Based on the characteristic that the air can form a vortex around the carrier after passing through the suspended carrier, a new layered fan-like carrier and a wave multi-channel carrier were prepared by designing the spatial structure of the suspension carrier and combining 3D printing technology. Compared with commercially available multi-faceted hollow sphere carrier, clear water oxygenation experiment was carried out in a transparent organic glass reactor, and the aeration volumetric flow rate was 0.28, 0.42, 0.56, 0.70, and 0.84 VVM, respectively. The results show that the growth rate of dissolved oxygen, the saturation value of dissolved oxygen, and the oxygen mass transfer coefficient in the new type of carrier reactor are higher than those of commercially available multi-faceted hollow spheres and blank reactors at various aeration intensities. Under the condition of aeration volumetric flow rate at 0.56 VVM, the reactor can reach dissolved oxygen saturation at a faster rate of dissolved oxygen growth. Combined with the FLUENT numerical simulation and sewage treatment experiments, it is proved that changing the spatial structure of the carrier can accelerate the reoxygenation of the water body, increase the value of dissolved oxygen saturated in the water, and create ideal mass transfer conditions for the MBBR (moving bed biofilm reactor).

The innovation of novel absorbing materials using composite materials and nanotechnology is of new trends for many researches. Here, the present study is concerning to enhance the distilled water productivity of a proposed solar still (PSS) using novel absorbing materials. The absorbing material is composed of chitosan (obtained from waste shrimp shells), ethylene diamine tetraacetic acid (EDTA), and Chrysopogon zizaniodes (Vetiver). The combination of these materials is coined as CHEDZ, and it acts as a super absorbent polymer that is coated on the stepped solar still. Evaporation rate increases due to this absorbent, which further increases the yield of the still. In this present study, the PSS is compared with the conventional solar still (CSS) for the use of assessing the yield of freshwater in the same atmospheric circumstance. The experimental setup was performed through the period from December to February 2020 in the Indian climatic condition. The freshwater productivity was improved to 3.05 L/day while the yield of the CSS is 2.47 L/day. The increase in efficiency obtained from a PSS is 39.71% more than the productivity attained from the CSS. The energy efficiency of the PSS is 18.34% and the exergy efficiency is 0.45%.

Problems of ecological environment and resources have become an important factor restricting the high-quality development of China’s economy. How to better integrate into the sustainable development model has become an important goal of macro-policy regulation in the transition period. Mining industry is a fundamental industry in China. Strengthening the incentive role of mining innovation is of great importance for ensuring China’s energy security, reducing emissions and promoting economic growth. However, whether environmental regulation can induce technological innovation ability, that is, the existence of Porter effect, is still controversial. It is helpful to study the influence of the Porter hypothesis on mining enterprises for their sustainable development. Based on the data of listed companies in China from 2003 to 2018, and against the background of the SO₂ emission trading pilot policy implemented in 2007, this paper studies the incentive effect of the market-incentive environmental regulation on the technological innovation ability of mineral resource enterprises, tests the existence of Porter effect, and discusses the heterogeneity. The results show that the market-incentive environmental regulation has a significant incentive effect on the innovation of mining enterprises, and there is significant Porter effect on mining enterprises. The robustness test confirms the correctness of this conclusion. At the same time, this paper also discusses the variation of the characteristics of heterogeneous enterprises, and finds that enterprises with utility model patents, no low-carbon behavior, and non-provincial cities and regions with high environmental regulation are more sensitive to the SO₂ emission trading pilot policy. This paper verifies the incentive effect of the market-incentive environmental regulation on the innovation ability of mining enterprises, and provides a reference for the formulation of innovation incentive policies for mining enterprises in China.

Different individually applied commercial salts at different concentrations are generally used to precipitate contaminants in wastewater. In this study, we developed a treatment complementary to the lagoon system of a wastewater treatment plant by adding a combination of trivalent metal salts to chemically precipitate phosphate contaminants. Laboratory tests were conducted to determine the most efficient treatment for the removal of phosphate in wastewater by analyzing orthophosphate using the ascorbic acid method. Three trivalent metal salts—iron (III) sulfate, aluminum (III) sulfate, and iron (III) chloride—were combined with each other at three different concentrations, obtaining an experimental design involving 27 treatments replicated three times each. Analysis of variance (ANOVA) with Tukey’s test revealed the treatment for which the highest percentage of orthophosphate removal (99.04%) was obtained. Finally, the selected treatment was implemented for field evaluation over three weeks, obtaining an average removal of 93.13%.

The present study sought to evaluate the efficiency and kinetics of nitrogen removal in Horizontal Subsurface Flow Constructed Wetlands (HSSF-CWs) cultivated with different plant species used in the treatment of swine wastewater (SWW), under different nitrogen loading rates (LRTKN). For this purpose, nine tanks measuring 2.0 × 0.5 × 0.6 m were used, one maintained without plants (CW₁), while in the others two plant species were evaluated: CW₃, CW₅, CW₇, and CW₉ were planted with Tifton 85 grass (Cynodon spp.) and CW₂, CW₄, CW₆, and CW₈ were planted with cattail (Typha latifolia). The CWs received TKN application rates between 110 and 413 kg ha⁻¹ day⁻¹, and the removal efficiencies ranged from 27.6 to 44.9%. The average mass removal rates (MRR) for TKN and NH₄⁺ ranged from 45.3 to 115.9 kg ha⁻¹ day⁻¹ and 28.9 to 66.5 kg ha⁻¹ day⁻¹, respectively. Tifton 85 grass and cattail contributed, respectively, to 2.22 to 8.7% and 0.03 to 1.67% of the TKN mass removed by the CWs (MRR), equivalent to extraction rates of 2.72 to 4.94 kg ha⁻¹ day⁻¹ and 0.04 to 1.11 kg ha⁻¹ day⁻¹. Coefficients estimated by conventional, modified, and residual first-order models ranged from 0.017 to 0.0187 day⁻¹, 0.0691 to 0.1285 day⁻¹, and 0.0298 to 0.0715 day⁻¹, respectively. The modified first-order model and that with residual, due to their higher R² values (R² > 93%), indicated a good fit and considerable reliability of these equations to describe the processes of nitrogen removal from swine wastewater treated in HSSF-CW, and due to their mathematical simplicity and improvements in the representation of real behavior, they should be preferred for modeling of these systems.

Investigations of the impact of heavy metals on microbial community structure are crucial for bioremediation of the contaminated sites. To this end, high-throughput 16S rRNA sequencing was performed to assess the variations of bacterial communities in 6 heavy metal-contaminated soils sampled from Liujiaping (LJP) and Shanping (SP) lead–zinc tailings situated in northwestern China. Compared with those of the farmland soil (NT), the heavy metal levels and chemical properties of the tailing soils were significantly different. Consistently, the bacterial community structures have been changed, displaying as the bacterial richness and diversity in the tailing soils were either increased or decreased, i.e., trending as SP > NT > LJP. The relative abundances of certain bacterial phyla mainly including Actinobacteriota, Acidobacteriota, Cyanobacteria, Gemmatimonadota, and Bacteroidota were significantly increased in certain SP and/or LJP soils. Further, the relative abundances of Actinobacteriota and Bacteroidota were positively correlated with Cd, TP, TK, SOM, TN, and pH. The abundance of Cyanobacteria was significantly upregulated by Cu, Zn, and TP. Acidobacteriota was notably positively correlated with Cr, Pb, and NO₃⁻_N. On the contrary, the relative abundance of Chloroflexi was negatively correlated with all the environmental parameters, especially with Cd, NO₃⁻_N, TP, SOM, and TN. Together, our results implied that the heavy metals and chemical properties were both driving forces of the variations of the bacterial community structures in the tailing soils. Overall, we have successfully identified certain bacterial species such as s__unclassified_g__Sulfurifustis, s__unclassified_f__Rhodanobacteraceae, s__unclassified_g__Conexibacter, s__unclassified_g__norank_f__norank_o__Gaiellales, and s__unclassified_g__Blastococcus which were probably heavy metal-tolerant in these specific tailing soils, and this will provide a theoretical support for further bioremediations.

Regular monitoring and measurement of Legionella in tower water and preventive measures against contamination are particularly important in hospitals. This study aimed at risk assessment and disease burden because of legionella presence in cooling towers of Iran’s central hospitals. Then its correlation with temperature, pH, turbidity, residual chlorine, and EC was investigated by the Pearson test. The health risk and burden of diseases caused by Legionella exposure were determined using QMRA and DALY models. Statistical analysis and modeling were performed in MATLAB₂₀₁₈. Of the total samples, 30–43% was infected with Legionella. The mean concentrations in hospital A and B were 5–102.5 ± 10 and 5–89.7 ± 0.7 CFU/L, respectively. Among environmental factors, turbidity and pH were the most effective factors in increasing and decreasing Legionella concentration, respectively. According to the QMRA model, the risks of Legionella infections and annual mortality in both hospitals were 0.2–0.3, 0–0.19, 2–2.9 × 10⁻⁵, and 0–0.7 × 10⁻⁵, respectively, which was higher than the acceptable risk range for Legionella (10-4–10-7). However, the trend of its change was negatively correlated with time (RB = − 0.77). According to the results, the concentration of Legionella and the exposure risk in both hospitals were higher than the permissible range, which is necessary to decrease to 0.1 current concentrations.

This study investigated the Pb(II) and Cd(II) sorption from aqueous solution by oily sludge-derived char (OSDC) prepared at different pyrolysis temperatures and chemical activation. The maximum Pb(II) sorption capacity for OSDC at pyrolysis temperature of 500 °C (OS500) was found as 351.48 mg/g, which was greater than that of OSDC produced at other temperatures. Post-sorption characterizations using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and sequential extraction test indicated the precipitation was the principal mechanism of sorption of Pb(II) onto OSDC prepared at low pyrolysis temperature (≤ 500 °C). The Pb(II) sorption capacity dramatically decreased as the pyrolysis increased from 500 to 900 °C. This is because the alkaline minerals decomposed at high temperature (≥ 700 °C), thereby the mineral precipitation with Pb(II) was inhibited. With increasing pyrolysis temperature from 500 to 900 °C, the contribution of precipitation to Pb(II) sorption decreased from 93.79 to 34.63%, while the contribution of complexation increased from 0 to 44.68%. The sorption capacity of Cd(II) was less than that of Pb(II), and no precipitation was formed during Cd(II) sorption by OSDC. Sorption results showed that OSDC prepared at pyrolysis temperature of 700 °C (OS700) had the best sorption capacity for Cd(II) (92.14 mg/g). The high sorption capacity of OS700 for Cd(II) was mainly attributed to the carboxyl/hydroxyl functional groups and complexation with mineral oxides. The hydrothermal treatment (8M NaOH solution) activated OS500 significantly with respect to surface area, cation exchange capacity (CEC), and total pore volume (PV). The substitution of Pb(II) with alkaline earth metals led to precipitation in the form of hydrocerussite (Pb₃(CO₃)₂(OH)₂) that was mainly responsible for Pb(II) sorption on activated OS500 (accounted for 93.79%). The activated OS500 showed a higher sorption capacity (90.06 mg/g) for Cd(II) than OS500 (23.95 mg/g) because the conversion of barite (BaSO₄) to witherite (BaCO₃) after chemical activation favored the precipitation of Cd carbonate. The contributions of precipitation to the total Cd(II) removal was 0% for OS500 but 76.12% for the activated OS500.

This work proposed a novel mathematical framework for the sustainability assessment of sewage sludge to energy (SStE) scenarios, by resorting to fuzzy multi-criteria decision-making (MCMD) methods. In which, an evaluation system including twelve criteria from four dimensions was introduced, while the fuzzy triangular number (TFN) was used to address the hybrid-data issue in the decision-making. More importantly, four fuzzy MCDM methods were used to make the following methodological contributions: (1) the fuzzy full consistency method (FUCOM) was extended into uncertain conditions to determine the weights easily and reliably, which preserves the consistency in ambiguous, subjective judgments; (2) a novel TFN-based fusion ranking model was developed by aggregating three fuzzy MCDM approaches, which not only takes the hybrid data as input information for decision-making (by combining the TFN) but also promotes the confidence in final prioritization (by reconciling different sequences). Four illustrative SStE scenarios were studied to test the feasibility of the model. Besides, the effectiveness and advantages of the model were verified by results comparison and discussion.

Ordered mesoporous MgO was synthesized via template method by using magnesium nitrate as a precursor and amphiphilic triblock copolymer Pluronic F127 as a template. The products were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), and the Brunauer-Emmett-Teller (BET) method was used to calculate the specific surface areas. The effects of aging time, relative humidity, and magnesium nitrate content on the morphology and textural properties of the products were studied. When the aging time was 36 h and the relative humidity was 40%, the ordered mesoporous MgO with uniform pore sizes (3.2 nm), high specific surface areas (517.2 m²/g), and high pore volumes (0.42 cm³/g) were obtained. Furthermore, the adsorption properties of ordered mesoporous MgO as adsorbent for removal of Pb(II) and Cd(II) ions were studied. The adsorption kinetics and isotherm data agreed well with pseudo-second-order model and Langmuir model, indicating that the adsorption of heavy metal ions on the ordered mesoporous MgO was mainly chemical and homogeneous adsorption. The maximum adsorption capacities for Pb(II) and Cd(II) ions were up to 3073.5 mg/g and 1485.1 mg/g, respectively.