Treatment of coffee cherry pulping wastewater by using lectin protein isolated from Ricinus communis L. seed

Abstract

Wet coffee pulping process generates organic pollutant rich wastewater, and causes serious threat to the local water bodies. Hence, the efficiency of Ricinus communis L. seed protein to remove colour, total dissolved solids (TDS) and chemical oxygen demand (COD) from the coffee cherry pulping wastewater (CCPWW) was studied. Treatment with 0.5 g optimum dosage of the seed protein reduced 80 % colour, 75 % total dissolved solids and 80 % chemical oxygen demand from the wastewater, along with a change in the pH from 3.7 to 5.2. Characterisation of the seed protein using sodium dodecyl sulphate polyacrylamide gel electrophoresis and matrix assisted laser desorption ionization – time of flight assay confirmed a ricin glycoprotein band at 28 kDa. This ricin B chain lectin protein with 262 amino acid residues caused the coagulation activity in the wastewater, due to its cationic nature, sugar binding sites and hydrogen bonding forces between molecules. Fourier transformed infrared characterization of the seeds showed the presence of amide groups involved in pollutant removal. A positive linear correlation ‘r’ 0.9 proved the degree of association between the removal of total dissolved solids and chemical oxygen demand from CCPWW. Hence, the study suggested that the pollutants from wastewater could be removed using Ricinus communis L. seed lectin protein, as an alternative eco-friendly coagulant agent replacing synthetic coagulant chemicals.