Factors to Consider When You Are a Water Quality Monitor
Water quality monitoring serves a wide range of purposes from ecological status compliance to safeguarding specific water uses. Phytoplankton, macroinvertebrates and other bioassays are often used to detect chemical contamination.
Alternative sensor systems can be costly and lack data interpretation capabilities. Using IoT and machine learning, we can improve upon these systems by making them smarter and more cost-effective.
Temperature
The temperature of water can influence many chemical aspects including pH levels, solubility and chemical reaction rates. This is why most guideline and policy documents mention temperature as one of the important factors in water quality monitoring (AWWA 2021).
In addition to affecting the chemical aspects of water, changes in temperature can also affect the physical properties. For instance, higher temperatures can increase electrical conductivity of the water and decrease its dissolved oxygen content (DO). This can be harmful for industrial processes that require high quality water.
To minimize these negative effects, it is necessary to monitor the water temperature continuously. Fortunately, online sensors are available to measure the temperature of the water and provide alerts when it is water quality monitor at risk. These online systems can be connected to a centralized server and are easy to operate. The authors of this paper have proposed a low-cost domestic water temperature, pH and turbidity monitoring system which is capable of continuously monitoring the water point and notifying the authorities if it deviates from the set standards.
pH
pH affects the solubility, transport and bioavailability of many chemical substances in water. It also influences the effects of these chemicals on aquatic plants and animals at specific concentrations. As a result, it is one of the most important factors in evaluating the water quality. It can be used to detect any chemical changes in the environment whether caused by pollution or natural environmental processes.
Recently, several methods have been developed for monitoring environmental water quality. These include contaminant screening using high-resolution mass spectrometry and effect monitoring using transfected receptor bioassays. However, these methods are limited in scope and require a substantial initial investment. They are also susceptible to human errors and require training to perform.
Moreover, they are difficult to use in developing countries due to lack of proper technical expertise and expensive equipment. To address this issue, a new method has been proposed that combines online water quality monitoring with IoT systems and machine learning algorithms. This system uses inexpensive sensors to measure key water quality parameters and transmits them to a remote server for analysis. This data can then be displayed through a web application.
Turbidity
Turbidity is a key water quality indicator that measures the clarity of a fluid. A rise in turbidity can signal that filters are failing, ineffective disinfection, the need for network pipes to be flushed or poor coagulation and flocculation processes.
Natural turbidity in water comes from the growth of phytoplankton, clay, silt, very tiny inorganic and organic matter, dissolved colored organic compounds and metals. Human activities can also cause a lot of turbidity as sediments are carried by storm water run off into natural waters.
A turbidimeter can measure the clarity of a liquid by shining a beam of light through it and measuring how much of the light is scattered by the particles in the sample. The scattering rate changes with the amount of suspended matter in the water and is reported as nephelometric turbidity units (NTU). Different measurement technologies deliver different results from the same sample due to the variability in optical characteristics of natural materials in the sample.
Conductivity
Conductivity is a measurement of the water’s ability to carry an electric current. It can be affected by a variety of factors such as temperature, salinity and water density, which all play an important role in the survival of aquatic organisms.
In a water quality monitor, the conductivity is measured by passing an electrical current through a probe with two or more metal plates (electrodes) placed a certain distance apart. The ions in the sample are attracted to one electrode and repelled by the other, depending on whether the ion is positive or negative. The electrical current passes through the cell of the sensor and is recorded on the data logger.
A significant increase in the dissolved solids or conductivity levels of an aquatic body can indicate pollution. This can occur from agricultural runoff, sewage leaks or even road salt. Organic compounds also tend to decrease the conductivity of water because they do not break down into ions. Specific conductance is usually reported in uS/cm at water quality monitor a standard temperature of 25deg C. This standardized reporting allows for the conductivity to be easily compared across different data sets.
Dissolved Oxygen
Oxygen is a crucial factor in water quality. Most fish and aquatic plants require oxygen to survive, and low concentrations can have devastating effects on an ecosystem. Measurement of dissolved oxygen can help identify problem areas within an aquatic habitat.
In general, oxygen gets into a body of water either through the atmosphere (by slow diffusion), or by means of aeration such as waves, wind, rapids, waterfalls, ground water discharge or plant photosynthesis. Running water, such as that of a stream or river, dissolves more oxygen than still water like a lake or pond.
The temperature and atmospheric pressure of the water determine how much dissolved oxygen is present. DO is commonly reported in milligrams per liter or as a percentage of air saturation; one milligram is equal to 1 ppm.
Dissolved oxygen is a common parameter monitored by agencies to assess the health of lakes and rivers. Agencies use a variety of methods for monitoring DO, including the membrane-electrode method, where a probe is inserted into a sample and the current measured as oxygen diffuses across the sensor.
