Life cycle assessment of a large water treatment plant in Turkey

Life cycle environmental impacts of urban water systems in China

Urban water systems in China are facing multiple challenges, including rapid urbanisation, climate change and infrastructure ageing. It is crucial to evaluate their environmental performance from a holistic perspective in planning and management processes. To the best of our knowledge, there is a lack of nationwide life cycle assessment (LCA) studies on China's urban water systems that cover all system stages. Therefore, this study aims to present a comprehensive and nationwide LCA analysis that pinpoints the environmental hotspots and their major sources across China. This study was conducted based on water utility databases at the province level, covering water abstraction and treatment, waterwork sludge treatment, water distribution, sewage collection, stormwater drainage, wastewater treatment and sewage sludge treatment. Nine environmental impact categories were calculated and analysed. The results reveal the inequity of environmental impacts across provinces, with overall impacts geographically higher in the east and south, lower in the west and north. However, at the functional unit level, the impacts in the northern and northeastern provinces are higher than other regions. Most environmental categories are dominated by multiple water system stages. The analyses of underlying drivers found that purchased electricity is the primary source of several environmental impacts. This study provides a holistic understanding of the environmental performance of China's urban water systems, offers some insights for comprehensive decision-making support on sustainable water system management, and can also serve as a benchmark for future scenario analysis to explore options for reducing environmental impact.

The comprehensive measurement method of energy conservation and emission reduction in the whole process of urban sewage treatment based on carbon emission

It is of great significance to establish a carbon emission management system and carbon emission reduction target to put forward emission reduction measures for each subunit of a sewage treatment plant. In this paper, a mathematical model was constructed for calculating carbon emission in the whole sewage treatment system process. Meanwhile, the model calculated the carbon emission changes after upgrading three sewage treatment plants and identified the critical controlling unit. The results showed that the CO₂ produced from electric energy consumption and chemical application was the primary source of carbon emission of wastewater treatment. Raising sewage discharge standards appropriately could effectively reduce the carbon emission generated by each link of the wastewater treatment plant. Further improvement of effluent standards could adversely affect sewage treatment plants in terms of energy, resources, and greenhouse gas emissions. In addition, raising the standard of total phosphorus concentration in the effluent may lead to a corresponding increase in the amount of phosphorus removal agents, as well as an increase in indirect carbon emission, material consumption, and chemical sludge. Therefore, it is necessary to develop sewage treatment technologies that are economical, applicable, energy-saving, and environmental friendly to realize the environmental benefits of carbon emission reduction in sewage treatment and sustainable utilization of energy and resource from wastewater.

Assessment of energy use and environmental impacts of wastewater treatment plants in the entire life cycle: A system meta-analysis

Wastewater treatment plants (WWTPs) play a critical role in the sustainable development of water resources due to its outstanding ability of removing pollutants from complex influent wastewater and generating clean and safe effluent. This paper innovatively adopted the meta-analysis method in view of published LCA studies to assess the energy use and environmental impacts of WWTPs during their life cycle. The search and screening process determined a useful data source with 54 LCA literatures covering 109 relevant case studies. The meta-analysis results revealed that, compared with other regions, the WWTPs in China have the higher intensity in terms of energy use, global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), photochemical oxidation (PHO), freshwater ecotoxicity potential (FETP) and terrestrial ecotoxicity potential (TETP) categories, implying that the energy conservation and emission reduction strategies are necessary to wastewater treatment industry in China. Moreover, compared with A/A/O and CASS processes, the A/O process consumes less energy and results in lower GWP and AP intensity, but affects adversely the natural water-body protection due to undesirable treatment efficiency. Furthermore, the treatment capacities of medium and large scales (i.e. 5-20 × 10⁴ m³/d) are most reasonable sizes for WWTPs since their intensity of energy use, GWP, EP and AP are under a relatively low level. Finally, a strict effluent discharge standard is highly recommended from the perspective of protecting aquatic environment, although it leads to a higher energy consumption. The findings of this study could provide valuable references for promoting healthy and sustainable wastewater treatment industry.

Comprehensive evaluation on water resource carrying capacity in karst areas using cloud model with combination weighting method: a case study of Guiyang, southwest China

It is important to maintain the sustainable development of water resources. Objective assessment on water resource carrying capacity (WRCC) is beneficial to the formulation of scientific and reasonable water management practices. In view of the problem that evaluation indicators of WRCC cannot describe the fuzziness and randomness, a cloud model was introduced into regional WRCC assessment. This study selected a typical karst area (Guiyang) as the research object to study WRCC by using cloud model with combination weighting method. WRCC was assessed from the following five dimensions: water environment subsystem, social subsystem, economic subsystem, ecological subsystem, and humanities (water resource management and policy regulation) subsystem. In addition, evaluation results after normalizing all of indicators data were also calculated. And these two kinds of evaluation results were compared with that of technique of order preference similarity to the ideal solution (TOPSIS), finding that evaluation results of cloud model were consistent with that of TOPSIS method. The cloud model realizes the transformation from qualitative evaluation to quantitative evaluation, which overcome insufficiencies of traditional evaluation methods in considering fuzziness and randomness. Results showed that during the period of 2008-2017, the state of WRCC in Guiyang was improving year by year, increasing from the serious overload carrying capacity level in 2008 to the strong carrying capacity level in 2017 (serious overload-overload-critical-weak carrying capacity-strong carrying capacity). However, some certain evaluation indicators are still in danger situation, such as population natural growth rate and use of the fertilizer per unit cultivated area, which needs to be further enhanced and improved. Moreover, the contradiction among economic development, population growth, and water resources is becoming increasingly apparent. To ensure the effective utilization of water resources in Guiyang, reasonable policies and measures should be formulated and put into effect. Research results could provide certain reference for the sustainable development of regional water resources.

Coupling life cycle assessment with scenario analysis for sustainable management of Disperse blue 60

Sustainable management of dyeing industry is of paramount importance in order to minimize resource consumption and reduce related environmental impacts. Herein, an environmental study is conducted wherein life cycle assessment (LCA) is applied to a two-scenario process for Disperse blue 60 production with short and long processing chains with different (a) material types, (b) consumptions, (c) processes, and (d) functional units with yields of 300 t/a. The most important influenced substances of the two scenarios were sodium cyanide and electricity next. Results proved that the largest damage of the dye production was attributed to resources and reached 46 and 62 kPt in the two scenarios. Compared with the conventional coal-fired power generation, damaged values of electricity from nature gas (NG) could reduce from 102 to 86 kPt in scenarios 1 and from 123 to 104 kPt in scenarios 2, respectively. When the electricity switched from NG to solar power, the values of the two scenarios could further decrease by 17 and 27 kPt, respectively. Therefore, the process of scenario 1 with the short process chain was more environmentally friendly for the production of Disperse blue 60 owing to the more efficient process and lower resource consumption. Graphic abstract.

Effect of operating parameters on hydrothermal liquefaction of corn straw and its life cycle assessment

As the shortage of non-renewable fossil fuels, the renewable fuels should be further developed. Biomass energy has emerged the great utilization potential, and liquefaction of biomass is a typical technology. This paper studied the effect of the operation parameters on the hydrothermal liquefaction of corn straw using a batch reactor, including liquefaction temperature, initial pressure, retention time, solvent, and catalyst. The optimal liquefaction conditions for corn straw were 300 °C under 4 MPa for 15 min using the mixture of water and methanol as the solvent. After the addition of catalyst, NKC-11 catalyst showed the excellent performance, and the primary components were phenol and derivatives, alkane, furan, and the low concentration of organic acids. Lastly, the life cycle assessment on the hydrothermal liquefaction of corn straw for bio-oil production was executed. The results of LCA suggested that a net 1.31 kg of CO₂ equivalent was produced for 1 kg of bio-oil product without considering syngas, while the value changed to 13.03 kg with considering syngas. Moreover, the results of sensitivity analysis further suggested that the syngas was a key factor on the environmental impacts in the hydrothermal liquefaction of corn straw process.

Sustainability

This review on Sustainability covers selected 2018 publications on the focus of sustainability. It is divided into the following sections: (a) Water quantity; (b) Water quality; (c) Climate change and resilience; (d) Planning and ecosystem evaluation; (e) Life cycle assessment (LCA) applications; (f) Sustainable management; (g) Sustainability and asset management; (h) Sustainability in wastewater treatment; (i) Sustainable water and wastewater utilities; (j) Sustainable water resource management.