Silver nanoparticles in carbon nanotubes (AgNPs-in-CNTs) were prepared through a simple thermal decomposition method. Synthesized AgNPs-in-CNTs were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). In the presence of hydrogen peroxide (H₂O₂), AgNPs-in-CNTs exhibited perfect photocatalytic activity in rhodamine B (RhB) degradation under visible light irradiation. Hydrogen peroxide (H₂O₂) concentration and initial pH values were comprehensively scrutinized. When the concentration of H₂O₂ was 20 mM, about 99.8% RhB (20 mg L⁻¹) could be degraded within 50 min while the initial pH (3–10) values had a negligible effect on the degradation. From the investigations of Raman spectroscopy, transient photocurrent responses, photoluminescence, and radical quenching experiments, the findings suggest that under light irradiation, AgNPs-in-CNTs can absorb photons and generate photogenerated electrons through localized surface plasmon resonance (LSPR) effect, the photogenerated electrons react with H₂O₂ to produce ·OH radicals for decomposing RhB.

As a global pollutant, Hg (Hg) since the turn of the last century has received increased attention. Decreasing the emission of Hg into the food chain and the atmosphere is an effective way to reduce the Hg damage. The current study provided information about pilot-scale horizontal subsurface flow (HSSF) constructed wetlands (CWs) to remove different Hg species in polluted water. Synthetic wastewater was fed to two HSSF CWs, one was planted with Acorus calamus L and the other was unplanted as a control. The total Hg (THg), dissolved Hg (DHg), and particulate Hg (PHg) from five sites along the HSSF CWs were analyzed to describe the process of Hg removal. Results show that the CWs have high removal efficiency of Hg which is more than 90%. The removal efficiencies of THg and DHg from the unplanted CW were 92.1 ± 3.6% and 72.4 ± 13.1%, respectively. While, the removal efficiencies of THg and DHg in planted CW were 95.9 ± 7.5% and 94.9 ± 4.9%, which were higher than that in blank CW. The PHg was mainly removed in the first quarter of the CWs, which was also revealed by the partition coefficient Kd. To a certain extent, the effect of plants depends on the hydraulic retention time (HRT). The results in the current study show the potential of the HSSF-CWs for restoration from Hg-contaminated water.

In the planning and authorization process of industrial plants or agricultural buildings, it needs to be ensured that odor emissions do not annoy nearby residents in an unacceptable way. Previous studies have shown that odor-hour frequency is an important predictor for odor annoyance. However, odor-hour frequencies can be assessed for day and night separately. The present study relates complaint rates with different odor types and different metrics of frequency calculated via a dispersion model. Binary logistic regression analyses show that odor type and frequency of odor-hours are important predictors for complaints, while type of residential area does not increase the predictive value of the model. The combination of calculated frequency of day time odor-hours and type of odor explains complaint rates best. It is recommended to keep odor emissions as low as possible, especially for highly annoying odor types.

This paper presents the treatment of a nitrite-limited wastewater by partial nitrification/anammox process under different dissolved oxygen (DO) concentrations of < 1.2 mg/L, < 0.5 mg/L, and 0 mg/L, and at temperatures of 35 to 27 °C in a pilot-scale single-stage hybrid bioreactor (BioCAST). The effect of operational parameters on microbial community structure and composition has also been investigated during the 1-year experimental period. Ammonium removal efficiencies of 73 ± 19% at 35–32 °C and 87 ± 9% at 29–27 °C were obtained from a synthetic nitrite-limited wastewater with ammonium concentration of 350–500 mg/L (175–250 g m⁻³ d⁻¹). The adaptation of bacteria to a lower temperature (27 °C) and lower free ammonia concentrations at 27 °C was showed to be key factors leading to the optimal nitrite production by aerobic ammonium-oxidizing bacteria (AOB). No nitrite accumulation was observed due to the effective distribution and transfer of nitrite produced by the AOB in the aerobic zone to the microaerophilic/anoxic zones. The fast enrichment of Candidatus species in the suspended biomass in the anoxic zone at temperatures of 35–30 °C and in the attached biofilm in the microaerophilic zone (DO < 0.5 mg/L) at 29–27 °C suggests that the growth media (e.g., suspended biomass vs attached biofilm) had a minor effect on the diversity of microbial community in this bioreactor. This study supports the effective treatment of nitrite-limited wastewater with ammonium concentrations of < 500 mg/L by partial nitrification/anammox process at 35–27 °C in a single-stage hybrid bioreactor by adjusting the DO concentration to < 0.5 mg/L and by providing longer retention times for aerobic (AOB) and anammox bacteria in the biofilm, which resulted in the long-term suppression of nitrite-oxidizing bacteria (NOB).

The effect of soil amendments, i.e., compost, zeolite, and calcium oxide, on the chemical properties of soil contaminated with Cr(III) and Cr(VI) and the uptake of selected heavy metals by spring barley (Hordeum vulgare L.) and maize (Zea mays L.) was determined in a pot experiment. The content of all investigated heavy metals in the tested plants varied significantly in response to the tested soil amendments and increasing concentrations of Cr(III) and Cr(VI). Compost, zeolite, and calcium oxide contributed to an increase in the average yield of the aerial parts of maize plants only in treatments contaminated with Cr(III). The concentrations of Cr, Zn, and Ni in the aerial parts of spring barley and maize were higher in treatments contaminated with Cr(III) than in treatments contaminated with Cr(VI). Calcium oxide induced a significant increase in soil pH relative to the control treatment. In treatments without soil amendments, the average Cr content of soil was higher in pots contaminated with Cr(VI). The concentrations of Zn and Cu in non-amended treatments were negatively correlated with increasing doses of Cr(III) and Cr(VI). Calcium oxide decreased the average content of Cr, Cu, and Ni in all experimental variants. Compost increased the average content of Zn in treatments contaminated with Cr(III) and Cr(IV) relative to non-amended soil.

Open dumping adversely affects the environment and remains the most widely used method for waste disposal in many developing rural areas in China. Information regarding the impact of rural solid waste (RSW) on the environment remains limited. The objectives of this study are to investigate the characteristics of RSW and the impact of different precipitation rates, and to evaluate the contamination potential of RSW using a leachate pollution index (LPI). The study showed that leachate concentration was significantly influenced by precipitation rates at the initial precipitation stages. Precipitation rates of 42.00 mm/day appeared to have the largest dilution effects. In contrast, the concentrations of leachate at rainfall rates of 24.00 mm/day and soaking were steady, and no similar trends were observed. The highest amounts of pollutants in leachate were the result of soaking. In the first week of our experiment, the LPI value for each rural area waste sample rapidly increased with rising precipitation rates from soaking to 42.00 mm/day. However, no significant change in LPI was observed thereafter (after 5 weeks) even with increasing precipitation rates. The values of chemical oxygen demand, biochemical oxygen demand, total nitrogen, and NH₃-N in the leachate after 10 weeks were 4.00, 7.34, 1.87, and 2.21 times higher, respectively, than those of the prescribed leachate quality standards in China. The results of our study suggest the following course of action for the three dump sites investigated: in Banqiao, given the size of the population and the size of the waste amount, landfill might be a suitable way for disposing of RSW. In Machen, building a standardized waste collection site would be an economical solution for reducing potential pollution risks. In Jiuduhe, increasing the transportation rate of solid waste might be an effective solution. The results of this study can help to improve the understanding of leachate pollution in Chinese rural areas.

The massive generation of electronic waste (e-waste) and the informal recycling of e-waste are serious concerns in China. As a hazardous waste stream, e-waste calls for sustainable management practices to avoid adverse effects on environment and health. However, consumers’ awareness and active participation are needed to make e-waste management successful. Therefore, this study is an exploratory attempt to investigate young consumer awareness, knowledge, and participation in sustainable e-waste management practices. Meanwhile, the study reviews the current situation of e-waste recycling, its related legislative framework, and practices in China. The survey revealed that the respondents have keen environmental consciousness, while they have low awareness about e-waste-related rules and regulations, recycling programs, and the formal and informal recycling sector. The findings provide valuable insights for practitioners in order to promote environmental awareness and sustainable e-waste management practices among young consumers in China.

Land production potential (LPP) was the maximum grain yield in one year that can be produced by land under the limitations of climate conditions and in the absence of pests and diseases and other factors. Whether climate change was increasing or reducing the LPP in a given region was uncertain. Therefore, Shaanxi Province was selected to analyze the regional differences in climate change and its effects on LPP change and to identify the main climatic factor restricting LPP in different regions by combining Global Agro-Ecological Zone (GAEZ) model with the Geodetector model. Results showed that the temperature in Shaanxi Province showed an upward trend in 2000–2015; the rise in temperature to the north of Qinling Mountain (QM) was less than that to the south of QM. However, rising temperature had a yield-improving effect to the north of QM and a yield-decreasing effect to the south of QM. There was a precipitation increase in Arid Sandy (AS) area and Loess Plateau (LP), and the precipitation reduced in all other geographical units. The increase in LPP of Shaanxi mostly was caused by increasing precipitation. However, precipitation was declined and reduced LPP to the south of QM; that is, precipitation decline was the dominated climatic factor for LPP decrease in QM, Hanjiang Basin (HB), and Daba Mountain (DM). To the north of QM, LPP in AS, LP, and Guanzhong Plain (GP) both dramatically increased, mainly improved by rising temperature, increasing precipitation, and rising temperature, respectively.

The low-cost composite film was prepared by incorporating chitosan, berry soap fruit extract (rarasaponin), and bentonite as the raw materials. The produced chitosan/rarasaponin/bentonite (CRB) composite exhibits outstanding adsorption capability toward copper metal ions (Cu(II)). A series of static adsorption experiments were carried out to determine the isotherm and kinetic properties of CRB composite in the adsorption process. The adsorption equilibrium shows a good fit with the Langmuir isotherm model; the CRB composite has maximum uptake of Cu (II) of 412.70 mg/g; the kinetic adsorption data exhibit a good fit with the pseudo-second-order model. The thermodynamic parameters, ΔH°, ΔG°, and ΔS°, obtained from the isotherm data indicate that the uptake of copper ions by CRB composite is more favored at low temperatures. This study shows that physicochemical modified adsorbent, namely CRB composite, can remove Cu (II) better than pristine adsorbent of AAB and chitosan. The CRB composite also shows potential reusability.

Organic matter (OM), a complex entity with diverse functional groups and molecular sizes, has important effects on aquatic systems. We studied the optical compositions and sources of dissolved organic matter (DOM) and particulate organic matter (POM) in Lake Taihu, a large, shallow and eutrophic lake in China. Significant differences in optical compositions and sources occurred between the POM and DOM. The temporal–spatial distribution of the fluorescence indices suggested that the POM in Lake Taihu was mainly from autochthonous sources, but more exogenous characteristics were shown in POM in the river mouths compared with other regions. The chromophoric DOM in Lake Taihu mainly displayed autochthonous characteristics. The POM–DOM PARAFAC model was used to examine OM optical composition and five components were identified, which contained three protein-like components (C1, C2, and C5), a microbial humic-like component (C3), and a terrestrial humic-like component (C4). The POM was dominated by C5 in summer and autumn and C3 in winter and spring, and the DOM was dominated by protein-like components (C1, C2, and C5) through the entire year. The algae-dominated region had a relative higher contribution of tryptophan-like components of POM compared with the macrophyte-dominated region. A conceptual model based on the theory of “four phases of cyanobacteria bloom development” was proposed to fully describe the relationship between POM–DOM exchanges and cyanobacteria bloom development.