Porous-carbon/manganese composite catalyst transformed from waste biomass as peroxymonosulfate activator for carbamazepine degradation.

Activation of peroxymonosulfate (PMS) with solid catalysts for organic pharmaceutical degradation still faces challenge due to the demand of inexpensive catalysts. In this study, manganese-oxidizing microalgae (MOM) and its associated biogenic manganese oxides (BMO) were employed to prepare biomass-transformed porous-carbon/manganese (B-PC/Mn) catalyst through high-temperature calcination (850 °C). Remarkably, 100 % of carbamazepine (CBZ) was degraded within 30 min in the B-PC/Mn/PMS system. The degradation kinetic constant was 0.1718 min-1, which was 44.0 times higher than that of the biomass-transformed porous carbon mixed with MnOx activated PMS system. 1O2 was generated in the B-PC/Mn/PMS system, which is responsible for CBZ degradation. The MOM-BMO-associated structure greatly increased the specific surface areas and the contents of the C = O and pyrrolic-N groups, which facilitated PMS activation. The structure also induced the generation of Mn5C2, which exhibited a strong adsorption towards PMS. This study provides a novel strategy for preparing catalysts by using waste biomass.

Adsorption of Heavy Metal Ions Copper, Cadmium and Nickel by Microcystis aeruginosa.

To investigate the treatment effect of algae biosorbent on heavy metal wastewater, in this paper, the adsorption effect of M. aeruginosa powder on heavy metal ions copper, cadmium and nickel was investigated using the uniform experimental method, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and TG-DSC comprehensive thermal analysis. The experimental results showed that the initial concentration of copper ion solution was 25 mg/L, the temperature was 30 °C, the pH value was 8 and the adsorption time was 5 h, which was the best condition for the removal of copper ions by algae powder adsorption, and the removal rate was 83.24%. The initial concentration of cadmium ion solution was 5 mg/L, the temperature was 35 °C, the pH value was 8 and the adsorption time was 4 h, which was the best condition for the adsorption of cadmium ion by algae powder, and the removal rate was 92.00%. The initial nickel ion solution concentration of 15 mg/L, temperature of 35 °C, pH value of 7 and adsorption time of 1 h were the best conditions for the adsorption of nickel ions by algae powder, and the removal rate was 88.67%. The spatial structure of algae powder changed obviously before and after adsorbing heavy metals. The functional groups such as amino and phosphate groups on the cell wall of M. aeruginosa enhanced the adsorption effect of heavy metal ions copper, cadmium and nickel. Additionally, M. aeruginosa adsorption of heavy metal ions copper, cadmium, nickel is an exothermic process. The above experiments show that M. aeruginosa can be used as a biological adsorbent to remove heavy metals, which lays a theoretical foundation for the subsequent treatment of heavy metal pollution by algae.

Combined Process of Biogenic Manganese Oxide and Manganese-Oxidizing Microalgae for Improved Diclofenac Removal Performance: Two Different Kinds of Synergistic Effects.

Biogenic manganese oxides (Bio-MnOx) have attracted considerable attention for removing pharmaceutical contaminants (PhCs) due to their high oxidation capacity and environmental friendliness. Mn-oxidizing microalgae (MnOMs) generate Bio-MnOx with low energy and organic nutrients input and degrade PhCs. The combined process of MnOMs and Bio-MnOx exhibits good prospects for PhCs removal. However, the synergistic effects of MnOMs and Bio-MnOx in PhCs removal are still unclear. The performance of MnOMs/Bio-MnOx towards diclofenac (DCF) removal was evaluated, and the mechanism was revealed. Our results showed that the Bio-MnOx produced by MnOMs were amorphous nanoparticles, and these MnOMs have a good Mn2+ tolerance and oxidation efficiency (80-90%) when the Mn2+ concentration is below 1.00 mmol/L. MnOMs/Bio-MnOx significantly promotes DCF (1 mg/L) removal rate between 0.167 ± 0.008 mg/L·d (by MnOMs alone) and 0.125 ± 0.024 mg/L·d (by Bio-MnOx alone) to 0.250 ± 0.016 mg/L·d. The superior performance of MnOMs/Bio-MnOx could be attributed to the continuous Bio-MnOx regeneration and the sharing of DCF degradation intermediates between Bio-MnOx and MnOMs. Additionally, the pathways of DCF degradation by Bio-MnOx and MnOMs were proposed. This work could shed light on the synergistic effects of MnOMs and Bio-MnOx in PhCs removal and guide the development of MnOMs/Bio-MnOx processes for removing DCF or other PhCs from wastewater.

Carbamazepine removal by the synergistic effect of manganese-oxidizing microalgae and biogenic manganese oxides.

Forty strains of Mn-oxidizing microalgae (MnOMs) with different Mn2+ oxidation mechanisms were identified from two aquatic environments. Among them, three strains of isolates (Chlamydomonas sp. WH1-1, Chlamydomonas sp. WH1-4, and Chlorella sp. WH2-5) oxidize Mn2+ by increasing the ambient pH and by secreting Mn oxidation factors (e.g., superoxide-production enzymes and/or other Mn oxidases) into the extracellular environment at the same time. In carbamazepine (CBZ) removal by MnOMs and/or Bio-MnOx, the combination of MnOMs and Bio-MnOx significantly increased the CBZ (1 mg/L) removal efficiency from 36.05% (by MnOMs alone) and 20.11% (by Bio-MnOx alone) to 80.13% by two synergistic mechanisms. One of the synergistic mechanisms was confirmed as that the Mn2+ was re-oxidized by MnOMs to Bio-MnOx, which can promote the CBZ removal, and another was the mutual exchange of degradation products of CBZ as shared reactants between MnOMs and Bio-MnOx. The degradation intermediates of CBZ were analyzed using high-performance liquid chromatography-tandem mass spectrometry, based on which the CBZ degradation pathway by MnOMs and Bio-MnOx was proposed. These findings expand existing knowledge on the Mn2+ oxidation mechanisms of MnOMs, and indicate that MnOMs and their generated Bio-MnOx are promising for the removal of CBZ or other pharmaceutical contaminants from wastewater.

A new insight into the mechanism of carbamazepine oxidation by MnO2: Crystalline structure versus Mn(III).

Mn(III) has been regarded as the origin of oxidative reactivity of MnO2 recently, however this remains controvertible. Herein, carbamazepine (CBZ), a typical refractory pharmaceutical, was treated by δ-, α-, ß-, and γ-MnO2 and the role of Mn(III) was investigated. After the removal of Mn(III) by pyrophosphate washing, the δ-MnO2 exhibited a higher kinetics rate (0.180 min-1) than the sample before washing (0.075 min-1). Dissolved Mn(III) in the forms of acetate-complex Mn(III), newly acid-dissolved Mn(III) from MnO2 solid, and in-situ generated Mn(III) showed negligible oxidative reactivity towards the oxidation of CBZ. These evidenced that Mn(III) did not play a critical role in the oxidation of CBZ. The oxidative reactivity of MnO2 with different structures for the oxidation of CBZ followed the order: δ-MnO2 >> > α-MnO2 ≈ Î³-MnO2 > ß-MnO2. Density functional theory calculations suggested that the crystalline plane of δ-MnO2 significantly contributed to the oxidation of CBZ, thus leading to the superior performance of δ-MnO2. A new surface reaction dominated mechanism was proposed, which implies that the oxidative reactivity of MnO2 may not result from Mn(III) as previously believed. These findings could shed light on the understanding of MnO2-involved oxidation in water treatment and natural processes.

Carbamazepine toxicity and its co-metabolic removal by the cyanobacteria Spirulina platensis.

Bioremediation of pharmaceutical-contaminated wastewater using microalgae has attracted increasing attention. Cyanobacteria, which are important prokaryotic microalgae, are widely distributed in different water environments, and have the advantages of simple culture and a fast growth rate. However, studies on either the toxicity of pharmaceutical contaminants (PhCs) to cyanobacteria or the removal of PhCs by cyanobacteria are scarce. In this study, carbamazepine (CBZ) and Spirulina platensis were selected as model PhCs and cyanobacteria, respectively. CBZ (>1 mg/L) had toxicity effects on S. platensis, showing maximal growth inhibition (34.0%) at 100 mg/L after 10 days of cultivation. At CBZ < 25 mg/L, S. platensis showed a trend similar to that of eukaryotic microalgae in increasing superoxide dismutase and catalase activities and content of chlorophylls, carotenoids, carbohydrates, and lipids. These results indicated that S. platensis had a similar protective mechanism to CBZ toxicity as that of the eukaryotic microalgae. Increasing CBZ concentration (50-100 mg/L) significantly decreased these biochemical characteristics and photosynthetic activity owing to the serious damage of the structure and function of S. platensis. However, with increasing cultivation time, the growth and photosynthetic activity of S. platensis recovered from the toxicity of CBZ. S. platensis showed a maximum of 30.97 ± 1.30% removal of CBZ (1 mg/L), mainly through biodegradation. Addition of 0.3 mg/L glucose enhanced this removal efficiency to 50.13 ± 2.51% via co-metabolism. These findings indicated that S. platensis can be used for the removal of CBZ or other PhCs from wastewater.

Effect of ammonium nitrogen on microalgal growth, biochemical composition and photosynthetic performance in mixotrophic cultivation.

To enhance microalgal growth and optimize ammonium utilization, the effect of ammonium on microalgal growth, biochemical composition and photosynthetic performance were investigated by mixotrophic cultivation of microalga Spirulina platensis comparing with autotrophic cultivation. The results indicated that elevated ammonium significantly affected the microalgal growth, but the microalga in mixotrophic cultivation showed better growth and stronger tolerance to higher ammonium. The microalgal proteins were increased by increasing nitrogen concentration. The synthesis of microalgal carbohydrates was inhibited by higher ammonium, especially in mixotrophic cultivation. The addition of ammonium decreased the microalgal lipids in autotrophic cultivation but increased microalgal lipids in mixotrophic cultivation. Ammonium negatively affected the microalgal photosynthetic performance. The inhibition was intensified by elevated ammonium, inducing stronger photosystem protection mechanism, particularly in mixotrophic cultivation. The rate of ammonium inhibition to the microalgal photosystem was quick in the early stage by decreasing electron transport rate of PS II.

Degradation mechanisms of carbamazepine by δ-MnO2: Role of protonation of degradation intermediates.

Carbamazepine (CBZ), a widely used antiepileptic drug, is refractory to biological wastewater treatment. Rapid removal of CBZ is possible using synthetic manganese oxide (δ-MnO2) but the removal mechanisms require further investigation. In this study, CBZ degradation by δ-MnO2 was carried out at different pH to further explore the degradation mechanisms. Results show that CBZ degradation by δ-MnO2 was highly pH dependent, and rapid degradation occurred when pH <2.8. Based on the density functional theory calculations, increasing [H+] not only increased the reactivity of δ-MnO2, but also enhanced the secondary reactions of the intermediates. During the degradation process, protonation of CBZ degradation intermediates, instead of CBZ, played an important role. The overall kinetics of CBZ degradation was then described by the retarded first-order model. The initial rate (rinit) in the model between pH 2.0 and 6.2 was determined to be rinit = (2.41 ±â€¯0.51) × 10-3[CBZ]1.21[MnO2]1.07[H+]1.41. This is the first report revealing that protonation of intermediates from CBZ degradation can improve the CBZ oxidation by δ-MnO2. The pathways of CBZ degradation by δ-MnO2 were also proposed. The results of this study provide a new insight into the processing mechanism.

Plant uptake of diclofenac in a mesocosm-scale free water surface constructed wetland by Cyperus alternifolius.

This study aimed to assess the uptake of diclofenac, a widely used nonsteroidal anti-inflammatory pharmaceutical, by a macrophyte Cyperus alternifolius in a mesocosm-scale free water surface (FWS) constructed wetland. Quantitative analysis of diclofenac concentrations in water solution and plant tissues was conducted by high performance liquid chromatography analysis after sample pre-treatment with solid-phase extraction and liquid extraction, respectively. The FWS with Cyperus alternifolius obtained a maximum 69.3% diclofenac removal efficiency, while a control system without plant only had a removal efficiency of 2.7% at the end of the experiment period of 70 days. Based on mass balance study of the experimental system, it was estimated that plant uptake and in-plant conversion of diclofenac contributed about 21.4% of the total diclofenac removal in the mesocosm while the remaining 78.6% diclofenac was eliminated through biotic and abiotic conversion of diclofenac in the water phase. Diclofenac on the root surface and in roots, stems and leaves of Cyperus alternifolius was found at the concentrations of 0.15-2.59 µg/g, 0.21-2.66 µg/g, 0.06-0.53 µg/g, and 0.005-0.02 µg/g of fresh weight of plant tissues, respectively. The maximum bioaccumulation factor of diclofenac was calculated in roots (21.04) followed by root surface (20.49), stems (4.19), and leaves (0.16), respectively. Diclofenac translocation potentiality from root to stem was found below 0.5, suggesting a slow and passive translocation process of diclofenac. Current study demonstrated high potential of Cyperus alternifolius for phytoremediation of diclofenac in FWS and can be applied in other engineered ecosystems.

[Cost-benefit analysis of netting cultivation to block the spread of Oncomelania snails in lake regions].

OBJECTIVE: To evaluate the cost-benefit of netting cultivation to block the spread of Oncomelania snails in lake regions. METHODS: The cost-benefit of netting cultivation was investigated by interviewing in the field, the cost of Oncomelania snail survey and control was investigated by retrospective review in Gaoyou Lake regions of Jinhu County from 2009 to 2011. The benefit of netting cultivation to block the spread of snails in lake regions was calculated by the benefit-cost ratio (BCR), and then the cost-benefit of them was calculated. RESULTS: The area of netting cultivation in Gaoyou Lake regions was 70.77 hm2, the average cost of netting cultivation was 495,595 yuan every year, the average income was 962,000 yuan every year, and the average benefit of netting cultivation was 466 405 yuan. The average cost of Oncomelania snail survey and control from 2009 to 2011 was 85,047.87 yuan in Gaoyou Lake regions. The ratio of cost-benefit was 1.11:1. The benefit was more than the cost. CONCLUSION: There is a well benefit in lake regions during blocking the spread of snails by netting cultivation.

[Evaluation of integrated control measures for soil-transmitted nematodiasis in Jinhu County, Jiangsu Province].

OBJECTIVE: To evaluate the effect of integrated control measures on soil-transmitted nematodiasis so as to provide the evidence for formulating the appropriate control strategies and measures in Jinhu County, Jiangsu Province. METHODS: Since 1995, the comprehensive control measures were carried out for soil-transmitted nematodiasis, and the measures included deworming, health education, safe water, sanitation and environmental remediation. The effects of the comprehensive control measures were evaluated by the investigations of the prevalence of soil-transmitted nematodiasis, awareness of health knowledge, and behaviors of residents. RESULTS: From 1995 to 2012, 646,437 person--times were administrated in deworming medication with 2.48 times per capita; the benefit rate of safe water was 97.90%; the popularity rate of harmless toilets was 86.89%. The awareness rate of health knowledge increased from 54.05% in 1996 to 95.60% in 2012, the difference between them were statistically significant (chi2 = 230.92, P < 0.01); the rate of correct health behaviors increased from 59.07% in 1996 to 96.40% in 2012, the difference between them had statistical significance (chi2 = 202.69, P < 0.01). The prevalence of soil-transmitted nematodiasis decreased from 62.57% in 1989 to 1.21% in 2012, the difference had statistical significance (chi2 = 1016.92, P < 0.01). The infection rates of Ascaris lumbricodes, hookworm and Trichuris trichiura were 0.58%, 1.12% and 0, respectively in 2012, and compared with the rates of those infections in 1989, the decline rates were 94.96%, 97.28% and 100% respectively, the differences between them were statistically significant (chi2 Ascaris = 129.50, chi2 hookworm = 544.62, chi2 Trichurisch = 254.19, all P < 0.01). CONCLUSION: The comprehensive control strategies and measures are effective and soil-transmitted nematodiasis has been controlled in Jinhu County.