PIXELGAE

P I X E L G A E : UR BA N WILDER NE S S

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INTRODUCTORY STUDIO

THE MORPHOGENESIS OF AN URBAN PHOTO-BIOREACTOR

P I X E L G A E : UR BA N WILDER N ESS

Students

Senior Faculty Student Assistant

Aman Jain Anuj Mittal Takeru Osoegawa Umit Ceren Bayazitoglu Claudio Pasquero Carmelo Zappulia Sebastian Amorelli

ABSTRACT

5 7 INTRODUCTION BACKGROUND

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Cyanobacteria . Spirulina

21 CULTIVATION

Parameters . Medium . Growth . Farming . Photo Bio-Reactor

PROCESS

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Urban Wilderness . Prototype 1 . Prototype 2 . Prototype 3

53 EXTRACTION Fermentation

CONCLUSION

57 58 BIBLIOGRAPHY

The future of mankind humanity appears bleak, if not apocalyptic.

Humanity’s impact on the environment has become undeniable and will continue to manifest itself in ways already familiar to us, except on a grander scale. In a warmer world, heavier floods, more intense droughts, and unpredictable, violent, and increasingly frequent storms could become a new normal.

Every person on Earth requires resources to survive. As population grows, more and more resources will be demanded, the most essential of which are food and water. If supply does not meet demand, we have a situation called food insecurity. The world needs to produce at least 50% more food to feed 10 billion people by 2050.

But climate change could cut crop yields by more than 25%. Unless we change how we grow our food and manage our natural capital, food security will be at risk. (World Bank, 2016).

ABSTRACT

Our aim is to explore alternative food to feed the exploding world population in the future – in a sustainable, cost-effective, and environmentally friendly way. Urban agriculture may be inefficient today, but it’s a model for a sustainable future. Of course, we can’t expect an Urban farm to have the same production capacity as a conventional, massive monoculture farm, but that doesn’t mean the urban farms have no true value; the amount of calories it yields shouldn’t be the sole metric of its worth.

The research explores the alternative approach towards urban farming by focusing on cultivating, harvesting and consuming ‘Spirulina’ in the urban context so as to bridge the gap between the urban and the natural as well as introducing ways in which the superfood becomes part of our daily diet.

KEYWORDS photo bioreactor design, Artrospira, Spirulina, superfood 5

INTRODUCTION

WHERE DOES OUR FOOD GROW?

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Anthropocentrism is the belief that considers human beings to be the most significant entity of the universe and interprets or regards the world in terms of human values and experiences. The ‘ecological footprint’ (Gaston 2005, p. 239) that resulted from humans’ greediness has lead over the decades to massive alteration in nature’s balance, as well as to many recognizable environmental crises the world is facing today.

The anthropocentric perception is widespread and is considered to be responsible for severe environmental crisis ranging from global warming, ozone depletion and water scarcity to the loss of biological diversity. Deforestation, for example, contributes to global warming where the trees-logging means less absorption of carbon dioxide, thus leading to more greenhouse gases trapped in the atmosphere. A domino effect of such would lead to severe climate changes resulting in the extinction of various species due to habitat-sabotage (Wilson 2003).

By contrast, ecocentrism, the term conceived

by Aldo Leopold (Leopold 1949), recognizes a nature-centered system of values, and extends the inherent worth to all living things regardless of their usefulness to humans (MacKinnon & Fiala, 2007) .

INTRODUCTION

According to the inelastic principles of both anthropocentrism and ecocentrism, the ability to make environmental decisions to satisfy both positions is difficult. Quite candidly, nature and humanity are devastated when anthropocentrism is practiced; and the conversion to ecocentrism overnight is impossible especially in the developed societies because of their heavy reliance on resources and generation of waste (Wapner & Matthew, 2009). However, we can distinguish our nature-consumption outcomes and intervene when the need is vital to our survival, and not because it is a desire or interest.

Ethical decisions towards nature can be quite conflicting, and the decent choice would yield less harm to the surroundings.

“Our planet’s human-carrying capacity,” as the ecologist Erle Ellis says, “emerges from the capabilities of our social systems and our technologies more than from any environmental limits.” (C.Ellis, 2013) In that sense, the survival of the human race for the foreseeable future is an engineering problem—a difficult engineering problem, but one that with enough time and effort we should be able to solve. Promising technologies that could increase the food supply and reduce our impact on planet’s environment 9

are in development or are already available.

Ronald Reagan put it beautifully—if a little too expansively—when he said that “There are no such things as limits to growth, because there are no limits on the human capacity for intelligence, imagination, and wonder.” (Reagan, 1983) The greatest stress on global resources is not how many of us there are, but how much we consume.

Broadly speaking, our ecological impact has grown with the global economy. As we’ve become richer, we’ve eaten more food, used more energy, produced more waste, and generally put more pressure on the natural systems that we depend on for our survival. While the planet should be able to support even a growing population, it’s not clear the planet can support a growing population as well as we might like.

i n t r o d u c t i o n

In 2003 the Australian philosopher Glenn Albrecht coined the term solastalgia to mean a “form of psychic or existential distress caused by environmental change”. He realized that no word existed to describe the unhappiness of people whose landscapes were being transformed about them by forces beyond their control. Albrecht’s coinage is part of an emerging lexis for what we are increasingly calling the “Anthropocene”: the new epoch of geological time in which human activity is considered such a powerful influence on the environment, climate and ecology of the planet that it will leave a long-term signature in the strata record.

A Stanford University team has boldly proposed that – living as we are through the last years of one Earth epoch, and the birth of another – we belong to “Generation Anthropocene”. (Macfarlane, 2016) The footprint of global agriculture is vast.

Industrial agriculture is absolutely responsible for driving deforestation, absolutely responsible for pushing industrial monoculture, and that means it is responsible for species loss. “We’re losing species we have never heard of, those we’ve yet to put a name to and industrial agriculture is very much at the spear-tip of that. Conferences are for forging the alliances and building the movement that will change the world.” (Marshall, 2017) Also, Agriculture is the largest single non-point source of water pollutants including sediments, salts, fertilizers (nitrates and phosphorus), pesticides, and manures. Pesticides from every chemical class have been detected in groundwater and are commonly found in groundwater beneath agricultural areas; they are widespread in the nation’s surface waters. Eutrophication and “dead zones” due to nutrient runoff affect many rivers, lakes, and oceans. Reduced water quality

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impacts agricultural production, drinking water supplies, and fishery production. The World Health Organization has stated that people who eat food treated with antibiotics are more susceptible to infections commonly treated by that type of antibiotic. Not only are we more likely to get those infections, but the microbes build up defenses against these drugs, creating superbugs, and those antibiotics are less likely to work.

The challenge of how we’ll feed the exploding world population in the future – in a sustainable, cost-effective and environmentally friendly way – is seeding an agricultural revolution. Welcome to farming of the future: a hi-tech, capital-intensive system of growing food sustainably and cleanly for the masses. Each second, the world’s population grows by nearly three more people, that is 240 000 people a day. By 2025, the global population will reach 8 billion people and 9.6 billion by 2050, according to the Food and Agriculture Organization (FAO). (Gasiorowski-Denis, 2017).

The world needs to produce at least 50% more food to feed 9 billion people by 2050. But climate change could cut crop yields by more than 25%.

Farms must increase production of food while preserving the environment, but they can’t do it alone and they can’t do it using today’s traditional farming practices. Unless we change how we grow our food and manage our natural capital, food security—especially for the world’s poorest—will be at risk. (World Bank, 2016).

Tom Heilandt, Secretary of the CODEX Alimentarius Commission – responsible for ­ setting international food safety and quality standards and one of two standards-setting bodies under the aegis of FAO – sums it up in a nutshell: “Agriculture exists first to feed people and has done so for thousands of years, and it will have to continue doing the same for hopefully many more.” Not surprisingly, he claims the biggest challenge is always going to be producing safe, good-­quality, nutritious and affordable food for a growing population. (Gasiorowski-Denis, 2017) Urban and peri-urban agriculture (UPA) is defined as the growing of plants and the raising of animals within and around cities, supplying its residents with different kinds of food products.

On the face of it, urban farming seems to be a difficult proposition because of the lack of space in cities, but at a practical level, there are some solutions that are extremely well-suited for urban farming.

All of this does not mean that cultivating crops on urban farms will solve the world’s food crisis.

However, urban agriculture should be evaluated for all of its outcomes, including the social and health benefits, and not just the volume of food produced.

The notion of growing your own food represents a paradigm shift in how most modern day urbanites perceive the food supply chain. You don’t necessarily need acres of land to do it and the inconvenience of growing your own food has been mitigated by innovations in micro-farming techniques.

Micro-farming in this context refers to growing enough food to take care of a portion or even all of what your household needs. Whether you live in a high rise building at the center of the city, or on sprawling acres out in the open countryside, you can adopt a “farm to plate” lifestyle if you are so inclined. The concept, in its purest form, can be summarized as fresher, nutrient-dense fruits and vegetables, grown close to where they are going to be eaten, ideally consumed within seven days of being harvested. No long distance haulage across or within countries, no genetic modification, no industrial pesticides, no artificial ripening and no mould. (Talabi, 2016) We are focusing on the nutritional value of the food rather than the quantity of the food. The advantages of Algae farming, are many – increased household food security, fresher and more nutritious food, provision of an income-generation opportunity for low-income households, and reduction in the net discharge of carbon di-oxide, a most conspicuous greenhouse gas. An algae production system can be an environmentally sound green food machine. Biomass can double every 2 to 5 days. With high protein algae like spirulina, this productivity breakthrough can yield over 20 times more protein than soybeans on the same area, 40 times corn and 400 times beef.

Other microalgae have even higher productivity.

Successful algae cultivation requires a more ecological approach than industrial agriculture.

As a living culture, if one factor changes in an algae system, the entire environment changes very quickly. Because algae grow so fast, the result can be seen in hours or days, not seasons or years like in conventional agriculture. Algae cultivation is a new addition to ecological food production. Ecological communities can combine algae and aquaponics with organic gardens. Local food production avoids costs of transportation fuels and multi-level distribution along the value chain in the current food system. A higher portion of the value of locally grown food is returned to the grower, encouraging local food producers, creating greater income equality and local selfsufficiency for a more just and stable social fabric.

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BACKGROUND

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b a c k g r o u n d

Cyanobacteria, or blue-green algae, is a single celled micro-organism that is aquatic and photosynthetic. Regarding to their simple prokaryote cell structure lacking a membranebound nucleus, cyanobacteria are classified as bacteria.

CYANOBACTERIA

According to Gaia theory, the life began on Earth after the optimization of atmospheric gas composition on the planet surface by the help of the natural circles of living organisms. While bacteria produce nitrogen, oxygen gas was provided by the first living photosynthesizing prokaryotes, blue-green algae. They used light energy to break apart the abundant carbon dioxide and water molecules into carbon food compounds, releasing free oxygen. (Henrikson, 2010) The characteristic blue-green color comes from the blue pigment ‘phycocyanin’, and green pigment ‘chlorophyll a’ that enables the photosynthesis process. The pigments efficiently capture specific wavelengths of light, and transferring the light energy to the cell. As the result of photosynthesis, carbon dioxide and solar energy are converted into biomass, food and oxygen.

Cyanobacteria have been cultivated for centuries as a nutritional supplement that produce high value of bio products.

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b a c k g r o u n d

In 1974, Spirulina was accepted as a Cyanobacteria and added to prokaryote kingdom in Bergey’s Manual Determinative Bacteriology (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003) Spirulina is a microscopic and filamentous cyanobacterium that derives its name from the spiral or helical nature of its filaments. Their cell division occurs by binary fission. Spirulina refers to the dried biomass of Arthrospira plantesis, an oxygenic photosynthetic bacterium found worldwide in fresh and marine waters. (Karkos, Leong, Kaskos, Sivaji, & Assimakopoulos, 2010).

It has a long history of use; a member of Hernàn Cortez’s troops reported in 1521, that Spirulina was harvested from the Lake Texcoco, dried and sold for human consumption in Tenochtitlan (Mexico City) market. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003). As Aztecs used spirulina as a food source, it is possible to say that it is one of the oldest foods.

From the scientific point of view, the microalgae cultivation began in 1919 with Warburg’s investigations. The easy manipulation under controlled conditions and the experimental reproducibility made the microalgae a favorite organism for biochemical, vegetable physiology and photosynthetic studies. Beginning from 1950, in USA and Japan, the experimental cultivations were made in order to investigate the chemical composition and industrial applications of this microorganism. The nutritional and medical studies on Spirulina were commenced by 1970.

(Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003).

SPIRULINA >> a superfood

Spirulina is one of the oldest foods of the world, and also it is considered as the food for future.

It has been approved by NASA. Spirulina is considered as an excellent food, lacking toxicity and having corrective properties against viral attacks, anemia, tumor growth and malnutrition.

Spirulina occurs naturally in warm, tropical and subtropical lakes and ponds with high pH and high concentrations of carbonate and bicarbonate.

(Habib, Parvin, Huntington, & Hasan, 2008).

The largest commercial producers are located in United States, Thailand, India, Taiwan, China, Pakistan, Burma, Greece and Chile. (Vonshak, 2002).

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>>content of spirulina

protein carbohydrates fats water

b a c k g r o u n d

vitamins

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Vitamin A, Beta-Carotene, B1, B2, B3, B5, B6, B9, B12, C, D, E, K

Calcium, Iron, Magnesium, Manganese, Phosphorus, Potassium, minerals Sodium

SPIRULINA

nutritional facts In many countries, Spirulina has been used as a human food as an important source for protein and vitamin; and it is gaining popularity considerably in health food industry. Today, because of its rich content, spirulina is healthy and nutritious for human beings, therefore it is called as superfood.

Apart from its use as food, it can be used as oxygen and energy (bio-fuel) source. Also, as it strengthens the immune system, and contains vitamins (A, B, C, K), proteins and minerals, spirulina has an important place in medical field in the last years. Moreover, recycling and treatment of waste water can be counted as the benefits of these algae.

PROTEINS Spirulina is significant in human nutrition due to its high quantity protein concentration in its biomass. Besides, it contains essential amino acids, thereby the nutritive value is also high. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003) VITAMINS Relatively, Spirulina has a high provitamin A concentration; also it is a very rich source in vitamin B12. That is why it is a great value for people needing supplements in the treatment of pernicious anemia. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003) LIPIDS Spirulina has essential fatty acids like linoceid acid and y-linoceid acid; it contains 4-7% lipids. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003)

MINERALS Spirulina provides an adequate source of iron for an anemic pregnant woman due to its absorbable iron content. (Sánchez, BernalCastillo, Rozo, & Rodríguez, 2003) CARBOHYDRATES Spirulina contains about 13.6% carbohydrates, like; glucose, rhamnose, mannose, xylose and galactose. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003) NUCLEIC ACIDS While consuming microorganisms, it is important to concern about the high contents of nucleic acids, as it may cause some diseases. Spirulina contains less RNA and DNA than Chlorella and Scenedesmus, the other microalgaes. (Sánchez, Bernal-Castillo, Rozo, & Rodríguez, 2003) Today, the international organizations are working for emphasizing the potentials of Spirulina, and therefore the overseas development in both large and small scales. According to the report presented in an organization by United Nations, the small-scale productions of Spirulina should be oriented towards; a) providing food for widespread use in rural and urban communities having poor and inadequate diet, b) allowing diversification in cases where land or water resources are limited, c) offering an integrated solution for wastewater treatment, smallscale aquaculture production or other livestock feed supplement, and d) supplying solution to emergency situations where a sustainable supply of high protein or vitamin foodstuffs is required (Habib, Parvin, Huntington, & Hasan, 2008).

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CULTIVATION

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c u l t i v a t i o n

PARAMETERS >> optimum environmental parameters

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TEMPERATURE Temperature is the most important climatic factor influencing the rate of growth of spirulina. Below 20°C, growth is practically nil, but spirulina does not die. The optimum temperature for growth is 35°C, but above 38°C spirulina is in danger. Growth only takes place in light (photosynthesis), but illumination 24 hours a day is not recommended.

During dark periods, chemical reactions take place within spirulina, like synthesis of proteins and respiration. Respiration decreases the mass of spirulina (“biomass”); its rate is much greater at high temperature so cool nights are better on that account, but in the morning beware that spirulina cannot stand a strong light when cold (below 15°C).

LIGHT Light is an important factor but full sunlight may not the best rate of illumination: 30% of full sun light is actually better, except that more may be required to quickly heat up the culture in the morning. Individual spirulina filaments are destroyed by prolonged strong illumination (“photolysis”), therefore it is necessary to agitate the culture in order to minimize the time they are exposed to full sunlight. Artificial light and heating may be used to grow spirulina, although they are not economical. Fluorescent tubes and halogen lamps are both convenient. Lamps can illuminate and heat the culture simultaneously.

(Jourdan, 2001) PH The pH range for most cultured algal species is between 7 and 9, with the optimum range being 8.2-8.7. Complete culture collapse due to the disruption of many cellular processes can result

from a failure to maintain an acceptable pH. The latter is accomplished by aerating the culture (see below). In the case of high-density algal culture, the addition of carbon dioxide allows to correct for increased pH, which may reach limiting values of up to pH 9 during algal growth.

(Lavens & Sorgeloos, 1996) AERATION/MIXING Mixing is necessary to prevent sedimentation of the algae, to ensure that all cells of the population are equally exposed to the light and nutrients, to avoid thermal stratification (e.g. in outdoor cultures) and to improve gas exchange between the culture medium and the air. The latter is of primary importance as the air contains the carbon source for photosynthesis in the form of carbon dioxide. For very dense cultures, the CO2 originating from the air (containing 0.03% CO2) bubbled through the culture is limiting the algal growth and pure carbon dioxide may be supplemented to the air supply (e.g. at a rate of 1% of the volume of air). CO2 addition furthermore buffers the water against pH changes as a result of the CO2/HCO3- balance. Depending on the scale of the culture system, mixing is achieved by stirring daily by hand (test tubes), aerating (bags, tanks). However, it should be noted that not all algal species can tolerate vigorous mixing.

(Lavens & Sorgeloos, 1996) SALINITY Arthrospira Plantesis are extremely tolerant to changes in salinity. Most species grow best at a salinity that is slightly lower than that of their native habitat, which is obtained by diluting sea water with tap water. Salinities of 20-24 g.l-1 have been found to be optimal. (Lavens & Sorgeloos, 1996)

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MEDIUM >> optimum culture medium

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Spirulina can live in a wide range of compositions of water; the following is a convenient analysis: Anions (mg/l) Carbonate Bicarbonate Nitrate Phosphate Sulfate Chloride

2800 720 614 80 350 3030 Cations (mg/l)

Sodium Potassium Magnesium Calcium Iron Total dissolved solids Density @ 20°C Alcalinity pH @ 20°C

4380 642 10 10 0.8 12847 1010 g/l 0.105 N (moles strong base/liter) 10.4

In addition, the solution contains traces of all micronutrients necessary to support plant life.

Such solution can be obtained by dissolving various combinations of chemicals; here is one example convenient for many typical waters: Fertilizer (g/l) Sodium carbonate (soda ash) 5 Sodium chloride, crude 5 Potassium nitrate 2 Sodium bicarbonate 1 Potassium sulfate, crystallized 1 Urea 0.02

Mono Ammonium Phosphate, crystallized Magnesium sulfate, crystallized (7 H2O) Lime Ferrous sulfate

0.1 0.2 0.02 0.05

The water used should be clean or filtered to avoid foreign algae. Potable water is convenient.

Water often contains enough calcium, but if it is too hard it will cause muds which are more a nuisance than a real problem. Brackish water may be advantageous but should be analyzed for its contents or tested. Seawater can be used under some very special conditions, outside the scope of this short manual.

The culture medium described above is used to start new cultures. The make-up medium should best be as follows: carbonate is replaced by bicarbonate (8 g/l in total), urea is up to 0.07 g/l.

Certain ions can be present in concentrations limited only by the total dissolved solids which should not be much over 25 g/l; these are: sulfate, chloride, nitrate, and sodium. Sodium or potassium nitrate can replace urea, the advantage being a large stock of nitrogen; urea is more efficient to supply nitrogen but is highly toxic at too high concentration. Spirulina can grow on either nitrate or urea alone, but using both together is advantageous.

Phosphate, magnesium and calcium cannot be increased much without precipitating magnesium or calcium phosphate, possibly leading to imbalances in the solution. Potassium concentration can be increased at will, provided it does not become more than five times the sodium concentration. Micronutrients traces contained in the water and in the chemicals are sufficient to support the initial growth. Solutions of iron should preferably be introduced very slowly and under agitation into the medium. (Jourdan, 2001)

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day 1

day 2

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500ml day 6

1500ml

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day 11

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day 15

GROWTH >> day by day As the studio process continued, we started to cultivate Spirulina. During this process, we had the chance to observe the growth behaviors of Spirulina according to the changes in the environmental parameters. By adding salty culture, the pH level is fixed around 9-10 (basic).

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day 16

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4000ml day 21

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7500ml

spirulina culture (ml)

pH level

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c u l t i v a t i o n

Cultivation process

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FARMING

seeding

A spirulina strain containing a high proportion of coiled filaments (less than 25 % straight filament), easy to harvest, and containing at least 1 % of gamma-linolenic acid (GLA) based on dry weight should be selected for cultivation.

Concentrated spirulina seed culture can be obtained either from the floating layer of an un-agitated culture, or by re-diluting a freshly filtered biomass. A concentration of up to 3 g spirulina (dry) per liter is permissible if storage and transportation last less than a week’s time, and provided the seed culture be aerated at least two times a day. If aeration can be continuous, the concentration may be up to 10 g/l.

It is advisable to maintain the growing culture at

harvesting

a fairly high concentration in spirulina after each dilution with culture medium, about 0.3 g/l: the “Secchi disk” reading should not be above 5 cm, i.e. the color of the culture should stay clearly green (otherwise shading is mandatory). The rate of growth is about 30 % /day when the temperature is adequate and the make-up culture medium based on bicarbonate (without carbonate). As the growth is proportional to the area of the culture exposed to light, it is recommended to maximize this area at all times.

When the final area and depth (10 to 20 cm) are reached in the tank, let the spirulina concentration rise to about 0.5 g/l (Secchi disk at about 2 cm) before harvesting. (Jourdan, 2001)

When the spirulina is in good condition, separating it from the water (“harvesting”) is an easy operation, but when it gets too old and “sticky” harvesting becomes difficult.The best time for harvesting is early morning for the following reasons :

The filtration is accelerated by gently moving or scraping the filter. When most of the water has filtered through, the biomass will often agglomerate into a “ball” under the motion, leaving the cloth clean. Otherwise it may then be necessary to scrape it out from the cloth.

1.the cool temperature makes the work easier,

The final dewatering is accomplished by pressing the biomass enclosed in a piece of filtration cloth plus a strong cotton cloth, either by hand or in any kind of press. The “juice” that is expelled comes out first colorless, later it turns green and the operation must then be discontinued otherwise too much product will be lost.

2. more sunshine hours will be available to dry the product, 3. the % proteins in the spirulina is highest in the morning.

There are basically two steps in harvesting: a. filtration to obtain a “biomass” containing about 10 % dry matter (1 liter = 100 g dry) and 50 % residual culture medium, b. removal of the residual culture medium to obtain the “fresh spirulina biomass”, ready to be consumed or dried, containing about 20 % dry matter and practically no residual culture medium.

Filtration is simply accomplished by passing the culture through a fine weave cloth, using gravity as the driving force. Synthetic fiber cloth (especially polyamide or polyester) with a mesh size of about 30 to 50 microns is the preferred filtering medium.

Practically all the interstitial water (culture medium) is removed, and some rinsing may be effected by the internal juices from ruptured cells. The pH of the well pressed biomass is near 7 (neutrality). This pressing operation effects a more efficient separation of the residual culture medium than washing the biomass with its weight of water on the filter. Washing with fresh water may cause rupture of the cell wall of the spirulina due to osmotic shock, leading to loss of valuable products; it may also introduce germs contained in the wash water. Washed biomass is a lot more prone to fermentation than pressed biomass.

(Jourdan, 2001)

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c u l t i v a t i o n

Snapshots of gas concentration at different bubble diameter after steady state

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Al-Mashhadani, Wilkinson, & Zimmerman, 2015

PHOTO-BIOREACTOR

The fundamental principle for photobioreactor design is a high surface area to volume ratio in order to use light energy efficiently, and is a requirement to obtain high values of PCE (Photon

closed pbr

Closed systems allow the prevention of contamination, allowing the operation in culture modes like photoautotrophic (Green plants and photosynthetic bacteria), heterotrophic, or mixotrophic. Also, closed systems can obtain up to three times more biomass than open systems, thus reducing harvesting costs. (Carvalho, Meireles, & Malcata, 2006) TUBULAR REACTORS One of the successful closed PBR design is the tubular type, in this the tubes configuration where the culture is held is one of the main factors affecting productivity of photosynthetic biomass (Luo, et al., 2003). Tubular PBRs can be built with plastic materials like rigid transparent polyvinyl chloride (PVC), polycarbonate or flexible plastic bags, among other materials. They can be arranged in vertical, horizontal, conical, and inclined form, with degasifying units that allow the removal of the O2 produced during photosynthesis (Ugwu, Aoyagi, & Uchiyama, 2008), the tubes can also be arranged in an annular form (Posten, 2009), each of these forms affect the productivity expected in this type of systems.

The tubes have diameters of 10 to maximum 60 mm, and lengths of up to several hundred meters.

The employment of tubes leads to a quite high surface to volume ratio SVR over 100 m-1, which is one of the main advantages of this design.

Furthermore, the so called “lens” or “focusing effect” has the added advantage of homogenous light distribution. Incident light is diluted along the circumference and is in radial direction focused onto the axis of the tube. In this way, exponential decrease of light by mutual shading of the cells is to some extent compensated by a geometrically enforced hyperbolic increase of radiation intensity.

In very thin tubes, e.g. 1 cm (Carlozzi, 2003) quite high biomass concentrations (see aspect 2) of more than 6 g/L can be obtained. Of course the arrangement of the tubes has to be calculated to achieve the most homogeneous incident light condition.

FLAT PLATE REACTORS Flat panel PBRs have also been studied in order to make an efficient use of light for algal biomass

conversion efficiency). Higher photosynthetic efficiency can result in higher biomass productivity and concentration, (Cañedo & Lizárraga, 2016)

production (Qiang, Zarmi, & Richmond, 1998).

These PBRs have a large illumination surface and the advantage of high area to volume ratio, and therefore optimum illumination of the cells and low oxygen concentration can be achieved. There are varieties with flat and curved semicircular bottom.

The flat plate reactors are surely the most robust design. Roughly speaking, two sheets have to be glued together to make a flat plate reactor with any desired light path length d in the range from a few mm up to 70 mm, resulting in SVR=1/d for one single plate and about 50 m−1 for practical installations.

Although, it is difficult to achieve efficient biomass productivity per area of land using flat panel PBRs. Factors affecting biomass productivity in this type of reactors are the angle, direction of flat panels, and the number of panels per land unit (Zijffers, Janssen, Tramper, & Wijffels, 2008).

Generally flat panels are displayed in vertical form but they can also be arranged inclined.

BUBBLE-COLUMNS AND AIRLIFT BIOREACTORS Bubble columns are frequently used especially in larger lab scale for indoor experiments. To work with sufficient volume, the diameters of 20 cm and more are higher comparing to tubular reactors. This leads to considerable high dark fraction in the middle of the cylinder. This part does not contribute to productivity or has even detrimental effects on growth. To leave this part out of the internal reactor space the so-called annular column has been developed (Zittelli, Rodolfi, Biondi, & Tredici, 2006). It consists of two 2-m-high acrylic cylinders of 40 and 50 cm in diameter placed one inside the other so as to form an annular chamber. The other way round, this can be seen as a wrapped flat plate reactor. It may be that the inner surface does not contribute too much to overall radiation, but for indoor applications or dark periods additional lamps could be fitted. To increase axial transport, the airlift principle has been employed (Miron, Camacho, Gomez, Grima, & Chisti, 2000). The down comer is usually arranged as a section of the cross-section (split cylinder) or in a coaxial inner cylinder (draft tube).

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c u l t i v a t i o n 32

life phases of spirulina culture

PHOTO-BIOREACTOR

growth parameters

There are five phases in growing algae in batch cultures: (1) lag, (2) exponential, (3) phase of declining growth rate, (4) stationary phase and (5) death. An algae culture is most productive when it is maintained in constant exponential growth.

LAG OR INDUCTION PHASE This phase, during which little increase in cell density occurs, is relatively long when an algal culture is transferred from a plate to liquid culture. Cultures inoculated with exponentially growing algae have short lag phases, which can seriously reduce the time required for upscaling.

The lag in growth is attributed to the physiological adaptation of the cell metabolism to growth, such as the increase of the levels of enzymes and metabolites involved in cell division and carbon fixation.

EXPONENTIAL PHASE During the second phase, the cell density increases as a function of time t according to a logarithmic function: Ct = C0.emt with Ct and C0 being the cell concentrations at time t and 0, respectively, and m = specific growth rate. The specific growth rate is mainly dependent on algal species, light intensity and temperature.

PHASE OF DECLINING GROWTH RATE Cell division slows down when nutrients, light, pH, carbon dioxide or other physical and chemical factors begin to limit growth.

STATIONARY PHASE In the fourth stage the limiting factor and the growth rate are balanced, which results in a relatively constant cell density.

DEATH OR “CRASH� PHASE During the final stage, water quality deteriorates and nutrients are depleted to a level incapable of sustaining growth. Cell density decreases rapidly and the culture eventually collapses In practice, culture crashes can be caused by a variety of reasons, including the depletion of a nutrient, oxygen deficiency, overheating, pH disturbance, or contamination. The key to the success of algal production is maintaining all cultures in the exponential phase of growth.

Moreover, the nutritional value of the produced algae is inferior once the culture is beyond phase 3 due to reduced digestibility, deficient composition, and possible production of toxic metabolites. (Lavens & Sorgeloos, 1996)

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PROCESS

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p r o c e s s

Penetrable, Jesus Rafael Soto

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INSPIRATIONS

kelp algae

leaf cell structure honey comb pattern

water lily underside texture

Microbial Home Philips Design

open cell foam pattern

lotus seed pods

Fibonacci’s Mashrabiya Neri Oxman 37

p r o c e s s

VISION

PIXELGAE: URBAN WILDERNESS

The vision for developing this project is to get people to discourse about the benefits of the ‘farm to plate’ theory and its advantages in the current world scenario. This project is developed with the intention of bringing people close to nature again. The vision for the Architectural prototype was not only to develop a prototype which can give good yield but also for people to get close to the production cycle. The design evokes the connection with nature and the feel of crossing a Jungle which has been lost for most of the Urban population. If an individual feels connected to nature (possibly by spending time in it), they may be more inclined to care about nature, and protect the environment. (Schultz, 2002).

Recent research has found that nature exposure (and feeling connected to nature at a trait level) provides many benefits to humans such as wellbeing (Mayer, Frantz, Bruehlman-Senecal, & Dolliver, 2008). As Stephen Jay Gould said: “We cannot win this battle to save species and environments without forging an emotional bond between ourselves and nature as well – for we will not fight to save what we do not love.” (Orr, 2004)

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p r o c e s s

PROJECT The Architectural prototype is a closed equipment which provides a controlled environment and enables high productivity of algae. As it is a closed system, all growth requirements of algae are introduced into the system and controlled according to the requirements. This facilitate better control of culture environment such as carbon dioxide supply, water supply, optimal temperature, efficient exposure to light, culture density, pH levels, gas supply rate, mixing regime, etc. The biomass production can be done at a high quality level and the high biomass concentration at the end of the production allows energy efficient downstream processing.

The PBR is designed as a combination of flat panels and tubular system. The algae are circulated from a closed container which is kept on the ground by the use of a submersible waterpump. The algae flow up to the flat panel at the top which then trickles down from the panel at the top back to the main tank. All the minerals are added in the main tank and a check on the culture environment is kept here. When the biomass density has reached the optimum volume, it is extracted from the main tank for consumption.

The flat panels increase the illuminated surface areas and the tubular system increases the surface area for the algae to flow through. The tubes also help in aeration of the algae my mixing the trapped air in the tubes when the algae flows through it.

MORPHOLOGY

PIXELGAE: URBAN WILDERNESS

The panels in the design are the canopy which have been designed so as to minimize the energy in the day to day running of the PBR. The inlet is at the highest point which then transforms into multiple lower bulges which are connected to the tubular system which takes the algae back to the feeding vessel. Multiple forms were tried at different scales to understand the constant circulation of the algae through the photobioreactor. The tubular system of the PBR should evoke the feeling of walking through the ‘vines’ of a Banyan tree which drop down from the canopy of the tree down to the ground. Utmost importance was given to the diameter of the tubes to get the desired effect when the algae is flowing through it.

Inlet pipe Outlet pipe

10-12mm 3-5mm, 4-6mm (combination)

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MDF mould (3 layers of 19mm boards)

PTG sheet (0,7mm) vacuum forming

p r o c e s s

panels in the frame

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PIXELGAE: URBAN WILDERNESS

acrylic frame joints

acrylic support

when requested or required the system pumps the spirulina culture into the panels from inlet pipes

vacuum formed PTG sheet

inlet pipe

acrylic frame

excess of the spirulina culture released from the panels to the tank through the outlet pipes

outlet pipes

inlet pipe

outlet pipes

screws

black box for solenoids and pipes

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p r o c e s s 44

PIXELGAE: URBAN WILDERNESS

user interface

interaction From our studies, we realized that the Algae doesn’t need to be in a constant state of agitation or in the presence of light continuously. The algae need to be agitated every once in a while, and not continuously. Vigorous agitation breaks down the cell walls and is harmful for the growth of the algae. We have devised a system in which our feeding vessel can hold around 25 liters of algae and the panels can hold around 14.4 liters of water. We have a total of 9 panels. The flow of Algae in each panel is controlled by a sketch from which the users can control which panel needs to get filled. The sketch is connected to an Arduino which controls a solenoid for each panel separately which lets the algae flow up the tubular system. The Arduino is further connected to a light source which gets switched on above the flat panel as the algae is getting filled up.

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p r o c e s s 46

PROTOTYPE 1

learnings The first prototype was developed to get an understanding of the working of a photobioreactor. Plain cylindrical tubes were used as pixels in the prototype. A 3X3 module was fabricated to test the concept of pixilation. A preset pattern was implemented in this prototype to experiment with the circulation of the water from the feeding vessel.

The inlet and the outlet pipe were of the same diameter and hence the pixel wasn’t getting filled with the algae. We realized that the diameter of the outlet pipes needs to be a bit smaller than the inlet pipe. The pump that was used to pump-up the water was of a lesser capacity than expected and hence we had to keep the feeding vessel much closer to the screen than what we had anticipated.

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voronoi pattern

polygonal frame

p r o c e s s

pipes carrying spirulina

PROTOTYPE 2

photo-bioreactor modules

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transparent modules

modules placed into frames

frame connection

plywood pentagonal frame

The second prototype was focused towards finding a morphology for the individual pixels. We experimented with vacuum forming techniques to form the pixels. The mould for the vacuum forming was made with a high-density foam sheet. The material used for the vacuum forming was an acrylic sheet 1.5mm thick. The frame for the pixels was fabricated with a 4mm thick Plywood sheet.

learnings The acrylic sheet was too thick to vacuumthermoform. The textures weren’t visible. The mould was a bit too soft to take the heat of the acrylic sheet and it got deformed. The frame was perfect for a small prototype.

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wooden frame

place for solenoids and arduino system

PBR panels

p r o c e s s

PETG sheet vacuum forming

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PROTOTYPE 3

The third prototype was the first attempt at making a full scale model with 36 panels. We continued to work with the vacuum-thermoforming technique. We changed the material from acrylic to PTEG sheet and changed the thickness from 1.5mm to 1mm. The mould used for the vacuumthermoforming was a MDF. The design changed a bit to get the return pipes in open which people could touch and interact with. The frame used for the prototype was again the 4mm thick plywood. when requested or required the system pumps the spirulina culture into the PBR panels wooden frame

PBR panels

pipes

excess of the spirulina culture released from the panels to the tank

place for solenoids and arduino system

learnings The PTEG sheet reacts with moisture at high temperatures and turns white. The thickness could still be reduced further for a perfect vacuum-thermoforming. Either the mould needs to be a bit thin to get fit into the thermoforming frame or the frame needs to be a bit thick for the mould to fit inside. The mould was missing holes for the air to pass through and there wasn’t enough suction for a perfect thermoforming. The 4mm plywood frame wasn’t strong enough to take the weight of the panels with the algae in them.

seating

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EXTRACTION

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e x t r a c t i o n 54

spirulina bread ingredients

FERMENTATION

Fermentation is an ancient culinary process, that has been used for thousands of years, for enhancing digestibility, nutrient density and flavor while preserving foods. While cheesemaking can be traced back 8000 years, the alcoholic fermentations including winemaking and brewing are thought to be developed during the period 2000-4000 BC by the Egyptians and Sumerians. (Paul Ross, Morgan, & Hill, 2002) With the development of pasteurization, the essential role of microorganisms was recognized in the fermentation process. After the industrial revolution with the emergence of need for large scale food productions, large scale fermentation processes were developed. (Paul Ross, Morgan, & Hill, 2002). The range of fermented food products is varied from meat to plant, milk and dairy products. In each fermentation process case, the oxidation of carbohydrates occurs to generate organic acids, alcohol and carbon dioxide.

Green microalgae and cyanobacteria typically

contain starch or glycogen to a content of 10 to 50% of their biomass, depending on the medium and growth conditions. Whole-cell material from starch-enriched green microalgae and glycogenenriched cyanobacteria has recently been used feedstock for bioethanol production by yeast fermentation. (Mรถllers, Canella, Jorgensen, & Frigaard, 2014) Fermentation process of algae converts sugar to biofuels, chemicals, nutritional products, cosmetics, etc. (Hannon, Gimpel, Tran, Rasala, & Mayfield, 2010) Biodiesels, one of the fermentation products, provides environmental benefits, and it is also a renewable resource. Also it can be used within any kind of engine throughout the year.

(Abishek, Patel, & Rajan, 2014) Apart from the usage as a fuel, today, it is thought that we are entering a new era in food production, and microorganisms will play an important role in culinary studies.

culinary experiments SPIRULINA BREAD While preparing the bread, dry yeast is used, and let it dissolved in the warm milk with spirulina and sugar. Yeast is become activated with the sugar, and after kneading the dough, the expansion in the volume of the dough can be observed.

fermented bread dough 55

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Today, Spirulina is typically consumed as a supplement, not just for its content of vitamins, minerals, and other nutrients, but as a remedy for a laundry list of conditions including cardiovascular disease, allergies, diabetes, and inflammatory and immune problems. The Spirulina is available majorly in 2 forms, in a powder form and in tablet form. At present, Spirulina is grown commercially in California, India, China, Hawaii, Chile in the open-pond system, making it susceptible to contamination from the changing environmental conditions. It is then dried and processed into powders and supplements and transported to the rest of the world. Spirulina is still being marketed as a superfood and because of all the embodied energy in bringing the supplements to the world, the cost increases significantly.

In this project, the cultivation and harvesting of spirulina in a photo-bioreactor under different conditions was studied. Along with that, different technics for the consumption were developed.

CONCLUSION

Working on this project has given us a confidence that Spirulina can be and should be grown all around the world by everyone. Spirulina needs light, salt culture and CO2 which is either already abundant in the world or can be easily obtained. The algae grow exponentially if the right conditions are met and can be consumed every day without any additive process.

We have been working towards creating a food which is eaten by more than 80% of the world and which is the basic necessity for survival. If we combine this with nutrients, it is enough for get rid of the hunger and malnutrition from the world.

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