Maximizing Benefits to Nature and Society in Techno-Ecological Innovation for Water

Between flood and drought: How cities are facing water surplus and scarcity

Droughts and floods are weather-related hazards affecting cities in all climate zones and causing human deaths and material losses on all inhabited continents. The aim of this article is to review, analyse and discuss in detail the problems faced by urban ecosystems due to water surplus and scarcity, as well as the need of adaptation to climate change taking into account the legislation, current challenges and knowledge gaps. The literature review indicated that urban floods are much more recognised than urban droughts. Amongst floods, flash floods are currently the most challenging, which by their nature are difficult to monitor. Research and adaptation measures related to water-released hazards use cutting-edge technologies for risk assessment, decision support systems, or early warning systems, among others, but in all areas knowledge gaps for urban droughts are evident. Increasing urban retention and introducing Low Impact Development and Nature-based Solutions is a remedy for both droughts and floods in cities. There is the need to integrate flood and drought disaster risk reduction strategies and creating a holistic approach.

Exploring the Potential in LID Technologies for Remediating Heavy Metals in Carwash Wastewater

Carwash wastewater (CWW) can be a significant source of environmental pollution due to the diversity and high concentrations of contaminants it contains. This toxic wastewater can contain several different heavy metals that if left untreated, can enter surface and sub-surface waters. Innovative, nature-based solutions such as low-impact development (LID) technologies may provide an eco-friendly CWW treatment process that is both effective and affordable. This research reviews the available literature to provide definitive values of flowrate and contaminant concentrations found in CWW around the globe. Dividing LID technologies into two groups, vegetated and unvegetated systems, the authors explored the literature for the general performance of these technologies to sustainably treat heavy metals in CWW. Depending on the car wash’s size and intended purpose, whether cleaning vehicles in agriculture-based rural communities, mining, or in high-density urban environments, volumetric flowrates requiring treatment found in six different countries ranged from 35–400 L/car. CWW also contains a wide range of contaminants at various levels, including COD, turbidity, TDS and TSS, surfactants, oils and greases, and heavy metals such as lead, cadmium, zinc, copper, chromium, and iron. Heavy metal removal by both vegetated and unvegetated LIDs shows mixed results in the literature, but given the different processes involved in both types, the authors propose a system that combines these types in order to provide all the necessary removal processes, including mechanical filtration, adsorption, sedimentation, chemical and biological treatment processes.