Advantages

Dares

Oxidants

Cl₂

CI⁻ is among the most abundant anions in most waters; lower standard potentials than most electrochemically generated oxidants; longer lifetimes allow for disinfection residual; can combine with ammonia to form chloramines with lower DBPs and more stable residual.

CI⁻ must be present in sufficient concentration or externally supplied; many oxidized CI species are toxic ( ${\text{CIO}}_2^{-}$ , ${\text{CIO}}_3^{-}$ , etc.); current efficiency depends on CI⁻ concentration, limiting performance in low salinity waters; can generate chlorinated DBPs (e.g., trihalomethanes and haloacetic acids).

^•OH

Strongest disinfectant among common electrochemically generated oxidants; can be generated without specific precursor ions (e.g., Cl⁻); can also oxidize total organic carbon (TOC) and many micropollutants; capable of treating Cryptosporidium at practical doses.

Highest standard potential of common electrochemically generated oxidants; radical species have very low lifetimes in solution; can generate ${\text{BrO}}_4^{-}$ and brominated compounds in Br⁻ containing waters.

Treatment context

Drinking water

Low organic carbon levels reduce scavenging and necessary dose, depending on placement in treatment train; does not require onsite hazardous chemical storage; lower overall dose required compared to wastewater.

May require CI⁻ addition if CI oxidant species are desired; most oxidants produced electrochemically have shorter lifetime, making residual generation difficult.

Centralized wastewater

CI⁻ concentration is usually sufficient to generate CI oxidant; high ${\text{NH}}_4^{\text{+}}$ levels can scavenge more oxidized CI species ( ${\text{CIO}}_2^{-}$ , ${\text{CIO}}_3^{-}$ , etc.) and produce chloramine; dose can be dynamically adjusted during severe events.

High carbonaceous chemical oxygen demand (cCOD) levels introduce competition for oxidant; electrochemical systems typically scale linearly for cost and energy demand.

Distributed wastewater

Electrochemical systems can be easily scaled down for portable units; a single unit can be used to

electrochemically generate oxidants for simultaneous treatment of cCOD, ${\text{NH}}_4^{\text{+}}$ , and pathogens.

Higher energy inputs are required for treatment of multiple target species; electrochemical systems typically have high capital cost compared to other methods.