Hybrid natural systems for treatment of olive mill wastewater

BACKGROUNDThis study examines the efficiency of various natural systems in treating untreated OMW before it is discharged to the environment. The experimental set-up consisted of two hybrid pilot-scale natural systems. The first hybrid system (HS-A) comprised two open tanks (OTs), one vertical flow (VF) constructed wetland (CW) and one free water surface flow (FWS) CW and the second one (HS-B) comprised two OTs and one FWS CW. RESULTSRegarding the HS-A system, TSS, COD, TKN and phenols (PHE) removals in the two OTs were 83.0%, 21.6%, 62.3% and 12.9%, and cumulative removals in the VF and FWS CW systems were 52.0%, 54.1%, 44.4% and 60.1%, respectively. Regarding the HS-B system, TSS, COD, TKN and PHE mean removals in the two OTs were 80.7%, 32.2%, 64.1% and 24.7%, and in the FWS CW were 72.0%, 49.4%, 26.9% and 51.1%, respectively. The final pollutant effluent concentrations remained high for disposal in water bodies or reuse for irrigation; further reduction could be achieved by adding additional FWS CWs in series. CONCLUSIONHybrid natural systems can be used in efficiently and economically treating OMW. Such hybrid systems could be applied to small family-owned olive oil producing enterprises to treat OMW economically. (c) 2017 Society of Chemical Industry