Xiu-Teng Wang

Comprehensive utilization of hazardous industrial waste can recover resources but may also transfer residual hazardous constituents into downstream products. Preparing water treatment agents with low environmental risk is an important path towards sustainable development for the sulfuric acid industry. Following the framework of hazard identification, exposure assessment, hazard characterization, and risk characterization in the forthcoming Chinese national standard “General Principles for Environmental Risk Assessment of Products from Comprehensive Utilization of Hazardous Wastes”, this case study evaluated the use-phase human-health and aquatic ecological risks of a liquid polyferric sulfate coagulant produced from waste sulfuric acid. As, Pb, Hg, Cr, Zn, and Ni were reported in the product at 8.6 × 10⁻⁴, 8.6 × 10⁻⁵, 1.5 × 10⁻⁷, 4.78 × 10⁻³, 7.96 × 10⁻³, and 2.10 × 10⁻⁴ mg/L, respectively. Three predefined scenarios were considered: direct worker dermal contact during dosing, indirect dermal contact with receiving water, and aquatic exposure after discharge. Under the case-study parameterization, the total carcinogenic and non-carcinogenic risks were 2.46 × 10⁻⁷ and 3.90 × 10⁻⁴ for occupational exposure and 8.04 × 10⁻¹⁸ and 5.47 × 10⁻¹⁵ for indirect population exposure, respectively. The available ecological-effect dataset supported only a partial Hg-based screening. Thus, the conclusions are limited to the measured product composition, selected scenarios, assumptions, and benchmarks and do not constitute a comprehensive occupational, life-cycle, or multimedia environmental-safety assessment.

The comprehensive utilization of hazardous waste may introduce heavy metals, organic pollutants, etc., into products, resulting in secondary pollution. The environmental risk assessment method for hazardous waste resource utilization products is an important technical means of environmental management. We have established a standardized method for hazard identification, exposure evaluation and risk characterization. This study selects waste sulfuric acid generated in the integrated circuit industry as the object and investigates the use of waste sulfuric acid to react with aluminum hydroxide to produce liquid aluminum sulfate flocculant, as well as the environmental risks brought to practitioners and the potential relevant population in the sewage treatment process. By analyzing sulfuric acid and aluminum hydroxide, toxic substances such as nitrate ions, fluorides, As, Pb, Cr, Hg, Cd, etc., were identified. Through exposure scenario analysis, the exposure levels of occupational and non-occupational populations were determined. Based on the dose–response relationship data in the IRIS database of the United States and the carcinogenic and non-carcinogenic data of skin contact routes, it was suggested that chromium and its compounds were the main contributors to carcinogenic risk, and cadmium, its compounds, and mercuric chloride were the contributors to the non-carcinogenic risk. The total carcinogenic risk to human health in occupational populations was 5.31 × 10⁻⁵, and the total non-carcinogenic risk was 8.80 × 10⁻¹. The total carcinogenic risk to human health in non-occupational populations was 1.73 × 10⁻¹⁵, and the total non-carcinogenic risk was 1.23 × 10⁻¹¹. Based on this research, it is clear that the production of liquid aluminum sulfate flocculants from waste sulfuric acid generated in the integrated circuit industry has a low impact on occupational and other populations during use, and the environmental risks generated by this product are acceptable even under the most dangerous conditions.

C₄₆H₂₈F₁₆N₄O₄P₂, monoclinic, P2₁/n (no. 14), a = 9.3041(2) Å, b = 22.4679(5) Å, c = 19.9446(3) Å, β = 98.154(2)°, V = 4,127.14(14) ų, Z = 4, R_gt (F) = 0.0478, wR_ref (F ²) = 0.1411, T = 173(2) K.

Recently, the stability of DC microgrids has attracted increasing attention. The traditional stability analysis method cannot not meet the requirements for the complexity and bidirectional energy flow of the system. In this paper, a passivity-based stability criterion (PBSC) is proposed to analyze the stability of the cascade system. In order to realize the passivity of the system, an improved feedback control method based on the traditional double-loop control strategy is proposed, which will improve the stability region and guarantee the passivity of the system. Moreover, a Buck-CPL simulation model is established based on MATLAB/Simulink R2008, and the correctness of the theoretical analysis is verified by experiments.

According to the general steps of comprehensive utilization of each type of bulk industrial solid waste, including fly ash, coal gangue, tailings, smelting slag, industrial by-product gypsum, and red mud, we construct the testing standards system for comprehensive utilization of bulk industrial solid waste in China. The standards system, according to the lifecycle stage of "raw materials - pre-treatment - processing - forming products - using products", can be divided into 5 standard subsystems, namely a subsystem of physical property testing standards for raw materials, a subsystem of chemical property testing standards, a subsystem of process testing standards, a subsystem of the product quality performance testing standards and a subsystem of the environmental impact testing standards. The standards system provide top-level guidance for the implementation and development of comprehensive utilization testing methods for bulk industrial solid waste.

High temperature melting is a harmless treatment technology for solid wastes, which is applicable to hazardous wastes containing heavy metals and other harmful substances, obtaining amorphous glassy substances. Vitreous residue usually has high stability and low leaching toxicity. This paper simulates the leaching test of vitreous residue under natural conditions in ordinary rain and acid rain, systematically detects the concentration of leachable substances of typical residue, and analyses its environmental risks according to groundwater quality standards, indicating that harmful substances such as heavy metals may bring potential environmental risks when the vitreous residue enters the environment.

Emission standards of air pollutants are the legal basis for environmental management. Compared with the point source emission, the non-point source pollution of the air is mostly unorganized, which has the characteristics of large scope, random, hidden and difficult to control. It is difficult to take effective measures to control pollution, and the emission standard of atmospheric non-point source pollution is basically blank. In order to design a scientific and reasonable standard system, we have summarized the characteristics of atmospheric non-point source pollution, summarized the difficulties that dates back to the atmospheric non-point source emission standard in China, analyses the problems in the process of atmospheric non-point source emissions standards, put forward the principles for atmospheric non-point source emission standards. Finally we present the feasibility of typical atmospheric non-point source emission standards in China.

Vitrification technology is one of the harmless treatment methods for hazardous waste containing heavy metals and other harmful substances, converting solid waste into vitreous residue with amorphous structure by high temperature melting. In this paper, we propose the acid dissolution rate in acidic environment to characterize the environmental stability of molten vitreous residues. We have tested six high temperature melting residues from different enterprises. The results of our experiments show that the higher the degree of vitrification, the lower the acid dissolution rate, and most of them are similar to basalt, quartz and architectural glass. This work demonstrate that the vitreous residue produced by high temperature melting has high stability and low leaching toxicity. Vitrification technology can solidify heavy metals and other harmful substances in the dense three-dimensional structure of glass state.

It is important to detect arsenic content in the process of comprehensive utilization of coal gangue in view of environment risk control. In this work, we proposed a rapid detect method of As(III) in coal gangue with anodic stripping voltammetry, and optimized the operating parameters by a large number of experiments. The result shows that the anodic stripping voltammetry can accurately analyse As(III) in coal gangue in real time. Anodic stripping voltammetry method is suitable for small and medium-sized enterprises because of its short detection time and low cost of equipment.