conducted by Hilt et al has shown that fresh urine is not sterile, so a sterelization step such as the one described above is necessary to ensure further sanitation.
However, reaching a pH of at least 9 is a process that can take several weeks up to a month depending on several conditions. There is little information on how to optimize this process, and as such its an essential area that warrants further research for future anthroponic applications.
Moving on to f-anthroponics:
Since there is no record of a feces based aquaponics system ever being constructed, there is little information on how safe this practice would be or if at all possible. However, there exists some base research done which allows us to infer how such a practice could be created and be sanitary, thus protecting its users.
As described in the Types of Anthroponics Systems, the feces would be collected into a recipient where black soldier fly larvae would consume the feces. This process is described by Banks et al 2014 research paper “Growth rates of black soldier fly larvae fed on fresh human faeces and their implication for improving sanitation” (Alternative Link), where it was reported that feeding black soldier fly larvae human feces resulted in significantly larger growth. On the other hand, feeding black soldier fly larvae is a well-known type of fish feed practice in the aquaponics community, having been documented by the master thesis “Integrating Biosystems to foster Sustainable Aquaculture: Using Black Soldier Fly Larvae as Feed in Aquaponic Systems” (Alternative Link).
In order to enable this type of feces-based anthroponics system, some sort of sanitary action must be taken between the harvesting of the black soldier fly larvae and its use for feeding the fish. I proposed a solution in the anthroponics subreddit, which explained:
- Only use feces from a healthy individual, under no type of medication or without an illness, and without any blood on the feces;
- freeze the papua before feeding them to the fish;
- most importantly, keep the handling of the feces/larvae and touching the plants separate, and always wash your harvest thoroughly just in case.
So, basically, the way to ensure the process is sanitary, according to my current understanding of some microbiological processes, is to follow a simple precautionary process to u-anthroponics, and on top of that to wash/clean the harvested black soldier fly larvae, to freeze them and to always keep the handling of the feces/larvae and the growing plants separate.
However, unlike u-anthroponics, f-anthroponics requires a much stricter waste handling since the feces arent sterilized, and overal has more problems that need to be overcome. In theory, f-anthroponics systems (as the one described in this blog) can be sanitary, but only a real world prototype with adequate testing material will be able to compare the final product with, for example, an equivalent product using cow manure as fertilizer.