Oxygen transfer and wide-plant energy assessment of primary screening in WRRFs

Primary screening is gaining interest as a method to achieve removal performances comparable to primary clarification while reducing the footprint and increasing operational elasticity. Aeration efficiency indicators in a pilot sequential batch reactor (SBR) and a full scale water resource recovery facility (WRRF) were investigated after the implementation of rotating belt filters/screens (RBF). To compare the impact between screened (350 mu m) and nonscreened primary influent, two identical treatment lines were monitored using off-gas and respirometric measurements. The study provides the first result on improved oxygen transfer efficiency due to primary screening. Consistent aeration efficiency improvements of 27% and 20% between screened and nonscreened were obtained at pilot and full scale, respectively. Changes in aeration efficiency and carbon redirection were integrated into a set of models to investigate the primary screening impact on the WRRF energy balance. While the wide-plant assessment for different scenarios improved the energy balance up to 15%, a detailed comparative analysis between various treatment schemes gained insight into the advantages and limitations of the energetic sustainability of primary screening. Practitioner points Aeration efficiency improved 27% at pilot scale Aeration efficiency improved 20% at full scale. Use of primary screening can improve the energy balance up to 15 Assessment of advantages and limitations of primary screening.

Automated summary

Primary screening can significantly improve oxygen transfer efficiency, with improvements of 27% at pilot scale and 20% at full scale. By integrating changes in oxygen transfer efficiency and carbon redirection, the impact of primary screening on facility energy balance can be explored. Through wide-plant assessment of different scenarios, primary screening can improve energy balance up to 15%, providing insight into the advantages and limitations of energetic sustainability.