Yearly Archives: 2018

Corn cob

Density

Fly ash

Mechanical properties

 

The research presented in this paper aim to analyze the effects of cement replacement by fly ash in 10 vol. %, 20 vol. %, and 30 vol. % and, afterwards, the effects of mineral aggregates substitution by 50 vol. % with vegetal aggregates. The used vegetal aggregates were shredded corn cobs, and were investigated the density, the compressive and split tensile strength of concrete. The results revealed that fly ash, as cement partial replacement, decreased the compressive strength comparing to the reference concrete, meanwhile, the splitting tensile strength was improved when were used 10% and 20% vol. of fly ash. Fly ash had a positive effect on the compressive strength of the vegetal concrete, in the case of the composition with 10% and 30% vol. of industrial waste, and also on splitting tensile strength in the case of 10% and 20% vol. of replacement rate. The concrete density diminished with 1.67%, 3.12% and 3.82% in the case of 10%, 20% and 30% vol. cement replacement by fly ash, respectively. Corn cob aggregates led to a concrete density decreasing with almost 25% compared to reference concrete.

Activated carbon

Adsorption 

Aqueous solution

Chemical activation

Dynamic conditions

Nut shells

 

In the paper the eliminating strontium ions from groundwater by using the CAN-7
activated carbon under dynamic conditions has been studied. The activated carbon
CAN-7 is obtained by the chemical method, through the treatment with orthophosphoric acid at distinct temperatures. It has been proved that by the reduction of
the filtration rate of the solution containing strontium ions through the adsorbent
column, the strontium ion adsorption is increased. The adsorption of strontium ions
from aqueous solutions on the CAN-7 activated carbon has been measured at
different lengths of working layer of the adsorbent column and at different filtration
rates of the solution. The length of working layer of the column with CAN-7 has
been determined as a function of the initial concentration of strontium ions and
filtration rates. The activated carbon CAN-7 with adsorbed strontium ions is
completely regenerated by 0.36% of hydrochloric acid. The obtained results for the
process of adsorption of strontium ions from aqueous solutions on the CAN-7
activated carbon under dynamic conditions has demonstrated the option of removing
this pollutant from the deep waters.

Black locust

Cooper ore

Oleaster

Tailing dumps

Wood

 

The present paper emphasizes the possibility of using wood from the plantations installed on waste heaps by analysing the density of wood mass and establishing the biomass of species planted on the waste heaps from Moldova Noua. In order to determine wood biomass for the analysed species, wood samples were gathered from a specific sample area. As such, their volume and mass were established both
before and after drying them in a stove at a temperature of 105 degrees Celsius for 24 hours. The plantations biomass was calculated by using wood density according to the work method previously described as well as the wood mass volume per hectare. The last element was determined after biometric measurements realized in
12 sample surfaces of 100 square meters each, arranged in four variants with three recursions. In the specific case of Moldova Noua waste heaps, the values obtained for wood density attest the high-quality wood of these plantations from the point of view of their density, in comparison with the wood from similar species grown
under favourable vegetation conditions. Furthermore, analysing the productivity of plantations installed on the waste heaps from Moldova Noua, attest the framing of these plantations in an inferior production class from a productive point of view. The papers conclusions discuss the obtained results in the context of data from specialty literature concerning the productivity and wood density of forest plantations from the waste heaps located in Moldova Noua.

Anolyte water

Squalene

Fodder protein

Growths activation

S. fibuligera Y-436

 

The phenomenon of growth activation of the industrial strain of mycelial fungus S.
fibuligera Y-436 under the influence of squalene and anolyte water has been
investigated. Squalene had a stimulating effect on the growth of the strain on YEPD
Broth in all doses. The stimulating effect of squalene was maintained for 54 hours,
in a dose of 0.0005% – up to 78 hours of the strain cultivation under aerobic
conditions. The growth rate of the strain in the exponential phase between 4 and 6
hours on medium with a squalene of 0.0005 % is 0.30, 0.001 % – 0.44, 0.002 % –
0.41, on medium without squalene – 0.24. Squalene promotes faster adaptation of
the strain to the substrate and reduces the duration of its lag phase of growth by 2-4 hours. The number of cells increases by 2.2-2.3 times with the use of squalene in
doses of 0.0005-0.001 % after 24 hours and by 1.4 times after 48 hours of
incubation on the nutritional mixture based on wheat flour. The strain reached the
stationary phase after 24 hours of cultivation with the use of squalene, while in the
control variant – after 48 hours. This reduces the duration of cultivation by 2 times.
Anolyte water contributed to the rise of generative activity of the strain due to the
acid reaction by 34.3 % in comparison with the initial water. The most effective
method of activation of the strain is the combined use of anolyte water and squalene in a dose of 0.0005-0.001 %.

Alga

Carbohydrate

Hydrothermal hydrolysis

Ionic liquid

Ulva sp.

 

Macroalgae represent a worldwide spread renewable source of valuable
biopolymers, polysaccharides and proteins that after pretreatment constitute an
intermediate platform for microbial and chemical production. In the present study
the potential of some ionic liquids (ILs) to extract and hydrolyze the algal
carbohydrates derived from Ulva sp. is examined and compared to the conventional
inorganic acid catalysts, H2SO4 and HCl. The experimental results reveal that the IL,
1 -butyl-3-methylimidazolium acetate, is superior to both acid auxiliaries in
extracting carbohydrates. The capacity of this IL for splitting reducing sugars under
the conditions of hydrothermal hydrolysis is comparable with the power of HCl, but
higher than HCl in terms of monosugar fraction and protein released. The highest
yields of reducing and monosugars and of protein are obtained by using the strong
dibasic acid, H2SO4. It could, however, produce dehydration by–products which
would incur inhibition of enzymatic and microbial processes fed by the algal liquor.

Mine water

Manganese

Reaction rate

 

Manganese removal from mine water by oxidation-precipitation often requires significant contact time and the use of a high pH-value for reaction stage. In order to avoid reactor over sizing or under sizing, kinetic data for manganese oxidation using
mine water or very similar aqueous systems are needed. As the batch type tests can be difficult to control (e.g. to set a certain pH value during the start-up), the continuous flow reaction systems seem to be more reliable as the direct determination of reaction rate is possible in this case.
Results obtained using manganese sulphate solution and real mine water are presented here. A third order reaction rate law was obtained, taking into account
homogenous and heterogeneous mechanism.

Activated carbon

Adsorption isotherms

Diffusion

Nano-iron

Uranium

 

This paper described the equilibrium and the kinetic of uranium adsorption from
waste water using activated carbon without/with nano-iron impregnated, applying
batch method. Adsorption isotherms of uranium equilibrium are analysed with
Freundlich isotherms which reveal high affinity to activated carbon impregnated
with nano-iron compared to nonimpregnate. Kinetic study showed that the decisive
step of the uranium adsorption process rate is the intraparticle diffusion.

 

Diesel oil

Electrode

Soil

 

The paper presents a study on the possibility of electrical decontamination of soils
contaminated with liquid petroleum products. The study involves the
characterization of a soil type by: capillary, permeability, retention and
granulometry. Electrically polluting is done with the help of stainless steel
electrodes arranged radially in a vessel. The pollutant-diesel oil product was
characterized by density and viscosity. The experiment had a duration of one week
and determined the degree of polluting and the influence of polluting soil on it.
Also, the germinating potential on such a depolarized soil was verified.

Degree of submergence

Downstream influence

Numerical modeling

Ogee spillway

 

 

The main aim of this study was to investigate flow over an ogee spillway and
simulating by numerical model. A commercially available computational fluid
dynamics (CFD) program, which solves the Reynolds-averaged Navier-Stokes
equations (RANS), was used to model the physical model setup. Flow over an ogee
spillway has free surface and turbulent flow so that in some cases calculating flow
rate and flow depths are difficult. Increasing in water level at downstream may
cause reduce in discharge because of suction forces and negative pressure. In this
study, different numerical turbulence models are used to predict discharge and
compared with experimental results. In experiments, discharge and flow depths of
physical model were recorded for 22 different total head over the crest. The results
show that there is reasonably good agreement between the physical and numerical
models for discharges.

Active carbon

Mechanism

Oxidation

Sulphide ion

 

The oxidation of sulphur (II) species with oxygen in the absence of catalysts is very slow, due to the unfavourable symmetry of the spin state resulting from the different
electronic configurations of the reactants. Among the efficient catalysts for the oxidation of sulphur (II) species the activated carbons are indicated, being able to
change the electronic configuration of the reactants (S(II) or O2). The type of the products and intermediates formed during the oxidation process with oxygen depends largely on pH, reagents concentrations (S(II), oxygen), and the type
of the activated carbon (as catalyst).
In this work the experimental results were corroborated with literature data, and plausible mechanism or reaction scheme was suggested for each case of active carbon used.

Adsorption

Autoclaved cellular concrete

Phosphate

Pumice stone

Wastewater

 

The need to develop new technologies for removing and recovering phosphates from wastewater has derived from increasing the demand for these sustainable compounds, setting stricter limits for discharges in order to prevent eutrophication of natural water resources, as well as tightening sludge disposal restrictions derived from wastewater plants. Removing phosphates from domestic and industrial wastewater and rationalizing the use of fertilizers in agriculture lead to reducing the main factors driving the proliferation of aquatic vegetation and hence, the secondary
pollution of surface water. The subject of this work is part of an environmental issue and proposes a method for wastewater depollution by using adsorption processes, taking into account the technical and economic aspects, by using low-cost adsorbents namely pumice stone and autoclaved cellular concrete (BCA). The
objectives of the present study were mainly to model phosphorus adsorption processes using Langmuir and Freundlich classical isotherms and to understand the influence of pH on these processes. For a complete description of the process,
isotherms were determined at pH values of 3 and 9, and mathematical processing of experimental data was attempted based on the above mentioned models. Based on the experimental results obtained, it is observed that the removal of phosphate ions
from the wastewater by adsorption processes on pumice stone and BCA is more efficient at a strongly acidic pH, and the Freundlich thermodynamic model offers better process behavior.

Ag-doped catalyst
dioxide

Rhodamine degradation

Titanium dioxide

 

In this work, the commercial titanium dioxide P25 was doped with silver ions via
wet impregnation method, in order to improve its catalytic activity. It is already well
established that Ag ions can improve the activity of a catalyst and diminish the
electron-holes recombination rate. The catalysts obtained by samples calcination at
450 and 600oC were tested as heterogeneous photocatalysts in the degradation of
Rhodamine 6G, a very stable fluorescent dye.
The obtained results confirm the improvement of the catalytic activity, compared to
TiO2 P25. Despite the degradation efficiency is not very high, it is worthy to note
that the Ag doped catalyst has a higher activity compared to commercial P25. Thus,
we can conclude that modifying the catalyst surface leads to an improvement of the
properties, probably by forming an intermediate energy level between the valence
and conduction bands of TiO2.

Dimensional analysis

Froude similarity

Hydraulic simulate

Ogee spillway

 

Ogee spillways are used to control the discharges and water levels in reservoir. In
some cases, steps and baffle blocks are placed at the stilling basin to change flow
regime supercritical to subcritical and improve energy dissipation. Physical models
are built in the laboratories to represent its real-world prototype; however some
scale effects may arise between models. Two open channel setups, called as model
and prototype, are used in this study. The experiments of the study are performed on
these channels using identical Froude Numbers and geometric scaling ratio of 4:1.
The flow depths at four different points are measured from model and prototype for
28 total head. The results showed that there is 92% consistency between model and
prototype, whereas this consistency was not observed at turbulence existing regions
due to scale effects.

Cr+6 ions

Electrocoagulation

Heavy metal removal

Wastewater

 

The removal of hexavalent chromium (Cr+6) ions from simulated wastewater was
investigated by using batch electrocoagulation. The influence of several variables on
the removal process was studied such as a type of electrodes, initial pH, initial
concentration of Cr+6 ions, electrolysis time, sodium chloride concentration and
current density. The experimental results showed that the removal efficiency of Cr+6
ions was more effective when using iron electrode comparing with the aluminium
electrodes. The maximum removal of Cr+6 ions was 96.58% at pH 6.0, initial ion
concentration 40 mg/L, electrolysis time 15 min, sodium chloride concentration 2
g/L, and the current density 30 mA/cm2.

Active carbon

Dynamic condition

Nitrite ions

Oxic condition

Removal

 

Active carbons have been found the most efficient and commonly used adsorbents
in water purification all over the world.
The purpose of this work was to investigate the possibility of applying active
carbons AG-5 and AG-5ox for the removal of nitrite ions from water in (i) dynamic
and (ii) oxic conditions.
Obtained results reveal that the sample AG-5 is more efficient for removal of nitrite
ions from water in the dynamic conditions but sample AG-5ox is more efficient in
oxic conditions.
The capacity of active carbon AG-5 for nitrite ions removal from water, expressed
in dynamic conditions as a ratio of the adsorbent volume to the solution volume
passed through column with adsorbent, is about 1:80.
Studies show that the application of the recommended method using the AG-5ox
carbonic adsorbent provides of 75% efficiency in the removal of nitrite ions from
natural water and 100% of the model solution.

Degraded terrains,
planting technology, soil remediation

Green infrastructure

Planting technology

Soil remediation

 

This paper aims to present a seedling planting innovative technology developed to
achieve forestation and rehabilitation works of degraded slope lands. Form the experimental data obtained from testing activity conducted to conclusion that the designed equipment’s are adequate and comply with the specific works
requirements, namely in heavy environmental conditions (degraded soil processing,
levelling and terrace surface modelling, planting settlement, etc.). This technology
answers to the need to implement measures of environmental rehabilitation (namely
restoration/ establishment of green infrastructure) and enhancement of slopedegraded forestlands. The innovation element consists in development of several adaptable equipment’s to the real working conditions (land stability, terrace dimensions, type of power source and seedlings planting variety) in order to achieve the highest performances and to respect labour safety standards. This technology
raises the mechanization performance of forestry and pomiculture works with impact on soil remediation, lowering the surface and depth erosion degree,
capitalization of rainwater, lowering the dust pollution and natural calamity risk and
the rehabilitation of inland flora. Appling this innovative technology within environmental management process can conduct to a good cost-benefit analysis that has a great impact on medium and long time by lowering the calamity risks and the
threads of entire populations and local species.

Dehydration

Drying process

Tunnel dryer

Sludge

 

The objective of this work is to give the fundamental information that should be
known about sludge drying methods. The purpose of all types of sludge processing
is to reduce the volume, stabilise the sludge, remove water and kill pathogenic
organisms. It is processed in stages that contain a sequence of treatments such as
thickening, dewatering and drying.
Sludge drying in tunnels using photovoltaic panels is a continuous operation from
the sludge treatment which reduces the water content of sludge by heating it for
short periods. Dried product not only reaches granular formation with 92 – 95% DS
but also gets stabilized. This is a complicated process with contemporary heat and
mass transfer attended by physical-chemical transformations. Drying occurs as a
result of vaporization of liquid by supplying heat to wet feedstock.

Carbon nanofibers

Characterization

Sol gel method

Nanocomposites,

Silver

 

The synthesis of ZnO/CuO with Carbon Nanofiber (CNF) and Ag nanocomposites
have been conducted. Nanocomposites were synthesized using sol-gel method. The
nanocomposite products were characterized by SEM, TEM, XRD and DSC. The
results of the XRD analysis showed that the CuO-ZnO composite has a nanometer
size with the average of 10 nanometer. The SEM-EDX analysis showed that the
ZnO has a hexagonal structure whereas the CuO has a monoclinic structure. The
importance of impregnating the nanofibers with the precursors has been
demonstrated. The hydrazine is a better reducing agent than tannic acid. In this study
was synthesized polycrystalline silver as evidenced by XRD. SEM-EDAX analysis
indicate presence of oxides, nanofibers and silver.

Absorption

Diluted solutions of NaOH

SO2

 

Ammonia

Copper (II)

Leaching

Thermodynamics

Thiosulfate