Copper (Cu) is a heavy metal that is mined for and used in a variety of industrial processes, including metals plating and printing as well as the manufacturing of electronic components, circuit boards, paints, pigments, paper, pulp, and fertilizer. Like other heavy metals, copper is a valuable yet potentially hazardous material that when present in effluent streams must be closely monitored and managed. If your industrial facility has copper high levels in your effluent, you might be wondering what are the best ways to remove copper from industrial wastewater?
In this article, we’ll identify some common treatment technologies for reducing copper levels in wastewater and explore the pros and cons of each.
What is the best wastewater treatment system for removing copper?
There are several technologies used for copper separation, each of which offers benefits that can vary widely according to the particularities of the application. In short, the best copper separation strategy is one that is most suitable to the facility in terms of the unique process conditions, waste stream characteristics, and objectives and priorities of the wastewater treatment project. When evaluating potential copper removal strategies, facilities need to assess their wastewater streams (e.g. concentration of copper and other constituents present, as well as temperature, pH, flow rates, and variability), while also balancing other factors, such as available space, upfront and ongoing costs, labor and training to support system operations and maintenance, and other considerations.
The below list provides a quick overview of wastewater treatment technologies that are commonly used for separating copper out of industrial waste streams:
Chemical precipitation is among the more popular treatment strategies employed for copper removal, as it is relatively simple and economical. The process essentially consists of adding chemical precipitants to a stream, which interact with copper ions to form insoluble precipitates that can then be removed by physical separation, such as filtration or clarification. When looking to chemical precipitation for copper removal, facilities should be aware that the degree of copper removal depends upon which chemical precipitants are used, and not all will reduce copper levels below allowable discharge limits.
Approaches include hydroxide and sulfide precipitation as well as chelating agents and lime precipitation. Precipitation can also entail excessive chemical consumption and sludge production when used for copper removal, so facilities need to plan for both of these aspects when considering potential treatment strategies.
In general, chemical precipitation is a good fit for wastewater streams with high concentrations of copper though it tends to be less efficient when metal content is low.
Dissolved air flotation
Dissolved air flotation (DAF) is a wastewater treatment technique where chemical coagulants are added to a stream to encourage contaminants to collect into small particles. Treatment proceeds with the introduction of air bubbles that encourage the particles to the surface, where they form a sludge layer that can be removed. While there are other types of flotation, including ion flotation and precipitation flotation, DAF remains the most popular type of flotation technology for the removal of copper and other metals. Among the benefits of DAF are high efficiency and selectivity for copper removal, short retention time, low operational costs, and smaller, more concentrated sludge volumes comparative to sedimentation. Facilities considering DAF for copper removal, however, do need to consider that the technology entails a high capital investment and significant maintenance demands.
Adsorption is a treatment technology that leverages forces of molecular attraction to separate contaminants from water. Physical adsorption technologies are commonly used for copper and other metals removal, and the process generally consists of passing a wastewater stream through adsorbent media. There are many kinds of adsorbent media that can be used for copper removal, including activated carbon, carbon nanotubes, zeolite, clay, as well as biomass comprised of fungi, algae, or microbes.
Since the copper ions (or other metals) are more attracted to the adsorbent media than they are to the water, they are effectively pulled out of solution and remain on the surface of the media while the wastewater effluent flows through. Adsorption offers many benefits to facilities looking for copper removal technologies, as it is a relatively simple process from a technical standpoint with low operational costs and easy accessibility for adsorbent media. Drawbacks to consider include low adsorption capacity and limited regeneration of adsorption media, both of which can result in higher costs associated with frequent media replacement. As a result, adsorption is best used for streams with relatively low concentrations of copper.
Ion exchange (IX) is a physical-chemical treatment process where a wastewater stream is passed through a resin substrate that facilitates the exchange of charged ions, such as copper. The resin selectively captures these charged particles from solution, retaining them until the resin is regenerated.
IX is an effective approach for copper removal in streams with low concentrations of metal ions, although effectiveness can vary depending upon stream pH. When using IX for copper removal, facilities need to plan for regular regeneration and maintenance schedules to ensure that the system continues to perform efficiently in reducing copper to allowable levels. Additionally, facilities will need to have a plan for treatment and safe disposal of IX waste products, including waste resulting from regeneration cycles and contaminated rinse water. Generally speaking, IX is a less viable option for streams with high concentrations of copper due to excessive maintenance and discharge costs.
Membrane filtration is a pressure-driven physical separation process where a liquid stream is passed through a semi-permeable filtration membrane. Any particles larger than the membrane’s pores are retained, while the liquid stream is able to pass through. The types of membrane filtration commonly used for copper removal include nanofiltration (NF), reverse osmosis (RO), and electrodialysis. Ultrafiltration (UF) can also be used, though its pore size range is too large to effectively capture copper ions on its own, so it must be used in combination with other treatment technologies. Membrane filtration technologies can be a good choice for wastewater treatment strategies where stringent discharge limits are an issue and where reclamation and recovery of copper or other valuable materials is a priority.
Facilities considering membrane filtration for copper removal need to weigh the drawbacks as well, which can include high operational costs for cleaning, maintenance, and replacement of membranes, moderate to high energy consumption, and flow rate limitations.
Can SAMCO help?
SAMCO has over 40 years’ experience custom-designing and manufacturing wastewater treatment systems, so please feel free to reach out to us with your questions. For more information or to get in touch, contact us here. You can also visit our website to set up a call with an engineer or request a quote. We can walk you through the steps for developing the proper solution and realistic cost for your wastewater treatment system to meet your copper and heavy metals removal needs.
For more articles on wastewater treatment, head on over to our blog. Some that might be of interest to you include:
- How Do You Know If An Industrial Facility Needs a Wastewater Treatment System?
- How to Choose the Best Wastewater Treatment System for Your Plant
- Seven Ways Your Facility Isn’t Meeting Effluent Regulations and How to Solve Them
- The Importance of Wastewater Treatment for Your Facility: Is it Necessary?
- 9 of the Best Industrial Wastewater Treatment Equipment Supply and Technology Companies
- What Is a Wastewater Treatability Study and How Does it Work?
- How Much Does a Water/Wastewater Treatability Study Cost for Your Plant?
- What Are the New Steam Electric Power Generating Effluent Guidelines and What Do They Mean for Your Plant?
- How Much Does a Wastewater Treatment System Cost? (Pricing, Factors, Etc.)