Recently it has occurred to me that the definition of Anthroponics (alternative farming methods using recirculating water and a soilless medium, and with human waste as the source of nutrients) can be expanded.
What is human waste? Human waste has been typically defined as biowaste, including both urine and feces, among other fluids. Traditionally it encompasses all body fluids and residue (such as nails, skin, hairs, etc) which are released by the human body in the environment and are biogradable. When we think of human waste we usually think of Blackwater, or the end result of combining water with urine and feces that reaches our contemporary wastewater treatment plants.
We can take a step back and also consider greywater as a type of human waste. Greywater can be defined as the water resulting after human use in activities such as washing (in sinks and dishwashers), showers, kitchen sinks and baths. This greywater usually contains a considerable less amount of human biowaste, but it will likely contain detergents and soap. The platform Greywateraction.org mentions using greywater for growing edible crops though keeping in mind that it is “essential to put nothing toxic down the drain–no bleach, no dye, no bath salts, no cleanser, no shampoo with unpronounceable ingredients, and no products containing boron, which is toxic to plants. It is crucial to use all-natural, biodegradable soaps whose ingredients do not harm plants. Most powdered detergent, and some liquid detergent, is sodium based, but sodium can keep seeds from sprouting and destroy the structure of clay soils. Chose salt-free liquid soaps. While you’re at it, watch out for your own health: “natural” body products often contain substances toxic to humans, including parabens, stearalkonium chloride, phenoxyethanol, polyethelene glycol (PEG), and synthetic fragrances.” (Source). This platform also provides a list of greywater friendly cleaning products.
It seems unlikely that a greywater system could work effectively in feeding a recirculating system without using soil, as many of the nutrients from human biowaste exist in lesser concentrations, and there are few widespread cleaning products that would not pose any risk to the crops and to human health. However, as environmental awareness increases and companies produce products that are biogradable and perhaps even benefitial when released into the environment, it is not surprisingly that greywater may in the near future acquire properties that make it usable for hydroponic use.
We could also take an even further step back in our definition of Anthroponics to include all human waste streams, particularly industrial wastewater. However, most of the current human waste streams are unfit even for release in the environment, let alone for use in agriculture, given that manufacturing processes create waste products not conducive to life. It is not unlikely to imagine a future where biofabrication methods (see relevant TED Talk) have transformed the manufacturing landscape, particularly in regards to leather and meat production, thus opening the door to Anthroponic applications. But for now it seems extremely hard to implement within current business practices.
It seems therefore apparent that embracing a wider definition of Anthroponics may be needed in the future, but the current definition and the current nutrient sources for Anthroponics (human biowaste) will provide enough challenges and opportunities for designers and engineers for the near future.