In situ evaluation of water and energy consumptions at the end use level: The influence of flow reducers and temperature in baths

The Evaluation System of the Sustainable Development of Municipal Solid Waste Landfills and Its Application

Improving the understanding of the stabilization process is of great significance to guide the sustainable development of municipal solid waste (MSW) landfills. An evaluation system of the stabilization process of MSW landfills has been established. The indices of the evaluation system involve the degradation degree of MSW, the release of landfill gas production potential, and the settlement of landfills. Based on the biochemical-consolidation-solute migration coupled model, an evaluation method of the MSW landfill stabilization process is proposed by combining field tests with numerical simulation. The stabilization process of the Jiangcungou landfill in China is investigated by using the proposed method. The analyzed results show that the stabilization process of high kitchen waste content landfills can be divided into three stages, which is different from the stabilization process of landfills in developed countries. For the Jiangcungou landfill, the ratio of cellulose to lignin in MSW decreases rapidly during the fast degradation stage when obvious settlement occurs. During the slow degradation stage, the hydrolysis rate is slow and settlement develops slowly. When the landfill reaches the stabilization stage, the ratio of cellulose to lignin of MSW changes very slowly; most of the landfill gas potential has been released; the settlement stabilization is completed basically. The change processes of the three evaluation indices are different, of which the degradation stabilization index is the main one. According to the findings above, leachate recirculation is recommended to adjust the degradation environment in the landfill, which can be helpful to avoid acidification at the fast degradation stage. Temporary cover is suggested to improve landfill gas collection efficiency at the beginning of the stable methanogenic stage. The landfill site closure should be operated when the settlement rate is low.

An agent-based spatiotemporal integrated approach to simulating in-home water and related energy use behaviour: A test case of Beijing, China

Water and energy consumptions in the residential sector are highly correlated. A better understanding of the correlation would help save both water and energy, for example, through technological innovations, management and policies. Recently, there is an increasing need for a higher spatiotemporal resolution in the analysis and modelling of water-energy demand, as the results would be more useful for policy analysis and infrastructure planning in both water and energy systems. In response, this paper developed an agent-based spatiotemporal integrated approach to simulate the water-energy consumption of each household or person agent in second throughout a whole day, considering the influences of out-of-home activities (e.g., work and shopping) on in-home activities (e.g., bathing, cooking and cleaning). The integrated approach was tested in the capital of China, Beijing. The temporal results suggested that the 24-hour distributions of water and related energy consumptions were quite similar, and the water-energy consumptions were highly correlated (with a Pearson correlation coefficient of 0.89); The spatial results suggested that people living in the central districts and the central areas of the outer districts tended to consume more water and related energy, and also the water-energy correlation varies across space. Such spatially and temporally explicit results are expected to be useful for policy making (e.g., time-of-use tariffs) and infrastructure planning and optimization in both water and energy sectors.

Energy consumption, CO2 emissions and costs related to baths water consumption depending on the temperature and the use of flow reducing valves

In the domestic segment, various appliances and processes consume great amount of water and, consequently, energy. In this context, the main aim of this study is to analyse the impact of water temperature, flow and bath duration in water and energy consumptions. The impact on CO₂ emissions and a simple costs analysis were also carried out. It included a monitoring plan of 197 baths taken under different scenarios of water temperature and flow. It was concluded that increasing water consumption leads to an increase on energy consumption and that both resources consumptions increase with bath duration. Bath temperature had influence not only on energy consumption, as expected, but also in water consumption, what may be explained by the user's satisfaction during baths with higher temperatures. The use of a flow reducing valve is not a guarantee of water saving which can also be related to the user's satisfaction patterns, given that the introduction of a flow reducing valve can lead to a bath duration increase. In what concerns to the CO₂ emissions, it was concluded, as expected, that higher values are obtained for baths with higher temperatures given their relation with higher energy consumptions patterns. A simple costs analysis revealed that having flow reducing valves, with a bath temperature of 75 °C, increased the costs with electricity and water in 119% and 32%, respectively, when compared with a temperature of 60 °C.