Treatment of olive mill wastewater with constructed wetlands asset management of medium and small wastewater utilitiesTreatment of olive mill wastewater with constructed wetlands asset management of medium and small wastewater utilities Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2015-11-072009enThe objective of this study was to investigate the application of constructed wetlands as a mean to manage olive mill wastewater (OMW). Two free water surface (FWS) constructed wetlands, one without (CW1) and one with effluent recirculation (CW2), were operated for a two-year period with diluted OMW (1:10) and evaluated in terms of the removal of COD, TSS, TKN, NH4+-N, NO3−-N, TP and total phenols. The organic loading rate of CWs was adjusted to 925 kg BOD/ha·d. In CW1 the removal efficiency averaged 80%, 83%, 78%, 80%, and 74% for COD, TSS, TKN, TP, and total phenols, respectively, during the operation period. Effluent recirculation further improved the treatment efficiency which approached 90%, 98%, 87%, 85%, and 87% for COD, TSS, TKN, TP, and total phenols, respectively. Constructed wetlands also showed high removal efficiency for NH4+-N. Nitrate concentration maintained low in both CWs basins, probably due to the prevalence of high denitrification rates that efficiently removed the NO3--N produced by NH4+-N oxidation. Despite the increased removal percentages, pollutant concentration in effluent exceeded the allowable limits for discharge in water bodies, suggesting that additional practices, including enhanced pre-application treatment and/or higher dilution rates, are required to make this practice effective for OMW management.http://creativecommons.org/licenses/by/4.0/260-271International Water Association Tsagarakis Konstantinos Angelakis Andreas Paranychianakis Nikolaos Παρανυχιανακης Νικολαος Kapellakis Iosif Καπελλακης Ιωσηφ Water nutrient removal