Uncertainty analysis of primary water pollutant control in China's pulp and paper industry

Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions

Emissions of chloroform (CHCl3), a short-lived halogenated substance not currently controlled under the Montreal Protocol on Substances that Deplete the Ozone Layer, are offsetting some of the achievements of the Montreal Protocol. In this study, emissions of CHCl3 from China were derived by atmospheric measurement-based "top-down" inverse modeling and a sector-based "bottom-up" inventory method. Top-down CHCl3 emissions grew from 78 (72-83) Gg yr-1 in 2011 to a maximum of 193 (178-204) Gg yr-1 in 2017, followed by a decrease to 147 (138-154) Gg yr-1 in 2018, after which emissions remained relatively constant through 2020. The changes in emissions from China could explain all of the global changes during the study period. The CHCl3 emissions in China were dominated by anthropogenic sources, such as byproduct emissions during disinfection and leakage from chloromethane industries. Had emissions continued to grow at the rate observed up to 2017, a delay of several years in Antarctic ozone layer recovery could have occurred. However, this delay will be largely avoided if global CHCl3 emissions remain relatively constant in the future, as they have between 2018 and 2020.

Mapping multiple water pollutants across China using the grey water footprint

The primary pollutants and pollution levels of surface water present spatial and temporal changes. This study quantified the grey water footprint (GWF) and surface water pollution level (WPL) in China from 2003 to 2018 based on four pollutants: chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), total nitrogen (TN) and total phosphorus (TP). Additionally, the spatiotemporal distribution of the primary water pollutant (PWP) and driving forces of the GWF were analyzed based on the WPLs and the logarithmic mean Divisia index (LMDI) decomposition method. The results showed that the GWF in China decreased by 13% from 2003 to 2018 and the WPL decreased from 1.11 in 2003 to 0.94 in 2018. An analysis of regional GWFs with multiple pollutants could prevent the underestimation of GWFs and WPLs caused by changes in the PWPs. The GWF spatial distribution was high in the southeast and low in the northwest, while the provinces with larger WPLs were mainly concentrated in northern China. The PWP changed from COD to TN in 2007 because of the increase in nitrogen application in China, the low TN reduction capacity of wastewater treatment plants and the improved comprehensive utilization rate of livestock and poultry manure. The driving force analysis results showed that water efficiency and technological and industrial structural effects promoted the reduced GWF. Our research conclusions and policy suggestions could provide references for reducing the GWF and improving the water quality in China.

Multi-criteria decision making for sustainability assessment of boxboard production: A life cycle perspective considering water consumption, energy consumption, GHG emissions, and internal costs

Papermaking is a capital-intensive industry that requires a high consumption of plant fibers, energy, and water. Previous sustainability assessments of papermaking industry primarily focused on separate evaluations for multiple criteria without the integration for criteria and could not compare the overall priority of the production alternatives. The life cycle sustainability for the most representative boxboard production is analyzed as a case study in this work. Life cycle water consumption, energy consumption, greenhouse gas emissions, and internal costs are selected as the assessment criteria. The two multi-criteria decision-making methods are applied to integrate the above criteria to obtain the sustainability sequence under different production pathways. When the papermaking enterprises are regarded as decision-makers, the alternative using waste paper as raw material to manufacture boxboard is the most sustainable, following by mixed fiber. The sustainability sequence of the alternatives using wood and straw as raw materials is controversial due to the different calculation models. Changing the proportion of raw materials and the criteria weights might adjust sustainability sequence of the alternatives.

A Review on Reverse Osmosis and Nanofiltration Membranes for Water Purification

Sustainable and affordable supply of clean, safe, and adequate water is one of the most challenging issues facing the world. Membrane separation technology is one of the most cost-effective and widely applied technologies for water purification. Polymeric membranes such as cellulose-based (CA) membranes and thin-film composite (TFC) membranes have dominated the industry since 1980. Although further development of polymeric membranes for better performance is laborious, the research findings and sustained progress in inorganic membrane development have grown fast and solve some remaining problems. In addition to conventional ceramic metal oxide membranes, membranes prepared by graphene oxide (GO), carbon nanotubes (CNTs), and mixed matrix materials (MMMs) have attracted enormous attention due to their desirable properties such as tunable pore structure, excellent chemical, mechanical, and thermal tolerance, good salt rejection and/or high water permeability. This review provides insight into synthesis approaches and structural properties of recent reverse osmosis (RO) and nanofiltration (NF) membranes which are used to retain dissolved species such as heavy metals, electrolytes, and inorganic salts in various aqueous solutions. A specific focus has been placed on introducing and comparing water purification performance of different classes of polymeric and ceramic membranes in related water treatment industries. Furthermore, the development challenges and research opportunities of organic and inorganic membranes are discussed and the further perspectives are analyzed.

Uncertainty analysis of industrial energy conservation management in China's iron and steel industry

There are remarkable uncertainty factors in the industrial sector that enhance the difficulties of setting energy conservation strategies, such as the macro economy, industrial structures, and technical uncertainties. However, current studies simply predict the possible trends or conduct scenario analyses, and neglect uncertainty factors in the management of industrial energy conservation. In response, this article considers China's iron and steel industry as an example and builds the Industrial Energy Conservation Uncertainty Analysis (IECUA) model to recognize and analyze the uncertainty factors via a 200-thousand-time Latin hypercube sampling. Then, we propose some management measures, including setting energy conservation targets and energy conservation strategies. The results show that energy conservation targets should be more flexible than just the predicted values, to enhance the feasibility of their realization. In addition, energy conservation strategies are set at industrial and technique levels. On the one hand, such key parameters as production output, the coke/steel ratio, and pig iron/steel ratio, should be strictly controlled to avoid non-compliance risks. On the other hand, energy conservation technologies can be considered under four quadrants depending on their sensitivity to energy conservation and economic efficiency. Finally, some differentiated technologies promotion suggestions are made, such as economic stimulation, market entry standards and technical application guidelines.