In the context of efficient and sustainable management of the elements of the urban water cycle as an aim of the Water Framework Directive (WFD), the evaluation of indicators such as the water footprint (WF) and the carbon footprint (CF) in a wastewater treatment plant (WWTP) provides a quantification of the environmental impact, both negative and positive, which implies its exploitation. In this study, in addition to WF and CF quantification, a joint evaluation of both indicators was conducted. Consumption is indicated by the blue water footprint (WF_Blue) and emissions by CF. Both are related to the operational grey water footprint (∆WF_G,mef) in two ratios, WFR and CFR. In this way, the water consumed and gases emitted are measured according to the reduction range of the pollutant load of the discharge. The results for four WWTPs show operational scenarios for better management in accordance with the WFD.

Sustainable Development Goals (SDGs) reflect the relationship among social, economic, and environmental aspects of society. Massive online open courses (MOOCs) represent an opportunity to promote lifelong learning (SDG 4), complementing university education or providing knowledge to society free and openly. The objective of this work is to analyze experiences in one MOOC about wastewater treatment applied to higher education in civil engineering (SDG 6). The proposed educational methodology and the achieved participation results are studied. The MOOC had three editions and was hosted on the Miríadax platform. Data about sociodemographic characteristics, initial motivation, and satisfaction level were collected from questionnaires. The results highlighted the importance of design decisions to obtain a high completion rate: defining a target audience, without prejudice to the course’s open character, where the prior knowledge of students is crucial. The teaching methodology is based on autonomous and progressive learning, with short and direct master classes, social support, with the motivation of students to continue their training with opening complementary topics in the forums, following up on their doubts, and their combination with social networks.

Small-scale hydropower plants (SHP), and in particular the micro-hydropower plants (MHP) and pico-hydropower plants (PHP), are considering as an alternative energy resource based on the hydroelectric potential available in urban water cycle because of the excess of pressure existing in some urban water supply systems (WSS). Nowadays, pressure-reducing valves are necessary to reduce water pressure in WSS, so the use of a pump as turbine (PAT) can be considered as a proper way for reaching both an enough water head reduction and a hydropower generation possibility (self-consumption or energy recovery). MHPs are based on existing hydraulic resources where the PAT location is necessary, especially in those points with an excess of energy, which derives in an extra cost in terms of conservation and maintenance of the infrastructure or lead to the necessary installation of dissipation devices. The locations of these points are strongly influenced by the geographical and hydrological conditions, so a Geographic Information System (GIS) is a very useful tool for implementation of SHP and MHP or PHP projects. This paper describes the assessment and comparison of the methodology followed in the SHP and MHP locations: necessary data, GIS development, hydrologic model and hydropower potential.

Energy recovery in water supply systems (WSS) is environmentally friendly, since it is a renewable energy based on exploiting the excess pressure existing in water pipes for obtaining electricity. This paper presents the methodology development for the identification of the hydropower potential in WSS and the possible installations by means of a Matlab rutine. The results showed the interactions among the design flow and maximum head have provided the possible scenarios with electric potential and the selection of possible turbines. The methodology proposed allows determining the suitability of electricity production in the urban water cycle by MHPs, in order to avoid the need for the installation of dissipation devices for this energy.