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Improving access to safe drinking water can result in multi-dimensional impacts on people's livelihood. This has been aptly reflected in the Millennium Development Goals (MDG) as one of the major objectives. Despite the availability of diverse and complex set of technologies for water purification, pragmatic and cost-effective use of the same is impeding the use of available sources of water. Hence, in country like India simple low-energy technologies such as solar still are likely to succeed. Solar stills would suffice the basic minimum drinking water requirements of man. Solar stills use sunlight, to kill or inactivate many, if not all, of the pathogens found in water. This paper provides an integrated assessment of the suitability of domestic solar still as a viable safe water technology for India. Also an attempt has been made to critically assess the operational feasibility and costs incurred for using this technology in rural India.

Abstract Italy reformed its water and sanitation services in 1994. The strategy aimed at transforming public entities, financed by the central budget, into self-sufficient professional companies regulated at arms' length. Nearly 20 years after, the reform has failed to deliver (despite some partial success). Italians have been divided in two parties: those blaming public sector inefficiencies and calling for competitive tendering; and those refusing to privatize water and willing to go back to the fiscal budget. In this article, we suggest that both parties are wrong. Underperformance is not related to the ownership structure of water companies, but rather to poor regulatory design and lack of understanding of the regulatory requirements that are implicit in the management model chosen, namely the concession contract.

Abstract The main purpose of salinity gradient solar ponds (SGSPs) is to store the maximum possible solar thermal energy. A well-established salinity and temperature gradients are the main points to achieved optimum storage efficiency. In this work, a high-fidelity model is developed using computational fluid dynamics (CFD) to simulate the SGSP behavior under hot climate regions. The model is able to simulate the double convective effect by solving Navier-Stokes and energy equations, simultaneously. Brines with different salinities (i.e. 10%,15, and 25%) are used to investigate their role on the developed salinity/temperature gradients. Simulation results show the successful establishment of the three zones (i.e. upper convective, non-convective, and lower convective) with relatively stable salinity and temperature gradients. However, injecting the lower convective zone (or storage zone) with 10% saline brine results in preserving the highest storage temperature of around 79.2°C after flow time of six hours.

ABSTRACTAn overview is given of an International Atomic Energy Agency Coordinated Research Project (CRP) on the treatment of irradiated graphite (i-graphite) to meet acceptance criteria for waste disposal. Graphite is a unique radioactive waste stream, with some quarter-million metric tons worldwide eventually needing to be disposed of. The CRP has involved 24 organizations from 10 Member States. Innovative and conventional methods for i-graphite characterization, retrieval, treatment and conditioning technologies have been explored in the course of this work, and offer a range of options for competent authorities in individual Member States to deploy according to local requirements and regulatory conditions.

The enhanced oil recovery technique of low-salinity (LS) water flooding is a topic of substantial interest in the petroleum industry. Studies have shown that LS brine injection can increase oil production relative to conventional high-salinity (HS) brine injection, but contradictory results have also been reported and an understanding of the underlying mechanisms remains elusive. We have recently developed a steady-state pore network model to simulate oil recovery by LS brine injection in uniformly wetted pore structures (Watson et al., Transp. Porous Med. 118, 201-223, 2017). We extend this approach here to investigate the low-salinity effect (LSE) in heterogeneously wetted media. We couple a model of capillary force-driven fluid displacement to a novel tracer algorithm and track the salinity front in the pore network as oil and HS brine are displaced by injected LS brine. The wettability of the pore structure is modified in regions where water salinity falls below a critical threshold, and simulations show that this can have significant consequences for oil recovery. For networks that contain spanning clusters of both water-wet and oil-wet (OW) pores prior to flooding, our results demonstrate that the OW pores contain the only viable source of incremental oil recovery by LS brine injection. Moreover, we show that a LS-induced increase in microscopic sweep efficiency in the OW pore fraction is a necessary, but not sufficient, condition to guarantee additional oil production. Simulations suggest that the fraction of OW pores in the network, the average network connectivity and the initial HS brine saturation are key factors that can determine the extent of any improvement in oil recovery in heterogeneously wetted networks following LS brine injection. This study highlights that the mechanisms of the LSE can be markedly different in uniformly wetted and non-uniformly wetted porous media.

The global energy demand is growing substantially. Clean and secure energy supply is a must for our civilization's sustainable development. Solar and wind energy is growing fast and can contribute significantly to meet the goals set by many countries to reduce greenhouse gas emissions. A deep and wide investigation of the environmental impact of solar and wind energy is important before any solar or wind plants' construction is made. In this study, the literature is reviewed to summarize the environmental impact of solar and wind energy systems in terms of the following factors; land use, water consumption, impact on biodiversity, visual and noise effects, health issues, and impact on micro climate. Although the benefits of solar and wind energy are obvious and great, negative perception of these technologies can inhibit their wide penetration in some regions. This review paper includes a critical and an inclusive analysis of solar and wind energy’s environmental impact and may serve as an important tool to conduct a proper environmental impact assessment. This critical analysis may serve also as a tool for developers, policy, and decision-when planning future solar and wind farms.

In hot climatic conditions, the temperature inside a greenhouse is much higher than the ambient temperature and requires significant cooling to maintain the temperature in the optimal range. This study proposes a novel concept for a self‐sustaining greenhouse, which integrates evacuated tube collectors, a multistage flash desalination system, vapor absorption cooling system, and photovoltaic thermal (PV/T) system to produce freshwater, cooling, and electricity. The PV/T system uses spectrum selective nanofluid that is circulated over the roof of the greenhouse and absorbs solar radiation having wavelengths greater than 1400 nm to reduce cooling load inside the greenhouse and optimize the spectrum use. The performance of the proposed system is evaluated using energy and exergy analysis. The energy efficiencies of the evacuated tube collector, desalination unit, and PV/T system are obtained as 45.85%, 46.16%, and 51.25%, respectively. The absorption cooling system achieves an energetic coefficient of performance of 0.83. The overall energy and exergy efficiencies of the proposed system are found to be 30% and 5.88%, respectively. The application of spectrum selective nanofluid on the roof of the greenhouse yields about 26% reduction in the cooling load of the greenhouse.

Abstract This paper is related to the previous work (Manenti et al., “Parametric Simulation and Economic Assessment of Heat Integrated Geothermal Desalination Plant”, Desalination, 317, 193–205, 2013) and extends the steady-state simulation and process layout optimization by investigating the procedure to start up multi-effect distillation (MED) desalination plants. The operations involved in the startup procedure, such as seawater supply, energy supply and vacuum generation along the process are considered together with the status of controls to prevent any possible overlapping of these relevant aspects. Segregation of the operations is demonstrated to be essential to prevent any redundancy in the oscillatory behavior of process units that can easily lead to dangerous instabilities of the plant. Moreover, whenever geothermal sources are used for sustainable production of desalinated water, it is fundamental to account for some peculiarities such as certain limitations in controllability and operability of the geothermal source. General guidelines to start up desalination processes are provided; special attention is given to geothermal-supplied plants.