Non-chemical biofouling mitigation systems for seawater cooling tower using granular activated carbon biofiltration and ultrafiltration

Abstract Biofouling is a serious problem in industrial cooling tower. It damages equipment through bio-corrosion, causes blockages, and increases energy consumption by decreased heat transfer. One of the most popular methods used in the cooling tower process to control the biofouling is disinfection by chlorination. However, chlorination forms harmful disinfection byproducts in the presence of organic. The research aims to remove the nutrients and microorganisms from seawater for biofouling mitigation in seawater cooling towers (SCTs) without chemical usage. Granular activated carbon (GAC) biofiltration and ultrafiltration (UF) membrane pretreatment systems were employed to reduce the amount of nutrients and the number of microorganisms in seawater entering the main process, respectively. Assimilable organic carbon (AOC) levels in the feed seawater are directly linked with a bacterial growth, thus it can be used as an indicator of biofouling potential after pretreatment. GAC biofilter exhibited a high efficiency in the reducing of biofouling potential by removing AOC in seawater feed. UF could minimize the initial microbial growth. Further, a hybrid GAC/UF system achieved the removal of DOC up to 78% with enhanced AOC reduction (less than 60% compared to value without pretreatment). It indicates that the GAC/UF hybrid is a promising process minimizing the chemical usage and mitigating the biofouling growth. This study can provide the useful information to operator of SCTs to manage the biofouling problems without chemical and to operate it environmentally-friendly.