AWWA WQTC58895

The broadly stated objectives of this project are to identify benefits and encourage usage of aerobic spore monitoring as a tool to supplement other tools available to water plant operators for evaluation and optimization of drinking water treatment. This includes evaluation of the treatment facility as a whole (raw through filtration) as well as individual unit processes. One particular application to be specifically addressed during this project is the use of spore monitoring for the demonstration of performance (DOP) credit allowed in the LT2ESWTR. DOP using aerobic spore monitoring is a potentially valuable and cost-effective tool (Cornwell et al. 2003) for regulatory compliance in the upcoming LT2ESWTR, particularly facilities needing credits without extensive monitoring and capital improvement requirements. The DOP credit can establish a 4 log or higher Cryptosporidium removal credit using existing facilities. Existing historical data indicate that spore concentrations in the filtered water at drinking water plants are frequently below the detection limit typically used (1 spore per 100 or 200 mL). Since many U.S. source waters also have low raw water spore concentrations, a key issue to be addressed in this project was to evaluate whether the current method can be refined by using larger filtered water sample volumes, resulting in lower detection limits, or whether development of an alternative sample collection and analysis protocol is needed to handle larger sample volumes. Modifications that would result in lowering the detection limit would increase the usefulness of spore monitoring. This project investigated raw water concentrations in order to evaluate how low the filtered water detection limits need to go in order to mathematically demonstrate a particular target spore log removal (e.g., typically facilities may want to evaluate whether they meet the 4-log target for the DOP credit). In addition, finished water data was investigated to see if spores are detected at levels below the current 1 cfu/200-mL detection limit but above the detection limit needed to demonstrate the target log removal. Includes 18 references, table, figure.