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Release of phosphorus from sewage sludge during ozonation and removal by magnesium ammonium phosphate
2017
The release rule of phosphorus from sewage sludge during ozonation and removal by the magnesium ammonium phosphate (MAP) method were investigated. The results showed that the concentrations of total phosphorus in aqueous phase (TP₍A₎) and orthophosphate (PO₄ ³⁻-P) in ozonized sludge supernatant rose obviously with increasing ozone dose when ozone dose was below 61.2 mg O₃/gSS then almost kept constant. The TP₍A₎ and PO₄ ³⁻-P contents in the ozonized sludge supernatant were 70.9 and 63.3 mg/L when ozone dose was 61.2 mg O₃/gSS, respectively. Total phosphorus in the sludge solid (TP₍S₎) was mostly distributed in inorganic phosphorus (IP) (more than 81.5% of TP₍S₎), and non-apatite inorganic phosphorus (NAIP) was the major component of IP in the sludge (more than 78.7% of IP) during ozonation. The release contribution (RC) of IP to TP₍A₎ accounted for over 73.9%. The optimized conditions for the removal of phosphorus from ozonized sludge supernatant were set at an initial Mg²⁺/PO₄ ³⁻-P molar ratio of 1.8, pH 9.5, and reaction time of 5 min, under which the removal efficiencies of TP₍A₎ and PO₄ ³⁻-P were 43.1 and 52.2%, respectively.
Show more [+] Less [-]Ecological determinants of health: food and environment on human health
2017
Li, Alice M. L.
Human health and diseases are determined by many complex factors. Health threats from the human-animal-ecosystems interface (HAEI) and zoonotic diseases (zoonoses) impose an increasing risk continuously to public health, from those emerging pathogens transmitted through contact with animals, food, water and contaminated environments. Immense challenges forced on the ecological perspectives on food and the eco-environments, including aquaculture, agriculture and the entire food systems. Impacts of food and eco-environments on human health will be examined amongst the importance of human interventions for intended purposes in lowering the adverse effects on the biodiversity. The complexity of relevant conditions defined as factors contributing to the ecological determinants of health will be illuminated from different perspectives based on concepts, citations, examples and models, in conjunction with harmful consequential effects of human-induced disturbances to our environments and food systems, together with the burdens from ecosystem disruption, environmental hazards and loss of ecosystem functions. The eco-health literacy should be further promoting under the “One Health” vision, with “One World” concept under Ecological Public Health Model for sustaining our environments and the planet earth for all beings, which is coincidentally echoing Confucian’s theory for the environmental ethics of ecological harmony.
Show more [+] Less [-]Life cycle analysis of perfluorooctanoic acid (PFOA) and its salts in China
2017
Meng, Jing | Lü, Yonglong | Wang, Tieyu | Wang, Pei | Giesy, John P. | Sweetman, A. J. (Andrew J.) | Li, Qifeng
China has been the largest producer and emitter of perfluorooctanoic acid and its salts (PFOA/PFO). However, the flows of PFOA/PFO from manufacture and application to the environment are indistinct, especially flows from waste treatment sites to the environment. Here, a life cycle analysis of PFOA/PFO is conducted in which all major flows of PFOA/PFO have been characterized for 2012. Processes related to uses and possible releases of PFOA/PFO include manufacture and use, waste management, and environmental storage. During manufacture and use, emission from application was the most important (117.0 t), regardless of whether it flowed first to waste treatment facilities or was directly released to the environment, followed by manufacture of PFOA/PFO (3.9 t), while flows from the service life and end of life of consumer products were the lowest (1.2 t). Among five waste treatment routes, flows through wastewater treatment plants (WWTPs) were the highest (10.6 t), which resulted in 12.8 t of PFOA/PFO being emitted into the environment. Masses of PFOA/PFO emission were estimated to be 96.3 t to the hydrosphere, 25.6 t to the atmosphere, and 3.2 t to soils. Therefore, control over reduction of PFOA/PFO should focus on application of reliable alternatives and emission reduction from WWTPs using effective treatment techniques.
Show more [+] Less [-]Degradation of Direct Red 81 mediated by Fenton reactions: multivariate optimization, effect of chloride and sulfate, and acute ecotoxicity assessment
2017
Marson, Eduardo O. | de Paiva, Vinícius A. B. | Gonçalves, Bárbara R. | Gomes Júnior, Oswaldo | Borges Neto, Waldomiro | Machado, Antonio E. H. | Trovó, Alam G.
The role of different operational parameters related to Fenton reactions (pH, concentration of Fe²⁺ and H₂O₂, and reaction time) and of Cl⁻ and SO ₄ ⁻ was investigated in the degradation of the azo dye Direct Red 81, expressed in terms of its decolorization. The factorial design and Pareto’s charts showed that only Fe²⁺ concentration and pH influence the decolorization under the conditions evaluated. So, only these parameters were optimized using the response surface model. Under the best experimental conditions (initial pH 2.5, 11 mg L⁻¹ Fe²⁺, 78 mg L⁻¹ H₂O₂, and 20 min of reaction), 94 % of decolorization was achieved. However, even under the these conditions, but in the presence of Cl⁻ and SO ₄ ⁻ , a striking loss of efficiency was observed as the concentration of these ions was increased, due the formation of chloride- and sulfate-iron complexes and less reactive inorganic radicals (Cl₂ •– and SO₄ •–). The results show that the presence of Cl⁻ is more deleterious, since sulfate-iron complexes are more reactive towards H₂O₂, and the SO₄ •– turns out to favor the degradation. On the other hand, the negative effect of Cl⁻ can be compensated by increasing the chloride concentration up to 300 mmol L⁻¹. In addition, although a high degradation level has been obtained by monitoring the dye absorbance and by HPLC-UV, a low mineralization occurred, being generated degradation products of higher ecotoxicity to Vibrio fischeri, showing the need of subsequent studies to identify these compounds as well as the application of additional treatments aiming the complete mineralization of the dye.
Show more [+] Less [-]Treatment of a simulated textile wastewater containing the Reactive Orange 16 azo dye by a combination of ozonation and moving-bed biofilm reactor: evaluating the performance, toxicity, and oxidation by-products
2017
Castro, Francine D. | Bassin, João Paulo | Dezotti, Márcia
In this study, an aqueous solution containing the azo dye Reactive Orange 16 (RO16) was subjected to two sequential treatment processes, namely: ozonation and biological treatment in a moving-bed biofilm reactor (MBBR). The most appropriate ozonation pretreatment conditions for the biological process and the toxicity of the by-products resulting from RO16 ozone oxidation were evaluated. The results showed that more than 97 % of color removal from the dye solutions with RO16 concentrations ranging from 25 to 100 mg/L was observed in 5 min of ozone exposure. However, the maximum total organic carbon removal achieved by ozonation was only 48 %, indicating partial mineralization of the dye. Eleven intermediate organic compounds resulting from ozone treatment of RO16 solution were identified by LC/MS analyses at different contact times. The toxicity of the dye-containing solution decreased after 2 min of ozonation, but increased at longer contact times. The results further demonstrated that the ozonolysis products did not affect the performance of the subsequent MBBR, which achieved an average chemical oxygen demand (COD) and ammonium removal of 93 ± 1 and 97 ± 2 %, respectively. A second MBBR system fed with non-ozonated dye-containing wastewater was run in parallel for comparison purposes. This reactor also showed an appreciable COD (90 ± 1 %) and ammonium removal (97 ± 2 %), but was not effective in removing color, which remained practically invariable over the system. The use of short ozonation times (5 min) and a compact MBBR has shown to be effective for the treatment of the simulated textile wastewater containing the RO16 azo dye.
Show more [+] Less [-]Thermoactivated persulfate oxidation of pesticide chlorpyrifos in aquatic system: kinetic and mechanistic investigations
2017
Zhou, Lei | Zhang, Ya | Ying, Rongrong | Wang, Guoqing | Long, Tao | Li, Jianhua | Lin, Yusuo
The widespread occurrence of organophosphorus pesticides (OPPs) in the environment poses risks to both ecologic system as well as human health. This study investigated the oxidation kinetics of chlorpyrifos (CP), one of the typical OPPs, by thermoactivated persulfate (PS) oxidation process, and evaluated the influence of key kinetic factors, such as PS concentrations, pH, temperature, bicarbonate, and chloride ions. The reaction pathways and mechanisms were also proposed based on products identification by LC-MS techniques. Our results revealed that increasing initial PS concentration and temperature favored the decomposition of CP, whereas the oxidation efficiency was not affected by pH change ranging from 3 to 11. Bicarbonate was found to play a detrimental role on CP removal rates, while chloride showed no effect. The oxidation pathways including initial oxidation of P=S bond to P=O, dechlorination, dealkylation, and the dechlorination-hydroxylation were proposed, and the detailed underlying mechanisms were also discussed. Molecular orbital (MO) calculations indicated that P=S bond was the most favored oxidation site of the molecule. The toxicity of reaction solution was believed to increase due to the formation of products with P=O structures. This work demonstrates that OPPs can readily react with SO₄ ·⁻ and provides important information for further research on the oxidation of these contaminants.
Show more [+] Less [-]Determination of low-level plutonium in seawater by sector field inductively coupled plasma mass spectrometry: method validation
2017
Vassileva, Emilia | Han, Eunmi | Lévy, Isabelle
Sources of plutonium isotopes to the marine environment are well defined, both spatially and temporally which makes plutonium (Pu) a potential tracer for oceanic processes. This paper presents the optimisation and validation of an analytical procedure for ultra-trace determination of Pu isotopes (²³⁹Pu and ²⁴⁰Pu) in seawater based on the external calibration and sector field inductively coupled plasma mass spectrometry (SF ICP-MS) determination. Additionally, method for Pu isotope ratio (²⁴⁰Pu/²³⁹Pu) in marine samples is also discussed. A combination of two-step anion exchange (AG1-X8) and one-step extraction chromatography (TEVA) was very efficient resulting in uranium (U) decontamination factor of 5 × 10⁶–1 × 10⁸. A full validation approach in line with ISO 17025 standard and Eurachem guidelines was followed. With this in mind, blanks, recovery (87 ± 8 %, k = 2), within-laboratory repeatability (5.6 %), limits of detection (0.12 and 0.08 fg mL⁻¹ for ²³⁹Pu and ²⁴⁰Pu, respectively) and expanded uncertainty (13 %, k = 2) were systematically assessed. The procedure was applied for the determination of ²³⁹Pu and Pu in seawater sample coming from Mediterranean Sea. Obtained results were in good agreement with results obtained with alpha spectrometry, applied on the same seawater sample. Pu/²³⁹Pu atom ratio in seawater sample from the Mediterranean Sea was also determined. The precision and accuracy of ²⁴⁰Pu/²³⁹Pu isotopic ratio analysis were carefully examined using NBS-947 isotopic standard. ²⁴⁰Pu/²³⁹Pu ratio was found to be 0.187 ± 0.006 and is in agreement with accepted ratios for the global fallout of Pu.
Show more [+] Less [-]Influence of UV-A radiation on oxidative stress and antioxidant enzymes in Mythimna separata (Lepidoptera: Noctuidae)
2017
Ali, Arif | Rashid, Muhammad Adnan | Huang, Qiu Ying | Lei, Chao-Liang
Abiotic stress factors, including ultraviolet (UV) radiation, significantly affect insect life. UV-A radiation (320–400 nm) has been widely used for insect control since it increases the production of ROS and causes oxidative cell damage. In the present study, we evaluated the effects of UV-A irradiation on an important pest in China, the ear-cutting caterpillar, Mythimna separata (Lepidoptera: Noctuidae). We exposed 3-day-old M. separata adults to UV-A radiation for different periods of time (0, 30, 60, 90, and 120 min) and evaluated the resulting total antioxidant capacity and the activity of the antioxidant enzymes superoxide dismutase, catalase, peroxidase, and glutathione-S-transferase. The total antioxidant capacity significantly increased after exposure to UV-A radiation for 60 min but decreased after 90 and 120 min of exposure, compared with the control. The antioxidant activity of glutathione-S-transferase, superoxide dismutase, catalase, and peroxidase increased after 60-min exposure, and it was decreased at the longest exposure period 120 min. The longest exposure time period relatively activates the xenobiotic detoxifying enzymes like glutathione-S-transferase, superoxide dismutase, catalase, and peroxidase enzymes. The longest duration of UV-A radiation may cooperate with pesticide detoxification mechanism in insects, making them more susceptible to insecticides. Our results demonstrated that UV irradiation causes oxidative stress, affects the activity of antioxidant enzymes, and disturbs the physiology of M. separata adults.
Show more [+] Less [-]Root-foraging behavior ensures the integrated growth of Vallisneria natans in heterogeneous sediments
2017
Chen, Jianfeng | Hu, Xu | Cao, Te | Zhang, Xiaolin | Xi, Yilong | Wen, Xinli | Su, Haojie | de Silva, Wasana | Zhu, Tianshun | Ni, Leyi | Xie, Ping
The present study was carried out to determine the efficacy of root foraging and the physiological response of Vallisnaria natans grown in heterogeneous sediments. V. natans was cultivated in two homogeneous and two heterogeneous sediments. The results suggested that V. natans grown in heterogeneous sediments presented a significantly higher root proportion in its total biomass, exhibited root foraging, and grew well, as indicated by a total biomass, ramet number, and plant height very close to those of plants grown in nutrient-rich clay sediment. Moreover, the more sensitive physiological response of the roots than the stems or the leaves to sediment nutrients suggested that root foraging occurred, and the approached values between the two heterogeneous sediments and the homogeneous clay sediment indicated that V. natans could satisfy its nutrient requirements via root foraging. The results may be useful in the recovery of macrophytes that remodel part (rather than all) of the substrate and can potentially improve habitats that are unsuitable for plant growth.
Show more [+] Less [-]Long-term broiler litter amendments can alter the soil’s capacity to sorb monensin
2017
Doydora, Sarah A. | Sun, Peizhe | Cabrera, Miguel | Mantripragada, Nehru | Rema, John | Pavlostathis, Spyros G. | Huang, Ching-Hua | Thompson, Aaron
Monensin is a common antiparasitic drug given to poultry that contaminates poultry manure and bedding material (broiler litter). As broiler litter is commonly applied to agricultural fields as fertilizer, monensin could be released beyond the farm if it is not retained or degraded in the soil. This study aimed to assess the impact of long-term surface application of broiler litter (i.e., 17 years) on the capacity of pasture soil to sorb monensin. The soils were exposed to a range of monensin concentrations (0.18 to 1.81 μmol L⁻¹), solution pH (pH 4–9), and temperatures (15, 25, and 35 °C) and monensin was measured as loss from solution (i.e., sorption). Soils receiving long-term litter applications were hypothesized to retain more monensin than unamended soils because they have higher organic matter concentrations. However, soils from broiler litter-amended fields sorbed 46% less monensin than soils from unamended fields, likely because broiler litter also increased soil pH. The sorption of monensin to soil was strongly influenced by pH, with an order of magnitude greater sorption at pH 4 than at pH 9. Both soils had similar capacity to sorb monensin under similar solution pH, despite differences in organic carbon content (with the broiler litter-amended having 25% greater relative to the unamended soil). Temperature did not significantly impact monensin sorption for either soil. Our findings suggest increasing soil pH, for instance through liming, could enhance mobility of monensin.
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