Application of large-scale honeycomb biofilter as pretreatment system to improve the quality of raw city water: Efficiency and economic analysis

Removal of natural organic contaminants using the biofilter technique is beneficial for raw city water treatment. Several studies have been conducted using various biofilters for organic contaminant biodegradation; however, a detailed study on honeycomb biofilters applied in large-scale water treatment plants (WTPs) in tropical seasons has never been reported. This study investigates the biofilm on the surface of fixed-in-place honeycomb biofilter to reduce chemical oxygen demand (COD), ammonia, and turbidity. The removal efficiency of COD, ammonia, and turbidity was satisfying at 52 %, 57.8 %, and 41.7 %, respectively, with the optimum hydraulic retention time (HRT) at 142 min and neutral pH. The increase in rain precipitation positively correlated with the COD and turbidity removals. However, the ammonia removal was negatively correlated with the increase in rain precipitation and turbidity. The operational cost of raw water treatment can be saved by controlling the use of chlorine for removing the excess ammonia at the loading between 250 kg/day and 415 kg/day. The result demonstrates the valuable potency of fixed-in-place honeycomb biofilter for raw city water treatment, attributed to its simplicity, low operational and maintenance cost, and high efficiency in removing natural organic contaminants