Degradation of recalcitrant organic contaminants by solar photocatalysis

2007 ◽  
Vol 55 (12) ◽  
pp. 119-125 ◽  
Author(s):  
L. Mansouri ◽  
L. Bousselmi ◽  
A. Ghrabi
Keyword(s):  
Organic Contaminants ◽  
Order Kinetic ◽  
Biological Degradation ◽  
Solar Photocatalysis ◽  
Photocatalytic Reactor ◽  
Operational Conditions ◽  
Toc Removal ◽  
The Matrix ◽  
Pre Treatment ◽  
Refractory Organic Pollutants

Biological pre-treated landfill leachates of Djebel Chakir contains some macromolecular organic substances that are resistant to biological degradation. The aim of the present work is to assess the feasibility of removing refractory organic pollutants in biological pre-treated landfill leachate by solar photocatalyse process. Leachate pollutant contents are studied to assess their contribution to leachate pollution and their treatability by solar photocatalyse process. Phenol is chosen as model of pollutants, to evaluate its removal and the efficiency of the photocatalytic system. The experiments were carried out in suspended photocatalytic reactor, using TiO2 Degussa P25, under sunlight illumination (UV-A: 15–31 W/cm2). Under optimum operational conditions, applied to single reactant (phenol), the system presents a TOC removal of 90% (the degradation follows a first-order kinetic). Based on the TOC removal, the results shows that the degradation of biological pre-treated leachate follows a zero-order kinetic. After 5 h of sunlight exposure, 74% of COT is removed. The TOC removal is the best without any correction of the pH and at the TiO2 concentration of 2.5 g/L. The photocatalytic degradation of organic contaminants as well as the formation and disappearance of the by-products were followed by GC/MS. The solar photocatalysis processes induce several modifications of the matrix leading to more biodegradable forms: all the remaining and new compounds generated after the biological pre-treatment of leachate are degraded and other types of organics appear, mainly carboxylic acid, aliphatic hydrocarbons and phtalic acids.

Treatment of local scrubber wastewater for semiconductor by using photo-catalytic ozonation

2009 ◽  
Vol 59 (11) ◽  
pp. 2281-2286 ◽  
Author(s):  
Chung-Yi Chou ◽  
Chien-Pin Huang ◽  
Neng-Chou Shang ◽  
Yue-Hwa Yu
Keyword(s):  
Ion Exchange ◽  
Removal Efficiency ◽  
Removal Rate ◽  
Catalytic Ozonation ◽  
Acidic Condition ◽  
Buffer Solution ◽  
Toc Removal ◽  
Pre Treatment ◽  
Alkaline Buffer Solution

This study investigates the oxidation of local scrubber wastewater (LSW) from semiconductor manufacture by using ozonation, catalytic ozonation (ozone/Al2O3 and ozone/TiO2–Al2O3), and photo-catalytic ozonation (UV/TiO2–Al2O3, ozone/UV and ozone/UV/TiO2–Al2O3). The results show that catalyst Al2O3 and TiO2–Al2O3 promotes the TOC removal under the condition of neutral or alkaline buffer solution during catalytic ozonation of LSW. The Al2O3 induces highest promotion in TOC removal efficiency, which is higher than ozone alone by 26% TOC removal under alkaline buffer solution. However, TiO2–Al2O3 and Al2O3 cannot display the promotion in TOC removal under acidic condition. In addition, a pre-treatment of anion ion-exchange is employed and the result indicates that decreasing the anion ions concentration before AOPs can imply higher TOC removal during AOPs of LSW. In this study, ozone/UV under raw LSW acidic condition and ozone/Al2O3 under alkaline buffer solution present 95% and 88% TOC removal rate respectively and show the higher TOC removal efficiency than other AOPs. Therefore, these two kinds of AOP can serve as the very viable AOP methods in the LSW reclamation for semiconductor.

Effect of Laser Pre-Treatment on the Machining Performance of Aluminum/SiC MMC

2003 ◽  
Vol 125 (4) ◽  
pp. 378-384 ◽  
Author(s):  
Stuart Barnes ◽  
Richard Morgan ◽  
Andrew Skeen
Keyword(s):  
Tool Wear ◽  
Wear Mechanism ◽  
Laser Heating ◽  
Surface Damage ◽  
Edge Condition ◽  
Machining Performance ◽  
Matrix Properties ◽  
The Matrix ◽  
Pre Treatment ◽  
Measuring Tool

Although the abrasive reinforcement in MMCs primarily controls their machining behavior, the properties of the matrix also exert an influence. A 1200 W diode laser was used, due to the large footprint (5×0.3 mm) and the short wavelength (0.94 μm) to pre-treat a 2618 (18% SiC) alloy. The laser heating and self-quenching of the material modified the matrix properties. Machining performance was then assessed by measuring tool wear and edge condition, cutting forces, surface finish, and sub-surface damage. Results indicated that pre-treatment gave less wear, lower forces, and less sub-surface damage although abrasion remained the primary wear mechanism.

Determination of 22 trace elements in high-purity copper including Se and Te by ETV-ICP OES using SF6, NF3, CF4and H2as chemical modifiers

2016 ◽  
Vol 31 (3) ◽  
pp. 642-657 ◽  
Author(s):  
J. Hassler ◽  
R. Matschat ◽  
S. Richter ◽  
P. Barth ◽  
A. K. Detcheva ◽  
...  
Keyword(s):  
Trace Elements ◽  
High Purity ◽  
Icp Oes ◽  
Chemical Modifiers ◽  
The Matrix ◽  
Scope Of Application ◽  
Pre Treatment ◽  
Purity Copper

Experiments with SF6, NF3, CF4and H2as new modifier gases for the matrix studied were performed. Pre-treatment steps of sub-samples (e.g., roasting) can now be omitted; the scope of application was enlarged to Au and hydride forming elements (such as Se, Te).

scholarly journals MATHEMATICAL MODELING SINGULARLY PERTURBED PROCESSES OF WATER SOFTENING ON SODIUM-CATIONITE FILTERS

2019 ◽  
Vol 9 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Andrij Safonyk ◽  
Ihor Prysiazhniuk ◽  
Olena Prysiazhniuk ◽  
Oleksandr Naumchuk
Keyword(s):  
Ion Exchange ◽  
Asymptotic Approximation ◽  
Model Problem ◽  
Initial Boundary ◽  
Theoretical Description ◽  
Water Softening ◽  
Operational Conditions ◽  
Calcium And Magnesium ◽  
Pre Treatment ◽  
Modelling Assumptions

Mathematical model of the process of water softening using ion exchange pre-treatment of waters to desalination, with a view to removal of scale forming components, such as calcium and magnesium, are formed in the paper. In this process, no additional chemicals, except for brines formed during desalination, are required for regeneration of ion-exchanger in operation cycles. An asymptotic approximation of a solution of a corresponding model problem is constructed. Theoretical description and modelling assumptions included the set of differential equations of mass balance, initial, boundary and operational conditions. The paper deals with the development of a computer model for description and prediction of the performance of ion exchange columns.

scholarly journals Properties of Latex Polymer Modified Mortars Reinforced with Waste Bamboo Fibers from Construction Waste

Buildings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 149 ◽  
Author(s):  
Banjo Akinyemi ◽  
Temidayo Omoniyi
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Latex Paint ◽  
Construction Waste ◽  
Calcium Silicate Hydrates ◽  
Cement Mortars ◽  
The Matrix ◽  
Bamboo Fibers ◽  
Pre Treatment ◽  
Scanning Electron

This study evaluated the properties of latex modified cement mortars from ordinary paints which were reinforced with treated bamboo fibers from construction waste. Fiber variations of 0, 0.5, 1 and 1.5% at 10% of the weight of cement were utilized. Mechanical properties were determined according to standards; similarly, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the microstructural and elemental properties of the samples. The experimental results revealed that the addition of 1.5% bamboo fibers and 10% latex solution produced excellent mechanical properties. This was as a result of improved fiber adhesion to the matrix through pre-treatment, coupled with the contributed high strength from the latex paint modified mortars. The micrograph showed that latex precipitated in the voids and on the surface of the bamboo fibers as well as gels of calcium silicate hydrates which contributed to the observed improvement in strength of the tested samples.

Sustainable wastewater management technology for tourism in Thailand: case and experimental studies

2019 ◽  
Vol 79 (10) ◽  
pp. 1977-1984
Author(s):  
W. Liamlaem ◽  
L. Benjawan ◽  
C. Polprasert
Keyword(s):  
Kinetic Constant ◽  
Experimental Studies ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Wastewater Management ◽  
Order Kinetic ◽  
First Order ◽  
Treated Effluent ◽  
Management Technology ◽  
Pre Treatment

Abstract Thailand has adopted the concept of eco-tourism as a protocol to protect environmental resources. One of the key factors in enabling the achievement of this goal is the improvement of the quality of effluent from those homestays and resorts which still lack efficient on-site wastewater treatment. This research utilized case studies of subsurface flow constructed wetlands (SFCWs), planted mainly with the Indian shot (Canna indica L.), which were designed to treat wastewaters at three resorts located in Amphawa District, Samut Songkram Province in central Thailand. The results showed that the treated effluent was of sufficient quality to meet the building effluent standards Type C, which require the concentrations of biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN) and suspended solids (SS) to be less than 40, 40 and 50 mg/L, respectively. In addition, the first-order kinetic constants for the design and operation of SFCWs were determined. For treating wastewater containing organic substances, with no prior pre-treatment, the first-order kinetic constant of 0.24 1/d can be applied to predict effluent quality. For treating other types of domestic wastewater, a first-order kinetic constant in the range 0.40–0.45 1/d can be used when sizing and operating SFCWs. This research highlights the great potential of SFCWs as a sustainable wastewater management technology.

scholarly journals Treatment of folic acid wastewater by 3D Fe-N-TiO2/AC photoelectrocatalysis system

2019 ◽  
Vol 80 (10) ◽  
pp. 1919-1930
Author(s):  
Junwo Zhou ◽  
Zhen Zhou ◽  
Yong Gao ◽  
Tingting Li ◽  
Manying Zhang ◽  
...  
Keyword(s):  
Folic Acid ◽  
Ph Value ◽  
Synergistic Effects ◽  
Three Dimensional ◽  
Degradation Process ◽  
Film Coating ◽  
Order Kinetic ◽  
Mechanism Study ◽  
Cellulose Acetate Film ◽  
Toc Removal

Abstract In this work, particles of activated carbon supported by Fe-N-TiO2 (Fe-N-TiO2/AC) were synthesized and used as the three-dimensional (3D) particle electrode for folic acid wastewater treatment in the 3D electrolysis and photocatalysis coupling process. The structure, morphology, and physical and electrochemical properties of the Fe-N-TiO2/AC particles were characterized, and the results showed that Fe-N-TiO2 was bound on the surface of AC particles by chemical attachment, and the Fe-N-TiO2/AC particles had better capability of adsorption and charge transfer as compared with the TiO2/AC particles. The effects of key operating parameters in the reaction process, including the current density (optimum 0.6 mA/cm2), aeration (optimum 5 L/min), pH value (optimum 5) and the ratio of Fe-N-TiO2/AC particles to cellulose acetate film coating AC particles (optimum 4:1), were optimized regarding the total oxygen carbon (TOC) removal. Under the optimum conditions, TOC removal from folic acid wastewater reached 82.4% during 120 min photoelectrocatalysis. The kinetic analysis and mechanism study showed that the degradation process fitted to the second-order kinetic model better than to the first-order, and the system exhibited synergistic effects in inhibiting photogenic electron–hole recombination and improving electrolytic efficiency. At the same time, this system has the ability to overcome the interference of the strong ionic strength in folic acid wastewater.

A New Pre-Treatment with Phosphoric Acid and Hydrofluoric Acid of Electroless Ni-P Plating on Mg Alloy

2015 ◽  
Vol 729 ◽  
pp. 21-26
Author(s):  
Zhi Hui Xie ◽  
Jun Li Zhou ◽  
Shu Rong Xiang ◽  
Fang Chen
Keyword(s):  
Corrosion Current ◽  
Treatment Method ◽  
Mg Alloy ◽  
Cross Sectional ◽  
Plating Bath ◽  
Pickling Solution ◽  
Before And After ◽  
The Matrix ◽  
Pre Treatment ◽  
Electroless Ni

In order to develop a chromium-free pre-treatment method for electroless Ni-P (ENP) plating on magnesium alloy from an acidic plating bath, several various pickling and activation processes were studied in the present work. The surface morphologies of the matrix before and after etching or activation as well as the surface and cross sectional appearance of the Ni-P coatings were observed by scanning electronic microscope (SEM), while the elemental compositions were detected by energy dispersive X-ray spectroscopy (EDS). Those surface characterizations along with the scribe and grid testing results showed that the coatings obtained from etching only in H3PO4 solution display poor adhesion due to the existance of an interlayer between the matrix and the coatings. When fluoride was added into the pickling solution, the adhesion of the Ni-P coatings was also unsatisfactory because of the bad mechanical interlocking. By comparison, the Ni-P coatings obtained from pickling in 400 cm3·dm−3 H3PO4 solution followed by 10 cm3·dm−3 HF activation exhibit good characteristics in both adhesion and anti corrosion. The polarization test in 3.5wt.% NaCl aqueous solution showed that the corrosion potential (Ecorr) and corrosion current density (Icorr) of the new achieved coatings increases positively from −1.65 V to −0.87 V and decreases remarkably from 2.09 mA⋅cm−2 to 3.58 μA⋅cm−2, respectively (both compared with the bare Mg alloy).

Ammonium removal in landfill leachate using SBR technology: dispersed versus attached biomass

2017 ◽  
Vol 77 (1) ◽  
pp. 27-38 ◽  
Author(s):  
A. Sivic ◽  
N. Atanasova ◽  
S. Puig ◽  
T. Griessler Bulc
Keyword(s):  
Landfill Leachate ◽  
Sequencing Batch Reactor ◽  
Wastewater Treatment Plants ◽  
Batch Reactor ◽  
Ammonium Nitrogen ◽  
Operational Conditions ◽  
Ammonium Removal ◽  
N Removal ◽  
Attached Biomass ◽  
Pre Treatment

Abstract Large concentrations and oscillations of ammonium nitrogen (NH4+-N) in municipal landfill leachate pose considerable constraints to its further treatment in central wastewater treatment plants. The aim of this study was to evaluate and optimize two technologies for the pre-treatment of 600 L/day of landfill leachate: in particular, to optimize their operational conditions for NH4+-N removal up to a level appropriate for discharge to sewers, i.e. <200 mg/L. Both technologies were based on a sequencing batch reactor (SBR), with two different biomass processes: (A) SBR with dispersed/flocculated biomass and (B) SBR with biomass attached to carriers. The results revealed that both technologies successfully reduced the NH4+-N from 666 mg/L (on average) at the inflow to below 10 mg/L at the outflow with alkalinity adjustment in a 12-hour cycle. Both technologies achieved 96% removal efficiencies for NH4+-N. However, SBR with dispersed biomass showed higher flexibility under varying conditions due to the shorter adaptation time of the biomass.

scholarly journals Impact of pre-treatment technologies on soil aquifer treatment

2016 ◽  
Vol 7 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. Besançon ◽  
M. Pidou ◽  
P. Jeffrey ◽  
B. Jefferson ◽  
K. S. Le Corre
Keyword(s):  
Treatment Options ◽  
Infiltration Rate ◽  
Soil Aquifer Treatment ◽  
Operational Conditions ◽  
Conventional Activated Sludge ◽  
Treatment Train ◽  
Pre Treatment ◽  
The One ◽  
The Impact

This study investigates the impact of pre-treatment options on the performances of soil columns simulating soil aquifer treatment (SAT). For this purpose a conventional activated sludge (CAS) process, a membrane bioreactor (MBR) and vertical flow reed beds were used as single units or in combination before SAT. The influent and effluent from each treatment train were monitored over three successive 6-month periods, corresponding to changes in the operational conditions of the MBR and CAS units from 6 days' sludge retention time (SRT) to 12 and 20 days. All the columns acted as efficient polishing steps for solids and bacteria. The column receiving effluent from the CAS system running at 6 days' SRT also presented high total nitrogen and total phosphorus removals, but this column was also associated with the lowest infiltration rates over that period. While the quality of the effluent from the column following the CAS process increased over 18 months of operation, the effluent quality of the columns receiving MBR effluent degraded. No correlations were found between variations in SRT of the MBR and CAS processes and the columns' performances. Overall, all columns, except the one receiving CAS effluent, underwent a reduction in infiltration rate over 18 months.

Sign in / Sign up

Export Citation Format

Share Document