Purifying Lakes: Removing Pollutants, Restoring Nature's Balance

Lakes are a vital source of freshwater, but they are also vulnerable to pollution. This pollution can come from many sources, including industrial waste, agricultural runoff, sewage, and atmospheric pollutants. As lakes are interconnected with other water bodies, pollution in one area can have far-reaching effects, and the consequences for aquatic life and human health can be severe.

So, how can we remove pollutants from lakes? There are several methods, including natural biological, chemical, and physical processes, as well as human interventions such as wastewater treatment and the use of technologies like phytoremediation. Preventing pollution in the first place is always the best approach, but when that is not possible, a combination of regulations, community action, and innovative solutions can help to mitigate the impact of contaminants on these precious water sources.

Remove debris, trash, chemicals, sewage, fertilizers, bacteria, and other contaminants

Removing debris, trash, chemicals, sewage, fertilizers, bacteria, and other contaminants from lakes is a complex and challenging task. Here are some strategies and techniques that can be employed:

Source Control and Prevention:

• The first step is to identify and eliminate the sources of pollution. This includes proper waste disposal, reducing the use of harmful chemicals, and implementing regulations to control industrial and agricultural pollution.
• Upgrading wastewater treatment plants can also help remove contaminants before they reach lakes.

Physical Removal:

• One method is to use screening and trash rakes to collect large debris and trash from the lake's surface or shoreline.
• Dredging can be used to remove contaminated sediment from the lake bed, but it is costly and time-consuming.

Chemical and Biological Treatments:

• Advanced wastewater treatment processes, such as filtration, biological treatments, and activated carbon filtration, can remove chemicals, pharmaceuticals, and personal care products from the water.
• Phytoremediation uses plants to absorb and remove contaminants from the water. It is a cost-effective and environmentally friendly approach.
• Bioremediation employs microorganisms to digest and convert contaminants into harmless substances.
• Chemical oxidation uses oxidants to convert harmful chemicals into less toxic compounds.

Public Awareness and Collaboration:

• Educating the public about the importance of proper waste disposal and reducing fertilizer and chemical usage can help prevent pollution.
• Collaboration between governments, industries, and local communities is crucial for effective pollution control and cleanup efforts.

It is important to note that a combination of these strategies may be required, and each lake ecosystem may need a customized approach depending on the specific contaminants present. Additionally, preventing pollution from entering lakes in the first place is always more effective and less costly than trying to remove contaminants after they have entered the lake.

Improve wastewater treatment facilities

Wastewater treatment facilities in the United States process approximately 34 billion gallons of wastewater every day. However, there is still room for improvement to reduce the amount of pollution entering lakes and other bodies of water.

Upgrading wastewater treatment systems can be expensive, but these upgrades can pay for themselves or even save a plant money in the long run. Here are some ways to improve wastewater treatment facilities:

• Upgrade pump stations: Older pumps were typically designed to operate at a single speed, but today's pump/motor/drive combinations are more efficient over a wider range of flows. Upgrading to variable frequency drives can match pump speeds to flow rates, reducing energy needs.
• Optimize aeration: The aeration system in a wastewater treatment plant accounts for over 50% of the annual electricity usage. Optimisation measures include upgrading blowers and air distribution system components with variable frequency drives and installing dissolved oxygen control systems. If you have an aging blower, consider replacing it with a single high-efficiency turbo blower, which has a wide range of operations and can be controlled based on dissolved oxygen levels.
• Improve sludge management: Solids handling processes use over 20% of the energy at a wastewater treatment facility. Options to save money and energy include minimising transported water and solids, and utilising biogas for electricity production and heating water (co-generation).
• Recover and recycle essential nutrients: Phosphorus is an essential component in fertilisers. If your plant is currently utilising or evaluating biological phosphorus removal, consider creating a marketable commercial-grade fertiliser. This turns an operational cost into a new source of revenue while also improving the plant's performance by reducing phosphorus loading in recycle streams.
• Reduce disinfection costs: Chlorine and dechlorination chemicals are expensive and energy-intensive to manufacture and transport. Replacing chlorine disinfection with an ultraviolet (UV) light disinfection system can reduce costs and improve safety by eliminating the need for hazardous chemicals.
• Upgrade lighting and HVAC systems: Operating a large facility consumes a significant amount of energy through lighting, heating, and cooling. Upgrading to more energy-efficient lighting fixtures, such as high-efficiency T-8 fixtures, can result in energy savings and rebates.
• Automate operations: Implementing a Supervisory Control and Data Acquisition (SCADA) system can provide real-time data on treatment processes, automate operations, and alert operators of emerging issues. This system can also monitor equipment and provide operators with the desired amount of hands-on versus hands-free control.

By implementing these improvements, wastewater treatment facilities can increase their efficiency, reduce their carbon footprint, and minimise the amount of pollution entering lakes and other water bodies.

Reduce agricultural pollution

Reducing agricultural pollution is key to protecting lakes and other bodies of water from harmful contaminants. Here are some strategies to achieve this:

Implement Buffer Strips and Living Cover

Vegetative buffer strips, planted alongside farmland borders and waterways, act as a natural barrier, preventing pollutants like nitrogen and phosphorus from reaching water sources. This simple and cost-effective measure can significantly reduce agricultural runoff. In addition, incorporating other living cover on agricultural land, such as cover crops or diverse vegetation, can further minimize erosion and reduce the risk of pollutants entering waterways.

Improve Farmland Drainage Systems

Artificial drainage systems, known as drain tiles or subsurface tiles, are commonly used to manage moisture levels in soil. However, these systems can negatively impact water quality. By increasing water flow into ditches, streams, and rivers, they contribute to flooding and erosion. To reduce agricultural pollution, it is essential to adopt drainage systems that minimize the amount of nutrient-rich water and pesticides entering nearby water bodies.

Regulate Industrial Factory Farming

Industrial factory farming, which involves confining tens of thousands of animals in close quarters, generates excessive amounts of animal waste. This waste often exceeds the capacity to apply it sustainably as fertilizer, leading to storage in pits that can leak into groundwater supplies. In some instances, pit walls have broken, resulting in catastrophic spills. To reduce agricultural pollution, regulations are needed to ensure proper waste management and storage practices in these facilities.

Promote Sustainable Chemical Use

The overuse of pesticides, fertilizers, and other chemicals in agriculture can have detrimental effects on water quality. Pests can develop resistance to chemicals, leading to a cycle of increased pesticide application. To break this cycle, it is essential to promote sustainable practices, such as integrated pest management, which utilizes natural alternatives and minimizes chemical inputs. Additionally, encouraging crop rotation and diverse farming practices can help reduce the reliance on pesticides and fertilizers, ultimately decreasing the amount of these pollutants in lakes and other water sources.

Encourage Conservation Practices

Conservation practices, such as wetland preservation and restoration, can play a crucial role in reducing agricultural pollution. Wetlands act as natural filters, trapping sediment and excess nutrients before they reach water bodies. By preserving and restoring these vital ecosystems, we can enhance their ability to mitigate the impacts of agricultural runoff, improving water quality in lakes and downstream water sources.

Clean up oil spills

Oil spills in lakes are a serious issue, and researchers say that we don't know a lot about how to clean them up. However, there are some methods that can be used to address this problem. Here are some ways to clean up oil spills:

Responding to Oil Spills on Shore:

• Shoreline Flushing/Washing: Water hoses can rinse oil from the shoreline into the water, where it can be more easily collected.
• Booms: Long, floating, interconnected barriers are used to minimise the spread of spilled oil.
• Vacuums: Industrial-sized vacuum trucks can suction oil from the shoreline or on the water surface.
• Sorbents: Specialized absorbent materials act like sponges to pick up oil but not water.
• Shoreline Cleaners & Biodegradation Agents: Chemical cleaners that act like soaps may be used to remove oil, but special permission is required. Nutrients can be added to help microbes break down the oil.
• Burning: Also known as "in situ burning," freshly spilled oil can be set on fire, typically when floating on the water surface or on oiled marsh vegetation, to remove it effectively.
• Manual Removal: Cleanup crews using shovels or other hand tools can pick up oil from the shoreline, especially when heavy machinery cannot reach the site.
• Mechanical Removal: When access is possible, heavy machinery such as backhoes or front-end loaders may be utilised.

Responding to Oil Spills at Sea:

• Dispersion: Chemicals are used to break down the oil into small droplets, facilitating its removal from the water surface.
• Burning: Similar to the previous method, this involves setting fire to freshly spilled oil while it's still floating.
• Booms: These long, floating barriers are employed to contain or prevent the spread of spilled oil.
• Skimming: Boats equipped with floating skimmers are used to remove thin layers of oil from the surface, often assisted by booms.

It's important to note that preventing pollution is always more effective and less expensive than treating contaminated water. Additionally, individuals can play a crucial role in reducing pollution by properly disposing of harmful substances and minimising their usage.

Implement natural vegetative buffers

Vegetative buffers are one of the most effective ways to protect water quality, lake ecosystems, and wildlife habitats. These buffers are strips of ground cover, shrubs, and trees that act as transitional areas between land and water, creating unique and highly productive ecosystems.

Planning the Buffer Zone

The first step is to identify the appropriate location for the buffer zone. It should be located along the shoreline of the lake, extending 3-5 feet from the water's edge and maintained at approximately 18 inches in height. This zone serves as a crucial filter for stormwater runoff, slowing down its flow and allowing for the absorption and filtration of excess nutrients, sediment, and pollutants.

Selecting the Right Vegetation

The selection of vegetation for the buffer zone is critical. It is recommended to choose a mix of native plants, including grasses, sedges, rushes, and flowering species. Examples include swamp milkweed, sweet flag, pickerelweed, arrowhead, cardinal flower, and rain lily. It is important to avoid invasive plant species like Phragmites and purple loosestrife, as they can quickly dominate the ecosystem and harm native species. Additionally, woody vegetation, such as trees and shrubs, should be minimized as they can contribute to bank destabilization and increase soil dryness.

Creating a Multi-Zone Buffer

The buffer zone can be designed with multiple zones to maximize its effectiveness. The littoral zone, closest to the water, is ideal for floating-leaved plants like pickerelweed. The riparian zone accommodates emergent plants, while the upland zone is suitable for deep-rooted species like sedges, grasses, and irises. This diverse vegetation provides habitat for a variety of wildlife, including beneficial birds, amphibians, and mammals.

Maintaining and Monitoring the Buffer

Once established, the buffer requires regular maintenance to ensure its functionality. This includes removing weeds, pruning plants, and introducing new plants as needed. Properly dispose of all trimmings to prevent them from decomposing in the water. Additionally, monitor the buffer area for invasive plant species and remove them promptly. Trees and plants with aggressive root systems, like willows and cottonwoods, should also be removed to prevent shoreline damage and erosion.

Benefits of Vegetative Buffers

Vegetative buffers not only improve water quality by absorbing excess nutrients and filtering pollutants but also provide numerous other benefits. They help recharge groundwater, limit flooding by absorbing stormwater runoff, stabilize banks, and provide essential habitat and food sources for a diverse range of aquatic and terrestrial life. Additionally, they offer economic, social, and environmental values, including aesthetic enhancement, recreational opportunities, and educational and research possibilities.

By implementing and maintaining natural vegetative buffers, you can effectively improve water quality, enhance wildlife habitats, and create a more sustainable and resilient lake ecosystem.

Frequently asked questions