TUESDAY, JAN 17, 2023: NOTE TO FILE
Module 2-11
Living Water Cities
WE’VE LOOKED AT systems from the smallest scale of simple constructed wetlands through to eco-machines and Food Chain Reactors that serve large populations in cities. Let’s have a look at some of the ways that cities can be revitalized with ‘living water’ in this short but inspiring video from Biomatrix Water.
https://www.biomatrixwater.com/living-water-cities/
The video is followed by an animated design for an entire city neighbourhood. You can click on the numbers to see the scope for ecological, plant-based technologies that cleanse while reconnecting citizens with nature.
Modelling for Decision-Making: what system is most suitable for your community or project?
IN THIS MODULE we have been looking at various problems arising from our present water crisis and the ways we can change our attitudes and our practices. A whole-systems approach to designing regenerative communities’ entails taking everything into account, the climate, the hydrological cycle, the local watershed and making choices based on ecological knowledge [except as relates to carrying capcity]. Working with nature, through various forms of ecological design, we can have both local and global impacts that enable the biosphere to regenerate its ecosystems and functional cycles.
As intentional communities, we can integrate our choices for water management into a broader vision for our watershed. We make choices that are determined by an understanding of the local ecology and aim for systems that provide for our needs while adding to ecosystem restoration [if the population is well under carrying capacity]. We can do this by applying the 12 permaculture principles starting with observation, and we can also make choices that maximize the potential ‘yields’, based on the ethics: Earth Care, People Care and Fair Shares. [We can persist by choicelessly being obedient to the nature of things as subsystems of Gaia who don't get a vote as to what works to persist long term.]
We can empower ourselves to be enablers of biosphere regeneration by mapping out the connections between the elements in our systems. [We can stand down from our hubris heights and listen only to Nature who has all the answers.] Above we looked at the mind-map of a whole-systems approach to water as the means to envisage the bigger picture and find our place within the system. We can draw up conceptual water budgets integrated with the watershed after some research into where our water comes from, how it is used, how and where it is treated and released back into the environment. For help drawing up a conceptual water budget, follow the link provided in the appendix.
We can use this model to make our own maps, adjusted for our own community/watershed and even make improvements. For example, rain doesn’t just fall into rivers (as shown in the map above), it falls mostly on land, and we have seen from the section on watersheds that healthy rivers cannot be regarded as separate from healthy, hydrated landscapes. So we can include restoration of the small water cycles, bioprecipitation, through ecosystem restoration as an essential aspect of a regenerative design [while rapidly reducing human, crop, livestock, and pet populations faster than we degrow the economy].
Choices between systems can also be mapped out to compare the pros and the cons as this mind-map illustrates in comparing a tank-based system with a lagoon-based system. [You can guess then test, but your guess may not have viable determinates.]
Source: Gaia Education
We can add to this mind-map too, comparing use of space, (embodied) energy, materials and costs along with environmental advantages.
If we have already decided for a constructed wetland, we can map out the flow of the system. Horizontal flow constructed wetlands for treating wastewater need a pre-treatment stage to lower influent BOD (Biochemical Oxygen Demand) and TSS (Total Suspended Solids), otherwise the wetland can get overloaded at the front end, which can cause clogging. We can see that in this flow diagram below, the choice for a septic tank has already been made. But there are alternatives. Would a biodigester be more appropriate? Let’s gather some information on both. What type of information do we need?
6.1. Septic Tanks
This allows wastewater to separate into layers and begin the process of decomposition while being contained within the septic tank. Bacteria, which are naturally present in all septic systems, begin to digest the solids that have settled to the bottom of the tank, transforming up to 50 percent of these solids into liquids and gases. Septic tanks provide initial reduction of organic matter (BOD and TSS) through anaerobic digestion. Septic tanks remove little nitrogen, unless nitrified effluent is recycled for denitrification.
When liquids (black water) within the tank rise to the level of the outflow pipe, they enter the discharge system (see diagram below). They can be allowed to disperse into land (through a French drain) or can be moved on to the next phase in the flow diagram for treatment in a wetlands system for discharge into rivers or re-use as grey water for irrigation.
Source: https://www.epa.gov/septic/types-septic-systems
While septic systems can handle plastic and other non-biological materials that get into the collection system, they cannot dispose of all the material. Solids that are not broken down by bacteria (grit and sand, plastic, undigested fats, etc.) and non-organic solids begin to accumulate in the septic tank as sewage sludge and eventually need to be removed when they are two-thirds full of sludge, some of which might need further treatment.
Module 2, lesson 12
