Decolorization of textile wastewater by ozonation and Fenton's process

Abstract

The aim of this study is to investigate the effect of some operational parameters on the efficiency of ozonation and Fenton's process for decolorization and COD removal. Acid Red 337 and Reactive Orange 16 dye solutions and the effluents of acid and reactive dye-bath effluents were used in the experiments. The influence of ozone dose and pH for color and COD removal from the wastewater were studied. Increasing the ozone dose increased the rate constants, and color and COD removal efficiencies. Ozone consumption ratio per unit color and COD removal at any time was found to be almost the same while the applied ozone dose was different. pH did not significantly affect color and COD removal from the wastewater by ozonation. In spite of having high color removal efficiencies (60-91%), limited COD removal efficiencies between 9-17% at 30 minutes ozonation time were obtained. In the Fenton oxidation experiments, the effects of pH, temperature, dosage of ferrous sulfate and hydrogen peroxide, and the proper ratio of Fe(II)/H2O2 were studied. The result indicates that up to 99% color removal and 82% COD removal can be obtained by Fenton's oxidation. While Fenton's oxidation was greatly affected by the pH value, temperature of wastewater did not significantly affect the Fenton process for color removal. Increasing the dose of both hydrogen peroxide and ferrous sulfate enhanced the removal efficiencies of color and COD. Suitable ratios of Fe(II)/H2O2 were found to be between 0.5 and 0.83.

Influence of Temperature and pH on the Stability and Colorimetric Measurement of Textile Dyes

“…Nevertheless, the oxidation of this dye on Ti/SnO 2 /SbOx (3% mol)/RuO 2 (1% mol) electrode showed 100% of decolorization and 60% of total organic carbon removal in Na 2 SO 4 0.2 M at pH 2.2 and potential of +2.4 V. Muthuraman and Palanivelu [9] conducted a laboratory study on supported liquid membrane (SLM) system for removal and recovery of textile dye from the aqueous solution using renewable, non-toxic, natural vegetable oils. The study was carried out at different pH levels (7)(8)(9)(10)(11)(12)(13)(14). Dye transport rate increases with increasing the pH and maximum extraction (as well as maximum transport) was achieved at a pH of 11.0.…”

“…Some dyes possess toxicity that is hazardous to aquatic life and posses serious health problems to human [9] . Textile dyeing effluents are also known to cause extreme variations of pH, dissolved oxygen (DO), temperature, chemical oxygen demand (COD) and dissolved salts of the receiving water bodies [10][11][12] . Reactive dyes are the most common dyes used in the textile industry because of their bright colours, excellent colourfastness and ease of application [13,14] .…”

Tratamento de efluentes industriais por processos oxidativos na presença de ozônio

“…Dentre os vários métodos que têm sido desenvolvidos para o tratamento deste efluente, o processo de ozonização tem sido sugerido na literatura recente como sendo um processo bastante promissor, devido à capacidade de descoloração e aumento da biodegradabilidade do efluente. Além disso, o fato do sistema não gerar resíduos sólidos (como no caso do lodo ativado) e ser de fácil instalação e operação torna sua aplicação ainda mais atrativa 41,42 . Durante o processo de ozonização ocorre a descoloração do efluente devido à clivagem oxidativa dos grupos cromóforos, seja por via direta ou indireta 41 .…”

<b>Development of Actual Dyestuff Wastewater Treatment by Ozone with Carbonaceous Materials Produced from Waste Fiber</b>

“…The turbidity after ozone treatment with CT was greater than that after the ozone treatment without CT. The fact that the COD reduction was low may reflect the decomposition of the dye molecules into small organic substances via the ozone treatment process [35], and the lower COD removal compared to the color removal can be explained by the incomplete oxidation of the organic materials [36]. On the other hand, the lower TOC removal rate under the experimental conditions can be explained by the Fig.…”