SOLUBILIZATION OF CELLULOSIC WASTEWATER

Abstract

Anaerobic treatment methods are increasingly becoming the core method of treatment for various industrial wastes and domestic wastewater especially in developing nations with tropical climates. Upflow anaerobic sludge blanket (UASB) reactor is the most preferred and widely used high-rate anaerobic system. Treatment of wastewaters with a considerable fraction of particulate matter is a matter of concern in UASB reactors. Domestic sewage, wastewater from slaughter house, food industry etc., contain partly soluble substrate and significant (30-80%) substrate in particulate form. Higher solids concentration prevents higher loading rates. Their accumulation can reduce the specific methanogenic activity of the sludge and disturb sludge granulation. Solids tend to accumulate basically because of their slow hydrolysis rates. Carbohydrates, proteins and lipids are the common organic polymers found in the domestic sewage and their hydrolysis is the rate limiting step in the anaerobic biodegradation. Bench scale investigations revealed that the solubilization of particulates prior to treatment in UASBR (two stage treatment) is better in terms of operation and performance than the single stage treatment. However, solubilization of sewage is a relatively new concept and a few studies carried out have not achieved any significant increase in soluble fraction after solubilization. In most of the cases, results indicate that a large fraction is retained in the hydrolysis reactor and a small amount is hydrolyzed. The perusal of such studies has shown that the adoption of anaerobic methanogenic sludge as seed inoculum has allowed methane conversion and hence the loss of solubilised part. Keeping these in view, in this project, experiments have therefore been carried out to ii facilitate hydrolysis and to curb methanogenesis. A synthetic complex wastewater based on cellulose has been used. Cellulose is the major particulate matter found in domestic sewage and hence it was chosen to represent the sewage solids. Care was taken to make synthetic wastewater representative of sewage.