Polling the Experts to Assess Biosolids Sampling and Handling Methods for USEPA-Approved Microbial Detection Techniques
Protecting human health and the environment while making the use of biosolid products more practical is a joint goal of utilities and regulatory agencies. As waste disposal costs rise and demands for sustainable use of resources increase, greater reliance on by-product reutilization will be needed. Assuring the safety of biosolids is paramount to gaining wide public acceptance of this reuse product. Making effective decisions about the safety of biosolids use relies on quality data. Much emphasis and research has been placed on the precision and accuracy of the laboratory methods used to quantify potentially hazardous constituents (i.e. pathogens and metals) in biosolids. However, the errors and variability in the data caused by differences in sampling practices may not be fully understood and could be a greater source than errors from the laboratory methods. Existing regulatory guidance includes requirements for the number of samples, sampling schedules, and sample handling and analyses but offers little detail as to actual practices in the field such as sampling frequency and techniques, sample locations within processes, or how to obtain statistically representative samples. This project (WERF Project 04-HHE-7) through a combination of literature review, a technical workshop attended by biosolids experts, and a survey of wastewater utilities, examines the current practices for obtaining sludge and biosolids samples for regulatory compliance with microbial testing requirements. Suggestions for improvement and further research with regard to sampling and sample handling were developed based on synthesis of results from the information gathering steps. Future efforts for project 04-HHE-7 include experimental analysis, development of communications strategy, and informing creation of guidance and training materials.