Bruce Johnson, Brewer Science Device Systems Engineer07.24.18
Water, soil and air have been identified as three natural resources that we cannot live without.[1] Of those three, water is considered the most critical because it sustains life and the global food chain. Water is also important to the global economy as it is necessary for industrial production.[2] Although 70 percent of the earth’s surface is covered in water, only one percent is available for human consumption. Additionally, only one percent of that fresh water is available as surface water coming from our lakes, rivers and streams. The remaining 99 percent of fresh water is located underground, making protecting our groundwater vital to human survival.[3]
Many sources of contamination exist to surface and groundwater supplies. The most common sources come from municipalities, industry and agriculture in the forms of human waste, hazardous waste, pesticides and fertilizers. While surface-water contamination is easy to measure, the natural filtration through the earth’s sedimentary layers can make it difficult to accurately test groundwater.
Figure 1: The various sources of water contamination.
This article focuses specifically on the impact of the agricultural industry on our groundwater supply, and how printed electronics sensor systems are being developed for broad use across communities to pinpoint the sources of contamination and develop more sustainable farming approaches.
Water: An Agricultural Challenge
Farmers are under tremendous pressure to increase crop yields and feed the ever-growing population. Water quality is intrinsic to agricultural success. In the United States alone, the USDA estimates that agriculture accounts for 80 percent of the country’s water use. Agricultural uses of water include growing fruits and vegetables, raising livestock, irrigation, application of pesticides and fertilizers, and frost control. Ironically, the overuse of pesticides and fertilizers is one of the main causes of surface and groundwater contamination.[4] It is vital, then, that farmers engage in sustainable farming practices to maintain the delicate relationship between agriculture and water. These practices can be enabled by adopting smart agriculture approaches supported by smart technologies.
Over-Fertilization
Over-fertilization is a byproduct of farmers’ efforts to increase crop yields. Consequences of over-fertilization vary, depending on factors such as weather conditions or proximity to either surface or groundwater sources. For example, unused fertilizer can either seep into the ground or, mixed in with surface-water runoff, be carried downstream to other bodies of water. This can cause algae blooms in rivers and streams. Algae consume all the available oxygen in the water and thereby create regions where aquatic plants and animals cannot live. These issues with over-fertilization extend beyond the impact it has on farming to what it does to wildlife. The EPA is now regulating what wastewater reclamation facilities can allow back into rivers and lakes.
Surface and Ground Water Monitoring
While groundwater is the source of the world’s water supply, its reliance on surface water is inherent due to the Hydrologic Cycle: Surface water evaporates into the vapor that then forms clouds in the sky. This condenses and falls to earth as precipitation, becoming runoff into water bodies or seeping into the ground for storage as groundwater.[5]
Many over-fertilization problems are largely surface-water-based issues because many contaminants are naturally filtered out of groundwater through the rocks and sedimentary layers. However, it is still important to test groundwater for a comprehensive understanding of the situation’s gravity. Contaminants detected far down into the groundwater can provide further data points to analyze the impact of over-fertilization and to determine where it is occurring as well as where it is going.
Controlling over-fertilization can be achieved by monitoring surface and groundwater sources for ions. The ions present in ground and surface waters are composed of a mixture of various molecules. Each molecule responds to an applied electric field by moving in a predictable way. The sum of these movements generates a measurable electrical current. The more ions present in the measured water, the higher the measured current. This signal may be used to generate a close approximation of the total ion concentration in measured water or total dissolved solids (TDS).
The Role of Printed Electronics
Ionic conductivity measurements are stimulated by a broad range of ions as the contaminants are geographically dependent. For agricultural areas, the ion concentrations are often caused by fertilizers containing nitrates and phosphates, both of which contribute to the ionic conductivity measurement reported in TDS. Implementing a series of TDS measurement locations along a waterway for continuous monitoring aids in pinpointing the source of a contamination site and/or event via a deviation from baseline levels.
This method of measurement is regularly used in drinking water and wastewater treatment plants to monitor treatment processes and quality/contamination levels of incoming water sources. It can be implemented for high-volume commercial farming applications, as well as for municipalities for turf building. Even home gardeners can integrate smart systems into watering and fertilization regimens. One requirement for the mass deployment of such a system is a relatively low cost of ownership. Printed electronics can provide such a system, allowing for the deployment of multiple measurement locations that make it possible to pinpoint the primary sources of over-fertilization.
The Well-Monitoring Approach
Current well-monitoring systems used by government agencies and municipalities rely on water-level sensors, which don’t provide as much data regarding temperature and contamination as deep-well sensors can. This is because the contamination level at the surface can be dramatically different than at the bottom of the well, where the water has been filtered through rocks and sediment.
Additionally, the current monitoring tools are heavy and difficult to deploy, use costly silicon-based sensors and electronics, and require a field engineer to gather the data manually. The current silicon-based chemical sensors used to measure ionic connectivity, pH, the presence of metals, nutrients, and other key indicators require frequently calibration. They are also expensive to remove and replace. The cost of these systems, combined with small budgets, limits the number of wells that can be tested.
Figure 2: An example of a lightweight Brewer Science water system module.
A hybrid approach that allows for sensors to be printed on flexible substrates and then connected to silicon-based electronics for processing and wireless transmission has been developed to mitigate the challenges of current well-monitoring systems. These new hybrid systems allow for the deployment of sensor arrays in both surface water sources and deep wells.
The cost of printed electronics using plastics and printed metal is much less than silicon. Their flexible substrates are purposefully chosen to provide optimized sensing and durability in the environment. Also, they are made to be easily replaceable. This modularity is enabled by a connector to the rest of the system that is designed for underwater use.
These lighter systems are easy to deploy and self-sufficient. The electronics are dropped down a well and suspended for periods of time. Data is gathered at different points in the well by having modules placed at different heights along a cable. Multiple modules are used because the properties of the water change the further down it is measured. This data is stored locally and can be communicated wirelessly to a host server where analytics can occur. Multiple tools can be deployed throughout a community using an existing infrastructure of decommissioned wells. This will fill the gaps between the working wells to pinpoint sources of nutrient ingress into the water supply.
Enabling Smart Farming Practices
While the technology industry has firmly latched on to the terms “smart” and “internet of things” for any object that captures, processes and communicates data thanks to sensors and integrated electronics, smart agriculture is described as “methods to increase efficiency with water, planting, fertilizing and treating crops, to minimize the impact on the larger environment while maintaining high crop yields.” Smart technologies put the tools for gathering and processing important crop data at farmers’ fingertips, to become more efficient and adjust their processes and activities. For example, fertilization, pesticide application and watering schedules can be adjusted based on real-time sensor data, to reduce the number of contaminants that enter surface-water runoff and reduce water consumption.
While many commercial farmers are embracing smart agriculture, it can be a tough sell in some areas of the world where farmers are set in their ways. In other cases, new generations of farmers are being drawn to the profession because solving issues through technology is making farming more profitable.
Many advantages exist for farmers to implement printed electronics sensor systems into their smart farming practices. By installing systems in wells or surface waterways and providing the data to government agencies, they save money, improve yields, and can help communities locate the origins of contaminants while simultaneously proving their own farm’s best practices and responsibility.
Other Uses
In addition to agriculture, printed electronics sensor systems are suited to community-wide well-monitoring systems, to measure pollutants in the water caused by anything from dry-cleaning chemistries to mining operations and landfills. Through broad deployment, they can help diagnose weaknesses in municipal infrastructures, including water-reclamation sites, sanitation systems and many others through a sensor-data-enabled process of elimination.
Figure 3: An example of a fully integrated system of various monitoring locations in a given city.
Next Steps
The development of printed electronics sensor systems is not without challenges. Exposure to harsh environments restricts where and how different types of printed sensors (e.g., optical, acoustic and capacitive) can be deployed. As such, there is still work to be done before these tools will be fully available. While the printed-sensor solution itself is ready for implementation, the development of the well-monitoring systems that will deploy these sensors is still underway. Sensors that measure ionic connectivity and temperature in well environments must be reliable and durable so they last, and printed electronics sensors provide exactly that.
Next steps to deployment include assembling the full system, such as a user interface to set up logistics and semantics details for where the data is being stored. Brewer Science is scheduled to complete internal testing of such a system in Q3 2018, with products available for wide deployment in early 2019. Future work in this area will expand the availability of water-based sensing platforms that provide solutions for pH monitoring, specific nutrient monitoring and specific metal monitoring.
Conclusion
Having an affordable and adaptable tool that allows for multiple deployments and connectivity to a larger system provides vital information concerning contaminants in ground and surface waterways. This information can help locate sources of pollution, provide insight into over-fertilization and enable smart farming. Furthermore, controlling the dispersion of excess nutrients into the waterways helps protect the wildlife and can improve water processing for consumption. It also reduces the occurrence of algae blooms, improving oxygen levels in surface water for fish and plants to breathe and survive.
By working with local agencies to refine these printed sensing systems for continuous improvement, it will be possible to integrate these tools into surface-water studies for a better understanding of agricultural impacts. Also, by deploying systems in both surface and groundwater locations, sources of nutrients in our water supplies can be monitored. Ongoing work is underway to enable the deployment of whole printed sensor arrays. Additionally, durability studies will ensure the continuous improvement of system capabilities.
References
1. Air, Water, and Soil, US Forest Service Website https://www.fs.fed.us/science-technology/water-air-soil
2. T. Siebert, “Water Is Life: Conserve It, Respect It, Enjoy It,” 2013, Infrastructure News, http://www.infrastructurene.ws/2013/03/05/water-is-life-conserve-it-respect-it-enjoy-it/
3. Groundwater Pollution vs. Surface Water Pollution, Which is Worse? http://all-about-water-filters.com/groundwater-pollution-vs-surface-water-pollution/#tab-con-1
4. Agricultural Uses of Water, Extension, Utah State University Website https://extension.usu.edu/waterquality/learnaboutsurfacewater/usesofwater/agriculture
5. Op Cit. http://all-about-water-filters.com/groundwater-pollution-vs-surface-water-pollution/#tab-con-1
Many sources of contamination exist to surface and groundwater supplies. The most common sources come from municipalities, industry and agriculture in the forms of human waste, hazardous waste, pesticides and fertilizers. While surface-water contamination is easy to measure, the natural filtration through the earth’s sedimentary layers can make it difficult to accurately test groundwater.
Figure 1: The various sources of water contamination.
This article focuses specifically on the impact of the agricultural industry on our groundwater supply, and how printed electronics sensor systems are being developed for broad use across communities to pinpoint the sources of contamination and develop more sustainable farming approaches.
Water: An Agricultural Challenge
Farmers are under tremendous pressure to increase crop yields and feed the ever-growing population. Water quality is intrinsic to agricultural success. In the United States alone, the USDA estimates that agriculture accounts for 80 percent of the country’s water use. Agricultural uses of water include growing fruits and vegetables, raising livestock, irrigation, application of pesticides and fertilizers, and frost control. Ironically, the overuse of pesticides and fertilizers is one of the main causes of surface and groundwater contamination.[4] It is vital, then, that farmers engage in sustainable farming practices to maintain the delicate relationship between agriculture and water. These practices can be enabled by adopting smart agriculture approaches supported by smart technologies.
Over-Fertilization
Over-fertilization is a byproduct of farmers’ efforts to increase crop yields. Consequences of over-fertilization vary, depending on factors such as weather conditions or proximity to either surface or groundwater sources. For example, unused fertilizer can either seep into the ground or, mixed in with surface-water runoff, be carried downstream to other bodies of water. This can cause algae blooms in rivers and streams. Algae consume all the available oxygen in the water and thereby create regions where aquatic plants and animals cannot live. These issues with over-fertilization extend beyond the impact it has on farming to what it does to wildlife. The EPA is now regulating what wastewater reclamation facilities can allow back into rivers and lakes.
Surface and Ground Water Monitoring
While groundwater is the source of the world’s water supply, its reliance on surface water is inherent due to the Hydrologic Cycle: Surface water evaporates into the vapor that then forms clouds in the sky. This condenses and falls to earth as precipitation, becoming runoff into water bodies or seeping into the ground for storage as groundwater.[5]
Many over-fertilization problems are largely surface-water-based issues because many contaminants are naturally filtered out of groundwater through the rocks and sedimentary layers. However, it is still important to test groundwater for a comprehensive understanding of the situation’s gravity. Contaminants detected far down into the groundwater can provide further data points to analyze the impact of over-fertilization and to determine where it is occurring as well as where it is going.
Controlling over-fertilization can be achieved by monitoring surface and groundwater sources for ions. The ions present in ground and surface waters are composed of a mixture of various molecules. Each molecule responds to an applied electric field by moving in a predictable way. The sum of these movements generates a measurable electrical current. The more ions present in the measured water, the higher the measured current. This signal may be used to generate a close approximation of the total ion concentration in measured water or total dissolved solids (TDS).
The Role of Printed Electronics
Ionic conductivity measurements are stimulated by a broad range of ions as the contaminants are geographically dependent. For agricultural areas, the ion concentrations are often caused by fertilizers containing nitrates and phosphates, both of which contribute to the ionic conductivity measurement reported in TDS. Implementing a series of TDS measurement locations along a waterway for continuous monitoring aids in pinpointing the source of a contamination site and/or event via a deviation from baseline levels.
This method of measurement is regularly used in drinking water and wastewater treatment plants to monitor treatment processes and quality/contamination levels of incoming water sources. It can be implemented for high-volume commercial farming applications, as well as for municipalities for turf building. Even home gardeners can integrate smart systems into watering and fertilization regimens. One requirement for the mass deployment of such a system is a relatively low cost of ownership. Printed electronics can provide such a system, allowing for the deployment of multiple measurement locations that make it possible to pinpoint the primary sources of over-fertilization.
The Well-Monitoring Approach
Current well-monitoring systems used by government agencies and municipalities rely on water-level sensors, which don’t provide as much data regarding temperature and contamination as deep-well sensors can. This is because the contamination level at the surface can be dramatically different than at the bottom of the well, where the water has been filtered through rocks and sediment.
Additionally, the current monitoring tools are heavy and difficult to deploy, use costly silicon-based sensors and electronics, and require a field engineer to gather the data manually. The current silicon-based chemical sensors used to measure ionic connectivity, pH, the presence of metals, nutrients, and other key indicators require frequently calibration. They are also expensive to remove and replace. The cost of these systems, combined with small budgets, limits the number of wells that can be tested.
Figure 2: An example of a lightweight Brewer Science water system module.
A hybrid approach that allows for sensors to be printed on flexible substrates and then connected to silicon-based electronics for processing and wireless transmission has been developed to mitigate the challenges of current well-monitoring systems. These new hybrid systems allow for the deployment of sensor arrays in both surface water sources and deep wells.
The cost of printed electronics using plastics and printed metal is much less than silicon. Their flexible substrates are purposefully chosen to provide optimized sensing and durability in the environment. Also, they are made to be easily replaceable. This modularity is enabled by a connector to the rest of the system that is designed for underwater use.
These lighter systems are easy to deploy and self-sufficient. The electronics are dropped down a well and suspended for periods of time. Data is gathered at different points in the well by having modules placed at different heights along a cable. Multiple modules are used because the properties of the water change the further down it is measured. This data is stored locally and can be communicated wirelessly to a host server where analytics can occur. Multiple tools can be deployed throughout a community using an existing infrastructure of decommissioned wells. This will fill the gaps between the working wells to pinpoint sources of nutrient ingress into the water supply.
Enabling Smart Farming Practices
While the technology industry has firmly latched on to the terms “smart” and “internet of things” for any object that captures, processes and communicates data thanks to sensors and integrated electronics, smart agriculture is described as “methods to increase efficiency with water, planting, fertilizing and treating crops, to minimize the impact on the larger environment while maintaining high crop yields.” Smart technologies put the tools for gathering and processing important crop data at farmers’ fingertips, to become more efficient and adjust their processes and activities. For example, fertilization, pesticide application and watering schedules can be adjusted based on real-time sensor data, to reduce the number of contaminants that enter surface-water runoff and reduce water consumption.
While many commercial farmers are embracing smart agriculture, it can be a tough sell in some areas of the world where farmers are set in their ways. In other cases, new generations of farmers are being drawn to the profession because solving issues through technology is making farming more profitable.
Many advantages exist for farmers to implement printed electronics sensor systems into their smart farming practices. By installing systems in wells or surface waterways and providing the data to government agencies, they save money, improve yields, and can help communities locate the origins of contaminants while simultaneously proving their own farm’s best practices and responsibility.
Other Uses
In addition to agriculture, printed electronics sensor systems are suited to community-wide well-monitoring systems, to measure pollutants in the water caused by anything from dry-cleaning chemistries to mining operations and landfills. Through broad deployment, they can help diagnose weaknesses in municipal infrastructures, including water-reclamation sites, sanitation systems and many others through a sensor-data-enabled process of elimination.
Figure 3: An example of a fully integrated system of various monitoring locations in a given city.
Next Steps
The development of printed electronics sensor systems is not without challenges. Exposure to harsh environments restricts where and how different types of printed sensors (e.g., optical, acoustic and capacitive) can be deployed. As such, there is still work to be done before these tools will be fully available. While the printed-sensor solution itself is ready for implementation, the development of the well-monitoring systems that will deploy these sensors is still underway. Sensors that measure ionic connectivity and temperature in well environments must be reliable and durable so they last, and printed electronics sensors provide exactly that.
Next steps to deployment include assembling the full system, such as a user interface to set up logistics and semantics details for where the data is being stored. Brewer Science is scheduled to complete internal testing of such a system in Q3 2018, with products available for wide deployment in early 2019. Future work in this area will expand the availability of water-based sensing platforms that provide solutions for pH monitoring, specific nutrient monitoring and specific metal monitoring.
Conclusion
Having an affordable and adaptable tool that allows for multiple deployments and connectivity to a larger system provides vital information concerning contaminants in ground and surface waterways. This information can help locate sources of pollution, provide insight into over-fertilization and enable smart farming. Furthermore, controlling the dispersion of excess nutrients into the waterways helps protect the wildlife and can improve water processing for consumption. It also reduces the occurrence of algae blooms, improving oxygen levels in surface water for fish and plants to breathe and survive.
By working with local agencies to refine these printed sensing systems for continuous improvement, it will be possible to integrate these tools into surface-water studies for a better understanding of agricultural impacts. Also, by deploying systems in both surface and groundwater locations, sources of nutrients in our water supplies can be monitored. Ongoing work is underway to enable the deployment of whole printed sensor arrays. Additionally, durability studies will ensure the continuous improvement of system capabilities.
References
1. Air, Water, and Soil, US Forest Service Website https://www.fs.fed.us/science-technology/water-air-soil
2. T. Siebert, “Water Is Life: Conserve It, Respect It, Enjoy It,” 2013, Infrastructure News, http://www.infrastructurene.ws/2013/03/05/water-is-life-conserve-it-respect-it-enjoy-it/
3. Groundwater Pollution vs. Surface Water Pollution, Which is Worse? http://all-about-water-filters.com/groundwater-pollution-vs-surface-water-pollution/#tab-con-1
4. Agricultural Uses of Water, Extension, Utah State University Website https://extension.usu.edu/waterquality/learnaboutsurfacewater/usesofwater/agriculture
5. Op Cit. http://all-about-water-filters.com/groundwater-pollution-vs-surface-water-pollution/#tab-con-1
