Sustainable energy management in the wastewater sector applies the concept of sustainable management to the energy involved in the treatment of wastewater. The energy consumed by the wastewater sector is usually the largest portion of energy consumed by the urban water and wastewater utilities. The rising costs of electricity, the contribution to greenhouse gas emissions and the growing need for global warming, are driving wastewater utilities to rethink their energy management, adopting more energy efficient technologies and processes and investing in renewable energy generation.

Among the water and wastewater services of a city, wastewater treatment is usually the most energy intense process. Wastewater treatment plants are designed with the purpose of treating influenza in a water body. These facilities play an important role in the protection of human health, preventing the discharge of pathogens normally present in the municipal sewage. Despite the key role of wastewater facilities, energy consumption can not be ignored because of its contribution to greenhouse gas emissions and the need to reduce the emissions to global warming, as established by the Kyoto Protocol in 1997 and most recently, by the Paris Agreement. Moreover, there is an uncertainty concerning energy costs. Because for a wastewater utility costs represent the second highest cost after plowing, an increase in the rate of increase of the operational budget of a municipality, and accordingly, the service rates for consumers. Therefore, it is important for the wastewater sector to invest in strategies for reducing greenhouse gas emissions.

Population growth, urbanization, climate change and increasing demand for natural resources are among the future biggest challenges for the urban wastewater sector.

World population and population density is expected to grow by 32% and 66% by 2050, respectively. An increase in population is expected to increase the volume of wastewater and sewage sludge. To handle a higher volume of sewage sludge, it is necessary to upgrade the existing wastewater facilities and the collection networks. Therefore, an increase in volume translates into high future costs for a low cost recovery rate. Moreover, as shown by Mizuta, there is a correlation between the volume of sewage treated and the energy consumption of a wastewater treatment plant. Hence,

Greenhouse gas emissions from human activities have almost doubled between 1970 and 2010. The increase in greenhouse gases is caused by the effects of climate change. In particular, the effects of water cycling on the water cycle, increasing the precipitation intensity and variability, increasing the risk of floods and droughts in many areas. The changes in the water cycle have had significant impacts on the aquatic ecosystems, increasing and worsening the stressors already affecting these systems. Nutrient loading represents one of those stressors, with the change in precipitation patterns, it is expected to increase significantly in nutrients entering aquatic ecosystems due to increased erosion events and frequent sewage systems overflows. This paper addresses the issue of nutrient loading in aquatic ecosystems, the target nutrient load of these ecosystems affects the treatment of wastewater treatment. Increased levels of nutrients in the receiving water bodies wastewater treatment plants to perform more stringent nutrients removal from the wastewater. In addition to strict limits, future standards for unregulated contaminants are most likely to be introduced. The combination of more stringent limits and new treatment requirements Population growth and climate change is increasing the energy needs of wastewater facilities. Because fossil fuels are still the most diffused source of energy, providing more than half of the global energy needs, the wastewater sector is still highly dependent on fossil fuel-based energy sources. Electricity, for example, is used on the grid and is used on-site for heating and back-up generators. High consumption of fossil fuel is one of the biggest emitters of greenhouse gases, contributing to 65% of the CO 2 emissions globally. It is used on the grid while it is used on-site for heating and to run backup generators. High consumption of fossil fuel is one of the biggest emitters of greenhouse gases, contributing to 65% of the CO 2 emissions globally. It is used on the grid while it is used on-site for heating and to run backup generators. High consumption of fossil fuel is one of the biggest emitters of greenhouse gases, contributing to 65% of the CO 2 emissions globally.

The pressure to reduce greenhouse gas emissions is increasing and the cost of water is increasing. Wastewater contains energy, nutrients and other organic and inorganic resources that can be successfully recovered and used in a wide range of applications. Energy can be recovered as biogas and heat. Biogas is an energy source with a wide range of uses. Among the nutrients, phosphate can be recovered as struvite for fertilizers, a very important application. Compost sewage sludge finds applications in agricultural setting and urban gardens. Besides energy and nutrients, effluent from the wastewater treatment plants can be reused in both irrigation and water applications. The reuse of treated water is particularly valuable in countries with limited or long periods of drought. These possibilities are changing the vision of wastewater management and the role of wastewater treatment plants. Wastewater treatment plants have the potential to not only recover from wastewater These possibilities are changing the vision of wastewater management and the role of wastewater treatment plants. Wastewater treatment plants have the potential to not only recover from wastewater These possibilities are changing the vision of wastewater management and the role of wastewater treatment plants. Wastewater treatment plants have the potential to not only recover from wastewater

Effective strategies adopted by wastewater utilities to reduce energy consumption and dependence of fossil fuel-based energy sources.

Since the recognition of anthropogenic causes of climate change in the late 80s’ and the identification of the energy sector, the contribution of the global contribution to greenhouse gas emissions . In Europe the energy analysis of the wastewater sector was conducted with two approaches. Germany (MURL, 1999) and Switzerland (BUWAL, 1994), for example, developed 38% and 50%, respectively. These manuals provided wastewater utilities with energy targets to achieve. On the other hand, in 1999 Austria promoted benchmarking that allowed annual comparison of wastewater treatment plants energy performance. This comparison is one of a number of wastewater treatment plants and their aspiration to improve their efficiency, which is one of the leading countries in the world to achieve energy neutrality in the wastewater sector. The energy benchmarking process has had the greatest impact on the environment. For example, the inefficiency of the aeration process identified by multiple studies has allowed the development of more efficient energy oxidation units, with a possible energy saving of about 20% to 50% in some cases according to Frijns and an EPA study. which led to the world in the world to achieve energy neutrality in the wastewater sector. The energy benchmarking process has had the greatest impact on the environment. For example, the inefficiency of the aeration process identified by multiple studies has allowed the development of more efficient energy oxidation units, with a possible energy saving of about 20% to 50% in some cases according to Frijns and an EPA study. which led to the world in the world to achieve energy neutrality in the wastewater sector. The energy benchmarking process has had the greatest impact on the environment. For example, the inefficiency of the aeration process identified by multiple studies has allowed the development of more efficient energy oxidation units, with a possible energy saving of about 20% to 50% in some cases according to Frijns and an EPA study.

Increased energy efficiency has failed to reduce the risk of cancer. However, they are not sufficient to achieve independence from the electricity grid and fossil fuel-based energy sources. To achieve energy neutrality, multiple studies have looked at the feasibility of integrating a variety of renewable energy sources into wastewater treatment plants. The wastewater itself is a carrier of energy and a theoretical calculation, based on the characteristic of the sewage, shows that the composition of the embedded energy is 80% thermal energy and 20% chemical energy. The thermal energy can be recovered as a result of the chemical energy is recovered as biogas. Renewable energy generation on site, In addition to increased energy efficiency, it is possible to produce more energy. Energy efficiency programs and renewable energy generation have been successful in reducing the dependence of the wastewater sector on the energy grid.

The production and recovery of energy supply and contribution to waste management and the contribution to waste management and cost-effectiveness in the case of power shortage. One of the main advantages of energy generation is the least stringent dependence of the electricity grid and the cost mitigation associated with it. Depending on the level of renewable energy generation, the wastewater treatment plant may be more expensive. When feed in tariffs are in place, wastewater treatment plants can sell electricity to the grid and reduce costs through the cost recovery of the energy. In some cases, the application of energy efficiency is a question of whether or not a wastewater utility is given a financial incentive. This helps the energy utilities to reduce the energy consumption of the wastewater. In countries where a renewable energy product is produced, the production of renewable energy is allowed to produce a product. The certificates are then bought by the electricity retailers, which surrender them every year to comply with the renewable energy regulation. Another advantage of renewable energy production, in particular of biogas from sewage sludge, is the contribution to waste management. In fact the recovery of the chemical energy involves the reduction of sludge volume. A smaller volume of sewage sludge is cheaper to transport and dispose of, decreasing operational costs. Moreover, a diversify portfolio of energy sources can contribute to a more resilient response in the case of energy shortage and grid problems.

Despite the numerous advantages offered by renewable energy generation, wastewater utilities are experiencing multiple difficulties in integrating renewables in their facilities. From a survey conducted by Beca it is one of the biggest barriers to success and is one of the most important business solutions for wastewater utilities and renewable energy projects. Moreover, each plant presents a solution for each situation, making it hard to generalize solution for the all sector. There is a lack of guidelines and roadmaps to follow, so they have to create specific solutions for their wastewater treatment plants. The changing price of electricity connected with the fossil fuel can affect the time of the investment. This can create an unsustainable situation, where investments in renewables projects can only be achieved by government. In the specific situation of biogas production, poor management can increase the fugitive emission of greenhouse gas emissions, reducing the environmental benefits of renewable energy generation.