152 research outputs found
Autotrophic denitrification by mixed culture of thiobacillus denitrificans and heterotrophs in an activated sludge system
No full textUse of Membrane Bioreactors for the bioremediation of chlorinated compounds polluted groundwater
No full textCombined removal of sulfur compounds and nitrate by autotrophic denitrification in bioaugmented activated sludge system
No full textAn autotrophic denitrification process using
reduced sulfur compounds (thiosulfate and sulfide) as electron donor in an activated sludge system is proposed as an efficient and cost effective alternative to conventional heterotrophic
denitrification for inorganic (or with low C/N ratio) wastewaters and for simultaneous removal of sulfide or thiosulfate and nitrate. A suspended culture of sulfurutilizing
denitrifying bacteria was fast and efficiently established by bio-augmentation of activated sludge with Thiobacillus
denitrificans. The stoichiometry of the process and the key factors, i.e. N/S ratio, that enable combined sulfide and nitrogen removal, were determined. An optimum N/S ratio of 1 (100% nitrate removal without nitrite formation and low thiosulfate concentrations in the effluent) has been obtained during reactor operation with thiosulfate at a nitrate loading rate (NLR) of 17.18 mmol N L-1 d-1.
Complete nitrate and sulfide removal was achieved during
reactor operation with sulfide at a NLR of 7.96 mmol
N L-1 d-1 and at N/S ratio between 0.8 and 0.9, with
oxidation of sulfide to sulfate. Complete nitrate removal while working at nitrate limiting conditions could be achieved by sulfide oxidation with low amounts of oxygen present in the influent, which kept the sulfide concentration
below inhibitory levels
Vibration Minimisation of Moving Flexible Slender Structures Based on Time-Parameterised B-Spline
No full textVibration mitigation of moving flexible structures is a key issue in many applications. Examples include antennas, solar arrays, radar reflectors, and manipulator arms, especially in the aerospace sector. These structures typically consist of inter-connected slender and flexible elements moved by external actuators to reach specific configurations and positions. The movements excite vibrations, which lead to the risk of structural and fatigue failures; once in position, residual vibrations can be further amplified by structure lightness, causing bad performance and malfunctioning of onboard sensors. This paper proposes an effective technique to minimise the vibration of moving flexible structures by calculating the control points of a time-parametrised B-spline representing the shape of the motion law. A testing case of a rotating cantilever beam is considered. Validation using multi-flexible-body simulation software has shown the method’s effectiveness in minimising residual vibrations
Autotrophic denitrification for combined hydrogen sulfide removal from biogas and leachate treatment
No full textSimultaneous biological removal of sulfide and nitrate by autotrophic denitrification in an activated sludge system
No full textThe feasibility of an autotrophic denitrification process in an activated sludge reactor, using sulphide as the electron donor, was tested for simultaneous denitrification and sulphide removal. The reactor was operated at nitrate (N) to sulphide (S) ratios between 0.5 and 0.9 to evaluate their effect on the N-removal efficiency, the S-removal efficiency and the product formation during anoxic oxidation of sulphide. One hundred per cent removal of both nitrate and sulphide was achieved at a NLR of 7.96 mmol N(.)L(-1.)d(-1) (111.44 mg NO3(-)-N(.)L(-1.)d(-1)) and at a N/S ratio of 0.89 with complete oxidation of sulphide to sulphate. The oxygen level in the reactor (10%) was found to influence the N-removal efficiency by inhibiting the denitrification process. Moreover, chemical (or biological) oxidation of sulphide with oxygen occurred, resulting in a loss of the electron donor. FISH analysis was carried out to study the microbial population in the system
Utilizzo di bioreattori a membrana per il risanamento di acque di falda contaminate da composti clorurati
No full textThe solution structure of a recombinant homologue of the fungal elicitor protein PcF reveals a helix-loop-helix motif
No full textInhibitory effect of rosemary essential oil, loaded in liposomes, on seed germination of Acacia saligna, an invasive species in Mediterranean ecosystem
No full textAcacia saligna (Labill.) Wendl. is native of southwestern Australia, but has been planted extensively in many areas of the world, including the Mediterranean region, becoming highly invasive especially in coastal habitats. The aim of this study was to test whether the indigenous Rosmarinus officinalis L essential oil (EO), loaded in liposomes, can inhibit the seed germination of the invasive alien Acacia sangria. Variability in seed germination requirements and responses among populations were evaluated. Germination tests under light, at constant temperatures and three concentrations of rosemary EO were carried out. Among the examined factors, only the EO amount and temperature had a highly significant effect on seed germination. The lowest EO quantity did not show differences compared with the control, while the highest amount inhibited significantly seed germination of all populations at all the tested temperatures. No seed recovered the ability to germinate after the EO treatment with either of the two washing methods. Our results allowed us to identify the minimum amount of rosemary EO capable of inhibiting the seed germination of the invasive Acacia saligna. These results could be useful for the control of this invasive alien species, thus allowing the conservation of indigenous Mediterranean plant species and habitats
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