Forecasting of H2S build-up in a reclaimed wastewater pipe

The present study has been carried out in a completely filled gravity pipe, 61 km long, which transports reclaimed urban wastewater (RUWW), for crop i rrigation in the island of Tenerife (Spain), at an average water velocity o f 0.4 m/s. Due to the long residence time of the reclaimed wastewater in th e pipe (40 hours), anaerobic conditions usually appear. and chemical transf ormation of reclaimed wastewater occurs during transportation, especially s ulfide generation. Field studies have been conducted from November 1994 to January 1997. The variation in sulfide and oxidation-reduction potential (O RP) among other parameters during wastewater transportation have been repor ted. The object of this work is to study the kinetics of the sulfide genera tion in a full scale reclaimed wastewater pipe, in order to obtain a foreca sting equation of sulfide generation, and to compare this equation with tho se previously proposed for raw wastewater sewers. Equations obtained from t his research differ quite from those previously proposed for sewers. This c an be due to the reclaimed wastewater used in this system, which has a very much lower organic matter content than raw wastewater. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.