Evaluating submicron-sized activated carbon adsorption for microfiltration pretreatment

Abstract

Submicron powdered activated carbon (PAC) rapidly adsorbed natural organic matter (NOM) fromwater samples: a batch test of the adsorption kinetics showed that the NOM concentration dropped substantially within 15 s and then leveled off. In a tubular flow reactor test, NOM removal after a 15 s contact time was almost the same as removal values attained at longer contact times. Laboratory-scale and bench-scale pilotplant ceramic microfiltration (MF) experiments with submicron PAC adsorption pretreatment were conducted to evaluate NOM removal and to examine the effect of the PAC on filterability. The laboratory scale MF experiment revealed that PAC adsorption pretreatment could be accomplished with a detention (2.4 s) that was much shorter than the time expected from the adsorption kinetics test. This result suggests that adsorption pretreatment for MF could be accomplished by adding the submicron PAC directly into the feed line to the membrane and that installation of a special PAC contactor before the membrane unit is unnecessary. Although micron PAC rather than submicron PAC was used unintentionally in the pilot plant experiment, these PAC showed much better NOM removal than normal PAC, and no adverse effects, such as transmembrane pressure buildup and reversible or irreversible membrane fouling, were observed.

Effects of super-powdered activated carbon pretreatment on coagulation and trans-membrane pressure buildup during microfiltration

“…The difference in TMP between Line 3 and Line 1 increased as the operation was extended to 63 days. Lower rates of TMP increase when MF was preceded by S-PAC adsorption pretreatment were also observed in previous studies, but for shorter operational times of 6 and 22 days (Matsui et al, 2006, Matsui et al, 2007.…”

A coagulation–powdered activated carbon–ultrafiltration – Multiple barrier approach for removing toxins from two Australian cyanobacterial blooms

“…Some authors have reported a reduced flux, longer backwash intervals or a reduced frequency of chemical cleaning when using PAC pre-treatment [18][19][20]. Others have shown little effect [21][22][23] or increased flux when using PAC [24][25][26]. Some studies have shown that the membrane hydrophobicity is the key to reduced flux when pre-dosing PAC.…”

Adsorptive removal of geosmin by ceramic membrane filtration with super-powdered activated carbon

“…Recently, Matsui et al (2004Matsui et al ( , 2005Matsui et al ( , 2006 proposed the application of an extremely small, micro-ground PAC (called here a super-PAC [S-PAC]), with a particle size of less than 1 mm, to treatment before ceramic MF to attain improved removal of naturally occurring organic matter.…”