Architecture and Extreme Environment, Architectural Device Paper
Algae Air Cleaner & Facade Module Otis Sloan Brittain
a
A Institute of Architecture and Technology, KADK, Philip De Langes Allé 10, 1435 København K, Denmark
Abstract In 2011 The World Health Organisation named Lanzhou, the capital of the Gansu Province, China's most air polluted city 1. This is in part due to Lanzhou's geography, situated between two mountain ranges next to the Gobi desert, which results in large quantities of dust being blown into the city whilst the air remains trapped in the valley. It is also due to industry, an energy structure dependent on coal and heavy traffic within the city 2. However, heavy pollution is not an environmental issue solely isolated to Lanzhou but affects many of China's cities and others across the globe. During a month long field trip to the Lanzhou, China, as part of the Architecture and Extreme Environments masters program, a device was created that investigated whether algaes could be integrated within facade systems to absorb pollutants from the air 3. Algae was cultivated from water sources across Lanzhou and Lanzhou New Area (LNA) using a specially designed incubation unit and tested using a portable facade panel to see whether air pumped through these cultures had reduced levels of air pollution, both gas and particle. The following scientific paper documents the results and findings of these tests and is part of an ongoing endeavor at Architecture and Extreme Environments to investigate how architects and designers might rethink the built environment as a means to address these environmental issues. © 2017 Otis Sloan Brittain.
Keywords: Algae; Air Pollution; China; Lanzhou, Air Filtration
1878-0296 © 2017 Otis Sloan Brittain.
2
Otis Sloan Brittain / Architecture and Extreme Environments
1.0 Introduction In 2011 the World Health Organisation named Lanzhou, the capital of the Gansu province, China’s most polluted city4. Sandwiched between two mountain ranges in the Gobi Desert, Lanzhou suffers from a lack of fresh air. This coupled with extensive industry within the city limits has led to Lanzhou’s severe air quality issues. Using a custom built device, it was investigated whether algae cultures, a diverse group of aquatic photosynthetic organisms that absorb air pollutants such as Carbon Dioxide and Nitrogen Oxide during photosynthesis whilst producing Oxygen, could improve air quality and whether this could be integrated into a building facade system 5. The device consisted of two units: one to cultivate algae and another portable facade panel that could be filled with algae and air filtered through it. Experiments were carried out to investigate whether algae could be cultivated from local water sources in Lanzhou like the Yellow river and whether air passed through algae cultures had increased air quality. Nomenclature Culture A,B,C... A2, B2, C2...
Liquid including algae, distilled water and nutrients, used to sustain organisms. Used to denote different algae cultures cultivated in Denmark prior to field trip Used to denote different algae cultures cultivated from water sources in Lanzhou/LNA during field trip.
2.0 Methods The device investigations and testing were split into two parts. The first investigated whether algae could be cultivated from local water sources in Lanzhou and Lanzhou New Area and the second tested if air pumped through these algae cultures had reduced levels of pollution and whether this could be integrated into a facade system. In order to cultivate the algae a specially designed incubator unit that accelerated algae growth by optimising light, air and nutrient levels was used. The samples were monitored over 10 days, looking at the change in colour and using a microscope to identify whether algae had been cultivated. After this period, experiments were conducted to test whether air quality could be improved by pumping polluted air through these cultures by recording the air before and after. The difference in temperature, humidity, pm1.0, pm2.5, pm10 and harmful gases including Carbon Dioxide (CO2), Ammonia (NH3), Nitrogen Oxide (NOx) and Benzene (C6H6) were recorded using a particle meter and an MQ-135 sensor. 2.1 Sampling Water samples were taken from shallow natural water sources across Lanzhou/LNA including the Yellow River, LNA and Zheng Quan pond. An algae sample collection net was used in order to obtain a 300ml sample with an increased algae content. The sample net was thoroughly cleaned and sterilised between samples to avoid cross contamination. Samples were also taken in Copenhagen from Sortedams Sø and Christiania prior to the field trip. Table 1. Algae sampling locations.
Algae No. A2 B2 C2 D2 E2 F2
Source Location Lanzhou New Area Xigu, Lanzhou Chengguan District Hua An Zheng Quan Chengguan District Chengguan District
Coordinates 36°28’15.2”N 103°40’32.8”E 36°04’58.3”N 103°42’05.6”E 36°03’50.3”N 103°49’25.8”E 36°03’25.1”N 103°50’18.9”E 36°04’06.0”N 103°51’17.5”E 36°03’50.9”N 103°50’15.8”E
Species Unknown Unknown Unknown Unknown Unknown Unknown
B G J
Moat - Christiania Stortdams n/a
55°40’23.0”N 12°36’27.1”E Unknown 55°41’41.7”N 12°34’32.6”E Unknown n/a Spirulina
Collected Cultivation Start 21/11/17 11:39 25/11/17 17:29 22/11/17 09:31 25/11/17 17:29 25/11/17 03:00 25/11/17 17:29 23/11/17 11:39 25/11/17 17:29 25/11/17 04:35 25/11/17 17:29 25/11/17 05:35 25/11/17 17:29 01/10/17 12:00 17/11/17 12:11 n/a
01/10/17 15:40 18/10/17 10:00 21/10/17 10:00
Otis Sloan Brittain / Architecture and Extreme Environments Fig 1. Map and sampling sites in Lanzhou and Lanzhou New Area
3
4
Otis Sloan Brittain / Architecture and Extreme Environments
2.2 Cultivation Cultivation took place indoors by a west facing window, maintained at approximately 22°C. 300ml water samples were diluted in 1000ml of distilled water in 1500ml plastic bottles along with 4ml of liquid plant fertiliser* and 4ml of soil nutrient mix** and shaken. Air was then pumped through each culture constantly at a rate of 0.2L/minute for 10 days. An additional 4ml of liquid plant fertiliser was added every 7 days. A 220W UV LED lamp on a timer provided additional light at a ratio of 16:8 hours of light per day, optimal for algae growth.
1. Air Inlet 2. Air Outlet 3. Air stone 4. 220W UV lamp 5. Air Pump
Fig 2. Algae Incubator unit set up
2.3 Air Filtration Testing Air quality tests were done using the incubator unit and the facade module.
1. Incubator Unit 2. Computer for recording MQ-135 readings 3. Arduino Board 4. Particle Meter 5. MQ-135 Sensor 6. Air Outlet 7. Air Capturing Balloon 8. Power Supply for Particle Meter 9. Timer 10. Air Pump
Fig 3. Incubator unit air filtration test set up
2.3.1 Incubator Unit Testing An experiment was run to verify the difference in the air quality of air passed through these cultures using the incubator unit. Testing took place indoors in a sealed room by a west facing window at approximately 20°C. A particle reader and MQ-135 sensor connected to an arduino board were inserted into a deflated, transparent balloon. * liquid fertiliser contents: Nitrogen (N) 12%, Phosphate (P2O2) 4%, Soluble Potash (K2O) 8%, Iron (Fe) 0.10%, Manganese (Mn) 0.05%, Zinc (Zn) 0.05% ** soil nutrient mix contains trace elements not found in liquid fertiliser. Mix is made by boiling garden soil in 1L of distilled water, adding 1.2g of calcium carbonate and filtering.
Otis Sloan Brittain / Architecture and Extreme Environments
5
Indoor polluted air was pumped through each 1300ml culture at a rate of 1.2L/minute and into the balloon for 15 minutes until the balloon was fully pumped. After the 15 minutes, 3 temperature, humidity, pm1.0, pm2.5, pm10 readings were taken at 20 second intervals to give a mean average. 20 MQ-135 sensor readings were taken at 5 second intervals to give a mean average. These readings provided an 'air profile' for the filtered air for all 6 cultures cultivated in Lanzhou and the 3 cultures from Denmark. Control was obtained by running the same experiment but not passing the air through the algae cultures.
1. Air Pump 2. Air Outlet 3. Facade Module 4. Air Capturing Balloon
Fig 4. Facade module test set up
2.3.2 Facade Module Testing The 4 cultures that provided the largest change in air quality were then tested in the facade modules. Testing took place indoors in a sealed room by a west facing window maintained at approximately 20°C. Each facade panel was attached to the filled with 400ml of algae culture. A particle reader and MQ-135 sensor connected to an Arduino board were inserted into a deflated, transparent balloon. Indoor polluted air was pumped through each panel at a rate of 1.2L/minute and the air outlet collected to the balloon for 15 minutes until the balloon was fully pumped. After the 15 minutes, 3 temperature, humidity, pm1.0, pm2.5, pm10 readings were taken at 20 second intervals to give a mean average. 20 MQ-135 sensor readings were taken at 5 second intervals to give a mean average. A control was obtained by running the same experiment but not passing the air through the algae cultures
6
Otis Sloan Brittain / Architecture and Extreme Environments
3.1 Cultivation Results Fig 5. (Above) View of algae cultivated under a microscope (zoom x500) Fig 6. (Below) Cultures after cultivation process
Otis Sloan Brittain / Architecture and Extreme Environments
7
3.2 Incubator unit filtration results Table 2. Results from incubator unit filtration tests Air Type Control A2 B2 C2 D2 E2 F2 B G J
AQI 176 26 19 19 32 29 36
MQ 135 (n/1023) 58.1 57.4 57.76 55.09 52.19 55.57 56.27
MQ 135 Decrease (%) 0.0 1.2 0.6 5.2 10.2 4.4 3.1
pm10 (µg/m3) 110 8 6 6 10 10 11
Pm2.5 (µg/m3) 136 8 6 6 10 9 11
Pm1.0 (µg/m3) 82 7 5 6 8 8 9
29 52 58
53.23 56.23 89.95
8.4 3.2 -54.8
10 16 20
9 16 19
8 14 15
Fig 7. Results from incubator unit filtration tests
Temperature (°C) Humidity (%) 19.7 17.7 22 78 22.4 80.9 22 81.3 20.8 86.6 21.5 77.8 21.8 85.2 22.9 22.9 24
73.7 51.1 78.9
8
Otis Sloan Brittain / Architecture and Extreme Environments
3.2 Facade module filtration results Table 3. Results from facade module filtration tests Air Type Control C2 D2 E2 B
AQI
MQ 135 (n/1023) 182 26 36 29 29
MQ 135 Decrease (%) 56.57 55.62 53.48 56.24 53.05
Fig 8. Results from facade module filtration tests
pm10 (µg/m3) 0.0 1.7 5.5 0.6 6.2
Pm2.5 (µg/m3) 111 8 11 10 10
Pm1.0 (µg/m3) 140 8 11 9 9
Temperature (°C) 89 7 9 8 8
20.2 22.4 20.8 21.5 22.9
Humidity (%) 18.1 82.4 86.6 77.8 73.7
Otis Sloan Brittain / Architecture and Extreme Environments
9
4.0 Discussion The cultivation phase of the project provided promising evidence that algae could be cultivated from local water sources in Lanzhou. Of the 6 water samples taken I was able to cultivate algae from 4. Sample A2, which showed no signs of algae, was taken from a frozen man made lake in LNA filled with water pumped from a river approximately 100km away. I believe there is less likelihood of algae present here due to the low temperature and the long period the water is not exposed to sunlight when it is pumped to the new lake. B2, taken from the Yellow River, also showed no sign of algae growth, despite other samples taken from the same water source containing algae. Interestingly this sample was taken in the Xigu industrial district, which has been heavily criticised for polluting the river. River pollution, particularly heavy metals, can affect algae growth and may be a contributing factor as to why there was no algae in this sample however, this is only speculation. Perhaps the most interesting result of the cultivation phase was that algae could be grown from multiple sources taken from the Yellow River. Further analysis is needed to establish which species are present however this proves that algae can be grown from local water sources in Lanzhou and perhaps these could be used to could help alleviate Lanzhou's pollution problems. Table 4. Air Quality Index groups and health implications6 AQI
Air Pollution Level
Health Implications
0 - 50
Good
Air quality is considered satisfactory, and air pollution poses little or no risk
51 -100
Moderate
Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
101-150
Unhealthy
Members of sensitive groups may experience health effects. The general public is not likely to be affected.
151-200
Very Unhealthy
Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects
201-300
Extremely Unhealthy
Health warnings of emergency conditions. The entire population is more likely to be affected.
300 and over
Hazardous
Health alert: everyone may experience more serious health effects
The air filtration experiments bared results that supported my original hypothesis but also some surprising outcomes. Air pumped through the cultures showed a sharp decrease in particle pollution, increased humidity and partial decrease in harmful gases including Carbon Dioxide (CO2), Ammonia (NH3), Nitrogen Oxide (NOx) and Benzene (C6H6) among the cultures containing algae (with some exceptions). All cultures, even those not containing algae, showed a dramatic decrease in particle pollution in some cases decreasing from an AQI of 176 (Extremely Unhealthy) to 19 (Good), which is lower than in Copenhagen. My assumption is that as the air is pumped through the cultures it is effectively being washed of many of the particles it contains. These results suggest that a very simple air particle filtration system could be created by simply pumping the polluted air through water. The reduction in harmful gases of the cultures with algae was around ranged from 3.2% (G) to 10.1% (D2). Experiments using culture J, which was a pure Spirulina culture, gave results that went against my original hypothesis and other research. Air pumped through this culture actually contained a higher concentration of harmful gases and considerably less decrease in particle pollution compared with the other cultures. Spirulina algae is particularly sensitive and may have died in transit to China. This could lead to harmful gases being released as the algae decomposed in the culture. The results from the incubator unit tests and the facade module tests were very similar despite the air being pumped through 400ml of liquid compared with 1300ml. Air pumped through the incubator unit traveled approximately 300mm up through the algae cultures whilst air pumped through the facade module traveled approximately 1200mm . This suggests that by increasing the length of time the air is passing through the culture by increasing the distance the air is pumped through the culture might increase its overall efficiency. These experiments did also reveal
10
Otis Sloan Brittain / Architecture and Extreme Environments
drawbacks in the design of the module. Of the 6 modules taken, 2 were damaged during the experiment and leaked algae. It also proved tough to clean out the modules so only one culture could be tested per module to avoid cross contamination. Improvements would need to be made to the design of the facade for algae maintenance, should the system be further developed into a building facade. 5.0 Conclusion I believe the results from these experiments support my original hypothesis that algae cultures could be provide a local resource in Lanzhou that could be used to remove air pollutants and help in reducing the city's air pollution problems. Of the 6 water samples taken in Lanzhou/LNA, 4 could be used to cultivate algae after 10 days of incubation. The air filtration tests revealed that air pumped through these algae cultures showed up to an 89% reduction in particle pollution and 10.1% reduction in harmful gases including Carbon Dioxide (CO2), Ammonia (NH3), Nitrogen Oxide (NOx) and Benzene (C6H6). However, it also revealed that a simpler system for reducing particle pollution, from which Lanzhou suffers most severely from, could be developed without the use of algae, simply by pumping polluted air through water. Tests using the facade modules bared similar results to those taken using the incubator unit, supporting that these cultures could be developed into a facade system that harnesses natural light to grow the algae. The process also revealed issues concerning regular maintenance and containing the liquid algae without it leaking that would need to be addressed if the facade is to be developed further. Given more time, it would have been beneficial to have cultivated the algae for longer and test to what extent the air quality changed with increased quantities of algae present and to run longer tests to see whether the cultures continue to filter air of particle pollution as effectively over time. It would also be interesting to analysis samples of the particle pollution to test whether there are any nutrients present, such as nitrates or phosphates, that might help sustain algae growth. 6.0 Acknowledgments I would like to thank David Garcia, Thomas Chevalier Bøjstrup, Jakob Brandtberg Knudsen and Marianne Hansen for organising the study trip. I would also like to thank Emanuele Naboni and Miriam Pappalardo for their help and expertise regarding measuring, data collection and sensors. Dr Nina Lundholm at the University of Copenhagen for her help regarding algae cultivation and for lending her algae sample net. Special thanks to Dr Zhou Yu and everyone at Lanzhou Technical University and Southeast University Nanjing for giving me a space to run my tests and all their help and assistance. 7.0 References [1 & 4] [2] [3 & 5] [6]
"WHO Global Urban Ambient Air Pollution Database (update 2015)." World Health Organization. Accessed January 01, 2017. http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/. Costabile F, Bertoni G, De Santis F, Bellagotti R, Ciuchini C, Vichi F, Allegrini I. Spatial Distribution of Urban Air Pollution in Lanzhou, China.. 2010. The Open Environmental Pollution & Toxicology Journal 8-15. Kodo K, Kodo Y,Tsuruoka M. System for purifying a polluted air by using algae. 2000. Patent no: US6083740 A.USA. US Patent Office. The World Air Quality Index project. Air Pollution: Real-time PM2.5 Air Quality Index (AQI). 2014. Aqicn.org. Accessed December 18, 2016. http://aqicn.org/.