Analysis of the pollutant removal efficiency and sludge reduction effect in the MPR-OSA process

To effectively address the disposal problem of residual sludge from wastewater treatment plants and reduce the generation of residual sludge, this study coupled a Micro-pressure reactor (MPR) with an Oxic-settling-anaerobic (OSA) to develop the MPR-OSA process, and systematically evaluated the pollutant removal efficiency and sludge reduction effect of this process, compared with the MPR process. The research results showed that the MPR-OSA process exhibited superior treatment performance, with a 10.1% increase in TN removal rate and a 2.1% increase in TP removal rate. In terms of sludge reduction, the new process was 36.6% lower than the MPR process, demonstrating significant sludge reduction potential. Further analysis of the sludge performance parameters revealed improved sludge settleability and dehydrogenase activity, while the content of extracellular polymer substances decreased. Microbial analysis indicated higher biodiversity in the sludge of the new process, along with increased abundance of functional bacteria involved in nitrogen and phosphorus removal. Functional gene prediction showed that the abundance of functional genes such as nosZ , nirS , ppx , and ppk increased, and the enrichment of these genes jointly promoted the nitrogen and phosphorus removal activity and energy utilization efficiency of microorganisms. This study not only expands the path of the micro-pressure reactor in the field of sludge reduction technology but also reveals the synergistic mechanism of the MPR-OSA process from multiple dimensions including pollutant removal, sludge characteristics, and microbial mechanisms, providing theoretical basis and technical support for its engineering application.