scholarly journals Electrochemical Oxidation of Effluents from Food Processing Industries: A Short Review and a Case-Study

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3546
Author(s):  
Alfredo Martínez-Cruz ◽  
Annabel Fernandes ◽  
Lurdes Ciríaco ◽  
Maria José Pacheco ◽  
Fátima Carvalho ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Anode Material ◽  
Food Processing ◽  
Oxidation Mechanism ◽  
Short Review ◽  
Cod Removal ◽  
Process Efficiency ◽  
Organic Load ◽  
Boron Doped Diamond

A short review on the treatment of effluents from food processing industries by electrochemical oxidation (EO) was performed. Olive mill wastewater (OMW) and boron-doped diamond (BDD) are the most reported effluent and anode material, respectively. The addition of NaCl or Na2SO4 as supporting electrolytes is common in these studies, and their influence on the EO performance depends, among other things, on the anode material, since the electrolyte oxidation mechanism is different when active and non-active anode materials are utilized. A case-study on the application of a pilot plant, working in batch mode with recirculation, equipped with a BDD anode, to treat 4 L of OMW, slaughterhouse (SW) and winery (WW) wastewaters, with initial chemical oxygen demands (COD) of 20.5, 3.6 and 0.26 g L−1, respectively, is presented and discussed. In 16 h assays, 94% COD removal was achieved for OMW, and for SW and WW the Portuguese COD legal discharge limit of 150 mg L−1 was accomplished. Process efficiency decreased for lower organic load. NaCl addition increased COD removal in SW and WW, but presented an adverse effect for OMW COD removal, when compared to Na2SO4 addition. Nevertheless, lower specific energy consumptions were attained in chloride medium (48 Wh (g COD)−1).

scholarly journals Insights into the Kinetics of Intermediate Formation during Electrochemical Oxidation of the Organic Model Pollutant Salicylic Acid in Chloride Electrolyte

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1322 ◽  
Author(s):  
Ambauen ◽  
Muff ◽  
Mai ◽  
Hallé ◽  
Trinh ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Electrochemical Oxidation ◽  
Density Functional ◽  
Oxidation Mechanism ◽  
Intermediate Formation ◽  
Anode Surface ◽  
Order Kinetic ◽  
Direct Oxidation ◽  
Boron Doped Diamond ◽  
Chloride Electrolyte

The present study investigated the kinetics and formation of hydroxylated and chlorinated intermediates during electrochemical oxidation of salicylic acid (SA). A chloride (NaCl) and sulfate (Na2SO4) electrolyte were used, along with two different anode materials, boron doped diamond (BDD) and platinum (Pt). Bulk electrolysis of SA confirmed the formation of both hydroxylated and chlorinated intermediates. In line with the density functional theory (DFT) calculations performed in this study, 2,5- and 2,3-dihydroxybenzoic acid, 3- and 5- chlorosalicylic acid and 3,5-dichlorosalicylic acid were the dominating products. In the presence of a chloride electrolyte, the formation of chlorinated intermediates was the predominant oxidation mechanism on both BDD and Pt anodes. In the absence of a chloride electrolyte, hydroxylated intermediates prevailed on the Pt anode and suggested the formation of sulfonated SA intermediates on the BDD anode. Furthermore, direct oxidation at the anode surface only played a subordinate role. First order kinetic models successfully described the degradation of SA and the formation of the observed intermediates. Rate constants provided by the model showed that chlorination of SA can take place at up to more than 60 times faster rates than hydroxylation. In conclusion, the formation of chlorinated intermediates during electrochemical oxidation of the organic model pollutant SA is confirmed and found to be dominant in chloride containing waters.

Treatment of ink effluents from flexographic printing by lime precipitation and boron-doped diamond (BDD) electrochemical oxidation

2009 ◽  
Vol 60 (10) ◽  
pp. 2477-2483 ◽  
Author(s):  
Evan Diamadopoulos ◽  
Helen Barndõk ◽  
Nikolaos P. Xekoukoulotakis ◽  
Dionissios Mantzavinos
Keyword(s):  
Electrochemical Oxidation ◽  
Supporting Electrolyte ◽  
Cod Removal ◽  
Effluent Treatment ◽  
Initial Value ◽  
Boron Doped Diamond ◽  
Treatment Performance ◽  
Boron Doped ◽  
Gravity Settling ◽  
Flexographic Printing

Effluent treatment from flexographic printing was investigated by precipitation/coagulation and electrochemical oxidation over boron-doped diamond electrodes. Precipitation with 3 g/L of lime led to complete removal of effluent turbidity (initial value of about 410 NTU) but only about 20% chemical oxygen demand (COD) decrease (initial value of about 1,900 mg/L). Higher lime dosages (up to 15 g/L) had no effect on separation. On the other hand, coagulation with alum in the range 0.05–1 mM failed to enhance the extent of solids separation achieved by gravity settling alone (i.e. about 60%). Preliminary electrochemical oxidation experiments in the presence of sulphuric acid as supporting electrolyte showed that treatment performance (in terms of COD removal and decrease in sample absorbance at 300 nm) increased with increasing applied current. The latter was more efficiently utilized at shorter treatment times and lower currents with efficiency reaching 30%. Following lime precipitation, the effluent was electrochemically oxidized at alkaline conditions for 360 min yielding 64% absorbance reduction and 50% COD removal (this corresponds to 60% overall COD removal for the combined process). The rather low electrochemical treatment performance may be attributed to limestone deposition and fouling of electrodes and other electrochemical reactor components as evidenced by the gradual drop in conductivity/current throughout the operation.

scholarly journals Kinetics of the Organic Compounds and Ammonium Nitrogen Electrochemical Oxidation in Landfill Leachates at Boron-Doped Diamond Anodes

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4971
Author(s):  
Barbara Krystyna Wilk ◽  
Małgorzata Szopińska ◽  
Aneta Luczkiewicz ◽  
Michał Sobaszek ◽  
Ewa Siedlecka ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Organic Compounds ◽  
Oxygen Demand ◽  
Ammonium Nitrogen ◽  
Cod Removal ◽  
High Concentration ◽  
Landfill Leachates ◽  
Boron Doped Diamond ◽  
Boron Doped ◽  
Energy Consuming

Electrochemical oxidation (EO) of organic compounds and ammonium in the complex matrix of landfill leachates (LLs) was investigated using three different boron-doped diamond electrodes produced on silicon substrate (BDD/Si)(levels of boron doping [B]/[C] = 500, 10,000, and 15,000 ppm—0.5 k; 10 k, and 15 k, respectively) during 8-h tests. The LLs were collected from an old landfill in the Pomerania region (Northern Poland) and were characterized by a high concentration of N-NH4+ (2069 ± 103 mg·L−1), chemical oxygen demand (COD) (3608 ± 123 mg·L−1), high salinity (2690 ± 70 mg Cl−·L−1, 1353 ± 70 mg SO42−·L−1), and poor biodegradability. The experiments revealed that electrochemical oxidation of LLs using BDD 0.5 k and current density (j) = 100 mA·cm−2 was the most effective amongst those tested (C8h/C0: COD = 0.09 ± 0.14 mg·L−1, N-NH4+ = 0.39 ± 0.05 mg·L−1). COD removal fits the model of pseudo-first-order reactions and N-NH4+ removal in most cases follows second-order kinetics. The double increase in biodegradability index—to 0.22 ± 0.05 (BDD 0.5 k, j = 50 mA·cm−2) shows the potential application of EO prior biological treatment. Despite EO still being an energy consuming process, optimum conditions (COD removal > 70%) might be achieved after 4 h of treatment with an energy consumption of 200 kW·m−3 (BDD 0.5 k, j = 100 mA·cm−2).

Characterization and treatability studies of cigarette industry wastewaters: a case study

1997 ◽  
Vol 36 (2-3) ◽  
pp. 69-74
Author(s):  
G. Bozarslan ◽  
S. K. Çelebi ◽  
F. Sengül
Keyword(s):  
Chemical Treatment ◽  
Biological Treatment ◽  
Continuous System ◽  
Cod Removal ◽  
Optimum Dose ◽  
Fenton Reagent ◽  
Cigarette Industry ◽  
Settling Behaviour ◽  
Characterization Studies

In this study, the wastewater of one of the cigarette factories in Izmir was characterized and treatability studies were done. The characterization studies of the wastewater showed that the COD, and the pH changes drastically. The chemical treatability studies of the influent wastewater were done by using Ca(OH)2, FeCl3 and Fenton Reagent. The optimum dose of FeCI3 was determined by jar tests. When using Ca(OH)2, the best flocculation, settling behaviour, and the highest COD removal occurred around pH 11. The optimum doses of Fenton Reagent (FeSO4 and H2O2) were determined. The supernatants of the previously chemically treated wastewaters were used for biological treatment. According to total COD removal efficiencies and the amount of sludge production during chemical treatment, FeCl3 was found to be the most economical and effective coagulant. Chemical treatment units were designed for a batch and a continuous system. The batch system has more advantages than a continuous system in this case.

Controlling the Settling of Activated Sludge in Pulp and Paper Wastewater Treatment Plants

1999 ◽  
Vol 40 (11-12) ◽  
pp. 223-229 ◽  
Author(s):  
Frédéric Clauss ◽  
Christel Balavoine ◽  
Delphine Hélaine ◽  
Gaëtan Martin
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Pulp And Paper ◽  
Organic Load ◽  
Forest Industry ◽  
Filamentous Bulking ◽  
Mineral Particles ◽  
Mineral Powder

Forest industry wastewaters are difficult to clean: hydraulic and organic load variations, filamentous bulking or pin-point flocs negatively impact depollution processes. The addition of a fine, mineral, talc-based powder, Aquatal, into the aeration tanks of wastewater treatment plants connected to pulp and paper factories has been successfully tested since end of '97. The first case-study presents full results obtained over a period of 18 months in a 20,000 p.e. plant connected to a paper factory. The mineral powder was regularly added to control sludge volume index, thereby ensuring low suspended solids concentration in the outfluent. Plant operators could easily adapt biomass concentration to match organic load variation, thereby maintaining pollution micro-organisms ratio constant. In a second case study, a trouble-shooting strategy was implemented to counteract filamentous bulking. A one-off, large dosage enabled the plant operator to deal effectively with poor settleability sludge and rapidly control sludge blanket expansion. In both cases, the main common characteristics observed were an increase in floc aggregation and the production of heavier and well-structured flocs. The sludge settling velocity increased and an efficient solid/liquid separation was obtained. After a few days, the mineral particles of Aquatal were progressively integrated into the sludge floc structure. When the mineral powder was added to the activated sludge in the aeration basin, chemical interactions frequently encountered with other wastewater treatment additives did not pose a problem. Moreover, with this mineral additive, the biological excess sludge displayed good thickening properties and dewatering was improved. Despite the addition of the insoluble mineral particles, the amount of wet sludge expelled did not increase. Aquatal offers a rapid solution to floc settleability problems which so frequently arise when physical or biological disorders appear in forest industry wastewater treatment plants.

Lean Solutions in Batch Manufacturing Process with Applicability in Bumpers Production

2016 ◽  
Vol 834 ◽  
pp. 205-210
Author(s):  
Elena Loredana Terzea ◽  
Antonia Cristina Barascu ◽  
Iulian Razvan Soare
Keyword(s):  
Automotive Industry ◽  
Food Processing ◽  
Lead Time ◽  
Batch Processes ◽  
Value Stream Mapping ◽  
Value Stream ◽  
Industry Sector ◽  
Current Value ◽  
Lean Methods

Batch processes includes paint manufacturing, food processing, pharmaceutical industry, etc. The paper focuses on the process of paint manufacturing. The main contribution is the design of the current value stream mapping, very useful to understand the causes of waste and lead-time. This paper points out the necessity of applying lean methods within automotive industry, sector of bumpers painting and assembly, based on a real case-study.

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