Evaluation of Organic Matter Removal Efficiency and Microbial Enzyme Activity in Vertical-Flow Constructed Wetland Systems

In this study, enzyme activities and their relationships to organics purification were investigated in three different vertical flow constructed wetlands, namely system A (planting Pennisetum sinese Roxb), system B (planting Pennisetum purpureum Schum.), and system C (no plant). These three wetland systems were fed with simulation domestic sewage at an influent flow rate of 20 cm/day. The results showed that the final removal efficiency of Chemical Oxygen Demand (COD) in these three systems was 87%, 85% and 63%, respectively. Planting Pennisetum sinese Roxb and Pennisetum purpureum Schum. could improve the amount of adsorption and interception for organic matter in the substrate, and the amount of interception of organic matter in planting the Pennisetum sinese Roxb system was higher than that in planting the Pennisetum purpureum Schum. system. The activities of enzymes (urease, phosphatase and cellulase) in systems A and B were higher than those in system C, and these enzyme activities in the top layer (0–30 cm) were significantly higher than in the other layers. The correlations between the activities of urease, phosphatase, cellulase and the COD removal rates were R = 0.815, 0.961 and 0.973, respectively. It suggests that using Pennisetum sinese Roxb and Pennisetum purpureum Schum. as wetland plants could promote organics removal, and the activities of urease, phosphatase and cellulase in those three systems were important indicators for COD purification from wastewater. In addition, 0–30 cm was the main function layer. This study could provide a theoretical basis for COD removal in the wetland system and supply new plant materials for selection

Effect of Water Immersion on Compressive Properties of Coir Fiber Magnesium Phosphate Cement

Magnesium phosphate cement (MPC) is a new type of inorganic cementitious rapid repair material, but it has poor toughness and is easy to crack. According to our previous research, these problems can be ameliorated by adding natural coir fiber (CF) into MPC. As coir fiber magnesium phosphate cement (CF-MPC) may be used in humid or rainy areas, its water resistance is an important property in consideration. However, at present, little research has focused on this aspect to provide a good theoretical and experimental basis for the practical application of CF-MPC. In this paper, static compression test and solubility test were used to study the mechanical properties and solubility of CF-MPC under water. At the same time, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to test the changes of hydration composition and microstructure of the test specimen, so as to understand the deterioration mechanism of CF-MPC in water. The results suggested that, when compared with CF-MPC cured in air, CF-MPC cured in water is more prone to encounter oblique cracks and through cracks in the compression process. Moreover, with the extension of curing time, the compressive strength and elastic modulus of CF-MPC cured in water will continue to decrease, the concentrations of PH, K+, and Mg2+ in the curing solution will change significantly, resulting in the gradual decrease in the mass ratio of MgO and MgKPO4·6H2O in CF-MPC matrix, cracks and pores, and looseness in the microstructure

Inhibition of the bioavailability of heavy metals in sewage sludge biochar by adding two stabilizers.

Agricultural application of sewage sludge (SS) after carbonization is a plausible way for disposal. Despite its benefits of improving soil fertility and C sequestration, heavy metals contained in sewage sludge biochars (SSB) are still a concern. In this study, two types of heavy metal stabilizers were chosen: fulvic acid (FA) and phosphogypsum (with CaSO4, CS, as the main component). The two stabilizers were incorporated into SS prior to 350°C carbonization for 1 h at the rates of 1%, 2%, or 4%. The obtained SSBs were then analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Total and available concentrations of four heavy metals, i.e., Zn, Pb, Cd, and Ni, in the SSBs were determined. In addition, a series of pot soil culture experiments was conducted to investigate the effects of stabilizers incorporation into SSB on heavy metal bioavailability and the uptake by plants (corn as an indicator) and plant biomass yield, with SS and SSB (no stabilizers) as controls. The results showed that incorporation of both FA and CS increased functional groups such as carboxyl, phenol, hydroxyl, amine and quinine groups in the SSBs. The percentage of heavy metals in sulfuric and oxidizable state and residual state of SSBs were significantly increased after carbonization, and hence the mobility of the heavy metals in SSBs was decreased. The introduction of the stabilizers (i.e., FA or CS) significantly lowered the total and available concentrations of Zn, Pb, Cd, and Ni. The reduction in available heavy metal concentration increased with incorporation rate of the stabilizers from 1% to 4%. In the treatments with FA or CS incorporated SSB, less heavy metals were taken up by plants and more plant biomass yields were obtained. The mitigating effects were more pronounced at higher rates of FA or CS stabilizer. These findings provide a way to lower bioavailability of heavy metals in SS or SSB for land application or horticulture as a peat substitute

Correction: Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity.

[This corrects the article DOI: 10.1371/journal.pone.0159802.]

Rapid Antibiotic Adsorption from Water Using MCM-41-Based Material

The contamination of antibiotics in the environment has raised serious concerns, impacting both human life and ecosystems. This has led to a growing focus on the development of cost-effective and environmentally friendly adsorbent materials. Mesoporous molecular sieve MCM-41, known for its strong adsorption capacity, low cost, and efficient regenerative properties, holds significant promise for addressing this issue. In this study, we investigated the adsorption behavior of demolded MCM-41 materials in relation to tetracycline, doxycycline, and levofloxacin at different temperatures and pH levels. Our experiments encompassed the adsorption of these three common antibiotics, revealing that a neutral or weakly acidic pH environment promoted adsorption, whereas alkaline conditions hindered it. Utilizing the equilibrium isotherm model, we determined the theoretical maximum adsorption capacities for tetracycline (TC), doxycycline (DOX), and levofloxacin (LFX) as 73.41, 144.83, and 33.67 mg g−1, respectively. These findings underscore the significant potential of MCM-41 in mitigating antibiotic wastewater contamination

What is the optimal dose of adipose-derived mesenchymal stem cells treatment for knee osteoarthritis? A conventional and network meta-analysis of randomized controlled trials

Abstract Background Despite increasing clinical investigations underscoring the efficacy and safety of adipose-derived mesenchymal stem cells (AD-MSCs) therapy in knee osteoarthritis (KOA), no article has recently reviewed the cell dosage. This study aimed to evaluate the efficacy and safety of varying doses of AD-MSCs in treating KOA using conventional and network meta-analysis. Methods A search of databases in in Chinese and English was performed to identify randomized controlled trials (RCT) on MSCs for knee osteoarthritis from the inception date to May 1, 2022. This study mainly analyzed the efficacy of AD-MSCs in the treatment of KOA, and subgroup analysis was performed on the therapeutic effects of MSCs from different tissues at the same dose. We divided the different cell doses into low, moderate, and high groups, with the corresponding cell doses: (0–25)*10^6, (25–50)*10^6, and > 50*10^6 cells, respectively. We further analyzed the improvement of improvement of the Visual Analog Scale (VAS) and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores and the incidence of adverse events (AEs) after varied dosage injection. Results A total of 16 literatures were included in this study, of which 8 literatures were about AD-MSCs. Conventional meta-analysis suggests that AD-MSCs can reduce pain and improve function in KOA patients, regardless of the cell doses, up to 12 months of follow-up. The network meta-analysis showed that intra-articular injection of AD-MSCs significantly improved pain and knee function scores in KOA patients compared with the control group at 3, 6, and 12 months. Among the three groups, the high-dose group had the best treatment effect, and the degree of joint pain and dysfunction indicators improved more significantly in the early stage. For adverse events, there was a dose–response trend that increased with increasing doses. Conclusions Both cell doses reduced pain and improved knee function in KOA patients. The effect surpassed in the high-dose group than in the moderate-dose, low-dose and control groups. However, adverse events also increase with the increase in dose, which should be carefully considered in clinical application, and the side effects still need to be paid attention to. Considering the limitations of this meta-analysis, future studies need to further explore the efficacy and safety of different doses of treatment, and carry out large sample, multi-center, randomized controlled trials to ensure the reliability and promotion value of the research results

Inhibition of the bioavailability of heavy metals in sewage sludge biochar by adding two stabilizers - Fig 7

<p>HR-XPS patterns of the samples: raw SSB (a), (d), (g), (j); SSBFA4 (b), (e), (h), (k); SSBCS4 (c), (f), (j), (l). (SSBFA4 and SSBCS4 are SSB incorporated with 4% FA and 4% CS, respectively).</p