Effect of dissolved oxygen in reclaimed wastewater transformation during transportation. Case study: Tenerife, Spain

Abstract

During treated wastewater transport, phenomena related to the presence or absence of dissolved oxygen (DO) have been observed. In Tenerife reclaimed urban wastewater (RUWW) transport from the capital, Santa Cruz to the south of the island for agriculture reuse was studied. Anoxic conditions and H2S generation were noted during transport. As RUWW has an electrical conductivity (EC) of about 1600 μS/cm, BALTEN decided to add fresh water (FW) with low EC, saturated or over saturated in DO at an intermediate point in the pipe to reduce the conductivity of water supplied to agriculture, also thus reducing the organic load and consequently H2S generation. However, injection of DO over-saturated fresh water brought on the appearance of nitrification and later denitrification. A study was carried out of H2S generation, nitrification and denitrification during RUWW transport with and without added FW.