Food, Water and Waste
Food, Water and Waste
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We’ve covered two big parts of the decentralisation story: how to make practically any chemical and hence any chemical industry product locally and how to generate and store energy locally. Its time to move on to other essentials.
Food
How can decentralized communities manage their food supply? Most people live in relatively dense areas (cities and surrounding areas). This means food needs to be grown in a quite small footprint. Let’s explore a few concepts:
Using existing methods
Vertical and rooftop gardens
Cell cultured meat
Bioreactors in general
Existing technology
The simplest idea possible is to use existing food production methods and just apply the best-known ones. The improvements will be enormous. As an example, in the Netherlands the production of one kg of tomatoes uses 9.1 liters of water, the global average being 210 liters.
Much of this production is in climate-controlled greenhouses.
On open fields production happens with driverless tractors, sensors measuring soil chemistry like water content and nutrients and automated quadcopters in the air detecting plant diseases and insects.
Vertical Gardens
The next small step is turning growing vegetables to be vertical. This means growing vegetables on top of each other in some form of vertical structure. This can be a trellis (rack), wall, specially made rack etc. Structures could be indoor or outdoors. Indoors naturally gives better control of the environment.
This packs food production into very small footprint. If energy is affordable or say solar energy in plentiful supply, this can be economically feasible and the wastage generated minimal. The left overs from food growing (live leaves and stem) can be processed in local biorefineries to generate additional products like electricity, heat, animal futter or chemicals.
If plants are growing inside, it’s much easier to control the growing environment. The whole growing process can be automated so that sensors monitor all key aspects such as carbon dioxide levels, nutrient mix used, growth and production and being able to trace every plant in the process. Creating excess pressure inside the growing area makes it difficult for pests to get in and reduces need for pesticides.
LED lightning keeps getting cheaper and it is possible to radiate on optimal light frequencies for plants. In practice in purple-magenta LED lighting.
(Side note: Plants are green because they reflect part of the green light and consume purple and magenta. Surprisingly most of the energy coming from sun’s radiation happens to fall into the green part of light spectrum. This is due to how life evolved originally. One theory is that first photosynthesizing bacteria about 3,4 billion years ago were purple. First chlorophyll using bacteria – cyanobacteria – are expected to have evolved in seas under a cover of these purple bacteria. Most remaining light available under this bed of purple was purple and magenta (reflected downwards rather than upwards). Chlorophyll evolved to use mostly purple and magenta light and reflect green. Since chlorophyll is more efficient and photosynthesis releases oxygen that is toxic to anaerobic bacteria, these new bacteria took over. This release of oxygen later caused the first large extinction event – The Great Oxidation.)
One benefit of this methods is that growing always takes place under same circumstances so produced food is of even quality. Food can also be grown around the year.
Old building can be repurposed this or facilities constructed say from containers.
Some newer growing methods can greatly increase yields such as hydroponic or aeroponic growing.
In hydroponics vegetables are grown in a nutrient-rich water where they pick up essential nutrients. Hydroponics may be completely soilless or use some porous growing medium like coconut coir, peat, pine bark, mineral wool, growstone, perlite or sand.
In aeroponic growing the roots of the plants are in air rather than in soil. In aeroponics, plants are typically housed in a closed or semi-closed system where the plant roots are suspended and exposed to the air and a misting or spraying system delivers nutrient-rich water solution to the roots. The mist consists of tiny water droplets with essential nutrients.
Growing can happen either in dedicated facilities built into containers and quickly transported anywhere globally or in more distributed manner inside existing buildings. Growing food at each building has additional benefits in cities. Lack of exposure to microbes is linked to increase in allergies in too hygienic environments. For example, studies have shown that having certain gut bacteria and exposure to fungi can reduce risk of asthma. Growing food nearby thus can protect people from some diseases.
The leftover greens from food production have many potential uses.
With digestation they can be used to produce methane as seen before. Methane in turn is both a fuel and a feedstock to chemical production. On more general note, they can be used in biorefineris to generate various kinds of chemicals like pectin or PHA (polyhydroxyalkanoates = orm of polyesters biocompatible, bioresorbable, and biodegradable and can replace plastics), proteins can be extracted, fibers
Several types of fish are herbivorous (eat plants) or omnivorous (can eat plants but also insects, other fish etc.) Leftovers can also be fed to for example tilapia, carp, and catfish.
And naturally fed to animals like pigs and goats as part of their diet. That’s the reason many animals were domesticated in the first place - to turn waste into important source or proteins
Or they can be used to feed insects although there are cultural barriers to eating insects. An additional downside is that some people allergic to seafood are also allergic to insects, especially arthropods. This is because they have similar protein structures.
Rooftop gardens are the idea of growing food at the top of the each building, some space reserved for solar cells to power the automations and additional energy for the houses.
Cell-Cultured Meat
Cell-cultured meat is a method where you take meat cells from animals such as a cow, lamb or chicken and grow new cells from them in a special environment inside a container. In essence make new meat by growing a sample of real cells from animals.
This can be done through a minimally invasive biopsy, taking a small muscle tissue sample. These cells are known as myosatellite cells (a form of stem cells) and have the ability to differentiate into muscle tissue.
No animal has to be slaughtered and the meat cells are exactly the same as meat cells in regular beef or chicken etc. The growing requires a lot less land – perhaps 90-99% less and there are no greenhouse gas emissions (methane) like when cows fart. Amount of used fresh water to grow meat reduces similarly.
The human body needs twenty different proteins to function and our bodies can make eleven of them. Meat is a natural source for the missing nine ones, is a big part of many cultures and has the positive side of producing happiness in eaters at least until they see the bill.
The stem cells taken from muscle can proliferate fast and turn into new muscle cells. This is the same process as in nature when muscles heal if they have been teared; new muscle tissue grows there to replace the damaged ones.
Once enough cells have multiplied, they need to made into a tissue that resembles the natural structure of meat. This can involve layering cells to create muscle fibers and interspersing fat cells to mimic marbling of traditional meat.
The growing is done in sterile bioreactor with nutrient solution. The environment for growing needs to be carefully controller with right ingredients such as amino acids, carbohydrates, vitamins, air, carbon dioxide and growth factors like hormones that signal the cells to multiply and form new muscle tissue. Growth factors are today the most expensive part with active research to find more economical alternatives.
The price today is still over that of regular meat, but prices are falling. Cell-cultured meat also allows creating new products such as selling meat of endangered animals (tuna, whales) or perhaps in future even extinct animals like mammoths.
Cell cultured meat reduces need for land usage and does not produce greenhouse gases making it similar in environmental impact to vegetables. If environmental impacts are allowed to guide our decisions, cell-cultured meat should logically be classified as vegetables and vegetables that have high environmental impact like avocados should be declared as meat. This would greatly increase the number of vegetarians globally and be a great benefit in the fight against global warming.
Mark Post:
Food Produced by Micro-Organisms
Another trend is to generate food proteins with modified micro-organisms. This is based on gene editing where one or more genes producing wanted proteins is moved to a different micro-organism like yeast or a bacterium. This recombinant DNA technology was first used to insert a human gene producing insulin to a yeast. This “recombinant” micro-organism then started now produce insulin encoded by the human gene.
Same can be applied to food where micro-organisms produce for example milk protein or egg yolk. For example, egg yolk is used in very many foods to create tasty texture or foams. Today about 1/3 of produced eggs are used as different ingredients in food and food industries. No replacement proteins have been found so far with similar good qualities. Chickens are the dominant bird on earth with 23 billion compared to 7 billion people. The core idea is to move the right genes (this time yolk producing) to a micro-organism and have it produce just the best parts of chicken. This then releases the land area used now for chicken feed and other animal fodder to grow food for people or released back to its natural state.
Same recombinant DNA technology allows to produce enzymes such as rennet for cheese production and amylase for baking.
This method of food production is very similar to brewing beer requiring mainly water and sugars with the right micro-organism in the right temperature and good control of the pH.
Let’s take the solarfoods example a little closer to round this part up.
Food from Air
The methane generated via Power-To-Methane can be used to cultivate Methylococcus capsulatus bacteria to produce protein rich feed for cattle, poultry and fish.
Different microbes can be used to grow protein rich food for human consumption using just CO2, H2 and electricity. As mentioned, solarfoods is developing a solution where hydrogen from electrolysis and CO2 with direct air capture is fed to microbes that produces a mixture with more than 50 per cent protein and 25 percent carbohydrates. The rest is fats and nucleic acids.
Other nutrients needed for cell growth like nitrogen, phosphorus, potassium, salts and micronutrient are used in their process well. Before consumption the grown mass is first filtered, treated in ultra-high temperature and dried. The resulting mixture resembles dry protein powder. Intent is that this mixture could be used in cooking as such with no further processing steps.
The end result is estimated to be about 10 times as energy efficient as common photosynthesis used in cultivation of for example soy. One of the alternatives being considered is a home reactor for food, a type of domestic appliance that the consumers can use to produce the needed protein themselves.
One benefit is also that growing food and futter this way is continuous process having no seasonality (as long as you use a stable energy source like geothermal, small modular nuclear, biomass combustion or hydro).
As a summary all ingredients are taken directly from air and food production can be taken anywhere on the planet.
Water Purification
After food, next water
For small communities, informal settlements etc. and as a decentralised alternative, small modular purification systems work well instead of building large facilities that are capital intensive with construction taking a long time. In addition, small modular units can be relocated with ease.
There are a number of common technologies for cleaning water such as reverse osmosis or micro-, nano- and ultrafiltration. These commonly work so that pressure is used to force water through a selective membrane -i.e., a membrane that has holes that block larger molecules but let smaller water molecules pass.
The membrane needs to be periodically cleaned with chemicals like citric acid, hypochlorite or sodium hydroxide and changed when cleaning stops working.
The membranes can be made of polymer thin films. Other membrane-based methods are electrodialysis reversal, forward osmosis and membrane distillation that have different mechanisms. For example, membrane distillation is thermally driven method where temperature difference causes water vapor to pass through the membrane’s pores.
A full system for example for sea water consists of several modules such as intake of water, pre-filtration removing large debris, sedimentation where flocs settle to the bottom due to gravity, disinfection with for example ultraviolet light, filtration through particle filter, the actual reverse osmosis phase, and storage in tanks. Plus of course regular testing of the water.
Waste Treatment
What goes in, must go out. And there is also waste produced as byproduct for growing foodstuff. Those need handling as well.
Organic Waste
There is always some amount of organic waste – vegetable peels, leftovers or animal slurry etc. These can be handled in small-scale modular organic waste digesters. We already covered that in previous post, but a quick refresher.
Digesters use anaerobic bacteria to break down waste and produce gas – mostly methane and some carbon dioxide. After further processing this gas can be used just like natural gas to generate electricity, use as fuel for vehicles or as a feedstock for further chemical processes. As side product for burning methane, heat is generated that can be used to warm up vertical gardens or houses.
The digester also creates digestate that can be used as a fertiliser and some parts as livestock bedding replacing sawdust or sand.
https://www.earthlee.com/useful-resources
Waste water purification
Black waters need to be purified before releasing back into the environment. Polymers are central to this process.
One of the first steps in treatment is the removal of natural organic matter, bacteria, viruses, clay etc. from water. Usually, inorganic coagulants like aluminum sulfate or iron salts are added. These salts cause chemical and physical reactions between particles forming precipitates that combine into larger particles easy to be removed in next phase called sedimentation. In sedimentation the flow of water is low, and floc settles to the bottom.
Organic polymers created from air captured carbon can replace inorganic coagulants. They were first developed in the 1960s and are molecules with high weight. When they are added to water, they compound to other particle surfaces and through interparticle bridges coalesce to form floc. The forming sludge is then removed. The water can then be further treated for example in a slow sand filter.
Polyamine and PolyDADMAC are widely used organic coagulants. Often blended organic and inorganic chemicals are more effective than either alone. In a decentralised world, a waste treatment plant might use coagulants purchased from outside but the prepared to work with locally sourced and manufactured polymers alone.
The created sludge is a potential source of energy and it can also be used for phosphorous recovery. Energy can be generated by several ways: feeding the sludge into an anaerobic digester where micro-organisms produce biogas from it or by heating it up in hydrothermal processing. The latter process creates either hydro-char or bio-crude oil or gases depending on temperature. This recovered energy can power up the water treatment plant making free running.
(See for example: Energy and phosphorus recovery from black water. By Graaff, M.S. de; Temmink, B.G.; Zeeman, G.; Buisman, C.J.N.. Water Science and Technology 63 (2011)11. - ISSN 0273-1223 - p. 2759 - 2765. Or https://en.wikipedia.org/wiki/Water_purification )
Trend in sanitation is towards closed cycles and recycling. Phosphor is one of the central ingredients needed by plants to grow. There are two main methods for reclaiming it – using incinerating toilets that burn it with electricity and create phosphor in the right format for plants or reclaiming it from black waters.
If such methods would be widely used, we could satisfy a quarter of the present worldwide artificial phosphorus fertiliser use.
Incinerating toilets use electricity or gas to burn our stuff into ash, also sterilising them at the same time. They are used in places where traditional plumbing and sewage systems are not available like recreational vehicles (RVs), boats etc. We’ll skip them here.
When using black waters, it is first purified to water that still contains a great deal of phosphate and then magnesium is added to transform the phosphate and a part of the ammonia into struvite, which can be used to fertilise fields. This recreates a cycle of nutrient use that was broken in the last century for reasons of hygiene.
There is also nitrogen in black waters, another key nutrient needed by plants but concentration is still low for efficient recovery.
So there is nothing that prevents local production of good, water and waste handling in a decentralised society model.
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