Microplastics in Water and Wastewater

Hrissi Karapanagioti, Ioannis K. Kalavrouziotis

• Publisher: IWA Publishing
• Year: 2019
• eBook ISBN: 9781789060041
• Topic: Biological Sciences
• Subtopic: Applied Sciences
• Index: Biological Sciences

This book covers the topic of microplastics in water and wastewater. The chapters start with introductory issues related to the growing interest in the scientific community on microplastics and the human water cycle and point out where the microplastics could interact with water. The subsequent chapters examine evidence of the microplastic presence in freshwater, such as in both rivers and lakes, in freshwater biota, and hazardous chemicals associated with microplastics in such systems. Another set of chapters discuss the presence of microplastics in wastewater: their sources; their transfer through a wastewater treatment plant; the concentration of microplastics in effluents throughout the world; the plastic biomedia used in wastewater treatment plants and the effect on the surrounding environment of effluent wastewater pipes. These chapters also discuss the sampling methods, the sample treatment and analysis techniques used so far for microplastics in wastewater. Additionally, the presence of microplastics in sewage sludge and in soils irrigated with wastewater or fertilized with sludge are discussed. The possible impact of plastics and their additives on plants, microalgae, and humans are reviewed and presented in a critical way. Finally, a chapter summarizes all the relevant regulations and initiatives that point to the necessity of a global directive for the protection of the environment from plastic and microplastic pollution. The topic of microplastics in freshwater systems and in wastewater has scarcely been studied and requires more attention. Microplastics in Water and Wastewater aims to bring these initial findings to the attention of a broader audience and especially to operators and managers of freshwater and wastewater systems. It will also be helpful to people already aware of the marine debris problem to understand the sources of microplastics in the oceans, from freshwater systems and wastewater treatment plants.

© IWA Publishing 2019. Hrissi K. Karapanagioti and Ioannis K. Kalavrouziotis Microplastics in Water and Wastewater DOI: 10.2166/9781789060034_0001

Chapter 1

Plastics and microplastics in the human water cycle

K. Katsanou¹, H. K. Karapanagioti² and I. K. Kalavrouziotis³

¹University of Patras, Department of Geology, Patras, Greece

²University of Patras, Department of Chemistry, Patras, Greece

³Hellenic Open University, School of Science and Technology, Patras, Greece

Keywords: Drinking water, Fibers, Groundwater, Microbeads, Rivers, Wastewater, Water treatment

1.1 INTRODUCTION

The world is continually faced by the increased complexities of water pollution and its effects. For all water systems, plastics and microplastics, along with nanoplastics, are pollutants of emerging concern (Hernandez et al., 2017). In the past decades, there has been a boom in the use of plastic mainly due to its properties i.e., its durability and multipurpose utility, and it is likely that the amount of plastic will continue to steadily accumulate (Horton, 2017). The constant increase in synthetic plastic production and poor management in plastic waste have led to a tremendous increase in dumping into water bodies across the world (Raza & Khan, 2018).

The sources of microplastics are both land- and ocean-based (Hammer et al., 2012). Ocean-based sources represent only 20% of the total plastic debris in the marine environment (Andrady, 2011), whilst microplastics from land-based sources contribute the remaining 80% (Jambeck et al., 2015). Terrestrial sources come from many different origins but mainly from personal care products, air-blasting processes, improperly disposed plastics and leachates from landfill (Cole et al., 2011). Once terrestrial microplastics are released into water ecosystems, most of them are transported to oceans by rivers, while the rest remain in the freshwater environment (Browne et al., 2010; Li et al., 2018). Although microplastics are easily transported from the source once released into the environment, it has been found that their concentrations in sediments correlate with urbanization and human activity (Horton, 2017).

Up until recently, the plastic-derived pollution in the marine environment has been the focus and thus this topic is well studied. Although large plastics, to a certain extent, can be manually removed from the environment, most plastic pollution is mainly attributed to microplastics which are not easily removed. There is also the issue of “biodegradable” and “oxodegradable” plastics that are manufactured to contain chemical bonds that can be easily degraded (esters, ethers and amides). However, these polymers still have a non-degradable hydrocarbon base and the resultant pieces left are non-degradable fragments, i.e. microplastics (Shah et al., 2008). The only kinds of plastics that are totally degradable under natural conditions are bioplastics or compostable plastics (Horton, 2017).

While the vast majority of plastic sources are land-based, much less research has been focused on the investigation of their presence in freshwater ecosystems. Today, research has shifted towards inland waters. Modern studies are focused on the sources of microplastics, their pathways to marine environments, and the potential for microplastics to affect freshwater ecosystems and human health (Eerkes-Medrano et al., 2015).

This chapter is an attempt to characterize the presence, levels and potential implications of microplastics in freshwaters and wastewater, as well as identify the research gaps and future priorities. Given waste management deficiencies, microplastic pollution is an unknown component of possible impact and injury to our freshwaters and freshwater-dependent biological processes.

1.2 BASIC CHARACTERISTICS OF MICROPLASTICS

Plastics are complex polymer items produced with the addition of dyes and plasticizers, etc., which give them their specific properties i.e. flexibility, durability and heat resistance. The most commonly-used polymers – and most abundant in the environment – are polyethylene (PE), polypropylene, polyester, polyvinyl chloride (PVC) and nylon.

Microplastics are particles with all their dimensions being less than 5 mm (GESAMP, 2015). They are categorized into primary and secondary microplastics: primary microplastics are originally produced to be less than 5 mm in size, ranging down to 100 nm, while secondary microplastics result from the breakdown of larger items. They include particles of a wide range of types, shapes, color and sizes. Microplastic particles can be spherical beads, fragments, fibers or films and can be made of a variety of polymers. Particles less than 100 nm are classified as nanoplastics (Rios Mendoza et al., 2018).

Primary microplastics are those that are specifically manufactured to be of a small size for a specific application. They include pre-production pellets that are used in the plastic industry to manufacture larger plastic items and microbeads i.e. tiny spheres or granules added to products such as toothpastes and face scrubs for their exfoliating properties, and cosmetics for their light-reflecting properties (Browne, 2015; Cole et al., 2011). Secondary microplastics are derived by the breakdown of larger plastic items and are therefore a consequence of the degradation of manufactured products due to processes such as photo-degradation, and physical, chemical and biological interactions (Galgani et al., 2013; Thompson et al., 2009). Some examples are plastic fragments from litter degradation, tire debris, microfibers from textiles and degradation products from road-marking paints, fishing nets, household items and other discarded plastic debris (Eerkes-Medrano et al., 2015). Nanoplastics – manufactured either for research and medical purposes or formed by the degradation of microplastics – also pose an environmental threat (Koelmans et al., 2016).

As already mentioned, when plastic particles break down, they gain new physical and chemical properties, increasing their potential toxic effect on organisms. Microplastics may have a toxic effect on human health (particle, chemical and microbial hazards) or may be associated with chemicals either due to the addition of plasticizer chemicals during their manufacture or by adsorption of chemicals from the environment (Takada & Karapanagioti, 2019).

1.3 THE HUMAN WATER CYCLE

There is a daily water cycle that is associated with human water consumption in urban and suburban areas which includes: water collection from a water body, treatment, storage, distribution, house use which turns it into wastewater, and then wastewater collection, transportation, treatment and discharge into the same or another water body.

Drinking water sources include surface water (e.g. rivers, lakes or dams), groundwater (springs or wells) and seawater. It is collected and sent to a water treatment plant. According to the water source, the treatment plant includes various water treatment processes. Examples of the most common treatment processes for surface water include coagulation, flocculation, sedimentation, sand and coal filtration, aeration and disinfection. For groundwater they include hardness removal, aeration, metal chemical precipitation and disinfection, whilst for seawater they include coagulation, sand and coal filtration, ultrafiltration, reverse osmosis, pH and taste adjustment, and disinfection. After treatment, water is kept in big tanks and it is usually distributed to individual houses through water pipes using gravity. In the past, water pipes were made of clay, cement, or PVC; today, most water pipes are made of blue high-density PE (West, 2014).

Water uses in homes include drinking, washing dishes, washing clothes, personal hygiene, house cleaning, cooking and toilet flushing (see Figure 1.1). These activities turn drinking water into wastewater, including the addition of dissolved and particulate organic matter, suspended solids, microbes, dissolved salts that increase conductivity, nutrients, surfactants and micropollutants such as caffeine, antibiotics, cosmetics, pesticides and disinfectants, etc. Wastewater is collected from each house and, by gravity, it flows towards the nearby wastewater treatment plant (WWTP) using water pipes (West, 2014).

Figure 1.1 Potential plastics and microplastics that can be released from a single house.

Municipal WWTPs are expected to lower...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• About the Editors
• Preface
• Foreword (Hideshige Takada)
• Foreword (Peter Kershaw)
• Chapter 1: Plastics and microplastics in the human water cycle
• Chapter 2: Association of hazardous compounds with microplastics in freshwater ecosystems
• Chapter 3: Microplastics in wastewater treatment plants: A literature review of sampling methods and results
• Chapter 4: Microplastics: Transport and removal at wastewater treatment plants
• Chapter 5: Method development for microplastic analysis in wastewater
• Chapter 6: Microplastics in sewage sludge: Captured but released?
• Chapter 7: Modeling microplastics transport and fate in the marine environment around a wastewater effluent discharge pipe
• Chapter 8: Evaluating wastewater effluent as a source of microplastics in environmental samples
• Chapter 9: Pollution of beaches and watercourses by plastic biomedia
• Chapter 10: Effects of microplastics on freshwater and marine microalgae
• Chapter 11: Possible effects on plants due to microplastics in soils from wastewater effluent reuse or sewage sludge application
• Chapter 12: Possible effects of microplastics on human health
• Chapter 13: The need for a global plastic strategy
• Index