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DOI: 10.3303/CET2185007

Paper Received: 16 December 2020; Revised: 14 January 2021; Accepted: 26 February 2021
Please cite this article as: Zarra T., Cimatoribus C., Oliva G., Belgiorno V., Naddeo V., 2021, Proactive Approach for Odour Emissions
Characterization in Wastewater Treatment Plant by H2odour System, Chemical Engineering Transactions, 85, 37-42
DOI:10.3303/CET2185007

CHEMICAL ENGINEERING TRANSACTIONS

VOL. 85, 2021

A publication of

The Italian Association

of Chemical Engineering
Online at www.cetjournal.it

Guest Editors: Selena Sironi, Laura Capelli
Copyright © 2021, AIDIC Servizi S.r.l.
ISBN 978-88-95608-83-9; ISSN 2283-9216

Proactive Approach for Odour Emissions Characterization in
Wastewater Treatment Plant by H2Odour System

Tiziano Zarrac, Carla Cimatoribusb*, Giuseppina Olivaa, Vincenzo Belgiornoc,
Vincenzo Naddeoac
a SPONGE Srl, Accademic Spin Off of the University of Salerno, Laboratory SEED, Via Giovanni Paolo II, 132, 84084
Fisciano (SA), Italy
b Building Services Energy Environment, University of Applied Sciences – Hochschule Esslingen, Kanalstraße, 33 - 73728
Esslingen, Germany
c SEED - Sanitary Environmental Engineering Division, Department of Civil Engineering, University of Salerno, via Giovanni
Paolo II, Fisciano, SA, Italy
carla.cimatoribus@hs-esslingen.de

The characterization and quantification of the odour emissions in wastewater treatment plant (WWTP)
represents a fundamental step in order to identify potential odour problems and establish the best and most
appropriate odour management tools. Nowadays odour emissions in WWTP are characterized by the use of
sampling techniques which take samples directly from the gaseous phase: i.e. when the emission and
consequently the potential problem are already present.
The definition of proactive tools for the assessment of potential odour emissions from the emitting sources can
prevent the occurrence of potential significant odours events and as consequence complaints.
The research presents and describes a novel system, called H2Odour, useful to measure the potential Odour
Emission Capacity (OEC) directly from liquids. The system has been designed and developed to standardize
the stripping phase of gaseous samples, ensuring the maximization of the odour compounds transfer from the
liquid to the gaseous phase. The application on a real full scale WWTP is highlighted. H2Odour represents a
novel, proactive device to prevent potential critical situations, allowing a preliminary characterization of the
maximum potential odour emissions directly from the liquid phase and through this control activity, leading to a
greater environmental and social acceptability of the WWTP.

1. Introduction
Achieving the best quality of life in urban areas is increasingly being discussed among academics, urban
planners and politicians. The study of complex interactions between human activities and biophysical
processes has been challenging in recent years (Belgiorno et al., 2012; Badach, et al., 2018). The dispersion
of unpleasant odours into the atmosphere has become a growing social problem in industrialized countries.
due to the proximity between urban areas and industrial and environmental protection plants(Giuliani et al.,
2012; Zarra et al., 2019). Consequently, to avoid complaints, the identification of smart and effective tools able
to prevent the occurrence of odour impact events with a proactive approach is a priority (Capelli et al., 2009;
Fasolino et al., 2016).
An internationally recognized method of data processing is the "Odor Emission Capacity" (OEC) method. The
method was first introduced in the technical-scientific literature by Frechen and Köster in 1998 and recently
standardized by the VDI3885 Blatt 1:2017-06 (“Olfactometry – Measurement of odorant emission capacity of
liquids). The OEC provides an equation for calculating the maximum odour-producing potential of liquid
samples (OEC), as the measure of the total mass of odorants, expressed in OUE m

-3, which can be removed
from 1 cubic meter of liquid under certain standardized conditions (Frechen, 2004; Zarra et al., 2012; Giuliani
et al., 2013). However, this method does not allow defining in a pattern and complete way the criteria in terms
of instrumental and structural equipment, for determining the gaseous samples to analyze.

To overcome these limitations, the research presents and describes a novel device, called H2Odour, with the
aim of generating the gaseous sample in a standardized and repeatable way, thus eliminating the
uncertainties of the method related to sampling phase. The application of the novel device for the OEC
determination in a real full scale wastewater treatment plant (WWTP) is discussed.

2. Material and method
2.1 H2Odour device

In Figure 1 is reported the layout of the H2Odour device, with the identification of the main components. The
device consists of a main body with an internal chamber, configured to host the liquid to be analysed in terms
of odour emissions capacity. The device comprises elements for heating the liquid contained in the internal
chamber and for the insufflation of odourless air.

Figure 1: H2Odour device and main parts

Moreover, the device includes a control unit for the activation of heating and air supplying components to
ensure predetermined operating parameters. The presence of volatile compounds within a liquid is intrinsically
connected to its odour-producing potential, as these compounds, by volatilizing, can generate odour nuisance.
In order to characterize the odorous potential of a liquid matrix, it is therefore essential to promote stripping of
the above compounds in the gas phase, subsequently subjected to suitable characterization..

2.2 Experimental plan and program

The experimental activity, conducted at the Sanitary Environmental Engineering Division Laboratory of the
University of Salerno (SEED), entailed fifteen sampling campaigns at a large Wastewater Treatment Plant
(WWTP), designed for 700,000 equivalent inhabitants. The campaigns were carried out twice a week, taking
15 liters liquid samples, according to the APAT CNR IRSA 1030 method, at four units of the wastewater
treatment line of the WWTP.
The identified sampling points are listed below:

• P1, coarse screening output;
• P2, primary sedimentation output;
• P3, oxidation tank;
• P4, secondary sedimentation output.

In Figure 2 is reported the localization of the investigated sampling points.

All collected liquid samples are characterized in terms of principal chemical-physical analysis and, using the
novel H2Odour device, in terms of OEC measurements.

Figure 2: Sampling points at investigated WWTP

2.3 Chemical-physical analysis

Onsite and laboratory analysis are carried out for all collected liquid samples in order to characterize their
chemical-physical composition. A multiparameter probe (Hanna Instruments model HI 9829) was used directly
on site to measure temperature, pH, dissolved oxygen and conductivity. After their transport to the laboratory
in a thermostat refrigerator at 4° C, LCK cuvette test and Oxitop method were applied to determine COD and
BOD5 respectively.

2.4 OEC characterization

The liquid samples were agitated for 1 minute in the original tank to promote the suspension of the sediment
materials. Five litres of liquid samples were then taken from the tank and placed in the H2Oodur device. In
Table highlights the main operating parameters of the H2Odour device set for the analysis.

Table 1: Operating parameters

Operating parameters
T[°C] 50

Air flow rate [lpm] 10
Volume of liquid sample [l] 5

The generated odorous air, obtained thanks to the bubbling of the odourless air inside the chamber where the
liquid was placed, were directly collected in 7 liters Nalophan® bags, inserted at the upper closing element
connection of the H2Odour device, at 2, 4, 7 and 12 min from the start of the test.
All collected gas samples were analysed with dynamic olfactometric analyses, conducted at the Sanitary
Environmental Engineering Division (SEED) Laboratory of the University of Salerno, according to the EN
13725:2003. A TO8 olfactometer (ECOMA, D), based on the ‘‘yes/no’’ method, was used, relying on a panel
composed of four trained persons. All the measurements were analysed within 14 h after sampling, according
to Zarra et al. (2012). OEC of all collected samples was calculated according to the following equation
(VDI3885:2015):

where: COD is the concentration of odour emission from air samples collected at the beginning of the
experiment (Vto) to the volume at time t (Vt); C100 is the concentration of odour emission established as the
limit which defines the end of the test, fixed at 100 OU/m3 (Frechen et al., 1998); VL is the volume of liquid
sample used for the analyses.

3. Results
3.1 Chemical-physical characterization

Figure 3 shows the results of the in-situ parameters characterization, in terms of mean values and related
standard deviations for the temperature (“T”), Dissolved Oxygen (“DO”), pH (“pH”) and conductibility (“Cond.”)
measured at all the sampling points during the sampling campaigns. Figure 4 and 5 report instead the box-plot
representation, respectively, of the COD and BOD5 measurements, determined for the liquid samples
investigated in the monitored period.

a) b)

Figure 3: In-situ chemical-physical characterization (3a: T, pH, DO; 3b: cond.)

Figure 4: COD Box-plot of the four liquid odour sources during the different campaigns

0.0
5.0

10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0

P1 P2 P3 P4
Sampling Points

T [°C] pH DO [%]

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

1600.0

1800.0

2000.0

P1 P2 P3 P4
Sampling Points

Cond. [µS/cm]

Figure 5: BOD5 Box-plot of the four liquid odour sources during the different campaigns

The chemical physical characterization results showed that the tendency of the monitored parameters, is quite
constant along the wastewater treatment line and even during the different sampling campaigns. In particular,
the pH value was quite stable at 7. Conversely, the results in terms of COD and BOD5 highlighted more
substantial differences in terms of organic contents along the treatment line. The trend of the ratio between
BOD and COD measured in the investigated points was indicatively constant: as the measured BOD
increases, the relative COD also increases and vice versa.

3.2 OEC characterization

Figure 6 shows the box-plot representation of the OEC values calculated with the H2Odour device for all the
four odour sources during the different sampling campaigns.
The highest values in terms of OEC were measured in P2, corresponding to the primary sedimentation tank.
The lowest values were detected at the secondary sedimentation tank.
The analysis of the chemical-physical characterization and the OEC determination of the investigated liquids
showed some matching trends, in particular with reference to the organic contents.

Figure 6: OEC Box-plot of the four liquid odour sources during the six different campaigns

4. Conclusions
OEC method is an important tool to pursuit proactive odour emissions prevention and control strategies
especially in wastewater treatment plants where the main odour sources are generated by liquid matrix. This
proactive approach matched the needs to increase the acceptability and sustainability of industrial plant and
environmental protection facilities in a context aiming to the switch at green and smart factories. The H2Odour
device can be included among the tools for environmental protection since it allows the identification of
potential odorous emissions responsible for negative impacts. The application to a large wastewater treatment
plant highlighted the ease and effectiveness of the device in order to generate odorous gaseous samples from
the liquid sources. The standardization of the sampling phase is of fundamental importance to ensure reliable
and consistent data, since the OEC determination can be used to control the treatment process, detect
possible undesired conditions and act before the occurrence of odour events. In this context H2Odour
represents an opportunity to spread and simplify the application of OEC method. The outcomes resulted in
reliable measurements, which can be easily replicated in standardized conditions, representing reference
values useful to preliminary detect possible causes of odour annoyance.

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