Microplastics are entering our soil via the sludge produced from wastewater, and their potential fate and impacts on soils and crops are the object of a study part-funded by a $180,000 Advance Queensland Industry Research Fellowship.
Dr Shima Ziajahromi, who is running the three-year study, is among 35 fellows in the latest round of Queensland Government funding of scientists who are carrying out original research that will benefit the state while partnering with industry.
Based at the Australian Rivers Institute at Griffith University on Queensland’s Gold Coast, Dr Ziajahromi is working closely on the microplastics project with partners that include Queensland Urban Utilities — the water treatment provider for much of south-east Queensland — as well as Eurofins Laboratory Environmental testing and other Australian wastewater utilities (Sydney Water and South Australia Water).
Wastewater treatment concentrates trillions of particles of microplastic — plastics measuring less than 5mm, such as polyester fibres — in sludge or biosolids that may then be used on cropping land.
Biosolids are made from treated and dewatered sewage.
They are used to boost soil productivity and reduce the amount of waste going to landfill.
In 2017, Australia produced 327,000 tonnes of dry biosolids in wastewater treatment plants, with 75 percent of that used in agriculture.
But where do the microplastics in the sludge then end up? Are they toxic to soil biota? What are their impacts on soils, crops and human health?
Dr Ziajahromi is working to answer those concerns. Her study investigating the fate and impacts of microplastics on soils and crops will help guide the management of cropping land, and decision-making by industry and governments when making ongoing updates to wastewater guidelines (a set of government guidelines which set out how waste should be managed).
Until recent times concerns about plastics in water were focused on the effects of pollution on marine life, but recently the focus has shifted to microplastics affecting wastewater, freshwater, land and human health.
Microbeads of plastic in body-care products and cosmetics are no longer the prime concern in wastewater pollution, as the beads are now banned in many countries. The bulk of microplastic in wastewater is now synthetic fibres (such as polyester and nylon) shed from clothing in the washing machine — that’s why underwear gets a bit thinner and less stretchy with each wash — but this seemingly innocuous addition to our water is now a widespread pollutant and a growing concern.
Dr Ziajahromi’s project is filling in gaps in knowledge for monitoring of microplastics, and will have international consequences. We asked her for more details about the study:
What fields of study led you to this project?
During my Masters in Environmental Pollution (in Tehran, Iran) I studied wastewater and sludge treatment processes and disposal methods. After completing my Masters, I worked as a research assistant studying environmental and human health risk assessment of contaminated soils and reviewed the level of contaminants in wastewater treatment plants (WWTPs).
I pursued my studies by doing a PhD on microplastics in Australian WWTPs and their fate and biological effects in aquatic systems, under supervision of Prof Fred Leusch and Dr Peta Neale at Griffith University. During my PhD I worked closely with Sydney Water to measure microplastics in wastewater effluent from three major WWTPs in Sydney.
I have also designed a new validated sampling device for on-site sampling of microplastics from wastewater, and established a laboratory processing methodology for accurate analysis of microplastics in wastewater, which has been identified as best practice in the latest WHO report on microplastics in drinking water.
After completing my PhD I established close collaborations with other Australian Water Utilities (Water Corporation and Queensland Urban Utilities) and successfully completed several industry-funded research projects on microplastics in wastewater influent, effluent and sludge (biosolid). The outcomes of these projects have substantially increased my knowledge of the prevalence of microplastics in biosolids from Australian WWTPs and provided the main impetus for this project.
How will the Advance Queensland fellowship aid your project?
The Advance Queensland fellowship will allow me to really integrate my work into practical outcomes for our industry collaborators, but also develop a much broader understanding of industry needs in this field.
It will also allow us to develop a better understanding of the presence of microplastics in sewage and biosolids from Australian WWTPs and to ultimately produce an evidence-based assessment of the risks associated with microplastics in biosolids for agricultural soils and crops.
Which microplastics are the biggest concern in wastewater, and why?
Wastewater treatment plants are a known pathway of microplastics to both aquatic and terrestrial environment, particularly for synthetic fibres from clothing (such as polyester, acrylic and nylon).
Similar to other studies worldwide, my research on WWTPs in Australia has shown that the majority of particles in both wastewater effluent and sludge are synthetic fibres (mostly polyester). Microplastic fibres from clothing are of great concern, not only due to their prevalence in wastewater, but also their toxic effects to aquatic organisms. For example, my recent study showed that microplastic fibres caused harm to a freshwater water flea Ceriodaphnia dubia.
What are other studies revealing about the presence of microplastics and their impacts on soils, crops and health?
Scientists recently reported the accumulation of microplastics from sewage sludge in agricultural soils in Chile, with substantial concentrations of up to 10,000 particles per kilogram.
Other studies have also shown negative effects of microplastics, including fibres from clothing impacting on soil physical structure and microbial activity as well as growth of plants, for example wheat. However, we have little knowledge about the fate of microplastics in soil-crop systems in biosolid-fertilised soils and their potential toxic effect to soil biota — the microbes in soil essential to soil health.
Is there evidence of microplastics harming animals?
Yes, microplastics have widely been shown to be harmful to a wide range of aquatic species from big animals such as fish and turtles to tiny zooplankton as well as terrestrial organisms such as earthworms.
The toxic effects are mainly related to ingestion, entanglement and release of bound pollutants. It has been reported that the ingestion of microplastics can negatively affect the feeding, growth, reproduction and survival of exposed organisms.
How will you conduct the study with partners such as Queensland Urban Utilities?
Queensland Urban Utilities (QUU) is playing a crucial role in this project, and will ultimately ensure that the findings are translated into beneﬁcial outcomes for Queensland.
Fifty percent of my time will be spent working with QUU at wastewater treatment plants, and I will work closely with QUU staff in collection and analysis of microplastics in sewage and biosolids.
QUU will provide access to and support for sampling of sludge and biosolids at wastewater treatment plants, as well as laboratory access. The QUU staﬀ including planners, environmental oﬃcers, and process engineers will transfer their scientiﬁc skills and experience about treatment and management of sludge and biosolids to me and help to successfully carry out the project.
Part of the project down the track will involve exposing plants and earthworms to soil containing different levels of microplastics, and monitoring any uptake.
How will your study aid environmental and agricultural management here and overseas?
The project will fill significant international gaps in knowledge and clarify whether microplastics are taken up by crops that are grown on soils with biosolids added, and in what amounts.
While Queensland is a major producer and user of biosolids, the Queensland Government is committed to protecting cropping land, for example against contamination, as outlined in the Queensland Strategic Cropping Policy.
Microplastics have been shown to impair plant growth. I am aiming to give policy makers information to establish policy and strategies to manage microplastics for safe, sustainable management of cropping land. This is also important to water utilities.
More about the fellowships
An important consideration in awarding the Advanced Queensland Industry Research Fellowships is that the researchers must partner with industry.
This is to ensure the research generated has real-life application, from developing therapeutics to benefit Queensland patients, to developing new technologies and innovations that have the potential to create jobs and bring investment to Queensland. The partnerships also assist research to move out of the lab, through commercialisation and into the market.
The Industry Research Fellowships are part of the $755 million whole-of-government Advance Queensland initiative to foster innovation and build a more diversified Queensland economy.
The 2019 Advance Queensland Research Fellowship recipients are listed at Microplastics are entering our soil via the sludge produced from wastewater, and their potential fate and impacts on soils and crops are the object of a study part-funded by a $180,000 Advance Queensland Industry Research Fellowship.