Experimental validation of a single-OUR method for wastewater RBCOD characterisation

Wastewater characterisation is of primary importance for the correct design and management of a treatment plant. The aim of this work was the evaluation of a new rapid and easy to use respirometric technique for the characterisation of readily biodegradable COD (RBCOD). When the necessary calibration curve is obtained, the RBCOD assessment procedure needs less than 30 minutes. On the contrary, conventional techniques require some hours. The first step consists in calculating a calibration curve in order to point out the correlation between oxygen consumed and known amount of added Sodium Acetate. To a well aerated biomass (in order to remove residual readily biodegradable substrate) a known amount of Sodium Acetate is added and the related OUR is measured. The oxygen consumed (DDO) is related to the added COD (as Sodium Acetate). Therefore, the RBCOD concentration in wastewater samples can be obtained according to the following steps: (1) measure ΔDO; (2) multiply ΔDO by the Volume of aerated mixed liquor used in the test; (3) from the calibration curve, calculate the readily biodegradable COD equivalent to Acetate; (4) estimate RBCOD concentration multiplying the wastewater sample volume tested in the reactor. Some advantages of this technique are described in the paper.