The parboiling process of paddy involves three main steps. They are soaking raw paddy, steaming the soaked paddy and drying. The paddy from parboiled process, also known as parboiled paddy, is then milled to remove the husk and rice is obtained. Parboiled rice has the advantages of de-husking easily and obtaining rice with fewer broken rice which increases the milling yield. In the paddy soaking process large quantities of water is used. The wastewater generated from this process has high biological oxygen demand (BOD) and chemical oxygen demand (COD). These characteristics vary from one parboiling process to another. In most paddy parboiling mills this effluent is discharged without any treatment into inland surfaces. Further, most of these wastewaters do not meet the standards required by the regulations enforced by the Central Environmental Authority of Sri Lanka.