The most effective way to address waste I have come across was popularised by William McDonough's Cradle to Cradle design, in which his motto became "waste equals food". A fortnight ago I introduced how McDonough designs with the goal of "eco-effectiveness" rather than "eco-efficiency" or, in other words, being good rather than being less bad.
This approach to design requires a holistic perspective and a clear set of desired outcomes. When I design systems, I seek to achieve the following: robustness, resilience, effectiveness, affordability, easy replication and low resource input.
See Also
Conservation comment: Surfing a metaphor for life
Conservation comment: Water never lies, understanding topographic landforms, overland flow paths, drainage and swales
Take wastewater, for example. In most cases it's considered a pollutant and disposal focuses on mitigation. I take the opposite view: it's a resource that can be harnessed for positive effects.
I'm in the finishing stages of designing a land application system from greywater that turns waste into food by using the effluent to "fertigate" (fertilise and irrigate) willows and other plants as part of a greater land management plan on our farm that involves growing food, sequestering carbon and building resilience to climate change. This approach to farming is called regenerative agriculture.
Central to our management plan is growing more trees and feeding them to goats while protecting slip-prone hillsides and unstable stream banks. This is a win-win-win farm plan in and of itself, but the greywater design adds to the overall productivity and resilience of the land while offering affordable, effective replication on other properties as needed.
The system addresses environmental challenges in these ways:
1) By using coarse woodchips instead of mined aggregate as the bedding material, the carbon footprint of building the system is reduced through eliminating the need to mine and transport aggregate over potentially long distances. Woodchips, on the other hand, are a local resource everywhere in New Zealand and can be processed and transported using relatively little fuel. Additionally, aggregate is a non-renewable resource while woodchips are renewable.
2) While serving as an aerobic medium for the biological treatment of greywater, the woodchip bedding material is stored as a carbon sink.
3) Fast-growing willows sequester large amounts of carbon from the atmosphere while also taking up nitrates and phosphates from the wastewater.
4) The system is designed to be affordable and to encourage those living rurally to engage in a lower-cost upgrade rather than continuing to use substandard systems or upgrading to an inadequate system. Redirecting greywater takes pressure off existing wastewater systems and extends their durability, thus reducing costs and dispersing wastewater over broader areas of land. (It's possible this approach can also be used for stock effluent.)
5) Willow branches are fed to stock (in our case goats) which takes pressure off grazing during summer months and helps prevent the need for buying in feed during droughts.
In a nutshell, this land application system is easy and inexpensive to build; adaptable to different soil conditions; replicable and scalable; low in embodied carbon footprint and increases the productivity of farmland while sequestering atmospheric carbon. How many wins is that?
+Nelson Lebo practices regenerative agriculture in Okoia. Column based on the work of Feidhlim Harty of FH Wetland Systems Limited.
