Alumina, a phosphorus-selective adsorbent, was used in a tertiary chemical process for phosphorus removal. A mobile pilot plant designed and built on the basis of laboratory results was fitted into a standard forty-foot van trailer. The secondary effluent was passed through a thirty inch multimedia filter bed and stored. Then the filtered sewage was pumped through one or more of three alumina beds approximately forty inches in depth and three feet in diameter. Phosphorus loading of the alumina columns can be in a downflow or upflow direction with the columns in series or parallel. NaOH was recirculated to remove absorbed phosphorus in an alumina column taken off the line. Valving and column washing was pH controlled. Ca(OH)2 as added to the NaOH solution in a mixing tank to precipitate phosphorus in the form of hydroxyapatite. The solids were removed in a continuous centrifuge and the Na(OH) returned for reuse. Initial operating costs are reported. (Author)