Using algae to treat dairy farm wastewater – Farmer’s Weekly SA
Using algae to treat dairy farm wastewater Farmer's Weekly SA
Using Algae to Treat Dairy Farm Wastewater
Introduction
South Africa’s dairy farming industry is a vital component of the agriculture sector, contributing significantly to the country’s economy. With approximately 360,000 cows being milked daily, South Africa stands out as one of Africa’s leading milk producers.
However, dairy farms are not only known for their economic benefits, they also consume substantial volumes of water and generate considerable volumes of wastewater, primarily in the form of slurry waste from milking parlour operations. This wastewater can pose a significant threat to the environment if not properly managed.
Now, a groundbreaking initiative in South Africa is exploring the use of algae to treat dairy farm wastewater with the aim of protecting our precious water resources.
Water Usage and Wastewater Generation in Dairy Farming
Water is crucial for dairy farming, serving various purposes like irrigation, washing cows, removing mud and dung, and cleaning milking equipment.
The milking process generates large volumes of wastewater, which contains both organic pollutants (for example, waste milk, manure, and urine) and inorganic pollutants (cleaning chemicals, disinfectants, medications, and so on).
If this wastewater is not managed responsibly, it can enter rivers and streams and have detrimental effects on sensitive aquatic environments. Moreover, wastewater applied to fields can leach into groundwater, potentially contaminating drinking water sourced from boreholes.
The agriculture sector, including dairy farming, utilises a large percentage of the world’s freshwater supplies, and South Africa is no exception. As the fourth-largest agricultural industry in the country, dairy farming plays a key role in the economy but also contributes significantly to the waste load due to high levels of wastewater generation.
Therefore, effective treatment of dairy farm wastewater is essential for environmental protection and ensuring the sustainability of water resources.
Current Wastewater Management Methods
In South Africa, settling ponds are the common method for managing dairy farm wastewater. These ponds allow solids to settle at the bottom, with the remaining water being used for irrigation onto grass pastures that are grazed by dairy cows.
However, this method often falls short of meeting national wastewater standards, leading to environmental concerns. Farmers may also utilise engineered wetlands, which focus on pollution removal, but this approach requires large areas of land that could otherwise be used for grazing.
Additionally, constructed wetlands can present challenges, such as high construction costs and potential pest breeding.
Recognising these issues, Milk South Africa commissioned research in 2021 to produce best-practice guidelines for wetland management on dairy farms. This research highlights the importance of wetland maintenance and the establishment of buffer zones around watercourses, which can enhance biodiversity and mitigate pollution.
However, the effectiveness of a wetland depends on its nature, condition, and placement within the watershed.
Dairy wastewater (DWW) can also be treated through various methods, including mechanical, physiochemical, and biological approaches. Biological treatment methods are particularly cost-effective for removing organic material from DWW due to its easily biodegradable organic contents.
Anaerobic processes, which require lower energy consumption and produce less sludge, are considered more efficient than other methods.
However, no single treatment method consistently produces wastewater that meets the minimum discharge standards, necessitating a combination of approaches to achieve optimal results.
Over time, a combination of aerobic and anaerobic treatments has been employed, resulting in benefits such as low energy consumption, minimal sludge production, and fewer chemical requirements.
Recently, there has been a paradigm shift in the dairy industry, with an increasing recognition of wastewater as a valuable resource rather than merely waste. Dairy farm waste contains nutrients that can be transformed into economically valuable bioproducts, such as biofuel and biofertiliser, with minimal changes to existing systems.
Research Gaps and the Need for Optimal Treatment Methods
Despite the advances in wastewater treatment technology, there are significant gaps in research regarding dairy farm wastewater treatment in South Africa. Notably, there is a lack of awareness of the on-site treatment technologies employed by farmers and variations in these technologies among different farms.
The success rates and efficiencies of these treatment methods concerning the specific chemical properties of each farm’s wastewater have not been adequately documented. This lack of data is concerning because farmer-based innovations that are not included in the existing literature may yield interesting and valuable results.
Characterising DWW across various farms and processing plants is critical in the South African context, particularly before and after on-site treatment. Additionally, exploring biological treatment technologies could yield positive results, as they are generally viewed as effective for treating dairy wastewater.
Given the diminishing freshwater reserves and rising costs of nitrogen-phosphorus-potassium-based fertilisers, research into optimal treatment methods for nutrient-rich dairy wastewater is crucial for both environmental sustainability and economic viability.
Emerging from the literature review, a process to audit DWW was developed, allowing farmers to self-report on a series of questions related to on-farm practices and wastewater management.
Notably, all farmers indicated that they did not monitor wastewater quality, nor did any report water quality issues associated with their DWW. This lack of monitoring highlights a significant gap in knowledge and practice that needs to be addressed.
A Breakthrough Solution: Phycoremediation
To tackle the challenges associated with dairy farm wastewater, scientists from the Institute of Natural Resources in Pietermaritzburg and the Durban University of Technology, KwaZulu-Natal, have collaborated to explore a low-cost, innovative solution called phycoremediation.
This technique utilises algae to clean wastewater, leveraging the algae’s natural ability to absorb nutrients and pollutants from the water. Algae, tiny green organisms that thrive in aquatic environments, use sunlight and carbon dioxide for growth, effectively acting as nature’s sponge.
Laboratory experiments have demonstrated that certain strains of microalgae can effectively clean dairy farm wastewater, removing more than 90% of harmful pollutants. This success underscores the potential of algae as a sustainable solution for treating dairy wastewater.
Advantages of Algae for Wastewater Treatment
- Water conservation. By cleaning and reusing wastewater, dairy farms can reduce their consumption of fresh water, which is crucial in water-scarce regions like South Africa.
- Environmental protection. Clean water contributes to healthier rivers, lakes, and other ecosystems, protecting wildlife and ensuring safe water for communities.
- Cost-effectiveness. Algae are relatively easy to grow and maintain, making this treatment method affordable for dairy farms. It reduces the need for expensive chemical treatments and complex wastewater systems.
However, challenges remain. High concentrations of nutrients from waste milk, manure, and urine can create a cloudy, oxygen-poor environment that hinders algae’s effectiveness.
While diluting the wastewater can help, further research is necessary to optimise the process and improve efficiency. Field trials are being initiated to test phycoremediation in selected dairy processing facilities, with the aim of refining the treatment process.
The Bigger Picture
This innovative approach not only helps protect the environment but will also help to support the sustainability of dairy farms, ensuring that natural resources are not further depleted or wasted, allowing future generations to benefit.
By using algae to treat wastewater, dairy farms can continue producing milk and other dairy products without negatively impacting the environment.
Phycoremediation presents a promising treatment alternative for both dairy farm wastewater and dairy processing wastewater.
Nonetheless, the high chemical oxygen demand levels in processing wastewater require dilution to achieve optimal nutrient removal.
Turbidity in dairy farm wastewater also interferes with light penetration, impacting the growth of photosynthetic algae and the efficiency of pollutant removal.
Research findings indicate that nutrient removal is optimal at 60% concentration of both dairy farm wastewater and dairy processing wastewater. However, some farms exhibited low nutrient removal rates due to high turbidity, which limited algal growth.
Conversely, facilities with favourable conditions for algal growth showed satisfactory nutrient removal rates.
Dairy farming is essential for providing us with the delicious milk products we enjoy every day, but it also comes with environmental challenges. The innovative work of scientists using algae offers a promising solution to effectively treat dairy farm wastewater while at the same time protecting our water resources.
By embracing sustainable practices and supporting clean water initiatives, we can all play a part in ensuring a healthy and vibrant environment for generations to come.
SDGs, Targets, and Indicators
1. Which SDGs are addressed or connected to the issues highlighted in the article?
- SDG 6: Clean Water and Sanitation
- SDG 12: Responsible Consumption and Production
- SDG 13: Climate Action
- SDG 15: Life on Land
2. What specific targets under those SDGs can be identified based on the article’s content?
- SDG 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping, and minimizing release of hazardous chemicals and materials.
- SDG 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity.
- SDG 12.4: By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water, and soil to minimize their adverse impacts on human health and the environment.
- SDG 13.3: Improve education, awareness-raising, and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning.
- SDG 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains, and drylands, in line with obligations under international agreements.
3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?
Yes, there are indicators mentioned or implied in the article that can be used to measure progress towards the identified targets. These include:
- Percentage of harmful pollutants removed from dairy farm wastewater through algae treatment.
- Reduction in freshwater consumption by dairy farms through the reuse of treated wastewater.
- Improvement in water quality in rivers, lakes, and other ecosystems due to the use of algae for wastewater treatment.
- Reduction in the use of expensive chemical treatments and complex wastewater systems in dairy farms.
- Increase in the efficiency of nutrient removal from dairy farm wastewater through phycoremediation.
Table: SDGs, Targets, and Indicators
SDGs | Targets | Indicators |
---|---|---|
SDG 6: Clean Water and Sanitation | 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping, and minimizing release of hazardous chemicals and materials. | – Percentage of harmful pollutants removed from dairy farm wastewater through algae treatment. |
SDG 6: Clean Water and Sanitation | 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity. | – Reduction in freshwater consumption by dairy farms through the reuse of treated wastewater. |
6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity. | – Improvement in water quality in rivers, lakes, and other ecosystems due to the use of algae for wastewater treatment. | |
SDG 12: Responsible Consumption and Production | 12.4: By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water, and soil to minimize their adverse impacts on human health and the environment. | – Reduction in the use of expensive chemical treatments and complex wastewater systems in dairy farms. |
SDG 13: Climate Action | 13.3: Improve education, awareness-raising, and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning. | – Increase in the efficiency of nutrient removal from dairy farm wastewater through phycoremediation. |
SDG 15: Life on Land | 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains, and drylands, in line with obligations under international agreements. | – Improvement in water quality in rivers, lakes, and other ecosystems due to the use of algae for wastewater treatment. |
Source: farmersweekly.co.za