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Coagulation-flocculation treatment of white pepper (Piper nigrum L.) processing wastewater

Authors:

M. A. Tharmalingam ,

University of Peradeniya, LK
About M. A.
Postgraduate Institute of Agriculture
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M. Gunawardana,

Sri Lanka Institute of Nanotechnlogy, Mahenawatta, Pitipana, Homagama, LK
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M. I. M. Mowjood,

University of Peradeniya, LK
About M. I. M.
Department of Agricultural Engineering, Faculty of Agriculture
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D. A. N. Dharmasena

University of Peradeniya, LK
About D. A. N.
Department of Agricultural Engineering, Faculty of Agriculture
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Abstract

Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment. Therefore, these experiments were conducted to investigate the effectiveness of electro-coagulation using aluminum (Al) electrodes and coagulation-flocculation with Alum [Al2(SO4)3.18H2O] in reducing the strength of pepper soaked effluent. A laboratory scale electro-coagulation unit was made using two aluminium plates (9 cm × 5 cm × 0.3 cm) as electrodes leaving a 0.5 cm gap between plates and powered with a 12 V DC power supply through a resistance box which is used to regulate the current density. The current density could be controlled between 0-1 A. Coagulation flocculation with Alum was tested at five doses; 1 to 5 g/L with 1 g increments at laboratory scale. The effluent colour was measured using a spectrophotometer at a wave length of 600 nm. According to the results, removal efficiencies of colour, Turbidity and COD were 94%, 91% and 89%, respectively for 20 minutes of electro-coagulation and 92%, 90% and 92%, respectively with 3 g/L Alum treatment. The pH of the effluent during electro-coagulation for 20 minutes increased to 9.0 while Alum treatment with 3g/L reduced to 5. When treated effluent filtered through a fine sand filter, Total Dissolved Solids (TDS), Electrical Conductivity (EC) and COD could be reduced further and reached the standard values to discharge in to the environment as irrigation water.
How to Cite: Tharmalingam, M.A., Gunawardana, M., Mowjood, M.I.M. and Dharmasena, D.A.N., 2017. Coagulation-flocculation treatment of white pepper (Piper nigrum L.) processing wastewater. Tropical Agricultural Research, 28(4), pp.435–446. DOI: http://doi.org/10.4038/tar.v28i4.8244
Published on 28 Dec 2017.
Peer Reviewed

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