Peracetic acid to reduce disinfection by-product formation in drinking water

Abstract

Laboratory experiments were conducted to evaluate the ability of peracetic acid (PAA—containing 10% hydrogen peroxide by weight in equilibrium) to reduce subsequent chlorination disinfection by-product (DBP) formation (trihalomethanes, haloacetic acids, and adsorbable organic halides) in raw and post-filtered water collected from four Canadian utilities over a typical pH range. A 5 mg L⁻¹ PAA/H₂O₂ (mixture) dose decreased DBP formation potential by up to 40%. It was also observed that H₂O₂ is more effective than PAA for reducing DBPs on a per mg L⁻¹ basis, however, at a 10% (mass) fraction of H₂O₂ in a PAA/H₂O₂ mixture (typical of commercial products), the poorer reactivity of PAA is compensated for by its higher concentration and is the dominant factor leading to DBP minimization. PAA solution was more effective in reducing DBP formation potential at a higher pH (7.8–8.2) when compared to pH 6.