Wastewater-borne environmental pollution from textile microfibres requires urgent action

Michael Bambridge, CST managing director, holding a fine screening that can mitigate the problem with screen capabilities down to 200microns

Microfibres are becoming a source of pollution as they often enter marine systems and waterways and are subsequently consumed by aquatic and other wildlife.

The textile manufacturing supply chain consists of manufacturing facilities in different countries. Although the products and processes may vary from one facility to the next, they all have the ability to shed fibres from textiles into the wastewater discharged from each facility. Shedding also occurs after manufacture with approximately 35% of microplastics released to oceans globally, originating from washing synthetic textiles.

Clothing fibres are the most abundant form of polymer currently found in the ecosystem and these have increased by over 450% in 60 years. These contaminants have been detected in seafood, tap and bottled water, fruits, vegetables, and even in table salt.

“Microplastics found in waste treatment plants are microfibres predominantly composed of manufactured synthetic fibres. Primary microfibres are produced during the manufacturing and processing of garments and allied products,” said Australasian and Asia-Pacific wastewater authority Michael Bambridge, managing director, CST Wastewater Solutions.

Such screening (top) complements coarser screening (bottom) to prevent pollution entering wastewater systems and damaging them

The Microfibre Consortium (TMC) is a UK-based organisation working with the textile industry to reduce the amount of microfibres released into the environment. It has members across the world and translates academic research into actionable solutions for textile production.

TMC’s preliminary manufacturing guidelines identify strategies to remove microfibres from textile wastewater and capture them, for example, in the sludge of wastewater treatment systems. The report analyses screens and strainers, clarification, membrane bioreactors and ultrafiltration to remove microfibres.

CST has already developed drum screen technology that can help minimise environmental damage with fine screening capabilities down to 200microns. “Our horizontal drum screens will screen out every microplastic, which is a step towards addressing this environmental threat,” said Bambridge, who has more than 40 yeas wastewater treatment experience in Australasia and Asia.

The TMC report also advocates for the proper handling of sludge from wastewater treatment plants. Once the microfibres are captured in the sludge, the sludge must be disposed of in a manner that does not release those microfibres back into the environment. TMC recommends the sludge handling guidelines laid out by multi-stakeholder organisation Zero Discharge of Hazardous Chemicals (ZDHC). Headquartered in Amsterdam, ZDHC works with the fashion industry to eliminate harmful chemicals from its global supply chain by promoting more sustainable manufacturing to protect workers, consumers, and ecosystems.

When dealing with textile related waste, the closer a mitigation step is to the point of generation, the larger the size of microfibres that will be present in the wastewater. However not all textile facilities have on-site effluent treatment, and it is common for effluent to be discharged to municipal plants for treatment alongside the discharges of multiple facilities.

Almost all manufacturing facilities are required to meet regulatory discharge standards for total suspended solids and failure to adhere to these will result in discharges of large quantities of textile fibres. Facilities will need to ensure existing processes for removal of solids are optimised and invested in more advanced, zero discharge filtration technologies.

TMC expects that wastewater treatment facilities will adopt mitigation technologies to stop the discharge of microfibres and divert microfibres from the discharge by using a dead-end ultrafiltration unit. Unlike a crossflow ultrafilter which flows a reject stream out of the filter, the upstream surface of a dead-end ultrafilter is cleared of microfibres and particles with a pulsed backwash where the pulsed backwash must be collected and treated.

Washing synthetic textiles in industrial laundries and households also create primary microplastics through abrasion and shedding of fibres. Fibres are then discharged in sewage water and potentially end up in the ocean.

Significant amounts of these textile fibres have been observed in many sampling studies both in open water and marine sediments. These fibres are typically made of polyester, polyethylene, acrylic or elastane.

While some manufacturers are considering biodegradable textiles as a solution to dealing with microfibres, TMC do not endorse biodegradability as a ‘solution’ to fibre fragmentation from textiles, although they would be open to getting to a position of support once adequate testing and toxicological work has been done.

TMC’s microfibre data portal now houses over 5000 data points collated from 391 tested fabrics representing 115 manufacturers and 16 countries. The current dataset constitutes one of the largest databases on fibre fragmentation globally.