Multi-barrier approach needed for Cryptosporidium - WRA
A multi-barrier approach will be needed in water reuse to guard against Cryptosporidium and Giardia occurrence and consequent health risks, says a new research report published by the WateResearch Association.The WRA study, Determination of Cryptosporidium and Giardia Occurrence, Infectivity, and Genotyping in Wastewater Effluents (WRA-06-003-1), indicates that species of these pathogenic organisms can readily pass through wastewater treatment processes. A clear association between the level of treatment and the occurrence of these protozoa in the effluents was noted.
Although secondary clarification processes yielded frequent positives at higher concentrations, even advanced treatment processes allowed pass-through of these protozoa. There is no doubt, says the report, that physical barriers such as membrane bioreactors, with their submicrometer pore size, have the potential to prevent these relatively large (5-20 µm) parasites from passing through into the effluent; however, this can only be successful if the membrane integrity is guaranteed.
As the need for reuse water continues to increase, the report concludes, risk mitigation strategies will need to be geared to adopting a multibarrier approach incorporating regular operational maintenance, continuous monitoring, adoption of best management practices to protect water quality during storage, and distribution and employment of UV disinfection with or without chemical disinfection.