China's industrial gray water footprint assessment and implications for investment in industrial wastewater treatment

Ecological footprint model of heavy metal pollution in water environment based on the potential ecological risk index

Social heavy metal pollution poses a significant threat to aquatic ecosystems. Heavy metals are easily adsorbed by sediments and have cumulative effects on aquatic organisms, which is different with the hypothesis of the conventional ecological footprint model that the pollutants are independently degraded by water bodies. To solve this problem, an ecological footprint for heavy metal pollution (EFHM) is constructed based on the potential ecological risk index (PERI). EFHM is defined as the sediment area to control the cumulative ecological risk of heavy metals within the allowable limit. And then, EFHM uses ecological footprint index (EFI) and ecological footprint contribution rate (EFCR) to quantify the hazard of social heavy metal load and recognize the key risk factor. EFHM is applied for assessing the heavy metal pollution of Central China. The results show that (i) the EFHM model can effectively evaluate the cumulative ecological hazards of heavy metals in sediment. (ii) The EFHM values of Central China in 2015 and 2020 are 20,764.56 and 17,358.59 km2, respectively. (iii) Compared with 2015, the EFI values of Hunan Province and Jiangxi Province in 2020 decrease from 1.53 to 0.87 to 1.23 and 0.39, respectively, both of which are improved by one grade. The EFI values of Hubei Province increases from 0.42 to 1.34, which is deteriorated by one grade. (iv) In 2020, both of the key risk factors of Hunan Province and Hubei Province are Hg, and the crucial hazard source of Jiangxi Province is Cd. (v) The mine pollution control in Central China should be further consolidated, and the wastewater treatment of electronics and machinery industries should be strengthened.

Socio-Economic Factors and Water Footprint in Smallholder Irrigation Schemes in Zimbabwe

Despite the need to grow crops with low water consumption needs, given the increasing water stress across many regions of the globe, assessments of crop water footprint (WFP) values have not received significant research attention in Zimbabwe. This unique study is the first of its kind to assess the mediation effect between socio-economic factors and crop WFP among smallholder irrigation schemes in Zimbabwe. A total of 317 farmers from three schemes in Midlands Province in Zimbabwe participated in this study. The following were the main findings in terms of the examined variables: (1) Schemes (p < 0.01), Gender (p < 0.05), and Maint (p < 0.1) all decreased WFP_Maize; (2) education showed a reduction effect on the link between scheme maintenance and WFP_Maize; (3) secondary education has a higher impact on the magnitude of Maint on WFP_Maize; and (4) Maint and WFP_Maize have a positive correlation. This study illustrates the interaction of socio-economic factors on WFP and has substantial implications for simultaneously addressing the sustainable consumption of water for crop production, food security, and malnutrition in a changing climate.

Adsorption of Lead Ion from Wastewater Using Non-Crystal Hydrated Calcium Silicate Gel

In order to obtain low-cost and excellent adsorption materials, this paper used calcium acetate and water glass as raw materials to synthesis hydrated calcium silicate gel by precipitation method. The performance and structure of hydrated calcium silicate gel were systematically studied by X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, specific surface area analyzer and scanning electron microscope. Studies have shown that, non-crystal hydrated calcium silicate gel (CSH) were successfully prepared, and the removal rate of lead ion using CSH reached more than 90%. The adsorption process is consistent with the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, and the limit adsorption capacity reaches 263.17 mg·g-1. The acid treatment experiment proved that the adsorption capacity of lead ion using CSH was satisfactory, and the adsorption rate remained at >60% after 5 cycles. The research may provide a low-cost, high-efficiency and high stability adsorbent.