Sebastian Ovidio Perez Baez

This study presents a comprehensive approach that combines the kinetic characterization of the activated sludge process with the application of microalgae culture systems to reduce direct and indirect greenhouse gas emissions in wastewater treatment plants (WWTPs). Based on experimental data obtained in laboratory reactors and real operating parameters extracted from a reference plant, the emission routes associated with secondary treatment were analyzed and the mitigation potential by microalgae in the tertiary stage was modeled. Comparative tables, CO₂ capture scenarios and integrated operation diagrams were developed. The results show that the integration of both technologies can significantly reduce BOD residual load, improve energy yield and capture up to 135 kgCO₂/day depending on the remaining substrate. The reduction in aeration demand reached 25%, and BOD removal increased from a range of 72 to 85% (conventional system) to 87–94% (hybrid system). The work supports the engineering plausibility and relevance of a hybrid sludge–microalgae system as an exploratory strategy for WWTP sustainability. Given the experimental design available in the historical laboratory record, the tertiary-stage outcomes are interpreted here as indicative algal–bacterial scenario responses. Because replicate runs under identical conditions and a parallel non-inoculated control reactor were not available, the manuscript does not present these results as definitive tertiary-performance validation. Complementary plant-scale records from the Canary Islands were considered solely as an external plausibility benchmark for the polishing-stage assumptions and were not interpreted as replicate evidence or as a substitute for a non-inoculated control reactor. The specific objective of this work is to derive activated sludge biokinetic parameters from laboratory assays and to use the experimentally constrained residual load framework to assess, at the scenario level, the mitigation potential of a tertiary algal–bacterial stage under Canary Islands conditions.

The Canary Archipelago, in general, and the island of Gran Canaria, in particular, operate with an independent energy system (SIE), which depends largely on local power generation. Today, its energy supply comes mainly from two sources: (a) Renewable energy, accounting for 19.90%, and (b) Fossil fuel combustion in thermal power plants, contributing the remaining 80.10%. The existing energy infrastructure faces challenges due to aging technology, requiring either modernization or replacement to prevent a potential energy crisis and ensure a sustainable production cycle. A transformative step to improve the system is the completion and commissioning in 2030 of the Chira-Soria pumped hydroelectric energy storage (PHES) plant. This installation will allow water to be transported to high altitudes by pumping, to be deposited until the right time and to be turbined to generate electricity in optimal conditions. To fully understand the impact of this integration, detailed analyses of annual energy production patterns, equipment performance, and real-time demand data (collected at five-minute intervals) will be conducted. These assessments will provide insights into how the Chira-Soria PHES can be seamlessly integrated into Gran Canaria’s energy network. Furthermore, they will help identify both the strengths and limitations of this storage solution, paving the way for a more resilient and efficient energy future for the island.

The sugar industry must be managed in a manner that encourages innovation with regard to the waste generated throughout the process. The organic load of sugar mill waste is high, as is its potential to pollute water bodies at various stages of the production process, including cooling bearings, mills, sugar cane washing, bagasse waste and cleaning products. It is therefore necessary to identify treatment mechanisms that not only reduce this waste but also return purer water to the environment, combining the reuse of water in various applications. The objective of this study was to analyze the results of the physical and chemical properties of the effluents generated and the principal treatment technologies employed for the remediation of industrial wastewater from sugar factories. The wastewater from Mozambique’s sugar mills has high levels of dissolved or suspended solids, organic matter, pressed mud, bagasse and atmospheric pollutants. The BOD/COD ratio is low (<2.5), indicating the need for secondary treatment or, more specifically, biological treatment. This can be achieved through humid systems built from stabilization ponds, with the resulting water suitable for reuse in agricultural irrigation. In this work, an educational proposal has been developed for engineering students where they learn to calculate and optimize, among other parameters, the natural wastewater treatment and compare it with a conventional wastewater treatment.

This study explores the potential of piloting desalination plants in a systematic way to evaluate energy improvements in water desalination processes. Pilot tests with the latest generation of reverse osmosis membranes in large desalination plants are becoming increasingly common, as small-scale experiments are carried out on the operation of new generation membranes with better salt rejection and lower energy consumption. This approach aims to achieve optimal water quality standard at the lowest possible cost. In this way, pilot tests are being carried out before the decision is made whether to change the reverse osmosis membranes, as this represents a significant investment. By carrying out these tests, we hope to minimize the risk of making a mistake to ensure the best results in terms of energy consumption, operating costs and reducing the environmental impact while complying with the required water quality. In this case, the Pareto analysis is used to identify the two or three most significant causes whose treatment affects more than 80% of the possible energy improvement to be implemented. This article introduces a novel approach to studying a total of 180 desalination plants at the territorial level in the Canary Islands. The global scarcity of freshwater resources has greatly contributed to the development of desalination technologies, in which reverse osmosis is one of the most widely used and highly regarded methods.

The penetration of renewable energies in island electricity systems (IESs) poses a series of challenges, which include, among others, grid stability, the response to demand, and the security of the supply. Based on the current characteristics of electricity demand on the islands of the Canary Archipelago (Spain) and their electricity production systems, this study presents a series of alternative scenarios to reduce greenhouse gas (GHG) emissions and increase the penetration of renewable energies. The goal is to optimize combustion-based (nonrenewable) energy production and combine it with renewable-based production that meets the requirements of dynamic response, safety, scaling, and integration with nonrenewable systems in terms of efficiency and power. As verified in the research background, the combination of power producing equipment that is generally employed on the islands is not the best combination to reduce pollution. The aim of this work is to find other possible combinations with better results. A methodology is developed and followed to obtain the lowest GHG production and to determine the measures to be applied based on: (a) changing the fuel type by switching to natural gas in the equipment that allows it; (b) using optimal combinations of the least polluting energy production equipment; (c) integrating, to the extent that it is possible, the Chira-Soria pumped hydroelectric energy storage plant into the Gran Canaria electricity system. A series of alternative scenarios are generated with different operating conditions which show the possibility of increasing the renewable installed capacity in the Canary Islands by up to 36.78% (70% in Gran Canaria), with a 65.13% reduction in GHG emissions and a 71.45% reduction in fuel consumption. The results of this study contribute, through the different measures determined through our research, to the mitigation of GHG emissions.

This article shows the optimization of the reverse osmosis process in seawater desalination plants, taking the example of the Canary Islands, where there are more than 320 units of different sizes, both private and public. The objective is to improve the energy efficiency of the system in order to save on operation costs as well as reduce the carbon and ecological footprints. Reverse osmosis membranes with higher surface area have lower energy consumption, as well as energy recovery systems to recover the brine pressure and introduce it in the system. Accounting for the operation, maintenance and handling of the membranes is also important in energy savings, in order to improve the energy efficiency. The energy consumption depends on the permeate water quality required and the model of the reverse osmosis membrane installed in the seawater desalination plant, as it is shown in this study.

The water situation in the Canary Islands has been a historical problem that has been sought to be solved in various ways. After years of work, efforts have focused on desalination of seawater to provide safe water mainly to citizens, agriculture, and tourism. Due to the high demand in the Islands, the Canary Islands was a pioneering place in the world in desalination issues, allowing the improvement of the techniques and materials used. There are a wide variety of technologies for desalination water, but nowadays the most used is reverse osmosis. Desalination has a negative part, the energy costs of producing desalinated water are high. To this we add the peculiarities of the electricity generation system in the Canary Islands, which generates more emissions per unit of energy produced compared to the peninsular generation system. In this study we have selected a desalination plant located on the island of Tenerife, specifically in the municipality of Granadilla de Abona, and once its technical characteristics have been known, the ecological footprint has been calculated. To do this we have had to perform some calculations such as the capacity to fix carbon dioxide per hectare in the Canary Islands, as well as the total calculation of the emissions produced in the generation of energy to feed the desalination plant.

Anaerobic lagoons are natural wastewater treatment systems suitable for swine farms in small communities due to its low operational and building costs, as well as for the environmental sustainability that these technologies enable. The local weather is one of the factors which greatly influences the efficiency of the organic matter degradation within anaerobic lagoons, since microbial growth is closely related to temperature. In this manuscript, we propose a mathematical model which involves the two-dimensional Stokes, advection–diffusion-reaction and heat transfer equations for an unstirred fluid flow. Furthermore, the Anaerobic Digestion Model No1 (ADM1), developed by the International Water Association (IWA), has been implemented in the model. The partial differential equations resulting from the model, which involve a large number of state variables that change according to the position and the time, are solved through the use of the Finite Element Method. The results of the simulations indicated that the methodology is capable of predicting reasonably well the steady-state of the concentrations for all processes that take place in the anaerobic digestion and for each one of the variables considered; cells, organic matter, nutrients, etc. In view of the results, it can be concluded that the model has significant potential for the design and the study of anaerobic cells’ behaviour within free flow systems.