Wyniki wyszukiwania - Biblioteka Nauki

1

The Treatment of Hospital Wastewater Using Electrocoagulation Process – Analysis by Response Surface Methodology

100%

Salah Al-Shati A. , Alabboodi K. O. , Shamkhi H. A. , Abd Z. N. , Emeen S. I. M.

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2023

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tom Vol. 24, nr 1

260--276

EN

Electrocoagulation (EC) can be defined a method utilized to remove pollutants from wastewater by applying an electric current to sacrificial electrodes. Many experimental variables like NaCl content (0–4 g/l), current density (5–25 mA/cm2), time (30–90 mins), and pH (4–10) that influence the removal efficiency regarding COD were considered. In the presented research, three distinct configurations related to electrodes, i.e. Al-Al, Fe-Al, and Fe-Fe, have been utilized to determine which was the most effective. RSM depending on BBD was utilized for optimizing various operational parameters with regard to HWW by use of EC. Maximum COD removal (97.9%) was reached at Fe-Al electrodes, NaCl (3.2 g/l), current density (24.7 mA/cm2), time (81.7 mins), and pH (7.4). COD removal (91.3%) was achieved at the Al-Al electrodes, NaCl (3.8 g/l), current density(23.5 mA/cm2), time-86.3 min, and Ph (7.7). At the Fe-Fe electrodes, the removal of COD (89.5%) was obtained at NaCl (2.3 g/l), current density (24.6 mA/cm2), pH 8.5, and time (86.9 min). This indicates that EC could remove pollutants from different types of wastewaters under many operating parameters and with arrangements of electrodes.

2

Transformation Analysis of Carbon and Nitrogen Compounds in Wastewater Treated in a Vertical Biofilter

100%

Wawrentowicz D.

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tom Vol. 22, nr 11

215--222

EN

Biofilter technology for wastewater treatment is relatively complex and is gaining more interest. However, it should be emphasised that various aerobic conditions may occur in biological filter beds, which depend primarily on the velocity of wastewater flow through the bed. Therefore, it is often difficult to precisely determine the transformations of carbon and nitrogen compounds that occur during wastewater treatment on these types of filter beds. This study investigated the effectiveness of the filter bed and analysed the extent of the transformation of carbon and nitrogen compounds in the range of filtration velocities from 0.02 to 0.60 m•h-1. The study was conducted under laboratory conditions, and model wastewater was prepared on the basis of sodium acetate, ammonium chloride, potassium nitrate and potassium dihydrogen phosphate. The model wastewater was prepared with parameters corresponding to those of the treated wastewater. The experiment showed that anaerobic and aerobic conditions occurred in the biological filter bed at filtration velocities of up to 0.16 m•h-1. Above this velocity, aerobic conditions prevailed in the biological filter bed.

3

Treatment of Petroleum Refinery Wastewater by Graphite–Graphite Electro Fenton System Using Batch Recirculation Electrochemical Reactor

88%

Kassob A. N. , Abbar A. H.

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tom Vol. 23, nr 10

291--303

EN

Water pollution and the lack of access to clean water are general global problems that result from the expansion of industrial and agricultural activities. Petroleum refinery wastewaters are considered as a major challenge to the environment and their treatment is mandatory. The present work investigated the removal of chemical oxygen demand (COD) from petroleum refinery effluents generated from the Al-Dewaniya petroleum refinery plant located in Iraq by utilizing a novel graphite–graphite electro-Fenton (EF) system. The electrochemical reactor was a tubular type with a cylindrical cathode made from porous graphite and concentric porous graphite rode acts as an anode. By adopting the response surface methodology (RSM), the impacts of different operating variables on the COD removal were investigated. The optimal conditions were a current density of 25 mA/cm2, FeSO4 concentration of 1.4 mM, and electrolysis time of 90 minutes, which resulted in the COD removal efficiency (RE%) of 99% at a specific energy consumption (SEC) of 10.34 kWh/kg COD. The results indicated that both current density and concentration of FeSO4 have a major impact on the elimination of COD, while time has a minor effect. The adequacy of the model equation was demonstrated by its high R2 value (0.987). The present work demonstrated that the graphite–graphite EF system could be considered as an effective approach for removing of COD from petroleum refinery wastewaters.

4

Non-circular ceramic membranes for use in wastewater treatment

88%

Chiu T. Y. , Lara Dominguez M. V. , James A. E.

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tom Vol. 31, nr 3-4

53-60

EN

An extensive use of membrane bioreactors in wastewater treatment often produces the effluent quality far beyond the current regulatory requirements for discharge to the environment. However, like other processes involving membranes, the severest constraint is the problem of fouling, the extent of which can be reduced by changing the flow pattern (maintaining in turbulent conditions) within the channels. In this study, the treatment of effluent from synthetic sludge production was investigated employing membrane bioreactors utilising non-circular multi-channelled membranes. Very high chemical oxygen demand (COD) and suspended solids (SS) removals were obtained for the range of pore sizes employed, up to 94% and 98%, respectively. As the pore size was increased, a decrease in efficiency was observed. Differences in the rejection behaviour are attributed to the difference in the characteristics of cakes which were formed. Specific cake resistance seems to increase moderately with diminishing pore size. The critical flux was found to be dependent on cross-flow velocity, introduction of inserts and pore size. Critical flux increased to about 82.5 l m-2 h-1 at a cross-flow velocity of 2.0 m s-1. The high critical flux can be attributed to the non-circular geometry of the channels which seems to promote turbulent flow, depolarising the solute built-up, even at low cross-flow velocity. Finally, the present paper demonstrates ways in which hydrodynamics and colloid interactions affect the critical flux.

5

COD removal from landfill leachate using H2O2, UV radiation and combination these processes

51%

Pieczykolan B. , Barbusiński K. , Płonka I.

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tom Vol. 38, nr 3

5--13

EN

Experiments for removal of organic compounds (expressed as COD) from "young" municipal landfill leachate, using oxidation by H 2O2, UV photooxidation and UV/H 2O2 process, were carried out on a laboratory scale. Studies have shown that the most effective method was UV/H 2O2 process. When oxidation was conducted under the most suitable conditions (parameters found during experiments), maximum value of COD removal equaled 74.6%, 19.6% and 19.3% when the treatment was realized by use of H 2O2/UV, H 2O2 and UV radiation, respectively. These results demonstrate that in order to attain high efficiency of COD removal, use of advanced oxidation process (H 2O2/UV) is necessary.