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Combination of microalgae cultivation and piggery wastewater treatment has become a hot topic in recent years. Nutrient removal from aerated piggery wastewater (APW) by Desmodesmus sp. CHX1 and the optimization of cultivation conditions were investigated in this study. Results indicated that Desmodesmus sp. CHX1 showed an efficient growth in APW, with specific growth rate of 0.26–0.56 d−1. The biomass yield based on nutrient consumption was 9.65 g biomass/g NH4–N and 209.15 g biomass/g total phosphorus (TP) respectively. Desmodesmus sp. CHX1 performed well in nutrient removal from APW, with ammonium nitrogen (NH4–N) and TP removal efficiency (RE) of 78.46% and 91.66% respectively after 7 days of culture. Nutrient removal process fitted the pseudo-first-order kinetic equations well, with removal rate (RR) constant of 0.24 d−1 for NH4–N and 0.28 d−1 for TP. The optimum conditions for nutrient removal from APW by Desmodesmus sp. CHX1 were light intensity of 150 μmol photons m−2 s−1 in the photoperiod for 24 h when the temperature was set at 35°C with alga cell inoculation concentration of 30%. The removal efficiencies of NH4–N and TP were 88.26% and 95.06% respectively under the optimal conditions after 7 days of culture. Our results can be a good reference for enhancement of microalga production and the nutrient RE and further extend the application of the large-scale piggery wastewater treatment under a controlled environment. [ABSTRACT FROM AUTHOR]

To promote growth and lipid production of microalgae for biodiesel, aeration effect was studied on growth of a microalga Desmodesmus sp. CHX1 cultured in BG - 11 medium. Results showed that aeration could dramatically increase the algal biomass, chlorophyll (a + b) content and lipid productivity. After 7d cultivation with the aeration 160L/h, the maximum biomass of CHX1 cell, chlorophyll (a + b) content and lipid productivity reached 7. 26g/L, 60. 5mg/L and 128.7mg/(L · d) respectively, which were significantly higher than those of control. Results suggested that aeration was favorable for the growth of microalgae and accumulation of valuable additional materials during the cultivation of Desmodesmus sp. CHX1, and was also for enhancement of cell growth and lipid production. [ABSTRACT FROM AUTHOR]

By using phosphoric acid as activation agent, active carbon was prepared from Thalia dealbata residues. The BET specific surface area of the active carbon was 1174. 13 m2 · g-1, micropore area was 426. 99 m2 ·g-1, and average pore diameter was 3. 23 nm. An investigation was made on the adsorption performances of the active carbon for crystal violet from aqueous solution under various conditions of pH, initial concentration of crystal violet, contact time, and contact temperature. It was shown that the adsorbed amount of crystal violet was less affected by solution pH, and the adsorption process could be divided into two stages, i. e. , fast adsorption and slow adsorption, which followed the pseudo-second-order kinetics model. At the temperature 293, 303, and 313 K, the adsorption process was more accordance with Langmuir isotherm model, and the maximum adsorption capacity was 409. 83, 425. 53, and 438. 59 mg·g-1, respectively. In addition, the adsorption process was spontaneous and endothermic, and the randomness of crystal violet molecules increased. [ABSTRACT FROM AUTHOR]

The content and speciation of heavy metals in composted sewage sludge is the main cause of negative impacts on environment and health of animal and human. An aerobic composting procedure was conducted to investigate the influences of some key parameters on phytotoxicity and speciation of Cu, Zn and Pb during sewage sludge composting. The pH value reached the optimal range for development of microorganisms, and content of organic matter (OM) and dissolved organic carbon (DOC) decreased with the composting age. The total amounts of Cu, Zn and Pb were much lower in the final compost. The results from sequential extraction procedure of heavy metals showed that composting process changed the distribution of five fractions of Cu, Zn and Pb, and reduced the total contents and sum percentages of four mobile fractions (exchangeable (EXCH), carbonate (CAR), reducible iron and manganese (FeMnOX), and organic matter bound (OMB)), indicating that the metal mobility and phytotoxicity decreased after aerobic composting. The seed germination and root growth of Pakchoi (Brassica Chinensis L.) were enhanced with composting age and reached the highest value at the end of compost. The decrease of OM and DOC was significantly correlated to changes of metal distribution and germination index (GI) of Pakchoi. Only for Cu in the compost, the GI could be predictable from the sum mobile metal fractions (EXCH+CAR+FeMnOX+OMB) (R =−0.814*). For Zn and Pb, R value was significantly increased by use of other components, such as pH, OM and DOC, which suggested that the transformation of heavy metal speciation and phytotoxicity of sewage sludge during an aerobic composting was rather strongly dependent on multiple components than a single element. [Copyright &y& Elsevier]

Parametric modeling and simulation based on manufacturing characteristics were studied. Combined VC and SQL server with Pro/E and Ansys as tools, framework of parametric computer integrated simulation with manufacturing characteristics was established. Through analysis of the output character of drill chuck, the feasibility of parametric simulation method considering manufacturing characteristics such as dimension and position errors and the validity of integrated simulation system were preliminarily verified. The results showed that modeling and simulation based on manufacturing characteristics could be more accurate, and could predict the running performance of mechanical system. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was carried out to compare differences in potential activities of ammonification, nitrification and denitrification in rhizosphere and bulk soil in a heavy-metal-stressed system. Exchangeable fractions of Cd, Cu and Cr were all higher in the rhizosphere of maize than in bulk soil. Results showed that the mineralization of N in soil was stimulated by low concentration of Cd. Addition of Cd at low levels stimulated the ammonifying and nitrifying activity in soil, while inhibitory influences were shown at high levels. Nitrifying bacteria was proved to be the most sensitive one, whilst the effect on denitrifying bacteria was very limited. Comparing Cd, Cu and Cr(VI) at 20 mg/kg soil, Cd was the most effective inhibitor of ammonification and denitrification, while Cr(VI) had the strongest inhibitory influence on nitrifying activity. Root exudates played important roles on the different exchangeable metal fractions and bacterial activities between rhizosphere and non-rhizosphere. Nitrate was the main form of mineral N in soil, as well as the main form of N absorbed by plants, but the formation and relative absorption of ammonium were promoted in response to high Cd exposure. [ABSTRACT FROM AUTHOR]

The ability of Elsholtzia splendens Naki (E. splendens) to accumulate copper appears to be governed by its high degree of copper tolerance. However, the tolerance mechanism on the physiological basis is unknown. Using transmission electron microscope (TEM) and energy dispersive analysis of X-rays (EDX), the likely location of copper within the cells of the tolerant and non-tolerant was determined. Here the role of vacuolar and cell wall compartmentalization in this copper tolerant plant were investigated. A direct comparison of copper locations of E. splendens and the non-tolerant Astragalus sinicus L. (A. sinicus) showed that the majority of copper in the tolerant was localized primarily in the vacuolar, cell wall, on the plasmamembrane, beside lipid grains induced by copper pollution, in the chloroplasts and amyloids; but in the non-tolerant, copper precipitates only be observed on the plasmamembrane, in the chloroplasts and cytoplasm under copper exposure conditions that were toxic to both species. This revealed that the tolerant accumulates more copper in the vacuole and cell wall than the non-tolerant, where was regarded as the storage compartment of tolerant plant or hyperaccumulator for heavy metals. [ABSTRACT FROM AUTHOR]

Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field practices, such as fertilization, flooding/draining management were investigated to study on agricultural activities on paddy field affect the dynamic process of the emission. Under no addition of fertilizers the average emission flux of nitrous oxide was 8.55 μg/(m^2·h) during the rice (Oryza Sativa L.) growth season. The results indicated that most of nitrous oxide emissions occurred during the crack forming-and-expansion period when paddy field was being drained. The diurnal emissions peak of nitrous oxide appeared at 20:30 at night in cracked rice fields. The statistical analysis suggested that the correlation of nitrous oxide emissions flux (Y) with soil water content (X_1), soil temperature (X_2), and Eh (X_3), could be described in a regression equation: Y= - 1498.95 + 2895.48 X_1 + 50.63 X_2 -96.99 X_1 · X_2 + 0.006 X_2· X_3. There were the different power equations to simulate the correlations between the everyday dynamic N_2O emissions and the mean surface area of cracks, mean volume and depth of cracks respectively during paddy soil drying by soil columns incubation experiments. Taken all together, the current study presented a dynamic analysis of nitrous oxide emission of paddy field under various conditions, therefore provided a basis for the management to balance between environmental effect and paddy field activities. [ABSTRACT FROM AUTHOR]

The literature from a long-term fertilization experiment in the Yangtze River Economic Belt from January 1992 to May 2022 was collected, and the data of farmland soil organic carbon were extracted and integrated. Using the normalization treatment and the analysis method of relative annual variation, the overall change in soil organic carbon content in farmland in the Yangtze River Economic Belt under different long-term fertilization measures was studied, and the change differences of soil organic carbon content under three tillage modes were compared so as to judge and analyze the influence of the duration of the experiment on soil organic carbon dynamics. The results showed that under different long-term fertilization measures, the organic carbon content of farmland soil in the Yangtze River Economic Belt in China showed an overall upward trend. The NP, NPK, O, and NPKO treatments all increased the organic carbon content of agricultural soils, with that of the NPKO treatment being the largest. The sole application of inorganic nitrogen fertilizer reduced the organic carbon content of the soil. The rates of change in soil organic carbon content were 0.22 g·(kg·a) -1 , 0.24 g·(kg·a) -1 , and 0.16 g·(kg·a) -1 for dryland, paddy, and water-dry rotation farmland, respectively. Additionally, the relatively rapid increase effect of organic carbon brought by the O and NPKO treatments could last for no more than 28 years in dryland soil but could still last for more than 28 years in paddy field and paddy-upland rotation soil. There was some variation in the rate of change of soil organic carbon content between soil types. The average rate of change of organic carbon was 0.25 g·(kg·a) -1 for red soils, 0.14 g·(kg·a) -1 for brown soils, 0.19 g·(kg·a) -1 for tidal soils, and 0.15 g·(kg·a) -1 for rice soils. The trend of NPKO>O>NPK>NPK>NP>N was basically maintained for the rate of change in soil organic carbon content. The NPKO treatments were all significantly higher than the chemical fertilizer (N, NP, and NPK) treatments alone. The N treatment showed a reduction in organic carbon content in both red soil and rice soils. Considering the carbon fixation of farmland soil, the combined application of organic and inorganic fertilizers is a more suitable fertilization method in this area.

By using phosphoric acid as activation agent, active carbon was prepared from Thalia dealbata residues. The BET specific surface area of the active carbon was 1174.13 m2 x g(-1), micropore area was 426.99 m2 x g(-1), and average pore diameter was 3.23 nm. An investigation was made on the adsorption performances of the active carbon for crystal violet from aqueous solution under various conditions of pH, initial concentration of crystal violet, contact time, and contact temperature. It was shown that the adsorbed amount of crystal violet was less affected by solution pH, and the adsorption process could be divided into two stages, i. e., fast adsorption and slow adsorption, which followed the pseudo-second-order kinetics model. At the temperature 293, 303, and 313 K, the adsorption process was more accordance with Langmuir isotherm model, and the maximum adsorption capacity was 409.83, 425.53, and 438.59 mg x g(-1), respectively. In addition, the adsorption process was spontaneous and endothermic, and the randomness of crystal violet molecules increased.