Optimal fresh water blending: A methodological approach to improve the resilience of water supply systems

Digital solutions for continued operation of WRRFs during pandemics and other interruptions

This paper includes survey results from 17 full-scale water resource recovery facilities (WRRFs) to explore their technical, operational, maintenance, and management-related challenges during COVID-19. Based on the survey results, limited monitoring and maintenance of instrumentation and sensors are among the critical factors during the pandemic which resulted in poor data quality in several WRRFs. Due to lockdown of cities and countries, most of the facilities observed interruptions of chemical supply frequency which impacted the treatment process involving chemical additions. Some plants observed influent flow reduction and illicit discharges from industrial wastewater which eventually affected the biological treatment processes. Delays in equipment maintenance also increased the operational and maintenance cost. Most of the plants reported that new set of personnel management rules during pandemic created difficulties in scheduling operator's shifts which directly hampered the plant operations. All the plant operators mentioned that automation, instrumentation, and sensor applications could help plant operations more efficiently while working remotely during pandemic. To handle emergency circumstances including pandemic, this paper also highlights resources and critical factors for emergency responses, preparedness, resiliency, and mitigation that can be adopted by WRRFs.

Janus membrane with novel directional water transport capacity for efficient atmospheric water capture

Fresh water scarcity has become a crisis affecting human survival and development. Atmospheric water capture with remarkable advantages such as energy-independence and low-cost is supposed to be a promising way to address the problem. Herein, a facile strategy is presented to design a membrane material with efficient atmospheric water capture capacity and high practical significancy. A hybrid Janus membrane with anisotropic wettability and morphology is fabricated by integrating electrospinning and in situ surface oxidation methods. Taking advantage of the anisotropic wettability and strong force provided by directional wicking to draw water drops from a hydrophobic to a hydrophilic layer, the Janus membrane exhibits novel directional water droplet transport and possesses efficient and excellent atmospheric water capture capacity. Janus membrane with larger pores in the hydrophobic layer shows higher atmospheric water capture capacity than that with smaller pores. Furthermore, the hybrid Janus membrane is successfully implemented in soil water retention in the plant cultivation process. This work provides an insight into the facile design of the Janus membrane for fresh water capture, which is important to extend its practical applications.

When the fourth water and digital revolution encountered COVID-19

The ongoing COVID-19 pandemic is, undeniably, a substantial shock to our civilization which has revealed the value of public services that relate to public health. Ensuring a safe and reliable water supply and maintaining water sanitation has become ever more critical during the pandemic. For this reason, researchers and practitioners have promptly investigated the impact associated with the spread of SARS-CoV-2 on water treatment processes, focusing specifically on water disinfection. However, the COVID-19 pandemic impacts multiple aspects of the urban water sector besides those related to the engineering processes, including sanitary, economic, and social consequences which can have significant effects in the near future. Furthermore, this outbreak appears at a time when the water sector was already experiencing a fourth revolution, transitioning toward the digitalisation of the sector, which redefines the Water-Human-Data Nexus. In this contribution, a product of collaboration between academics and practitioners from water utilities, we delve into the multiple impacts that the pandemic is currently causing and their possible consequences in the future. We show how the digitalisation of the water sector can provide useful approaches and tools to help address the impact of the pandemic. We expect this discussion to contribute not only to current challenges, but also to the conceptualization of new projects and the broader task of ameliorating climate change.

CO2 utilization: Turning greenhouse gas into fuels and valuable products

This study critically reviews the recent developments and future opportunities pertinent to the conversion of CO₂ as a potent greenhouse gas (GHG) to fuels and valuable products. CO₂ emissions have reached an alarming level of around 410 ppm and have become the primary driver of global warming and climate change leading to devastating events such as droughts, hurricanes, torrential rains, floods, tornados and wildfires across the world. These events are responsible for thousands of deaths and have adversely affected the economic development of many countries, loss of billions of dollars, across the globe. One of the promising choices to tackle this issue is carbon sequestration by pre- and post-combustion processes and oxyfuel combustion. The captured CO₂ can be converted into fuels and valuable products, including methanol, dimethyl ether (DME), and methane (CH₄). The efficient use of the sequestered CO₂ for the desalinization might be critical in overcoming water scarcity and energy issues in developing countries. Using the sequestered CO₂ to produce algae in combination with wastewater, and producing biofuels is among the promising strategies. Many methods, like direct combustion, fermentation, transesterification, pyrolysis, anaerobic digestion (AD), and gasification, can be used for the conversion of algae into biofuel. Direct air capturing (DAC) is another productive technique for absorbing CO₂ from the atmosphere and converting it into various useful energy resources like CH₄. These methods can effectively tackle the issues of climate change, water security, and energy crises. However, future research is required to make these conversion methods cost-effective and commercially applicable.

Economic Dispatch Optimization of Multi-Water Resources: A Case Study of an Island in South Korea

Ensuring stable and continuous water supplies in isolated but populated areas, such as islands, where the water supply is highly dependent on external factors, is crucial. Sudden loss of function in the water supply system can have enormous social costs. To strengthen water security and to meet multiple water demands with marginal quality, the optimized selection of locally available, diversified multi-water resources is necessary. This study considers a sustainable water supply problem of Yeongjong Island, 30 km west from Seoul, South Korea. The self-sufficiency of several locally available water resources is calculated for four different scenarios based on the volume and quality of the various water sources. Our optimization results show that using all the available local sources can address the water security issues of the island in the case of interruption in the existing supply system, which is fed from a single source of mainland Korea. This optimization framework can be useful for areas where water must be secured in the event of emergency.

The Potential of Small Dams for Conjunctive Water Management in Rural Municipalities

The drinking water supply to Vila Pouca de Aguiar municipality in North Portugal is based on high quality groundwater, namely on nearly one hundred artesian springs and fifty boreholes. The groundwater resources are plentiful on a municipal level, but evidence some deficits at the sub-municipal (village) level, especially during the dry period (July- August) that coincides with the return of many emigrants for holiday time. The deficits affect mostly the municipal capital (Vila Pouca de Aguiar) and a neighboring village (Pedras Salgadas), which populations nearly double or even triple during that period. The estimated annual deficits approach 55,000 m³/yr in those villages. If the anticipated increase in consumption/habitant and decrease in annual rainfall become reality in the next two decades, then the deficits may raise to approximately 90,000 m³/yr. To balance the water supply system, this study proposes its transition towards a conjunctive water management based on surface water stored in small dams and groundwater. A hydrologic modeling involving small forested catchments (< 15 km²) elected the Cabouço watershed as most suited basin to store stream water, because surface water availability is large (2.4 Mm³/yr) and forest cover is dominant (84.8%). Estimated nutrient loads are also compatible with drinking water supply.