Evaluation of DWTUs Which Consist of Multiple Technologies Testing of systems which fall under multiple DWTU Standards.

Background The performance tests under the ANSI/NSF DWTU standards are designed to evaluate a specific technology. Different technologies have different performance characteristics that must be evaluated. –Capacity limited vs. Efficiency limited –Water quality effects –Physical operation effects The tests are conservative in evaluating performance of the target technology, but remove the effects of other technologies that may affect reduction.

Background The approach of addressing only the core technology in each Standard has led to overly conservative testing of systems which use more than one technology to treat drinking water. Each treatment stage can be evaluated separately under the appropriate Standard but must pass the full reduction requirements without assistance from other stages.

Treatment Train Solution Provide options within the standards to evaluate systems that take advantage of multiple technologies to achieve treatment goals.

A Treatment Train Treatment of water in a sequential manner - each treatment stage connected in series. Effluent of prior stage is influent of next stage. Not all stages within a system may be relevant for a particular performance claim. Many claims are achieved by a single technology. Some claims may only be effectively achieved by a combination of technologies. –HAA5 –Perchlorate –Arsenic –Emerging contaminants

Treatment Train Definition Treatment Train: A sequential series of two or more contaminant reduction technologies applied within a system to achieve a final water quality goal.

Example of a Treatment Train Many RO systems combine adsorption (activated carbon) and reverse osmosis technologies. –Influent water is first treated with carbon pre-filters to remove sediment and chlorine. –Water is then treated by a reverse osmosis membrane, controlled by a shut off valve and stored in a pressure tank. –Water is treated with carbon post-filter following the membrane.

Example RO System

Three Treatment Stages using Two Technologies Pre-Filter carbon treatment Reverse Osmosis treatment Post-Filter carbon treatment

Stage One: Pre-Filter Carbon Treatment Capacity limited technology Normal function is to reduce chlorine exposure of membrane and prevent large particulate from entering membrane. All water entering system passes through this filter, including reject water Since many systems operate at an efficiency of <10% this volume of water is very great. Example: 10 gpd system, 8% efficiency, 90 day change of pre-filter =11,250 gallons minimum capacity. ANSI/NSF Standard 42 & 53 appropriately address this treatment technology if the above volume issue is properly addressed.

Stage Two: Reverse Osmosis Treatment Performance of system is use-pattern, water chemistry and operating condition controlled. ANSI/NSF Standard 58 appropriately addresses this treatment technology. Testing generates percent reductions of contaminants from specified challenge levels. Useful for ionic contaminants and mechanical filtration. Very limited use for contaminants that may be present (completely or partially) in non-ionic or neutral form.

Stage Three: Post-Filter Carbon Treatment Capacity limited technology Only product water passes through this stage. Life of this product is directly related to water consumed by user. Influent levels dependent on performance of prior stages. ANSI/NSF Standard 42 & 53 appropriately address this treatment technology.

Evaluation Options: Option One Isolate the primary treatment technology from the other technologies that may be present in the system. Evaluate the treatment technology in a manner that is conservative and appropriate for that technology. Require the primary treatment technology to meet all performance requirements for the claim. Current method used for testing in DWTU standards.

Evaluation Options: Option Two Evaluate the system as a complete system. Perform several test methods on the complete system to cover all of the treatment technologies used within the system. –For our example system: Evaluate the System using Standard 53 test methods (carbon technology). Evaluate the System using Standard 58 test methods (RO technology). Must meet all performance criteria under both Standards for the performance claim.

Evaluation Options: Option Three Isolate each technology stage and test them separately. Use the maximum effluent from the previous stage to determine the influent target level. Use the appropriate Standard test method to evaluate each technology in a manner that is conservative to its application within the system. Performance requirement is met if the reduction across all technologies combined meet the requirement. Not all technology stages must be evaluated, but at least two are evaluated and they are evaluated in the sequence that they occur within the system.

RO System – Option Three Example Stage 1 Stage 2 Stage 3 Not Evaluated Evaluated as first treatment stage Evaluated as final treatment stage

RO System – Option Three Example Stage 2 (RO) is evaluated under NSF/ANSI Standard 58 for reduction of the claimed contaminant using the full influent challenge level. Stage 1 and 3 are removed from the system. The maximum effluent observed from Stage 2 is used as the target influent challenge level for Stage 3. Stage 3 is evaluated under NSF/ANSI Standard 53 for reduction of the claimed contaminant using the revised target influent challenge level. Effluents from Stage 3 are evaluated against the performance criteria of both standards and must meet all requirements.

Recommendation 1.Send proposed language to ballot to incorporate these concepts into the body of the DWTU performance standards: 42, 44, 53, 55, 58, 62, 244 and Send proposed definition language to ballot to include the Treatment Train definition into NSF/ANSI Standard 330.

Thank You for Your Attention Questions?