Electrostatic Separators

Electrostatic Separators Market Outlook

The global electrostatic separators market is anticipated to reach approximately USD 800 million by 2035, growing at a CAGR of around 5.8% from 2025 to 2035. This growth is driven by increasing demand for efficient separation techniques across various industries, particularly in mining, recycling, and food processing. The rising focus on sustainability and environmental concerns has led to a heightened interest in recycling processes, which utilize electrostatic separation technology to enhance material recovery. Additionally, advancements in technology and increased investments in research and development are further propelling the market growth. As industries seek to optimize their processes and reduce waste, electrostatic separators are becoming an integral part of modern manufacturing practices.

Growth Factor of the Market

One of the primary growth factors driving the electrostatic separators market is the urgent need for efficient waste management solutions, particularly in the recycling sector. As global urbanization and population growth continue to escalate, the volume of waste generated is increasing, leading to an urgent need for effective waste separation technologies. Furthermore, the mining industry is also contributing significantly to market growth as the demand for precious and rare minerals rises, necessitating the use of advanced separation technologies to enhance recovery rates and minimize environmental impact. The expanding food processing sector is another key factor, as manufacturers are increasingly adopting electrostatic separators to ensure product purity and safety. Additionally, the rising consciousness regarding environmental sustainability and regulatory pressures are encouraging industries to adopt cleaner and more efficient separation methods.

Key Highlights of the Market

• Significant growth in the mining and recycling sectors is driving demand for electrostatic separators.
• Technological advancements in electrostatic separation methods are enhancing efficiency and effectiveness.
• Rising regulatory pressures for sustainable practices are increasing adoption of electrostatic technology.
• Wide range of applications across multiple industries ensures a diverse market landscape.
• The market is characterized by significant investments in R&D to innovate and improve separation technologies.

By Type

Belt Type Electrostatic Separators:

Belt type electrostatic separators are designed to effectively separate materials based on their electrical properties using a conveyor belt system. These separators utilize a combination of gravitational and electrostatic forces to increase the efficiency of the separation process. The belt's continuous movement allows for the steady feeding of material, making it suitable for large-scale operations in industries such as mining and recycling. With advancements in technology, these separators have improved their processing capabilities, yielding higher purity levels and recovery rates. Their robustness and versatility make them a preferred choice for many applications, further driving their market demand.

Plate Type Electrostatic Separators:

Plate type electrostatic separators involve the use of a series of plates that create a high-voltage electric field to separate particles based on their charge. This technology is particularly effective for separating fine particles and has a wide range of applications across various industries. These separators are known for their compact design and ease of maintenance, making them a popular choice in environments with limited space. The efficiency of plate type separators increases with advancements in technology, as manufacturers continuously innovate to enhance their performance. As industries seek to improve separation techniques, the adoption of plate type electrostatic separators is expected to grow significantly.

Drum Type Electrostatic Separators:

Drum type electrostatic separators consist of a rotating drum covered with an electrode that develops an electrostatic charge. As materials are introduced, they are subjected to the electric field created by the drum, which separates them based on their electrical properties. This type of separator is particularly effective for separating non-metallic materials and is commonly used in the recycling and mineral processing industries. The efficiency of drum type separators is enhanced by their ability to process large volumes of material continuously. With ongoing innovations in design and materials, drum type electrostatic separators are gaining traction, contributing to the overall market growth.

Roller Type Electrostatic Separators:

Roller type electrostatic separators utilize a cylindrical roller coated with an electrode that generates an electric charge. The materials being processed are introduced onto the roller, where they are subjected to the electric field created, allowing for effective separation based on their electrical conductivity. This type of separator is particularly advantageous for applications that require high purity and recovery rates. Its design allows for easy integration into existing processes and minimizes operational costs. As the demand for efficient separation technologies continues to rise, roller type electrostatic separators are expected to play a significant role in enhancing material processing across various industries.

Triboelectric Separators:

Triboelectric separators rely on the triboelectric effect, where materials are charged through friction, allowing them to be separated based on their electrostatic charges. This technology is gaining popularity due to its effectiveness in separating a wide variety of materials, including plastics and minerals. The design of triboelectric separators allows for a compact and efficient processing system, making them suitable for small to medium-sized operations. With the increasing focus on recycling and sustainability, triboelectric separators are becoming an essential tool for industries looking to optimize material recovery and reduce environmental impact. Their versatility and effectiveness are driving their adoption across multiple sectors.

By Application

Mining:

The mining sector is one of the primary applications for electrostatic separators, as they play a critical role in mineral processing. These separators are utilized to enhance the recovery of valuable minerals while minimizing waste material. The ability to separate ore based on electrical properties allows for a more efficient extraction process, leading to increased productivity and profitability in mining operations. With the growing demand for precious metals and minerals, the mining industry is increasingly investing in advanced separation technologies, including electrostatic separators, to improve their overall operational efficiency.

Recycling:

Electrostatic separators are extensively employed in the recycling industry to improve the recovery of recyclable materials from waste streams. By effectively separating different materials based on their electrical properties, these separators contribute to reducing landfill waste and promoting sustainability. Recycling facilities are integrating electrostatic separation technology to enhance the quality of recycled materials, increasing their value in the market. As environmental regulations become more stringent and the need for sustainable practices grows, the recycling sector is expected to witness significant growth in the adoption of electrostatic separators.

Food Processing:

In the food processing industry, electrostatic separators are utilized to ensure product purity and safety. These separators can effectively separate contaminants and foreign materials from food products, enhancing the quality and safety of consumables. The ability to maintain stringent hygiene standards while maximizing efficiency makes electrostatic separators an attractive solution for food manufacturers. As consumer awareness regarding food safety increases, the demand for efficient separation technologies in food processing is expected to rise, further boosting the market for electrostatic separators.

Chemical & Petrochemical:

The chemical and petrochemical industries leverage electrostatic separators to enhance the separation of different chemical components and improve the purity of end products. These separators provide an efficient means of processing raw materials, contributing to the optimization of production processes. As the demand for high-quality chemicals and petrochemicals grows, industries are increasingly adopting electrostatic separation technology to achieve operational efficiency and maintain competitive advantages. The versatility of electrostatic separators in handling various chemical compositions makes them a valuable asset in these sectors.

Others:

Beyond the primary industries mentioned, electrostatic separators find applications in several other sectors, including textiles, plastics, and electronics. These separators provide efficient solutions for material recovery and separation in diverse processes, contributing to waste reduction and sustainability. As industries continue to seek innovative solutions to enhance their operational efficiency and minimize environmental impact, the adoption of electrostatic separators in various applications is expected to grow, further diversifying the market landscape.

By User

Mining Industry:

In the mining industry, the use of electrostatic separators is crucial for improving the recovery of valuable minerals from ore. These separators optimize the mineral processing workflow, allowing for enhanced separation and maximizing resource extraction. As the demand for precious and rare minerals continues to rise, mining companies are increasingly investing in advanced electrostatic separation technologies to boost operational efficiency. The adoption of such technologies not only improves yield but also minimizes environmental impact by reducing waste generation, making electrostatic separators a key asset in modern mining practices.

Recycling Industry:

The recycling industry utilizes electrostatic separators to improve the recovery rates of recyclable materials from waste streams. These separators enable the effective separation of various materials, enhancing the quality of recyclables and promoting sustainability. As environmental concerns become more pressing, recycling facilities are increasingly turning to electrostatic separation technology to meet regulatory requirements and optimize their processes. The growing need for effective waste management solutions is expected to drive the adoption of electrostatic separators within the recycling sector.

Food Industry:

In the food industry, electrostatic separators are employed to ensure the purity and safety of food products. These separators effectively remove contaminants and foreign substances, which is essential for maintaining high hygiene standards in food processing. As consumer awareness regarding food safety continues to grow, manufacturers are increasingly adopting electrostatic separation technologies to enhance product quality and comply with food safety regulations. The potential for improved processing efficiency and reduced contamination risks makes electrostatic separators a valuable tool in the food industry.

Chemical Industry:

The chemical industry benefits from the use of electrostatic separators to optimize the separation of chemical components and improve the purity of final products. By enhancing separation efficiency, these separators contribute to the overall productivity of chemical manufacturing processes. As the demand for high-quality chemicals rises, manufacturers are increasingly investing in advanced electrostatic separation technologies to maintain competitive advantages and comply with industry regulations. The versatility and efficiency of electrostatic separators make them indispensable in the chemical industry.

Others:

Other industries, including textiles, plastics, and electronics, also utilize electrostatic separators for their effective separation capabilities. These separators allow for precise material recovery and separation, contributing to sustainability efforts and waste reduction across various processes. As industries search for innovative solutions to optimize their operations, the demand for electrostatic separators in these sectors is expected to grow, further expanding the market landscape. The adaptability of electrostatic technology to diverse applications makes it an attractive choice for a variety of industries.

By Voltage

High Voltage Electrostatic Separators:

High voltage electrostatic separators are designed to operate at elevated voltage levels, enabling them to efficiently process materials with different electrical properties. These separators are particularly effective in applications requiring significant separation force, making them suitable for use in the mining and recycling industries. The ability to create a strong electric field enhances the separation efficiency, leading to improved recovery rates of valuable materials. As industries continue to adopt advanced technologies for material processing, the demand for high voltage electrostatic separators is expected to grow significantly.

Medium Voltage Electrostatic Separators:

Medium voltage electrostatic separators operate at voltage levels that balance efficiency and safety, making them suitable for a wide range of applications. These separators are commonly used in recycling and industrial processes where a moderate separation force is required to effectively separate materials. Their versatility allows for integration into various systems, and as industries seek to optimize their operations, the adoption of medium voltage electrostatic separators is expected to rise. Ongoing advancements in technology will further enhance the performance and efficiency of these separators.

Low Voltage Electrostatic Separators:

Low voltage electrostatic separators are designed for applications that do not require high levels of electric force, making them ideal for smaller operations or specific material types. These separators are commonly used in smaller-scale recycling processes and applications where material separation is needed without the risks associated with higher voltage systems. The efficiency of low voltage separators continues to improve as technology advances, leading to greater adoption across various industries. As sustainability initiatives gain momentum, the demand for low voltage electrostatic separators is likely to grow.

Ultra-High Voltage Electrostatic Separators:

Ultra-high voltage electrostatic separators are engineered to operate at exceptionally high voltage levels, providing outstanding separation capabilities for challenging materials. This type of separator is particularly effective in mining applications where the separation of fine particles is critical. The enhanced electric field generated by ultra-high voltage separators allows for improved recovery rates and product purity, making them a valuable asset in mineral processing. As mining operations evolve and the demand for precision increases, the adoption of ultra-high voltage electrostatic separators is expected to rise.

Extra-Low Voltage Electrostatic Separators:

Extra-low voltage electrostatic separators are designed for specialized applications that require a gentle separation process. These separators are often used in industries with specific safety standards or sensitive materials where traditional separation methods are not feasible. The use of extra-low voltage technology allows for efficient material separation without compromising product integrity. As industries focus on enhancing their sustainability practices, the adoption of extra-low voltage electrostatic separators is likely to increase, further diversifying the market landscape.

By Region

The North American electrostatic separators market is anticipated to hold a significant share, driven by the robust mining and recycling industries within the region. The United States and Canada are key contributors to this growth, with increasing investments in advanced separation technologies. As sustainability becomes more critical, companies in this region are expected to adopt electrostatic separators to enhance material processing efficiency. The CAGR for the North American market is projected to be around 6% over the forecast period, reflecting a steady growth trend in response to evolving industry demands.

In Europe, the electrostatic separators market is also witnessing significant growth, fueled by stringent environmental regulations and a growing emphasis on recycling initiatives. Countries such as Germany, France, and the UK are leading the charge in adopting advanced separation technologies to improve material recovery rates. The European market is expected to experience a CAGR of approximately 5.5% during the forecast period, indicating the region's commitment to sustainable practices and innovation in material processing techniques. Collectively, the North American and European markets are set to play a critical role in shaping the global electrostatic separators landscape.

Opportunities

The electrostatic separators market presents numerous opportunities due to the increasing emphasis on sustainable waste management practices. As global awareness of environmental issues heightens, industries are seeking efficient solutions to reduce waste and enhance recycling processes. Electrostatic separators provide a viable means of improving material separation, thus facilitating higher recovery rates and reducing landfill waste. The ability to innovate and improve separation technologies positions manufacturers to cater to the rising demand for effective waste management solutions, creating a favorable environment for growth in the electrostatic separators market. Additionally, the expansion of recycling initiatives across various sectors, including construction and manufacturing, offers significant market potential for electrostatic separators, allowing businesses to capitalize on sustainability trends.

Moreover, advancements in technology are opening new avenues for growth in the electrostatic separators market. The integration of automation and artificial intelligence into separation processes is enhancing operational efficiency and accuracy, driving the demand for innovative separation solutions. Manufacturers are increasingly focusing on research and development to create next-generation electrostatic separators that can operate under diverse conditions and handle a wide range of materials. The trend toward digitalization in industrial processes is also creating opportunities for companies to differentiate themselves through technological innovation, thereby gaining a competitive advantage in the market. As industries continue to prioritize efficiency and sustainability, the electrostatic separators market is poised for substantial growth in the coming years.

Threats

Despite the promising growth prospects, the electrostatic separators market faces several threats that could impact its trajectory. One of the primary concerns is the intense competition from alternative separation technologies, which may offer similar benefits at a lower cost. Industries are often looking for cost-effective solutions, which can lead to a preference for traditional methods over electrostatic separation. Additionally, economic fluctuations and uncertainties can influence capital investments in advanced technologies, potentially slowing down the adoption of electrostatic separators. Companies must remain vigilant and adaptive to market changes to mitigate these threats and maintain their competitive edge.

Another challenge facing the electrostatic separators market is the regulatory landscape, as compliance with environmental and safety regulations can be complex and costly. Manufacturers must navigate a myriad of regulations related to emissions, waste disposal, and safety standards, which can impede their ability to innovate and expand. Moreover, the rapid pace of technological change requires companies to continuously invest in research and development to keep their products relevant and compliant with industry standards. Failure to adapt to these changes may result in lost market opportunities and diminished customer trust. Thus, managing regulatory compliance and technological advancements will be crucial for companies in the electrostatic separators market.

Competitor Outlook

• Eriez Manufacturing Co.
• Hamos GmbH
• Mineral Technologies
• ST Equipment & Technology LLC
• Electrostatic Separator Co.
• Macsalab
• Separators & Sorters LLC
• Metso Outotec
• Goudsmit Magnetics
• Clyde Bergemann Power Group
• CommodasUltrasort
• Yantai Jinpeng Mining Machinery Co., Ltd.
• FLSmidth
• Innovation & Technology Group
• Siebenbürgen Maschinenbau

The competitive landscape of the electrostatic separators market is characterized by a mix of established players and emerging companies, all vying for market share through innovation and technological advancements. Major companies in this sector are focusing on enhancing their product portfolios by integrating advanced technologies such as automation, artificial intelligence, and data analytics into their electrostatic separation systems. This tech-driven approach enables them to offer more efficient, cost-effective, and environmentally friendly solutions to industries, thus catering to the growing demand for sustainable practices. As industries increasingly recognize the value of advanced separation technologies, competition is intensifying, compelling companies to differentiate themselves through innovation and customer service.

Key players such as Eriez Manufacturing Co. have established a strong foothold in the electrostatic separators market, leveraging their extensive experience in material handling and separation technologies. Their commitment to research and development allows them to introduce cutting-edge solutions that address the diverse needs of various industries. Similarly, companies like Metso Outotec and FLSmidth have built robust reputations by providing innovative and reliable separation technologies tailored to the mining and recycling sectors. As these companies continue to invest in product innovation and enhance their customer engagement strategies, they are well-positioned to capitalize on the growth opportunities within the electrostatic separators market.

Emerging players in the electrostatic separators market are also making significant strides by focusing on niche applications and specialized technologies. These companies are often agile and can quickly adapt to changing market dynamics, allowing them to seize opportunities that larger firms may overlook. For instance, firms like Hamos GmbH and CommodasUltrasort are gaining traction in the recycling sector by developing tailored solutions that enhance material recovery rates. As the market evolves and new technologies emerge, collaboration and partnerships among competitors may also become more prevalent, leading to innovative solutions that benefit the entire industry. Overall, the competitive landscape is expected to intensify, driving advancements in electrostatic separation technologies and expanding the market further.

• 1 Appendix

  • 1.1 List of Tables
  • 1.2 List of Figures

• 2 Introduction

  • 2.1 Market Definition
  • 2.2 Scope of the Report
  • 2.3 Study Assumptions
  • 2.4 Base Currency & Forecast Periods

• 3 Market Dynamics

  • 3.1 Market Growth Factors
  • 3.2 Economic & Global Events
  • 3.3 Innovation Trends
  • 3.4 Supply Chain Analysis

• 4 Consumer Behavior

  • 4.1 Market Trends
  • 4.2 Pricing Analysis
  • 4.3 Buyer Insights

• 5 Key Player Profiles

  • 5.1 FLSmidth
    • 5.1.1 Business Overview
    • 5.1.2 Products & Services
    • 5.1.3 Financials
    • 5.1.4 Recent Developments
    • 5.1.5 SWOT Analysis
  • 5.2 Macsalab
    • 5.2.1 Business Overview
    • 5.2.2 Products & Services
    • 5.2.3 Financials
    • 5.2.4 Recent Developments
    • 5.2.5 SWOT Analysis
  • 5.3 Hamos GmbH
    • 5.3.1 Business Overview
    • 5.3.2 Products & Services
    • 5.3.3 Financials
    • 5.3.4 Recent Developments
    • 5.3.5 SWOT Analysis
  • 5.4 Metso Outotec
    • 5.4.1 Business Overview
    • 5.4.2 Products & Services
    • 5.4.3 Financials
    • 5.4.4 Recent Developments
    • 5.4.5 SWOT Analysis
  • 5.5 CommodasUltrasort
    • 5.5.1 Business Overview
    • 5.5.2 Products & Services
    • 5.5.3 Financials
    • 5.5.4 Recent Developments
    • 5.5.5 SWOT Analysis
  • 5.6 Goudsmit Magnetics
    • 5.6.1 Business Overview
    • 5.6.2 Products & Services
    • 5.6.3 Financials
    • 5.6.4 Recent Developments
    • 5.6.5 SWOT Analysis
  • 5.7 Mineral Technologies
    • 5.7.1 Business Overview
    • 5.7.2 Products & Services
    • 5.7.3 Financials
    • 5.7.4 Recent Developments
    • 5.7.5 SWOT Analysis
  • 5.8 Eriez Manufacturing Co.
    • 5.8.1 Business Overview
    • 5.8.2 Products & Services
    • 5.8.3 Financials
    • 5.8.4 Recent Developments
    • 5.8.5 SWOT Analysis
  • 5.9 Separators & Sorters LLC
    • 5.9.1 Business Overview
    • 5.9.2 Products & Services
    • 5.9.3 Financials
    • 5.9.4 Recent Developments
    • 5.9.5 SWOT Analysis
  • 5.10 Clyde Bergemann Power Group
    • 5.10.1 Business Overview
    • 5.10.2 Products & Services
    • 5.10.3 Financials
    • 5.10.4 Recent Developments
    • 5.10.5 SWOT Analysis
  • 5.11 Electrostatic Separator Co.
    • 5.11.1 Business Overview
    • 5.11.2 Products & Services
    • 5.11.3 Financials
    • 5.11.4 Recent Developments
    • 5.11.5 SWOT Analysis
  • 5.12 Innovation & Technology Group
    • 5.12.1 Business Overview
    • 5.12.2 Products & Services
    • 5.12.3 Financials
    • 5.12.4 Recent Developments
    • 5.12.5 SWOT Analysis
  • 5.13 ST Equipment & Technology LLC
    • 5.13.1 Business Overview
    • 5.13.2 Products & Services
    • 5.13.3 Financials
    • 5.13.4 Recent Developments
    • 5.13.5 SWOT Analysis
  • 5.14 Siebenbürgen Maschinenbau
    • 5.14.1 Business Overview
    • 5.14.2 Products & Services
    • 5.14.3 Financials
    • 5.14.4 Recent Developments
    • 5.14.5 SWOT Analysis
  • 5.15 Yantai Jinpeng Mining Machinery Co., Ltd.
    • 5.15.1 Business Overview
    • 5.15.2 Products & Services
    • 5.15.3 Financials
    • 5.15.4 Recent Developments
    • 5.15.5 SWOT Analysis

• 6 Market Segmentation

  • 6.1 Electrostatic Separators Market, By Type
    • 6.1.1 Belt Type Electrostatic Separators
    • 6.1.2 Plate Type Electrostatic Separators
    • 6.1.3 Drum Type Electrostatic Separators
    • 6.1.4 Roller Type Electrostatic Separators
    • 6.1.5 Triboelectric Separators
  • 6.2 Electrostatic Separators Market, By User
    • 6.2.1 Mining Industry
    • 6.2.2 Recycling Industry
    • 6.2.3 Food Industry
    • 6.2.4 Chemical Industry
    • 6.2.5 Others
  • 6.3 Electrostatic Separators Market, By Voltage
    • 6.3.1 High Voltage Electrostatic Separators
    • 6.3.2 Medium Voltage Electrostatic Separators
    • 6.3.3 Low Voltage Electrostatic Separators
    • 6.3.4 Ultra-High Voltage Electrostatic Separators
    • 6.3.5 Extra-Low Voltage Electrostatic Separators
  • 6.4 Electrostatic Separators Market, By Application
    • 6.4.1 Mining
    • 6.4.2 Recycling
    • 6.4.3 Food Processing
    • 6.4.4 Chemical & Petrochemical
    • 6.4.5 Others

• 7 Competitive Analysis

  • 7.1 Key Player Comparison
  • 7.2 Market Share Analysis
  • 7.3 Investment Trends
  • 7.4 SWOT Analysis

• 8 Research Methodology

  • 8.1 Analysis Design
  • 8.2 Research Phases
  • 8.3 Study Timeline

• 9 Future Market Outlook

  • 9.1 Growth Forecast
  • 9.2 Market Evolution

• 10 Geographical Overview

  • 10.1 Europe - Market Analysis
    • 10.1.1 By Country
      • 10.1.1.1 UK
      • 10.1.1.2 France
      • 10.1.1.3 Germany
      • 10.1.1.4 Spain
      • 10.1.1.5 Italy
  • 10.2 Asia Pacific - Market Analysis
    • 10.2.1 By Country
      • 10.2.1.1 India
      • 10.2.1.2 China
      • 10.2.1.3 Japan
      • 10.2.1.4 South Korea
  • 10.3 Latin America - Market Analysis
    • 10.3.1 By Country
      • 10.3.1.1 Brazil
      • 10.3.1.2 Argentina
      • 10.3.1.3 Mexico
  • 10.4 North America - Market Analysis
    • 10.4.1 By Country
      • 10.4.1.1 USA
      • 10.4.1.2 Canada
  • 10.5 Middle East & Africa - Market Analysis
    • 10.5.1 By Country
      • 10.5.1.1 Middle East
      • 10.5.1.2 Africa
  • 10.6 Electrostatic Separators Market by Region

• 11 Global Economic Factors

  • 11.1 Inflation Impact
  • 11.2 Trade Policies

• 12 Technology & Innovation

  • 12.1 Emerging Technologies
  • 12.2 AI & Digital Trends
  • 12.3 Patent Research

• 13 Investment & Market Growth

  • 13.1 Funding Trends
  • 13.2 Future Market Projections

• 14 Market Overview & Key Insights

  • 14.1 Executive Summary
  • 14.2 Key Trends
  • 14.3 Market Challenges
  • 14.4 Regulatory Landscape

Segments Analyzed in the Report

The global Electrostatic Separators market is categorized based on

By Type

• Belt Type Electrostatic Separators
• Plate Type Electrostatic Separators
• Drum Type Electrostatic Separators
• Roller Type Electrostatic Separators
• Triboelectric Separators

By Application

• Mining
• Recycling
• Food Processing
• Chemical & Petrochemical
• Others

By User

• Mining Industry
• Recycling Industry
• Food Industry
• Chemical Industry
• Others

By Voltage

• High Voltage Electrostatic Separators
• Medium Voltage Electrostatic Separators
• Low Voltage Electrostatic Separators
• Ultra-High Voltage Electrostatic Separators
• Extra-Low Voltage Electrostatic Separators

By Region

• North America
• Europe
• Asia Pacific
• Latin America
• Middle East & Africa

Key Players

• Eriez Manufacturing Co.
• Hamos GmbH
• Mineral Technologies
• ST Equipment & Technology LLC
• Electrostatic Separator Co.
• Macsalab
• Separators & Sorters LLC
• Metso Outotec
• Goudsmit Magnetics
• Clyde Bergemann Power Group
• CommodasUltrasort
• Yantai Jinpeng Mining Machinery Co., Ltd.
• FLSmidth
• Innovation & Technology Group
• Siebenbürgen Maschinenbau