A quantitative analysis of swimming pool recirculation system efficiency

The primary objective of this study was to conduct a quantitative analysis of the hydraulic efficiency of a 1:25 bench-scale swimming pool and to determine whether the recirculation efficiency could be increased by modifying parameters such as turnover rate, inlet/out configuration, and extent of mixing within the pool. Salt tracer studies were conducted using KCl to determine the residence time distribution and describe the hydraulic characteristics of the pool. The results indicated that the removal of the tracer always followed an exponential decay curve, i.e. 63, 86, 95% for the first, second, and third turnover periods, respectively. In the majority of experiments, the exponential decay rate matched the inverse of the theoretical hydraulic detention time of the system. The results showed that none of the investigated parameters had any significant impact on the tracer removal efficiency. Increasing removal efficiencies of current treatment technologies such as sand and cartridge filters from approximately 25-90% would provide significant improvements in the rate of removal of Cryptosporidium-sized particles. Improving the treatment efficiency beyond 90% would have little additional impact, but further improvements could be achieved by decreasing the system turnover rate.