Table 1.
Treatment train scenarios examined for de facto reuse and direct potable reuse (DPR). Wastewater is shortened to ww. The log removal values used for activated sludge and membrane bioreactor (MBR) processes include primary sedimentation.
| Train Scenarios | Cases Considered a | Type | Source Water | Treatment Train Processes | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| (1) | b, c | De facto | Wastewater impacted surface water | Coagulation/ sedimentation | Media filtration | chlorine | |||||
| (2) | a, c | DPR | Raw ww | Activated sludge | MF | RO | UV/H2O2 | chlorine | |||
| (3) | a, c | DPR | Raw ww | Activated sludge | Ozone | BAC | MF | RO | UV/H2O2 | chlorine | |
| (4) | a, c | DPR | Raw ww | MBR | RO | UV/H2O2 | chlorine | ||||
| (5) | a, c | DPR | Raw ww | Activated sludge | Ozone | BAC | MF | NF | UV/H2O2 | BAC | chlorine |
a See Section 2.5 and Equation (3). Case a: When Fblend = 0, only DPR trains are considered and no blending with de facto reuse source water is considered but DPR effluent undergoes additional conventional drinking water treatment; Case b: Fblend = 1, only de facto reuse is considered; Case c: For 0 < Fblend < 1, DPR water is blended with de facto reuse source water prior to conventional drinking water treatment. For cases b and c, 0 < Fdilution < 1 where 0 is pristine, pathogen-free source-water, and 1 is source water comprised of 100% conventionally-treated wastewater effluent.