What are the best ways to safely dispose of nanoparticles in the environment?

1 Why is nanowaste a problem?

Nanowaste is the term used to describe any waste that contains nanoparticles or nanomaterials, such as leftover products, packaging, equipment, or by-products. Nanowaste can be generated from various sources, such as industrial processes, consumer products, medical devices, or research laboratories. Nanowaste can be problematic because nanoparticles can have different chemical, physical, and biological effects than their larger counterparts. For example, some nanoparticles can be more reactive, toxic, or mobile in the environment, and can interact with other substances or organisms in unexpected ways. Therefore, nanowaste needs to be managed carefully to prevent or minimize any negative impacts on the environment and human health.

2 How to classify nanowaste?

Before disposing of nanowaste, it is important to classify it according to its characteristics and potential hazards. There is no universal system for classifying nanowaste, but some general criteria can be used, such as the size, shape, composition, surface properties, solubility, and biodegradability of the nanoparticles. Based on these criteria, nanowaste can be categorized into different groups, such as inert, hazardous, or biohazardous. For example, nanowaste that contains metal or metal oxide nanoparticles, such as silver, titanium dioxide, or zinc oxide, can be considered hazardous, as they can be toxic to aquatic life or cause oxidative stress in cells. Nanowaste that contains biological or organic nanoparticles, such as liposomes, proteins, or DNA, can be considered biohazardous, as they can pose a risk of infection or contamination. Nanowaste that contains carbon-based nanoparticles, such as carbon nanotubes, graphene, or fullerenes, can be considered inert, as they are relatively stable and non-reactive in the environment.

3 How to treat nanowaste?

Once nanowaste is classified, it can be treated using different methods to reduce its volume, toxicity, or mobility. Thermal treatment involves heating the nanowaste to high temperatures to destroy or decompose the nanoparticles, such as through incineration, although this method can generate air pollutants or greenhouse gases and may not be effective for some nanoparticles that are resistant to heat. Chemical treatment uses chemical agents to dissolve, neutralize, or precipitate the nanoparticles, although this method can also generate secondary waste or hazardous by-products and may not be suitable for some nanoparticles that are insoluble or inert. Lastly, biological treatment uses microorganisms, plants, or enzymes to degrade, transform, or accumulate the nanoparticles; however, this method can also pose a risk of bioaccumulation or biotransformation and may not be effective for some nanoparticles that are stable or toxic to the biological agents.

4 How to dispose of nanowaste?

After treating nanowaste, it can be disposed of using different methods depending on its final form and residual risk. Landfill is a common method, where nanowaste is buried in an isolated site; however, this could lead to leaching, erosion, or migration of the nanoparticles. Recycling is another option, where nanowaste components are recovered and reused; however, this could cause separation or purification issues. Release into the environment is also an option, although this could cause exposure, accumulation, or interaction of the nanoparticles with other environmental factors or organisms. All of these methods require careful assessment and monitoring to ensure safety.

5 How to prevent nanowaste?

The best way to dispose of nanowaste is to prevent it from being generated in the first place. Strategies for achieving this include designing nanomaterials and products that are safer, more efficient, or more durable, and thus reduce the need for cleaning, repairing, or assembling. Additionally, reducing the amount of nanomaterials and products used, consumed, or discarded can help reduce waste production. Reusing nanomaterials and products that are still functional or useful for other purposes can also reduce waste generation. For example, nanomaterials and products that have multiple or adaptable applications can be reused for different purposes.

6 How to learn more?

If you are looking for resources to gain knowledge on how to properly dispose of nanoparticles in the environment, you can refer to the Nanosafety Cluster, the NanoWaste Project, and the NanoSafety Database. The Nanosafety Cluster is a network of European research projects and initiatives that offer information, guidelines, and recommendations on nanosafety and nanorisk governance. The NanoWaste Project is an EU-funded project that works to develop a framework for the identification, monitoring, and management of nanowaste. Lastly, the NanoSafety Database is maintained by NIOSH and provides data and information on the safety and health effects of nanomaterials.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?