Phosphorus removal in sewage treatment effluents using TechPhos

Abstract

This project evaluates the application of TechPhos, a product obtained from iron-modified bentonite as adsorbent, aiming at the removal of phosphorus present in sewage treatment effluents. The patent for this product was already required. TechPhos consists of an expandable bentonite clay, in which Fe(III) cations have been incorporated and can be applied as a dry powder or pellet. The release of sewage into aquatic bodies causes the degradation of water resources, including phosphorus enrichment and consequent eutrophication of such environments, resulting in an increase in primary productivity processes, growth of often toxic algae and aquatic macrophytes. Such scenario compromises the multiple uses of rivers, lakes and reservoirs, with deleterious consequences for aquatic life, human health and maintenance of economic activities. Conventional biological sewage treatment systems are designed for the removal of solids and dissolved organic matter, primary and secondary treatments respectively, resulting in effluents with concentrations of nitrogen and phosphorus close to those of raw sewage, as such nutrients would only be removed in tertiary treatment units, which are uncommon in Brazil. Resolutions from some states in the country consider significant restrictions on the release of phosphorus in water bodies. For example, at Rio Grande do Sul State, Consema Resolution No. 355/2017 sets as a limit for phosphorus concentration in effluents the value of 1 mg / L for emission of high flow rates, or alternatively at 75% removal. The Piracicaba, Capivari and Jundiaí River Basin Agency (PCJ), which encompasses a region with 76 municipalities and approximately 5 million inhabitants, highlighted in its 2010-2020 Master Plan the need for priority inclusion of Biochemical Demand parameters. Oxygen (BOD), Dissolved Oxygen (DO), nitrogen, phosphorus and thermotolerant coliforms for the framing of water resources in the PCJ Basins. Total phosphorus and thermotolerant coliform parameters will already be included in the Agency's next revision of targets, which highlights the need for tertiary treatment in the municipalities, while primary and secondary treatments are currently predominantly performed. Thus, it is necessary to develop and present a system for phosphorus removal in effluents to be released in the PCJ Basins, and also in the ETE Monjolinho in São Carlos - SP, where the first tests with TechPhos have already been performed. In an earlier stage of the research, laboratory tests were considered, which demonstrated the effectiveness of TechPhos in removing phosphorus even in a matrix as complex as the effluent coming out of anaerobic reactors. Throughout this project, we will be required to produce TechPhos on site and evaluate its application at the stations under real conditions, focusing on the design, construction and testing of a pilot mobile unit to be initially installed at ETE Monjolinho. (AU)