Clean-soil Air Water最新文献

This study aims to explore the effect of the activator type, activation time, and activator concentration on the denitration performance of activated carbon (AC). Combined with denitration experiments, scanning electron microscopy, pore size analysis, and Fourier transform infrared spectroscopy characterization methods, an orthogonal experiment was conducted using zinc chloride (ZnCl₂), phosphoric acid (H₃PO₄), and potassium hydroxide (KOH) as activators to explore the interaction between various factors and their effect on the denitration performance of AC. The results show that the denitration rate of ZnCl₂-activated AC is generally low because a high concentration of ZnCl₂ will block the micropores of AC and destroy the original structure. The denitration rate of H₃PO₄-activated AC decreased with the increase in H₃PO₄ concentration, especially severe blockage occurred on the AC-H3 surface. KOH activation can optimize the pore structure of AC and generate some oxygen-containing functional groups, which is beneficial to improve the adsorption performance of AC. Orthogonal experiments showed that the activator type had the most obvious effect on the denitration rate, followed by the activation time, whereas reagent concentration had little effect on the denitration rate. The optimum activation condition was 3 mol L⁻¹ KOH at 80°C for 3.5 h.

Carbon sequestration is the process of capturing, securing and storing carbon dioxide from the atmosphere. In this study, the carbon sequestration capacity of Hedera colchica was investigated in soil of a semiarid region in Iran. Samples were taken from plants cultivated in the semiarid area of the polluted metropolis of Tehran and the amount of sequestered carbon in the aboveground and underground parts of the plant was measured. The conversion coefficient of carbon sequestration of plant organs (stem, leaf, and root) was determined separately by the combustion method. Carbon tax policy was used to evaluate the carbon sequestration function, as the shadow price of carbon. The results showed a significant difference in the amount of carbon sequestration in different organs of the plant. Stems and roots with 29.3 and 4.3 t ha⁻¹, respectively, showed the highest and lowest amount of carbon deposition. The results of the economic value showed that the carbon shadow price was $40567.6 ha⁻¹ on average. In general, the results of this study showed that the organs of H. colchica can have a beneficial effect in the process of carbon sequestration.

Since phosphorus resources are limited, optimal management of available phosphorus (P) and phosphorus recovery is a vital issue for the entire world. Studies continue on more efficient and economical phosphorus recovery techniques from wastewater and sludge. Recovery of phosphorus as vivianite is a current issue worldwide and studies are ongoing. Vivianite is a valuable mineral used in some industrial facilities and agricultural activities. Therefore, recovery of P from wastewater based on vivianite formation not only contributes to the sustainable use of phosphorus but also provides potential economic opportunities. In this study, it was aimed to determine the recovery potential of phosphorus as vivianite and to evaluate the effects of operational conditions on phosphorus recovery. For this purpose, two types of lab-scale crystallizer, semibatch completely mixed and fluidized bed, were used. In experimental studies, the effects of operating parameters such as pH, Fe/P ratio, Fe feeding rate, and P concentration for vivianite crystallization were investigated. The highest phosphorus recovery was found at a Fe/P ratio of 1.8 and P removal efficiency of up to 69% was achieved by vivianite crystallization.

In general people spend most of their time in enclosed environments, therefore, they are exposed to indoor radon and its progeny. The paper discusses the variables influencing indoor radon levels. It assesses the correlation between indoor radon levels with temperature, humidity, and pressure, as well as seasonal variables. Radon activity concentrations were measured in Ege University's laboratories and Classroom using a digital radon gas detector. After statistical analysis, the results were compared to committee-permissible limit levels (ICRP, WHO, and EU). It was found that the average radon activity concentrations were below the recommended 300 Bq m^–3 limit value (EU), ranging from 58.4 to 216.0 Bq m^–3. This study emphasized the significance of measuring and assessing the indoor radon levels in laboratories and classrooms in particular, in order to safeguard the students and faculty members from radon-related health issues.

Advances in biodigester technology have been promoted by the growing study of anaerobic digestion, with the aim of improving processes related to the utilized waste load. This research used the statistical tool Central Composite Rotatable Design to optimize the combination of microorganisms and enzymes for biodigestion. The experiment involved testing two microorganisms (EA and EB) and five enzymes (amylase, protease, lipase, cellulase, and amyloglucosidase) with food waste from nearby restaurants and WWTP sludge as an inoculant. The experiment was set up as Central Composite Rotatable Design (CCRD) 2^6-1, with 50 trials and a concentration of 14.5 g of volatile solids per liter. The dependent variables of cumulative biogas production (BG) and cumulative biomethane production (BM) were evaluated. The results showed that the independent variables EB and CA had negative and significant effects on BG and BM production. With optimized process conditions, the bioaccelerator significantly improved BG and BM responses compared to control trials by 72% and 88%, respectively. The biodigestion technique is a viable option for the treatment of organic waste, and the use of bioaccelerators may be a promising approach to improving biodigestion processes. This study contributes to the ongoing research on anaerobic digestion and biodigester technology, which seeks to improve the sustainable management of organic waste while producing renewable energy.

Activated sludge filtration performance is a significant mean to evaluate membrane fouling trend for wastewater treatment. Here the impact of sunlight irradiation on activated sludge filtration performance and microbial communities in sequencing batch reactors (SBRs) when treating raw landfill leachate were studied. The sludge in photic SBR (i.e., SBR exposed to natural sunlight) exhibited better filtration performance compared to dark SBR (i.e., SBR unexposed to sunlight). The removal efficiency of COD and NH₄⁺-N in the photic SBR were slightly higher than those in the dark SBR. The contents of the extracellular polymeric substances (EPSs) of sludge in both SBRs initially increased and then decreased. However, in the later period, the sludge filtration performance worsened due to the fungal activity in the dark SBR. Natural sunlight irradiation promoted sludge filtration performance by affecting the microorganism structure in the photic SBR. The bacterial genus Thauera was dominant in the photic SBR (39.35%), whereas Planktosalinus and Ottowia were dominant in the dark SBR (16.84% and 12.55%, respectively). Natural sunlight irradiation had a prominent effect on the fungal diversity in the system, and filamentous bulking caused by the fungi genus Trichosporon’s proliferation was observed in the dark SBR but not in the photic SBR, which also increased the polysaccharide content.

Hydrogen sulfide (H₂S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H₂S) gas from the atmosphere is very essential. In the present work, self-priming venturi scrubber is employed to extract H₂S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H₂S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H₂S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H₂S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R² resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H₂S removal efficiency, whereas inlet H₂S concentration has the least effect.