Exergy and Emergy: Complementary Tools for Assessing the Environmental Sustainability Use of Biosolids Generated in Wastewater-Treatment Plant for Energyproduction

Abstract

Taking advantage of the energy contained in the biosolids generated in a wastewater treatment plant (WWTP) is one of the processes of greatest interest due to the opportunity to obtain an energy resources from a waste. The aim of this research was to analyze the environmental sustainability use of biosolids generated in a wastewater-treatment plant for energy-production by fluidized-bed gasification under exergy analysis. The energy-production system was based on previous studies of sustainable-emergy alternatives using biosolids. Sustainability of the process was evaluated by identifying stages in the energy-production system (from drying application to electricity generation) where it is possible to reduce useful energy losses as well as identifying the value of waste streams within the system through exergy analysis. It was illustrated the destroyed exergy and the efficiency by stage and by product in order to assess the effects of inefficiencies in the process sustainability. The mixture of biosolids with coal was identified as a highly sustainable stage of the process, as it presents the highest index of exergy sustainability (0.99), in contrast to the stages of energytransformation (turbine) and gas-cleaning, which efficiencies are 0.17 and 0.4, respectively. Energy-transformation and gas-cleaning stages are of interest in terms of an improved energy recovery process, making it more efficient by applying new technologies and/or using the waste streams that have high energy potentials.

Biofortification of Kidney Bean (Phaseolus vulgaris L.) Crops Applying Zinc Sulfate and Ferric Sulfate: Pilot Crop in Colombia

“…This statement is ratified in Table 3, where the maximum chlorophyll a and b occurs in treatment 1, followed by treatments 2, 4, and 5, until reaching the minimum in treatment 3; and in Table 4, when the maximum chlorophyll a and b occurs in treatment 5, then in treatments 2, 1, and 4, until reaching the minimum of this pigment in treatment 3, which leads to the fact that at 0.050 µmol dm −3 for zinc sulfate and iron sulfate, the lowest contents of chlorophyll a and b are obtained in the leaves; hence, it is an unfavorable treatment for photosynthetic development. These effects have been observed in various crops, such as beans; as reported by Zewail [36], the present results did not show a convincing response; in the case of total carotenoids, no difference was observed, while chlorophylls a and b had minimal uptakes with the contributions of iron and zinc by the foliar route in bean plants; that is, it is not a favorable treatment for photosynthetic development [37][38][39].…”

Analysis of Environmental Sustainability through a Weighting Matrix in the Oil and Gas Industry

“…The domestic energy context, characterized by economic dependence on extractive activities and the goal of achieving energy self-sufficiency, presents a contrast with climate objectives and commitments. While there is an intention to adhere to international emission reduction targets, it often overlooks solutions concerning the production and sale of fossil fuels, posing challenges for systemic transformation [33][34][35][36].…”

Process Optimization of the Flaring Gas for Field Applications

“…Table 2 shows the equipment considered for the energy consumption base model of a standard petroleum field; this data is obtained and shown as synthetic data. This model considers two energy power consumptions: gross and net [33][34][35]. The net electric power represents the minimum energy consumption per day required for each piece of equipment, and this value represents the minimum quantity of energy essential to be supplied for each equipment operation.…”

“…Multicriteria analysis (MCA) is a technique that presents a set of alternatives that are evaluated considering three generic elements: decision-maker(s), alternatives, and criteria [35]. The multicriteria analysis used and considered for the selection of the equipment in this paper involved three steps: identify the decision context, identify the options to be appraised, and identify the criteria and variables on which the comparison of the alternatives was made, and the final decision was taken based in the results of previous research with similar purposes and which experiences were a guide to the appropriate selection.…”