Open access publications in the SLU publication database

The purpose of this review report is to contribute to the knowledge base for continued research in the field of upstream work and sustainable cycles of plant nutrients from wastewater. The report was initiated by the Swedish Water Development (SVU) in 2016 demanding that the VA cluster Mälardalen substantially should expand the research in this area. The focus of this report is on the organic micro-pollutants including pharmaceuticals residues, highly-fluorinated substances (PFAS) and microplastics.

This report has six chapters by different authors. For building real knowledge, reliable analyses results are essential. However, reliable analyses results are challenging go get for organic micro-pollutants. In chapter one, Cajsa Wahlberg gives advice and recommendations on how to best plan and carry out sample collection, storage and analysis as well as processing of results, in order to ensure that the analysis results will be as reliable as possible.

The consumption of pharmaceuticals and use of PFAS substances determine the amounts and concentrations of these substances in wastewater. In chapter two, Sahar Dalahmeh describes the use of different pharmaceuticals within the society, i.e. which types of pharmaceuticals that are most prescribed, prescription rates and distribution between hospitalised and home patients, and between patients of different age groups. The review shows that for some substances, especially contrast agents, certain dermatological pharmaceuticals and antibiotics given intravenously, the concentration in hospital wastewater is significantly higher than in mixed municipal wastewater, despite the fact that the largest amount of pharmaceuticals is used out at home within the society. Elderly people (65 years and older) use significantly more pharmaceuticals than young people. Upstream measures to minimize unnecessary consumption of pharmaceuticals and hence decrease their flow in wastewater might include: 1) drug reviews for patients with multiple drug prescriptions to eliminate unnecessary and harmful over- prescriptions, 2) when possible replace prescription of pharmaceuticals with prescription of none-drug based therapies and/or lifestyle changes such as dietary change, exercise, acupuncture,etc., 3) develop and apply policies to promote development and use of less environmentally harmful pharmaceuticals, and 4) local treatment of wastewater from point sources such as hospitals and elderly houses, where wastewater is likely to contain high concentrations of pharmaceuticals.

Due to their surface activities, thermal tolerance and persistence, PFAS substances are frequently used in many different commercial and consumer products as impregnating and surface coating agents. They have been detected in low concentrations in many clothing and household products. Since several PFAS substances are non-degradable in the environment, continuous accumulation takes place.

Upstream measures such as minimized or ceased production and use of environmentally harmful PFAS are likely to be the most effective measures, and can be implemented with different means of control. However, there is already large amounts of PFAS substances in society. The largest flow to Swedish territory is through atmospheric deposition and the largest flow reaching wastewater is probably contaminated tap water. Several drinking water sources have been shut down due to PFAS contamination. Several of the substances that replaced PFOS after it was banned in EU have unfortunately been shown to form PFOS and other PFAS substances during their degradation.

In a chapter three, Katarina Hansson et al. summarizes a compilation of existing data on concentrations of pharmaceuticals and other environmentally harmful organic substances in various wastewater pipe networks and treatment plants within the VA cluster 5 Mälardalen. To facilitate prioritization of the substances to analyse, the authors have linked the environmental substances to various lists of priority substances, such as lists in the Water Directive, the Drinking Water Directive and the Swedish Medicines Agency's list of substances which should be monitored. A database in Excel format with the existing data from the project is freely available on the website of VA cluster Mälardalen.

In chapter four, Jesper Olsson shows that about half of the amount of pharmaceuticals in the incoming wastewater to the studied treatment plants remained in the treated effluents and the fraction of incoming pharmaceuticals that ended up in the sludge was small, less than 1% according to two studies. For some pharmaceuticals, however, a large fraction, about 100%, ends up in the sludge. The pharmaceuticals that largely end up in the sludge are usually those that are bind strongly to organic matter and have a low water solubility. The uncertainty is great about what happens to these substances when the sludge is used as fertilizer and mixed into arable soil.

In chapter five, Erik Levlin presents a number of upstream technologies to reduce the flow of pharmaceuticals and other environmentally harmful organic substances to wastewater treatment plant. Among these technologies, dosing of degrading enzymes in toilet, the use of source diversion toilets and separate treatment of urine can be if interest in places where urine rich in pharmaceuticals is excreted e.g. elderly houses or hospitals. In addition, projects are ongoing with local treatment of hospital wastewater rich in pharmaceuticals with ozone, biochar or active carbon before it is disposed to the municipal sewer system. Erik Levlin also points out the importance of the pipe material for minimizing the contamination of the water with pollutants contained in the pipe material and with pollutants that can penetrate through the pipe material from surrounding masses.

In chapter six, Amanda Folkö and Cecilia Bertholds review the flow of microplastics in wastewater and their effects in the environment. They discuss various sources of microplastics for mixed municipal wastewater, sludge and storm water. They emphasizethe need for development of standardized methods for sampling and analysis of microplasticsand the need for increased knowledge on the contributions from differentsources and how these contributions can be reduced. They suggested to first focus on the flushing down non-toilet solid waste, the laundry of textiles and the storm water (which contains large amounts of particles from tires, roadways and artificial turf).