Scaling, corrosion and biofouling are three main problems in circulating cooling water system. These problems occur simultaneously and have great economic impacts. This study has been carried out to develop the inhibitor compounds for mitigating scaling, corrosion and biofouling simultaneously. The monomer inhibitors, such as sodium of polyaspartic acid (PASP), amino trimethylene phosphonic acid (ATMP) and benzyldimethyltetradecylammonium chloride (BDTAC), were first investigated to obtain the appropriate concentration ranges. Orthogonal array design (OAD) was used for achieving the optimal composition of the inhibitor compound. The applied conditions of inhibitor compound, such as pH, temperature, calcium ion and bicarbonate radical were also optimized. The results indicated that the optimal composition of inhibitor compound consisted of 40 mg/L ATMP, 20 mg/L. PASP, 80 mg/L BDTAC and 2 mg/L zinc salt. The performances of the inhibitor compound were superior to the single inhibitors separately, which suggested that there had a synergistic effect among the inhibitors. The inhibitor compound had good performances of corrosion inhibition, scale inhibition and bactericidal action at the pH and temperature ranges of 65-9 and 30-70 degrees C, respectively. The inhibitor compound had the wider tolerance of calcium ion and bicarbonate radical. (C) 2012 Elsevier B.V. All rights reserved.