Treatment of university campus wastewaters by anaerobic reactor and multi-stage constructed wetlands

Abstract

Sustainable and decentralized sanitation is essential for a continental country like Brazil to mitigate its untreated sewage liabilities. This may be directly related to the constructed wetlands (CWs), since these systems are considered clean technology alternatives for the treatment of wastewaters. So, the present research investigated the treatment of university campus wastewaters by a hybrid system composed of: anaerobic reactors (AR) + vertical flow constructed wetlands (VFCW) + floating treatment wetlands (FTW) + horizontal subsurface flow constructed wetlands (HSSFCW). Effluents were treated in batch mode, with a loading time of 1 h, a flow after preliminary treatment of 1.6 m3 h−1 to load the system and hydraulic detention time of 3 days for the AR, and 7 days for each CW unit. CW were planted with 4 different macrophytes: Hymenachne grumosa, Vetiveria zizanoides, Papyrus and Lemna minor sp. The obtained results showed removal rates of 67 % for COD, 53 % for BOD5, 94 % for Total N, 90 % for DOC, 98 % for turbidity and of 5log for E. coli. Almost all the investigated parameters of the treated wastewaters were in accordance the emission limits established by current Brazilian legislation. Moreover, the good performance of the hybrid system brings new reuse possibilities for the treated wastewaters, so that they would be adequate to be reused in orchards, cereals, forages, pastures for livestock and other crops through runoff or by punctual irrigation system.