Performance evaluation of planted and unplanted subsurface-flow constructed wetlands for the post-treatment of UASB reactor effluents

摘要

A system comprised by a UASB (Upflow Anaerobic Sludge Blanket) reactor followed byntwo horizontal subsurface-flow constructed wetlands in parallel was evaluated for thentreatment of the wastewater generated in the city of Belo Horizonte, Brazil (50 inhabitantsneach unit). One unit was planted (Typha latifolia) and the other was unplanted. Influentnand effluent samples were collected for a period of seven months. The systems were ablento produce final effluents with low concentrations of organic matter and suspended solids,nbut showed not to be efficient in the removal of nutrients. Mean effluent concentrationsnfor the planted and unplanted units were, respectively: BOD: 15 and 19mg/L; COD: 42nand 64mg/L; TSS: 3 and 5mg/L; TN: 27 and 33mg/L; N-NH3: 25 and 29mg/L; P Total:n1.2 and 1.5mg/L. The planted wetland presented effluent concentrations and removalnefficiencies significantly (Wilcoxon matched-pairs test, 5% significance level) better thannthe unplanted unit for most constituents. The study shows that horizontal subsurface-flownconstructed wetlands can be effectively used as a post-treatment option for the effluentnfrom UASB reactors..