Effects of EBCT and Water Temperature on HAA Removal using BAC

Abstract

The effects of empty bed contact time (EBCT) and water temperature on the removal of haloacetic acids (HAAs) in biologically active carbon (BAC) filters were investigated. Experiments were conducted at four temperatures (4, 10, 20, and 30°C) and four EBCTs (5, 10, 15, and 20 min). The results indicated that increasing EBCT or increasing water temperature increased the HAA removal in BAC columns. To achieve an HAA removal efficiency of 50% or higher in a BAC filter, the authors suggest a 10‐min EBCT for 4°C waters and a 5‐min EBCT for waters at 10°C or higher. The kinetic analysis suggested a first‐order reaction model for HAA (except trichloroacetic acid) removal at 10°C and a zero‐order first‐order reaction model for HAA removal at 4°C. The pseudo‐first‐order reaction rate constants and half‐lives were also calculated for HAA removal at 10°C. The half‐lives—ranging from 5.9 to 17.3 min—could be used to assist water utilities in designing and operating BAC filters for HAA removal.

Treatment of Specific NDMA Precursors by Biofiltration

“…Contact time is known to heavily influence dissolved organic removal (Hallé et al 2015, Reungoat et al 2011), but the relationship is not directly proportional (Urfer et al 1997) as was seen in the present study for TMDS. Also, the effect of EBCT on removal seems to occur only at low water temperatures (Hallé et al 2015, Wu & Xie 2005) as compared with the present study and another (Zearley & Summers 2012) above 20°C in which EBCT had very little effect on removal. The peak removal for TMDS in Figure 3 matches the peak DO concentration in Figure 2.…”

Evaluate HAA removal in biologically active carbon filters using the ICR database

“…This is likely due to the lower biodegradation rate for Cl 3 AA, especially at low water temperatures, as amplified in Quarter 3 (January to March) when the lowest water temperature typically occurs in the United States. The impact of water temperature on HAA degradation were also reported in previous studies [21,24]. It is also possible that more Cl 3 AA were generated in low temperature condition than Cl 2 AA, or some Cl 3 AA might decompose to chloroform at warmer weather as reported by Zhang and Minear [25].…”

Biologically active carbon filtration for haloacetic acid removal from swimming pool water

“…Ratasuk et al (2008) reported similar findings in absence of the disinfectant -ozone and suggested an EBCT of at least 20 min to remove 90-100% of HAAs. Wu and Xie (2005) showed an EBCT of 5 min could be used for dechlorinated water above 10°C. The major difference of the experimental conditions between our study and the two literatures was the presence of the disinfectant -chlorine.…”