Spirulina Cultivation System for Smart People

Spirulina is unicellular and filamentous blue - green algae. Many species in the category of algae and cyanobacteria showed an anti-cancer effect in animal tests, and some of them are in the clinical trials currently. Especially Spirulina Platensis which is the species focusing on this study showed antiviral, anti-epilepsy and many other medically active performances. Because of this popularity, the consumption of the microalgae products rapidly increases and the necessity of the stable and efficient production of the microalgae arouse. However, the technical and financial limitations, stable mass production of microalgae are not easy tasks to solve.

Precise control over the environmental conditions in the place where microalgae grow and timely supply of the necessary materials would be the most prerequisite requirements for the stable growth of the microalgae. This requirement might be sufficed by mass cultivation and automated microcontroller system. Smart Spirulina system is developed and evaluated to bring automation in the entire production of Spirulina algae.

The main objective of the system is to avoid human intervention and to design a system which is embedded of various sensor units and a stirrer. Sensor unit is capable of monitoring the tank for overall process. The project comprises of RTC (Real Time Clock) module attached with DC motor is used to stir the tank automatically for every one hour. Sensors like pH sensor, Temperature sensor is used for daily monitoring of algal conditions. IR sensor is used to determine the growth of Spirulina. Once the algae are ready for harvest a notification is sent to the cultivator via GSM module.

Spirulina is fresh water blue - green algae that were the first plant life on earth almost three billion years ago. Spirulina is concentrated with nutrition that forty years ago the United Nations declares it to be the healthiest food in the world. Algae’s nutritional profile is so impressive that the scientific, nutrition, sports and medical communities have conducted over 100,000 scientific studies about its health benefits [1].

Spirulina provides the highest concentration of protein in the world, all in the form of essential amino acids for muscle, health and cellular growth. It’s over forty nutrients ensure complete nutritional health and its natural nitric oxide provides immediate and enduring physical and mental energy. Spirulina is also rich in all the B Vitamins, all the electrolytes and other minerals that need to be healthy, including zinc and magnesium. Various health benefits of Spirulina are it helps to improve athletic performance, powerful anti-oxidant, protects the brain, boosts immunity, provides physical energy and mental wake up, helps to build muscle, stop fatigue and also in weight loss. It is also a great replacement for animal protein or greens.

Consequently, the commercial production of spirulina has gained worldwide attention for use in human food supplements, animal feed and pharmaceuticals. The growth of Spirulina and composition of biomass produced depends on many factors, the most important of which are nutrient availability, temperature and light [1]. In addition Spirulina requires high pH values between 10 and 10.5, which effectively inhibits contamination by most algae in the culture.

Production of Spirulina with reduced cost is necessary when considering large scale cultivation for industrial purposes. The cost of nutrient is considered the second major factors influence the cost of spirulina biomass production after labor. In this study Zarrouk’s medium is used for Spirulina cultivation and production. Zarrouk’s medium has successfully served as a standard medium for Spirulina culture for many years.

Nutrition Content in Spirulina

UN figures show that over 250 million children suffer from malnutrition. Spirulina has very high micronutrient content, is easy and cheap to produce locally. It is therefore a very realistic and also sustainable solution to the problem of malnutrition. Spirulina contains 28.9mg of iron in 100 g of the products and this is 210 % of daily recommended intake. In addition studies revealed the fact that it has a lot of vitamin B. The Spirulina platensis of 100g can contain 207 % of daily recommended intake amount of Thiamine (Vitamin B1) and 306 % of daily suggested intake amount of Riboflavin (Vitamin B2). By these result of studies, many pharmaceutical or health supplemental companies highlighted the potential of Spirulina. For all these reasons Spirulina production is considered to be essential for making revolution in algal growth.

Yao Yao et al improved a previously developed optical density (OD) sensor for the measurement of biomass concentration in algae cultures, and test the performance of the improved sensor. The sensor was improved in the following several aspects. First, the sensor housing was redesign to accommodate new optical measurement configuration and a reference cell. Second, a constant current LED driver circuit was build and included. Third, a feedback controlled mechanism (including thermistors and thermo electrical cooling modules) was build to control the temperature of the LEDs. Ultimately, a logarithmic IC chip was used for processing of raw outputs from photodiodes.

Optical-Density-Based Feedback Feeding Method

Bao, Yilu et al proposed method for cultivating of Spirulina platensis using ammonium salts or waste water containing ammonium as alternative nitrogen sources is considered as a commercial way to reduce the cost. In this research, by analyzing the relationship between biomass production and ammonium-N consumption in the fed-batch culture of Spirulina platen sis using ammonium bicarbonate as a nitrogen nutrient source, an online adaptive control strategy based on optical density (OD) measurements for controlling ammonium feeding.

Algae Culturing Using Microcontroller Platform

Minju Jennifer Kim et al stated that Spirulina plantensis, many microalgae have acquired attention from a diverse field of divorse field of research because of the highly applicable potentials on many global problems such as energy depletion and green house effects. The consumption of the microalgae products rapidly increases and the necessity of the stable and efficient production of the microalgae arouse. The microcontroller system might be applied with more elaboration in the algae culturing technologies.

Growth Yield Of Spirulina Maxima in Photobioreactors

A. Saeid and K. Chojnacka deal with the evaluation of the parameters for the cultivation of Spirulina maxima in two reactors (large-laboratory scale (LL) and semi-technical (ST)), whose illuminated volume are different, and with the operating costs. It was proved that it was possible to perform the cultivation of Spirulina maxima under temperate climate conditions in simply constructed, low cost reactors.

Mass Production of Spirulina

Avigad Vonshak & Amos Richmond reviewed details basic requirements required in order to achieve high productivity and low cost of production. There is a need for a wide variety of algal species and strains that will favourably respond to the varying environmental conditions existing outdoors. Another essential requirement is for better bioreactors, either by improving existing open raceway types or developing tubular closing systems. The later solution seems more promising. These developments must overcome the main limitation confronting the industry today which is the overall low a real yields which fall too short of the theoretical maximum and which are associated with scaling up micro algal culture to commercial size.

Evaluating Techniques

Most farmers grow Spirulina in open channel, shallow raceway ponds and use paddle wheels to move the water. The motors that pump fresh water into the Spirulina ponds can use solar cells to minimize energy consumption and waste. These bacteria can double their biomass every two to five days. Farmers can easily convert unfertile land into Spirulina growing ponds as these ponds can operate anywhere. Growers must continually add clean, fresh water and nutrients to keep the Spirulina thriving. Spirulina need nitrogen, potassium and iron the most, so farmers must add these nutrients to the water.

Spirulina culture changes rapidly if not cared for properly. Cultures can grow quickly or perish in under a few hours. Spirulina ponds are easily contaminated by toxic microorganisms and farmers must carefully control environmental conditions. Therefore, spirulina must grow in man-made ponds [2]. The water must be kept between 84 and 95 degrees Fahrenheit at all times.

Spirulina needs sunlight so any growing premise should be able to provide it. It is also important that the premise be able to provide shade, as direct sunlight may harm Spirulina, especially in its early stages.

Spirulina used here is cultivated in open pond/pool. Since it is an open pond a cover is needed for protection from rain, as rain will dilute the growing culture and alter pH level. It is also important when the pool is exposed to strong winds which carry dust and soil, as well as in cases where there are many insects. The pond should be cleaned from sediment every six months. When cleaning, the liquid containing the spirulina is transferred to another pool, basin, or even pots and buckets. Water and soap used for dishes are good for cleaning the pool.

In existing system, an arduino microcontroller is used to monitor the algae culture medium [3]. The completed microcontroller system was leaned and taped carefully on the back side of the culture vessel in a closed acrylic plastic cover chamber that was equipped with antibacterial HEPA filters and electric fans. The system should sense multiple parameters and response accordingly. For example, when the chamber space was higher than 35ₒC, it turns on the electric fan to cool down the climatic temperature. It also sense pH, temperature range and light intensity. On the other hand, sound alerts and warning LED was activated when the parameters are out of range in the software sketch [3].

Parameters are monitored and only LED indication is given to the cultivator. The LED indication alone will not be helpful for the cultivator to monitor the system.

Components Description

Arduino Microcontroller

Arduino is fast becoming one of the most popular microcontrollers used in robotics. There are many different types of arduino microcontrollers which differ not only in design and features, but also in size and processing capabilities. There are many features that are common to all Arduino boards, making them very versatile. All Arduino boards are based around the ATMEGA AVR series microcontroller from ATMEL which feature both analog and digital pins. Arduino also created software which is compatible with all Arduino microcontrollers [3].

Pin Description

Pin 1, 2: Connections for standard 32.768 kHz quartz crystal. The internal oscillator circuitry is intended for operation with a crystal having a specified load capacitance of 12.5 pF. X1 is the input to the oscillator and can alternatively be connected to an external 32.768 kHz crystal. The output of the internal oscillator, X2 is drifted if an external oscillator is connected to X1. Pin 3: Battery input for any standard 3V lithium cell or other energy source. Battery voltage should be between 2v and 3.5v for suitable operation.

Pin 4: This pin is grounded. Pin 5: Serial data input/output. The input/output for the I2C serial interface is the SDA, which is open drain and requires a pull up resistor, allowing a pull up voltage upto 5.5v. Regardless of voltage on VCC. Pin 6: Serial clock input. It is the I2C interface clock input and is used in data synchronization. Pin 7: Square wave/output driver. Pin 8: Primary power supply. When voltage is applied within normal limits, the device is fully accessible and data can be written and read. When backup supply is connected to the device and VCC is below VTP, read and writes are inhibited. However at low voltages, the time keeping function still functions.

The DS1307 real time clock (RTC) IC is an 8 pin device using an I2C interface. The ds1307 is a low-power clock with 56 types of battery backup SRAM. The clock/ calendar provides seconds, minutes, hours, day, date, month and year qualified data. They are available as integrated circuits (ICs) and supervise timing like a clock and also operate date like a calendar.

The main advantage of RTC is that they have an arrangement of battery backup which keeps the clock/ calendar running even if there is power failure. RTC is found in many applications like embedded system and computer mother boards etc., Here RTC module is used to stir the tank automatically for an interval of every one hour. RTC is connected from digital pin of an arduino microcontroller which is attached to a DC motor to stir the tank in both clockwise and anti-clockwise directions for well grown Spirulina species [3].

The sensor was water-proof stainless steel encapsulated temperature sensor [3]. The LM35 is one kind of commonly used temperature sensor that can be used to measure temperature with an electrical o/p comparative to the temperature (in °C). It can measure temperature more correctly compare with a thermistor.

This sensor generates a high output voltage than thermocouples and may not need that the output voltage is amplified. The LM35 has an output voltage that is proportional to the Celsius temperature. The scale factor is .01V/°C. In this project, it is used to maintain constant temperature of around 28ºC to 35ºC. The Algal growth is better around this temperature.

IR Sensor

An Infrared light emitting diode (IR LED) is a special purpose LED emitting infrared rays ranging 700 nm to 1 mm wavelength. Different IR LEDs may produce infrared light of differing wavelengths, just like different LEDs produce light of different colours [2]. IR LEDs are usually made of gallium arsenide or aluminium gallium arsenide. In complement with IR receivers, these are commonly used as sensors.

IR Sensors work by using a specific light sensor to detect a select light wavelength in the Infra-Red (IR) spectrum [1]. By using an LED which produces light at the same wavelength as what the sensor is looking for, you can look at the intensity of the received light. When an object is close to the sensor, the light from the LED bounces off the object and into the light sensor. This results in a large jump in the intensity, which we already know can be detected using a threshold.

Here, the IR sensor is used to detect the density of the algae. The density of the algae is sensed by IR sensor and if the density of the algal growth is the important factor to check whether the algae is ready for cultivation or not.

pH sensors measure the level of pH in sample solutions by measuring the activity of the hydrogen ions in the solutions. This activity is compared to pure water (a neutral solution) using a pH scale of 0 to 14 to determine the acidity or alkalinity of the sample solutions [2]. The most common method of measuring pH is to use an electrochemical pH sensor. Combination pH sensors are a type of electrochemical pH sensor that features both a measuring electrode and a reference electrode. The measuring electrode detects changes in pH value, while the reference provides a stable signal for comparison. A high impedance device, known as pH meter, is used to display the millivolt signal in pH units. Here, pH sensor is used to monitor the pH level of Spirulina in the tank.

The pH meter is calibrated with solutions of known pH, typically before each use, to ensure accuracy of measurement. To measure the pH of a solution, the electrodes are used as probes, which are dipped into the test solutions and held there sufficiently long for the hydrogen ions in the test solution to equilibrate with the ions on the surface of the bulb on the glass electrode. This equilibration provides a stable pH measurement.

In pH 0.0 to pH 14.0 ranges, the output voltage was highly linear. It was used with a module power of 5.00Vwith the dimension of module size of 43mmx32mm (1.70"x1.26") [3]. The measuring range fell within pH 0.0 to pH 14.0 under the temperature of 0 ~ 60℃. It had the accuracy of pH±0.1 at 25℃ with response time of less than 1.0 minute[3].

Dc motor converts DC electrical energy into mechanical energy. It works on the principle, when a current carrying conductor is placed in a magnetic field; it experiences a torque and has a tendency to move [3]. This is known as motoring action. If the direction of the current in the wire is reversed, then the direction of rotation also reverses. When magnetic field and electric field interacts they produce a mechanical force and based on that the working principle of DC motor is established. The direction of rotation of the motor is given by Fleming’s left hand rule. Here, we use DC motor for rotating the stirrer in both clockwise and anticlockwise direction.

GSM is a digital cellular contact system. It is used for transmitting voice calls and messages. SIM800A is a complete Quad band GSM/GPRS solution in a SMT type which can be embedded in the customers mobile. SIM800A supports 850/900/1800/1900 MHZ, it can transmit voice, SMS and data information with low power consumption with tiny size of 24*24*3 mm, it can fit into slim and compact demands of customer design.

Sim 800a Module

Featuring Bluetooth and Embedded AT, it allows total cost savings and fast time- to-market for customer applications. GSM module weighs around 3.14g. It’s operating temperature ranges from 40-85 degrees and its supply voltage ranges from 3.4 to 4.4 volts.

The automation process of spirulina cultivation system helps in reducing the man power to great extent. It is a low cost module preferred by all the cultivators. Time consumption is less for the cultivator in the entire cultivation of algae.

Further enhancements are yet to be made in the field of automation. The future scope of this system is entirely based on IoT automation system for spirulina growth measuring and monitoring. Thus completely reduces the man power.

Thus, an automatically controlled system for efficient culturing of spirulina was assembled successfully. This system monitors the growth pattern, pH level, temperature and density of the algae. The system also contains the stirrer which rotates in both clockwise and anticlockwise direction for every one hour.