Water Pollution Sensors
Water pollution is a global problem that affects the quality of our drinking water. A water pollution sensor can be used to detect pollutants and alert the user about unsafe levels.
The main hardware of this system consists of off-the-shelf electrochemical sensors, microcontroller and wireless communication system. It monitors water temperature, dissolved oxygen and pH in a pre-programmed time interval.
Temperature
Temperature is one of the most basic properties of water and is a critical indicator of the overall quality of water. It varies naturally with the seasons, but activities such as discharging warmer water from thermal power stations, releasing water from dams and diversions can also impact temperature.
For example, warmer water can be more corrosive and have a lower solubility of oxygen which can affect aquatic life. This can lead to eutrophication, depletion of nutrients and increase in the risk of disease.
Water pollution sensors need to be able to accurately measure several different parameters to provide accurate data for the quality of water. These include oxidation-reduction potential (chemical indicators), pH, total dissolved solids (mainly salts), turbidity and temperature.
Fortunately, many people are building their own real-time water quality equipment using low-cost probes and circuit boards paired with open-source software. This has made it possible to build powerful, weatherproof devices for real-time monitoring of water without breaking the bank.
The temperature sensor in the Waka is a high-precision thermistor sensor that can accurately measure temperature up to 50 degrees Celsius. The resistance of the thermistor changes with temperature, and this is converted into temperature using an algorithm.
This technology is used for environmental monitoring applications such as industrial wastewater, surface water and drinking water. Its use is increasing as more people are unable to access clean water.
It also is being used for environmental health and safety purposes such as determining the extent of the algal bloom in water bodies, monitoring fish populations and identifying contaminants in seawater.
A p-type silicon wafer and drop-casted poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film were fabricated in a Wheatstone bridge configuration to obtain a high temperature sensitivity with negligible drift. The temperature sensor was also tested for interference behavior with a 2 ppm free chlorine solution containing 400 ppm of interfering ions, including CaCl2 and (NH4)2SO4.
A 7-day long study of the pH, free Cl and temperature of a lake, tap and pool water sample from the Waka was conducted. The pH and temperature sensors showed negligible drift while the free chlorine sensor showed gradual decay of the sensor over time.
Conductivity
The conductivity of water is a useful measure of the concentration of dissolved solids in a solution, and water pollution sensor can be used to assess the quality of the water. Generally, the higher the conductivity, the more dissolved solids are present.
The specific conductance of a solution is defined as the amount of current flowing through a solution, measured in siemens per meter (S/m). The unit is SI (International Standard) and the reading is corrected to the temperature of the liquid at the time of measurement. This is typically 25 degC.
Conductivity is often used to gauge the overall condition of a water body, and it is a common indicator of anthropogenic impacts on the natural environment and aquatic life. Changes in conductivity can be indicative of the presence of contaminants such as sewage or pollution from agriculture.
As a general rule, most water bodies have a relatively consistent range of conductivity. Conductivity measurements should be made on a regular basis to monitor changes in conductivity over time.
A significant increase in conductivity is an indication that there has been some type of a discharge or other pollution that has entered the water, resulting in changes to the water’s total dissolved solids (TDS). A decrease in conductivity could be a sign that something is altering the overall quality of the water, or that it is no longer safe to drink.
For example, an agricultural runoff or sewage leak can increase conductivity because of the addition of chloride, phosphate and nitrate ions into the water. The same can be said of an oil spill or the addition of organic compounds that do not break down into ions.
To determine the electrical conductivity of a solution, an electrode is placed in a solution and a voltage is applied to the device. The electrode’s resistance will change in response to the voltage, and the sensor will measure the current flowing through the solution. In most cases, the current will be equal to the electrical conductivity of the solution at the temperature at which the electrode is placed in the solution. The result is a digitized reading that is displayed on the screen of the device.
Turbidity
Turbidity is an important indicator of a water pollution sensor’s ability to accurately measure the number of suspended solids in the sample solution. The higher the turbidity, the more visible particles are present in the solution.
A turbidity sensor is a simple device that measures the amount of light that is scattered or absorbed by particles in the water. Different sensors use different types of detectors to detect the light.
Most turbidity sensors work by shining a light beam into the sample solution and measuring how much of the light is scattered off particles. The turbidity measurement is then converted to Nephelometric Turbidity Units (NTU).
The light source of a turbidity sensor can be any type of light source, but some are better than others at detecting small particles. For example, a white light source is better at detecting small particles because it has a shorter wavelength. It also reduces stray light from other sources and prevents color from affecting the turbidity reading.
Some turbidity sensors use an infrared beam to illuminate the sample solution. This method is often used for low turbidity measurements because the infrared beam doesn’t scatter the light as much as other methods, but it can be problematic in high turbidity measurements.
Another turbidity measurement method uses a backscatter detector to detect the light that is reflected from the particles in the water. This is most effective for lower turbidity levels and can be used in a variety of applications.
The distance between the light source and the backscatter detector is also an important factor. A 90-degree path to the backscatter detector is best for turbidity measurements, as it offers less interference. A 180-degree path to the backscatter sensor is also useful, as it can be used in areas where stray light or incoming sunlight is less of an issue.
Turbidity sensors can be used for many different applications, from environmental monitoring to industrial wastewater treatment. It’s important to understand the differences between the different types of turbidity sensors and how they can be used in order to choose the most accurate and cost-effective turbidity sensor for your application.
Water Level
A water pollution sensor measures the level of contaminants in a liquid sample. The level of contaminants is often a critical indicator of a water’s health status and quality, and this is why it is important to have the ability to detect and monitor these pollutants in real time.
The most common measurements of water quality involve pH, conductivity and turbidity. However, these parameters are not enough for a comprehensive evaluation of a water’s health status and it is therefore important to have more than one type of sensor.
Various sensing approaches have been developed for the detection of different pollutants, some of which are based on molecular imprinted polymers (MIPs). Other approaches rely on electrochemical sensors, resonant cavities and planar sensors, as well as spectroscopic techniques such as X-ray fluorescence and microwave absorption spectroscopy.
These sensing systems have proven to be reliable and able to perform a wide range of tests online with real water samples. The most interesting developments, however, aimed to develop multisensor systems that could be applied for continuous water quality control.
For example, a long-term online measurement of the processed water quality at an aeration plant with 23 multisensors was successfully completed in [78]. The system was able to register the responses of each sensor every seven seconds and the data were available immediately. water pollution sensor The achieved precision of analysis was suitable for monitoring possible alarm events.
In addition, the device was able to collect data on temperature, pH, dissolved oxygen and redox potential, as well as turbidity. This allowed for a better understanding of the contaminant pathways and types depending on the water basin, seasonal factors and anthropogenic load.
The sensors were mounted on aluminum oxide and could operate continuously or be dipped into the water for short-term measurements. The system also included a data acquisition unit that could be used to transmit the data remotely.
In 2009, EPA investigated water quality monitoring sensor technologies that could be part of a real-time contamination warning system. This report outlines the results of that investigation and provides an overview of the different sensor technologies that were evaluated.
