In recent years, technology has evolved swiftly. This has led to the emergence of new areas of business activities and industrial development. Nonetheless, pollution has become a major concern in modern metropolises. Possible air pollutants include volatile and semi-volatile organic compounds, as well as heavy metals. Notable water pollutants include organic matter, inorganics, pathogens, and nutrients. Before discharging into water bodies, industrial wastewater needs to be treated with those pollutants removed, as stated by Evoqua Water Technologies. The project presents remarkable significance when regulation of industrial emissions becomes crucial.
Conventionally, individual devices equipped with environmental sensors would be installed at the monitoring sites, constantly taking measurements. These devices are not optimized and may take up a lot of power. In addition, they are very costly. Oftentimes, these monitoring devices are installed at hard-to-access locations. To make sure that the devices are working fine, regular checks have to be carried out. It is a tedious task having to be physically at the sites to check on the status of the devices. Frequent access to the monitoring sites would mean higher health risks due to pollutant exposure, on top of safety concerns while entering the sites.
The team’s solution is Dragonfly 2.0, a two-in-one industrial wastewater and air toxicity monitoring system that is environmentally friendly, non-invasive, and cost effective. The project utilizes Narrowband IoT (NB-IoT) technology to achieve low power requirements. Low-power sensing devices will be installed at the sites for air quality and water quality monitoring. Locations such as the top of a chimney and the middle of a lake are included as well. After installation, the devices will not be altered physically. A drone equipped with environmental sensors, known as a Dragonfly, will be used to periodically fly to the monitoring sites, making sure the installed monitoring devices are well-calibrated and able to give accurate readings. This is done by running an automatic comparison between the readings obtained from on-board sensors on the Dragonfly, and those from ground devices. In the event that the acceptable ranged is exceeded, the end user will be alerted.
In the system, the parameters for air quality are: nitrogen dioxide (NO2), carbon monoxide (CO), ammonia (NH3), methane (CH4), ambient temperature, and humidity. These are amongst the prominent air pollutants as outlined by organizations such as World Health Organization (WHO) and Department of Environment (DOE) Malaysia. On the other hand, turbidity and electrical conductivity are the parameters for water quality. The ground devices come in two types, for air quality monitoring and water quality monitoring, depending upon the on-site requirements.
To achieve low-power specifications, the devices will be put into sleep mode when not in use. The devices will take sensor readings four times a day, at 6-hour intervals. Then, the readings will be pushed to Microsoft Azure platform via NB-IoT technology. Power consumption is greatly reduced using NB-IoT protocol as compared to other cellular network protocols. It is much more desirable, in terms of coverage and power consumption, as compared to other wireless technologies such as Wi-Fi. To further optimize the system, data will only be sent to the server when there is a meaningful difference as compared to the previous. Having said that, there is at least one transmission every two days to ensure the devices are still alive. The ground devices can easily last for more than ten years without recharging or battery replacement, making the system ideal for low-cost and low-maintenance applications.
In terms of technical aspects, the embedded ATMEL SAMD21 microcontroller on each board provides high performance at low power consumption. Enhancement is realized by tweaking the boards to use the ultra-low-power oscillator. Multichannel gas sensor working on metal-oxide semiconductor (MOS) technology is installed to measure air pollutant concentrations, complemented by temperature and humidity sensor. High-quality turbidity sensor provides reliable turbidity measurements. Whenever possible, integrated sensors are utilized as opposed to many separate sensors, in an attempt to reduce device size and weight, breakdown probability, power consumption, need for maintenance, and overall costs. On the Dragonfly, sensors for air and water qualities are packed into two modules, namely Air Monitoring Unit (AMU) and Water Monitoring Unit (WMU) respectively. Whenever applicable, the data is sent to the Cosmos DB database (NoSQL) and stored. The raw data is processed online, yielding noteworthy insights with high clarity, on the end user’s mobile application. Furthermore, the system comes with a meticulously-designed GUI, compatible on all Android platforms. User authentication and registration features are integrated into the system as well. With that, it ensures the right person/organization gets the right information and allows the sharing of collected data among people of the same organization. For optimization purposes, a separate database with MySQL architecture will be employed for storing user credentials information. All the data is kept highly confidential thanks to advanced encryption schemes.
Primarily to the regulatory authority, governing body, non-governmental organizations (NGOs), scientific institutions and environmental advocates, water quality and air toxicity monitoring can be performed systematically and periodically, with minimal effort by humans. The advent of the well-developed Dragonfly 2.0 brings a fresh perspective to the famous Internet of Things (IoT) concept.