Team:TU-Munich/Results/Implementation

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Implementation of a Plant Biofilter

How does a biofilter look like? To face this question we considered the requirements for a moss filter and took a look at existing solutions. We talked to Prof. Dr.-Ing. Clemens Posten, who is head of the Institute of bioprocess engineering in Karlsruhe. So we were shown the institutes's bioreactors and Prof. Posten gave us an idea how a symbiosis between plant and technology can look like. Although his institute mainly works with algae, two solutions became apparent as sensible. The tube reactor mainly consists of glass tubes in which the plant is grown. The open pond model is a meander-shaped pond or slowly floating stream.

Closed tube reactor

Figure 3:

left

Open filter on felt base

Figure 3:

right

Our swimming PhyscoFilter Prototype pod

minimizing

At least there are problems both reactor types don't solve. In both cases upscaling involves a great deal of expense. The tube reactor guarantees a big contact surface between water and moss which is an asset to the filter properties, but the carbon dioxide exchange is a major problem due to the lack of water-air through mix. To manage big scale filtering on an appropriate area it's inevitable to stack the tubes. That makes extra lighting necessary. The open pond model brings along a smaller water-moss surface, therefore the filter properties may suffer and a wider area is needed. As opposed to the tube reactor the costs are lower and there are no air exchange problems to face.

Slightly we return to the question how a biofilter could look like. It has to be a solution that can be implemented in any scale. The costs must be kept as low as possible. Additionally the energy consumption and maintenance must be kept to a absolute minimum to make it universally usable.

Blueprint for pod

Such a solution has to be engineered cleverly. Robust to environmental influences, expendable, modular and handy, even when in use. It must provide an ideal environment for the moss to grow and set off an alert if such a setting is no longer provided.

Our answer to that is the PhyscoFilter pod.
It consists of a triangular shaped tube in which a felt cloth is stretched. As a float, the pod raises and falls with the water level, so the cloth is always kept on the water surface. Our experiments showed that felt is a very good matrix for the moss to grow on and its roots maintain stable on the fibers. The light weight and handy size make it mobile and and transportable and a higher quantity of pods can easily arranged to a honeycombed structure. That makes pods are very applicable at any location. In ponds, lakes and rivers; any scale is thinkable.

Shopping for the pod

Table 1: Shopping list for our Arduino-Project
Component Quantity Source Price Figure
Tubes 3 Building center
Connectors 6 Building center
Felt base xx m3 Building center

Images from our trip to the construction center

Automatic monitoring of moss on a swimming pod by an Arduino Microcontroller

Introduction

Figure x: Idea for a measuring device

One advantage of our pod is that it works quite autonomic. Once the moss is installed it filters until it's "saturated", assumed that the environmental parameters fit and a proper living space is provided. The main goal of our measurement device is to monitor these environmental parameters in real time. Since the filter's the costs should be kept as low as possible, the usage of ordinary lab measurement tools is limited. Looking one step ahead it is conceivable to use a moss-filter in order to clean ponds or streams etc. Places that are not continuously supervised by humans. So our aim was to engineer a low cost and low energy solution, that maintain the filters autonomy.

Fig A: Arduino Uno, released in September 2010

This is where Arduino comes into play. Arduino is a platform that is based on one microcontroller which is attached to a circuit board. Its convenient handling and easy programming, the lots of available hardware and the great community support make it one of the most popular prototyping platforms these days, especially for multidisciplinary applications. Among its many fans it already enjoys cult status. We first used the Arduino Uno. It is the most commonly used board. The first revision was released in September 2010. Designed for beginners, it gave us an easy start into the handling, since none of us had any experience working with microcontrollers. Most libraries already worked out of the box and all shields and sensors we ordered came with an example code. But the Arduino Uno came to it's limits, when we tried to get a display, WiFi and several sensors working.

Therefore we ordered the Arduino Due, which is the most powerful Arduino board at the moment. It has 16 times more flash memory (code storage) than the Arduino Uno and its clock runs 5 times faster. Instead of 2KB SRAM there are 96KB. At least there are a lot more free pins that can be used for sensors etc, and still its costs don't exceed 50€€ (~60$).

We installed a solar powered Arduino on one edge of our pod in order to monitor the setting. A temperature and a light sensor collect weather data and a water sensor attached to the side of the pod registers, if the pod's tubes take on water and the pod lowers its height on the surface. For testing purposes we even attached a display. All collected data are sent via WiFi and stored at a server's MySQL database in real time. Alternatively the data can also be sent via GSM if there is no WiFi hotspot close by. All data can then easily be displayed.

The controller can easily be expended by other sensors, such as a color sensor to monitor the moss's health or a potential die off, a pH-Sensor or even a webcam.

Concerning the low costs, the unlimited capabilities and the handiness we highly recommend the use of the Arduino as measuring device. We have created a tutorial how to set up an Arduino Due with some basic functions.

components
Table 2: Shopping list for our Arduino-Project
Component Quantity Source Price Figure
Arduino Due microcontroller 1 [http://www.watterott.com/de/Arduino-Due?xfb7d6=d868f3f07c538128ec6013c6d984b089 watterott] 46.41 € Fig. 1 A
Arduino WIFI Shield 1 sparkfun 63.58 € Fig. 1 B
Watterott mega msd-shield 1 [http://www.watterott.com/de/Arduino-Mega-mSD-Shield watterott] 19.49 € Fig. 1 C
Display MI0283QT-9 1 [http://www.watterott.com/de/MI0283QT-2-Adapter watterott] 36.00 € Fig. 1 D
Light sensor TSL2561 1 [http://www.watterott.com/de/TSL2561-Lichtsensor watterott] 7.74 € Fig. 1 E
Temperature sensor DS18B20 1 [http://www.exp-tech.de/Sensoren/Sparkfun-Temperature-Sensor---Waterproof--DS18B20-.html exp-tech] 8.80 € Fig. 1 G
Water sensor 1 [http://www.exp-tech.de/Sensoren/Seeedstudio-Grove---Water-Sensor.html exp-tech] 2.90 € Fig. 1 H
Lithium-Battery 1 [http://www.amazon.com/s/ref=nb_sb_noss_1/176-6668907-5443152?url=search-alias%3Daps&field-keywords=lithium%20battery&sprefix=lithi%2Caps&rh=i%3Aaps%2Ck%3Alithium%20battery amazon] 16.35 €
Stackable Headers 3 [http://www.exp-tech.de/Zubehoer/Steckverbinder/Arduino-Stackable-Header-Kit.html exp-tech] 5.37 €
Linking wires and resistors 1.00 €
Photo-diodes 3
207.64 € 280.77 $

How could it look installed in a river?

NY parallel networks

Fig x: ‘Water as the 6th Borough’ Design Competition for NYC

In the design competition that focuses on New York and its waterways in 2011, we found an impressive proposal working on New York's Upper Bay. Re-imagining recreational space, public transportation, local industry, and native environment, the [http://op-n.net/filter/work/PARALLEL-NETWORKS NY PARALLEL NETWORKS] project considered using swimming triangles as versatile platform for various purposes. The winning contribution for the [http://www.bustler.net/index.php/article/one_prize_water_as_the_6th_borough_-_winners_announced/ ONE PRIZE: Water as the 6th Borough] was designed by the Canadians Ali Fard and Ghazal Jafari. These triangles, so called pods, fulfill different tasks such as the fixation of carbon dioxide, food production and local recreation without hindering the renewable energy generation, furthermore the transportation of passengers and goods. As we were amazed finding such a great sustainable concept, we didn't hesitate to get in touch with Op.N (Ali Fard and Ghazal Jafari). We asked for their permission for mentioning their work on our page, and gave us a nice and fast feedback affirming the "great structural flexibility and expandability of the triangular floating pods".

We believe that this design is feasible and that an additional PhyscoFilter-pod could extend this design. Using the pods close to big cities doesn't bring along the problems other solutions have to face. Most cities use just a fraction of their water surface, leaving much space that could easily be made use of. At this point the the PARALLEL NETWORKS concept establishes. The pod's great flexibility also enable a short time of usage, simply changing their location if they get in the way of other schemes, avoiding greater costs.
Fig x: Types of swimming pods

Commercially available pods called "Kampen"

Fig x: Commercially available swimming pods

In the search for a possibility to built swimming pods for our moss filter we found [http://www.bestmann-green-systems.de BGS Ingenieurbiologie und -ökologie GmbH] which is a German company which developed and provides solutions for the revegetation of rivers and wetlands.

Swimming PhyscoFilter Pod in action

References:

http://www.ncbi.nlm.nih.gov/pubmed/6327079 Edens et al., 1984

  1. http://www.ncbi.nlm.nih.gov/pubmed/6327079 Edens et al., 1984 Edens, L., Bom, I., Ledeboer, A. M., Maat, J., Toonen, M. Y., Visser, C., and Verrips, C. T. (1984). Synthesis and processing of the plant protein thaumatin in yeast. Cell, 37(2):629–33.

http://www.bustler.net/index.php/article/one_prize_water_as_the_6th_borough_-_winners_announced/ ONE PRIZE: Water as the 6th Borough - Winners Announced; Posted on http://www.bustler.net Thursday, August 04, 2011