The tertiary treatment pilot plant of PubliSer SpA (Florence, Tuscany): A multistage experience

The multiservice company PubliSer SpA has constructed and monitored the ope ration of a multistage tertiary constructed wetlands wastewater treatment p ilot plant for experimental and demonstration purposes. The facility was de signed by and is partially monitored by the environmental engineering compa ny WS SaS in Cerbaia, Florence, Italy. The experimentation with natural was tewater tertiary treatments is particularly important within central Italy as there are recurring environmental problems related to the poor functioni ng of small wastewater treatment systems. The present study is designed to compare the utility and efficiency of different multistage configurations f ollowing an active sludge process through an intensive monitoring programme that was initiated in November 1997. In this paper, we report the principa l design specifications, a detailed description of the pilot plant, the dim ensioning criteria and an analysis of the influent and effluent characteris tics (COD, BOD, N, P, microorganisms, TSS, etc.) for each compartment monit ored in the first period of plant operations. The pilot plant consists of t wo experimental lines, each characterised by a first and second treatment s tage. The effluents of the first stages are divided into three different se cond-stage basins. The plant demonstrated high removal of nutrients, a good buffering capacity and a reasonable reduction of microorganisms after only a limited number of months of operation. Continued monitoring and comparis on of the different constructed wetland strategies is providing interesting information for future designs and operation. (C) 1999 IAWQ Published by E lsevier Science Ltd. All rights reserved.