Neutralization of Alkaline Waste Water from Pulp and Paper Industry by Alkaliphiles

Abstract

Two alkaliphilic bacterial strains T1 and T2 capable of lowering pH and alkalinity of alkaline wastewater from pulp and paper industry were isolated in the present study. Bacterial strain T1 reduces the pH from 12 to 8.1 and alkalinity from 1040 mg/L to 480 mg/L whereas strain T2 reduces the pH from 12 to 7.95 and alkalinity from 1080 to 460 mg/L. Both alkaliphilic bacterial strains were gram positive and spore forming. Strain T1 has regular margin, glistering, convex and oval round in shape whereas strain T2 has regular margin, flat and irregular in shape. Both the strains can grow at wide range of Temperatures (10 - 44oC), pH (6 - 12) and NaCl concentrations (0 – 20 %). Strains T1 and T2 can utilize all the different types of Carbohydrates. Strain T1 can hydrolyse starch and show positive result for Catalase Screening whereas strain T2 can utlize citrate, hydrolyse casein and show positive results for Lipase Screening, pectinase screening and gelatin liquification test. Neutralization of highly alkaline wastewater without addition of any external carbon source highlights the potential use of the isolate as an alternative to the conventional acid neutralization method for treatment of alkaline wastewater.