Document Type : Research Paper
Corn steep water as effluent which arrives in environment from starch processing industry has adverse effects on the environment and also large volume of fresh water is wasted. Corn step water is composed of high concentration of proteins, sugar, starch, vitamin and minerals, so it can be used as substrate for production of biological products. Hence, corn steep water concentration is important task both in environmental consideration and reuse of water. In this study, reverse osmosis membrane was used for concentration of steep water. The pilot consisted of two parts: pretreatment and reverse osmosis membrane. Pretreatment section contains ceramic filter with pore size of 50 micron and polypropylene filter which operates at 3-7 bar pressure. Surface area of reverse osmosis membrane was 1.11 m2 and operating pressure is 250 psi. Results showed that permeate flux is reduced exponentially over time and transmission through the polyamide membrane of calcium ions are less than sodium and potassium ions. For membrane cleaning, at first acid solution (pH= 3.5) and then soda solution (pH= 11-11.5) were used. For removal of microorganism like bacteria from polyamide membrane, acetic acid solution (4000 ppm) or hydrogen peroxide (2000 ppm) could be used. In general, reverse osmosis system with polyamide membrane is suitable process for concentration of steep water.