TT (advanced treatment)

Benefits

Obstacles

Recommendations

a or b (UV)

・ Efficient disinfection (comprising ARB demobilization)

・ No DBPs generation contrasted to chemical disinfection

・ Poor/no CECs elimination

・ •Partial elimination of ARGs

・ Compliance with local residual bacterial density standards should be evaluated

c (chemical disinfection)

・ Efficient disinfection (comprising ARB demobilization)

• Poor/no reduction of CECs and ARGs

・ Generation of DBPs

• Toxicity trials recommended

・ DBPs (following the disinfectants utilized) must be controlled

d (O₃/AOP and biological

post-treatment)

・ Efficient disinfection (comprising ARB demobilization)

・ CECs reduction: Elevated throughout ozonationand (solar) photo Fenton, moderate with UV/H₂O₂

・ Full-scale evidence on practicability onlyfor O₃

・ Generation of numerous DBPs (Nnitrosodimethylamine (NDMA), bromate) throughout ozonation

• Production of oxidation transformation products throughout AOP and ozonation

・ Partial ARGs reduction

• Toxicity trials recommended

・ NDMA and bromate must be controlled inO₃ treatment

e (GAC and UV)

• Efficient disinfection via UV

• Elevated CECs reductionvia GAC

・ Full-scale evidence on practicability

• Poor/no reduction of ARB & ARGs via GACalone

・ For UV see above, TT a & b

・ Reducing adsorption capacity with elevating bed volume must be considered

f (PAC and UV)

• Efficient disinfection via UV

• Elevated CECs eliminationvia PAC

・ Full-scale evidence on practicability forCEC removal by PAC

• Poor/no reduction of ARB & ARGs via PACalone

・ • For UV see above, TT a & b

g (NF or RO membrane filtration, with potential pre-treatment with MF or UF membranes)

• Efficient disinfection for bacteria (comprising ARB) and protozoa for all membranes; viruses well removed by UF, NF & RO

• ARGs well removed by NF and RO

・ CECs removal from poor (MF, UF) to verygood (NF, RO) following membrane type

• RO and partially also NF reduce salinity

・ For post UV-C see TT a & b

• Poor/no reduction of ARGs at full-scale byMF (for UF some reduction is expected)

• Poor CECs elimination for MF and UF

• Elevated energy needs for NF and RO

• Formation of a substantial concentrate waste stream by NF and RO

・ For post UV-C see TT a & b

• Effect of membrane features on disinfection, ARB, ARG, and CEC reduction has to be carefully taken into account in design

• Consider AOP instead of UV disinfection ifthe risk of unknowns and spills is considered high

・ Consider high UV doses if NDMA can be suspected in the membrane effluent (e.g. following prior chloramination)