Studies on Sequential Degradation of Procian Blue Present in Textile Effluent by Bio, Electro and Photo Oxidation Using Bacteria and Fungi

Keywords: Procion blue, COD, Electro, Bio and Photochemical oxidation.

Introduction

Water pollution is a growing problem of developing nation. The principle sources are industrial and domestic wastes. Over the past 25-30 years, the textile industry play a vital role in the national pollution. Generation of waste water from a textile dye industry is due to the processing operations employed during the conversion of fiber to the textile fabric. These textile industries produce large quantities of effluent with high COD content and unacceptable color. The color is mostly due to the presence of dyes and dyestuffs discharged from textile, food, paper making and cosmetic industries (Anderson 1986). The presence of even small amount of dyes in the water affects the aesthetic merit, water transparency and gas solubility in lakes, rivers and water bodies. Hence, color removal has become the focus of contemporary research interests (Chen et al 1999). Procion blue dye represent a major class of synthetic organic pigments. The carcinogenic nature of this dye are the precursors for environmental pollution. The electrochemical methods are mainly used for desalination of water or for effluent treatment.

The physiochemical process like adsorption, flocculation, chemical coagulation, precipitation, electrochemical oxidation are used to treat the effluent. But some of them generate secondary pollution such as sludge (Kothandaraman et al 1967). There fore biological methods are used to remove the color, and for the reduction of COD which are cost effective and technologically feasible.(Murugesan and Kalaichelvan 2003)

Materials and Methods

Effluent Preparation

Synthetic dye effluent was prepared by dissolving 0.75g (grams) of procion blue reactive dye in 1000ml of distilled water. This effluent was characterized before and after combined treatment of electrochemical, biological and photochemical degradation mainly in terms of chemical oxygen demand and absorbance. The COD was measured according to APHA (1995) 5 g of sodium chloride was added in the prepared effluent which acts as an exhausting agent. The prepared sample was mixed by shaking properly.

Characteristics of reactive dyes:

• Ability of the reactive groups to form covalent bond with textile fibers.
• Facilitate interaction with fiber and reduce energy consumption.

Characteristics of effluent:

• The color of the effluent was purple blue.
• It has a high alkaline pH with range of 8-10.

Squential Degradation Methods

The pre electro chemical oxidation treatment (Vlyssides et al., 2000) of effluent was carried out in an electrochemical batch reactor under galvanostatic condition at current density 3.8 A/dm² for a period of 4 hours. The test was based on treating the waste with a known amount of dichromate, digesting at an elevated temperature to oxidize the organic matter and titrating the unconsumed dichromate with the N/10 ferrous ammonium sulphate solution. The oxygen equivalent of dichromate destroyed is reported as the COD. The sample was collected for every one hour and then COD and the absorbance values are measured for percentage removal of COD and color. The biological treatment was carried out with two bacterial (Bacillus cereus, pseudomonas putida) and three fungal strains (Pleurotus ostreatus, Fusarium oxysporum, Trichiderma viridae). 100ml of partially treated dye sample was taken in 5 flasks and 100ml of nutrient broth culture (bacteria) and potato dextrose broth culture (fungi) was added and kept in shaker for five days. After 24 hours incubation 1ml of samples was collected every day form every flask to analyze the COD reduction and 5ml was collected for absorbance. After biological treatment post electro oxidation process was done. Followed by that photo oxidation process was carried by placing 400ml of biologically treated sample inside a photoreactor for 5 hours with continuous stirring for proper exposure of UV radiation. 1ml of sample was collected after every one hour for the analysis of COD and color removal.

Result and Discussion

By the electro oxidation process the COD was decreased from 14440 to 800mg/l. So the percentage of COD removal by this process was around 50% (Sangyong Kim et al 2003) (Table1).

Calculation:

COD (mg/l) = (V1 − V2) × N × 8 × 1000 ⁄ X

Where,

V1 = Volume of ferrous ammonium sulphate run down in the blank experiment

V2 = Volume of ferrous ammonium sulphate run down in the test experiment

N = Normality of ferrous ammonium sulphate solution, and

X = Volume of test sample taken

The reduction rate of COD was calculated as follows

(COD-initial − COD-final) ⁄ COD-initial

The results observed in a bacterial batch set up is shown in tables 2 and 3 and the color removal in figures 1 and 2. The percentage of COD removal by Bacillus cereus was 50% and by Pseudomonas putida it was 32% (Ian R. Haridin et al.). The fungal biochemical action is shown in the table 4,5,6 and the color removal which is sequentially continued up to 120 hours for both bacteria and fungi after pre treatment.

The result showed that maximum 42% removal of COD was achieved by using Fusarium oxysporum similar observation was also made by Ryuel et al 1992 followed by 39% and 33% by Pleurotus ostreatus and Trichiderma viridae. In the post electrochemical oxidation process considerable amount removal of color and odor was observed than the Control. The odor quality is smelled by human nose. It was observed that COD was decreased from 6230 to 1280 mg/l. The percentage of COD removal was 79% (Table7). The result of photooxidation process was shown in the table 8.By this method the COD was decreased form 1280 to 560 mg/l. The percentage of COD removal was 65%.

Flowchart

References

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