Innovative wireless tool for reducing energy consumption and GHGs emission of water resource recovery facilities.

Newsletter 3.


Procedure development for off-gas monitoring with LESSDRONE

The first off-gas measurement campaign within Cuoiodepur WRRF is completed. The project provides for a total of 6 measurement campaigns to be carried out at Cuoiodepur, distributed throughout the year so as to cover the different environmental and load conditions of the plant. As foreseen in the Work Program, the following tests were carried out during the first measurement campaign:

  1. Measurements on several points of the tank with constant air flow. On each point the oxygen transfer efficiency and the concentration of greenhouse gases (CO2, N2O and CH4) was detected. The off-gas flow rate and the concentration of dissolved oxygen in the different points were also detected, in order to evaluate their spatial distribution within the tank;
  2. Measurements in a single point of the tank for a prolonged time (one week). The oxygen transfer efficiency and the concentrations of the greenhouse gases were measured on a fixed point of the tank in order to assess their temporal distribution in different operating conditions (night/day, high/low load, ...);
  3. Sampling and analysis of the inlet and outlet of the oxidation tanks, during the measurement tests.

During the first measurement campaign, tests on a single point and tests on different point were both carried out on each of the two oxidation tanks studied (tanks 5 and 6).

As an example, the following graph shows the trend of the air flow rate and of the oxygen transfer efficiency of a test in a point of tank 6. The increase of the air flow reduces the efficiency of oxygen transfer.
The results of the measurements in different points of the tank can be summarized as follows:
  • The air flow in the tanks is greater in the initial part, where the wastewater enters, and decreases as you move towards the end of the tanks, where the treated wastewater comes out, according to the diffusers distribution on the tank floor.
  • The oxygen transfer efficiency, αSOTE (%), is greater in tank 5 than in tank 6; this is in line with the fact that air diffuser membranes in the tank 6 are older than in the tank 5.
  • CO2 (%) and N2O (ppm) emissions are similar for both tanks with variable trends from point to point. On average, CO2 is 3%, while N2O is around 7 ppm.
The results of the measurements in a given point of the tank can be summarized as follows:
  • The daily trend of incoming polluting loads, mostly of industrial origin, varies according to the tanneries productivity, and therefore varies according to the day of the week. During working days, the load increases during the day, vice versa on weekends and in particular on Sundays, the load progressively reduces.
  • The air flow in the tanks follows the trend of the organic load entering the plant: the greater the loads, the greater the air flow to be supplied.
  • As air flow increases, oxygen transfer efficiency in the tanks reduces.
The next measurement campaigns planned at Cuoiodepur, will allow to deepen the dynamics involved in the biological processes of oxidation tanks. This will optimize the LESSDRONE and all the accessory equipment used.
The dissemination and networking actions of the project continue. On June 11, 2019, the fourth didactic visit was held at the CUOIODEPUR WRRF with the students of the ITS course for "Senior Technician for the coordination of the processes of design, communication and marketing of the fashion product" organized by MITA ACADEMY. During the visit, the WRRF operation and the development of the project with particular reference to the B3 action and the first measuring campaign carried out with the LESSDRONE prototype was illustrated.
To follow the progress of the project and the initiatives promoted, we invite you to consult the website ( For detailed information on technical activities, please send an e-mail to the following address:
Contact: Cecilia Caretti
Civil and Environmental Engineering Department (DICEA)
University of Florence - Via S.Marta, 3 – 50139 Florence, Italy
Tel. +39 055 2758850
Copyright © 2019 Lessawatt Project, All rights reserved.

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