There are 2.4 billion people without improved sanitation and another 2.1 billion with inadequate sanitation (i.e. wastewater drains directly into surface waters), and despite improvements over the past decades, the unsafe management of fecal waste and wastewater continues to present a major risk to public health and the environment (UN, 2016). There is growing interest in low cost sanitation solutions which harness natural systems. However, it can be difficult for wastewater utility managers to understand under what conditions such nature-based solutions (NBS) might be applicable and how best to combine traditional infrastructure, for example an activated sludge treatment plant, with an NBS such as treatment wetlands. There is increasing scientific evidence that treatment systems with designs inspired by nature are highly efficient treatment technologies. The cost-effective design and implementation of ecosystems in wastewater treatment is something that exists and has the potential to be further promoted globally as both a sustainable and practical solution. This book serves as a compilation of technical references, case examples and guidance for applying nature-based solutions for treatment of domestic wastewater, and enables a wide variety of stakeholders to understand the design parameters, removal efficiencies, costs, co-benefits for both people and nature and trade-offs for consideration in their local context. Examples through case studies are from across the globe and provide practical insights into the variety of potentially applicable solutions.

This book provides an essential overview of ecotechnologies (also known as green infrastructure or nature-based solutions) which are considered to be relatively resilient to variations in stormwater and wastewater inflow. In particular, it focuses on various types of constructed wetlands, biofilters and ponds. Stormwater flows are inherently variable, due to rainfall events and fluctuations in loading. This variability has significant effects on the performance of treatment systems, but has rarely been specifically addressed in design manuals, performance assessments or modelling. The book's respective chapters cover the main contaminant categories of interest (nutrients, faecal microbes, metals and emerging contaminants) and their removal processes using ecotechnologies, addressing urban, industrial and agricultural applications. In addition, they review modelling tools with the potential to improve our understanding of flow variability and the ability to simulate and predict responses to it.