Curated by Vinay Prabhakar Minj
We need IoT in environment monitoring to be able to conserve energy, water and other natural resources, which are being contaminated every second.
In conventional environmental monitoring methods, you get the samples, process it and do the analytical instrumentation on that. There are two ways of doing it:-
- Manual, in which you go and collect the samples.
- Instrumental, where you go to the lab and analyse the quantity of the pollutant it has.
Instrumental methods have direct analytics, where you automatically get the readings and the results. In Indirect methods, you need to pre-treat the samples and then do sedimentation, isolation and other processes.
When we talk about environmental monitoring using IoT, we primarily focus on areas such as waste management, air pollution and extreme weather.
Why do we need IOT for environment monitoring?
When we go deep into the environment monitoring, it is a very complex system, and so we can’t just start using sensors for regulatory purposes. The need for IoT in environment monitoring is actually to conserve energy, water and other resources because resources are being contaminated every second. If we have data for water and air, then we could have more judgemental things, like AI and ML tools.
There are environmental sensors for measuring water quality, radiations and hazardous chemical conditions. Similarly, in Industrial IoT also, we need to have such methods for the safety of the workers because some industries generate obnoxious gases like sulphur, methane and sulphur’s compounds which are bad for human health. By getting the data out of the sensors, they would be able maintain a good safety record. Also, places that are inaccessible could also effectively utilise the sensors.
Since 2012, research is happening all over the world on environmental sensors. Few reviews have already been done:-
- People have done outdoor air quality monitoring using using ZigBee-based wireless sensor network. Indoor environment is more polluted than the outdoor environment and so the system developed for the outdoor environment will not suit the indoor environment.
- Some people have also developed an air quality system that actually records the PM (Particulate Matter). The system categorises the PMs into PM 10, PM 2.5 and PM 1. Once the PMs go into the lungs, then it will lead to health issues.
THERE ARE ENVIRONMENTAL SENSORS FOR MEASURING WATER QUALITY, RADIATIONS AND HAZARDOUS CHEMICAL CONDITIONS. IN INDUSTRIAL IOT ALSO, WE NEED TO HAVE SUCH METHODS TO ENSURE SAFETY OF THE WORKERS
Standards are being implemented for PM 1 also, but more precisely we are measuring PM10 and PM 2.5.
- Mobile sensing systems have also developed and proposed for recording PM 2.5 in cities.
- Few research papers have described low-cost, portable monitoring system, which monitors multiple parameters, like humidity, PM 2.5, VOC (Volatile Organic Compounds), CO2, CO illuminance and sound levels.
Sensors are divided into two categories: electrochemical-based sensors and metal-oxide-based sensors.
Companies use these sensors based on their requirements. Both types of sensors have advantages and disadvantages. But research is being done mostly on metal-oxide sensors to get more sound results for environmental monitoring.
Likewise, the micro sensor-based air quality monitoring system was developed for detecting the real-time monitoring of airborne fine particultes. It has already been tested.
Top sensors used in environment
As the environment is heterogeneous, the system needs to be utilised well, because you cannot just develop one protocol based system and expect it to work in all the situations. Therfore, you need to have a multi-protocol system. Also we need to understand the interference of pollutants because pollutants such as ozone, NO2 or NOx particles have the interference capability. Therefore, people need to understand the science behind that interference, how the data is coming and what could be the reason for the deviation in the data. Then only a sensor can be well characterised and developed.
The top sensors used in environment are :
- Temperature sensors
- Proximity sensors
- Water quality sensors which measure the pH, BOD, COD and other microbial contaminants. It also measures the ion parameters like Arsenic, Iron or any other compounds.
- Gas sensors detect air quality conditions.
- Smoke sensors are required for industrial environmental conditions or maybe for a place which is smoke-prone.
THERE IS NO COMMON AGENCY TO APPROVE IOT-BASED SENSORS. THIS IS ONE OF THE PROBLEMS WE ARE FACING.
USEPA (US Environmental Protection Agency) has evaluated sensors with their conventional methods so that they can be utilised for research purposes and IoT applications. The Alphasense OPC N2 sensor is for PM 10 and PM 2.5 monitoring. This was tested through GRIMM, which is a certified handheld monitor. So far, these sensors have not been internationally certified. What I meant to say is that you won’t get USEPA certified sensors, but you will get USEPA evaluated sensors. This is because the technology is new and it keeps on evolving. After every six months, you will find a new version of those sensors.
AQMesh, CairClip and CitySense are gas phase sensors. These are being evaluated by the USEPA and are internationally funded projects. The systems are being tested against standard instrumentation techniques.
A typical regulatory monitor is quite expensive, and is based on analytical methods (not sensor). It is highly reliable but it is stationary, that means it cannot be moved from one place to another. Moreover, trained staff is required to operate it. One of its advantages is that it can operate upto 10+ years. But it needs to be calibrated quarterly.
On the other hand, a typical low-cost monitor does not require too much training, but then it has a limited lifetime.
Challenges in deploying IoT-based sensors for environment monitoring
The current technology is expensive, provides only a snapshot of the data, requires expertise to use it and takes time in lab analysis.
What we at the National Environmental Engineering Research Institute are targeting is, to develop a new technology, with IoT included in it, that will be low cost, easy to use and will provide continuous data. However, those technology needs to have a QA/QC approval and there is no common agency which is approving these techniques. This is one of the problems we are facing.
Major research findings for sensors or systems were in microprocessors. This system includes a wide variety of low cost components (varying from $100 to $300). If you are not a good integrator, you cannot integrate these components well. You also cannot use multiple sensors in a single board. That is another challenge.
If a balance can be maintained between the power, the cost and the latency, then only we can start using the system in the real environment.
Sensor characteristics include stability, detection limit, repeatability and reproductibility and cost, while user requirements includes measurement duration, data quality and budget.
THE SENSITIVITY, STABILITY AND THE LONGEVITY OF THE SENSORS NEED TO BE IMPROVED FOR ITS OPERATION.
A sensor’s lifetime is only two or three years. The sensitivity, stability and the longevity of the sensors need to be improved for its operation.
The Indian Government has defined the air quality index. It uses “one number-one colour-one description” to judge air quality. From this, it can be known that PM 10 is the highest polluting among all pollutants.
We have conducted our own case study by installing ten IOT based-sensors in Delhi.
Our findings say that low-cost sensors dominate the market and a few sensing elements exist. More research needs to be done on sensing elements. PM sensors are widely available as compared to the gas phase sensors. The sensors are mostly dominated by electrochemical or metal oxides.
Two major challenges for sensor application are:
- Sensor performance values vary widely.
- Basic testing by manufacturers is lagging.
From 2012 till now, there is a huge cost reduction. Reliability is there but more is required before getting into reality. Also, the cost involved in installation, maintenance and data analysis needs to be reduced.
Going forward, we are looking towards seamless implementation, data quality and reliability.
About the author:
The above article is an abstract from a speech presented by Poonam J Prasad, Senior Scientist, Analytical Instrumental Division, CSIR- National Environmental Engineering Research Institute -Nagpur, at the IOTSHOW.IN 2019, held in Bangalore. The institute’s Analytical Instrumental Division focuses on R&D on environmental sensors and internet of things.
Speaking on the use of IoT for environmental monitoring, she highlighted the need for IoT-based environmental sensors to conserve energy, water and other resources.
|Q. If you analyse the data and find that the air/water is polluted. How will you purify it or solve the problem?
A.If you have the data, the main game start from there. You will get the AQI (air/water quality index), and once you get that you will get to know which parameters are high in that particular area. Then your systems can automatically adjust the level of, say CO2. Environmental sensors cannot eradicate the pollutants, but can suggest methods to reduce it.
Q. Is the air quality/water quality (test methods) also getting integrated into the smart city projects?
A. Yes, it is one of the parts of smart city projects. But these (test methods) will be mostly used for management purposes, not for the core R&D purposes in smart city projects.