Monitoring & metering
the site’s odours and to thereby install monitors that are capable of detecting the specific odorous compounds that exist at the site. Using the same training, a quantitative fingerprint allows the identification of the nature of the odours as well as their sources. At Green Star, the incinerator is burning domestic waste, from which odour production varies according to the weather (temperature), which is why continuous monitoring is so important. Each of the ELLONA monitors (WT1) at Green Star features a comprehensive array of sensors measuring temperature, humidity, pressure, hydrogen sulphide, ammonia and VOCs. Other important variables are wind speed and direction, which have obvious effects on odours. Wind is therefore monitored at the site continuously; not just to be able to model the movement of odour plumes but also to be able to differentiate any odours that arrive from an external source. ELLONA therefore worked in partnership with the high-performance computing and modelling company NUMTECH to model the complex air flows that take place in the plant and in the surrounding urban environment. Meteorological conditions determine whether the site’s emissions are dispersed in the local streets. The combination of numerical simulations (forward and backward) and the network measurements make it possible to identify the contribution of the site and the potential sources. The WT1 units store measurements internally, but the data are also transferred to the Cloud every 10 seconds for processing. Data from the physical sensors and from the virtual sensors (created from the physical sensors’ data and mathematical models) provide information on air quality, odour identity, intensity and duration. The measurements and the derived odour information are provided in real-time to Syctom via a dedicated website, which also provides the facility to view historical data.
THE ADVANTAGES OF NETWORK MONITORING
It would have been possible to install a single ELLONA monitor at the Green Star site, and to model odour around that point, but by installing a network of 19 WT1 monitors Syctom derives a number of important advantages. For example, networks of IoT monitors improve the capability to track the speed and direction of odour as it moves across the network, which in turn helps to identify odour sources. Similarly, if all of the monitors report an unrecognised odour moving across the network, it is likely that it is derived from a diffuse external source or a distant point source. However, if one monitor in the network reports an odour incident; it is more likely to be derived from a point source within the network. Odour levels at any point are generally comprised of odours from different sources, so the ability of the ELLONA system to identify sources means that it is able to measure the relative contribution of the different individual sources to each odour incident.
Most of the WT1 monitors are located within 22
the local neighbourhood. This enables the evaluation of the amplitude of odour change in comparison with the reference situation. Alarm thresholds have been set for the physical and the virtual sensors, and an alert is issued each time a threshold is exceeded. Consequently, Syctom is able to respond quickly to any odorous incident.
SUMMARY
Continuous, smart odour monitoring has been shown to offer major advantages over spot sampling. However, the unique features of the ELLONA solution are that the monitoring network is developed to match the specific odours that exist at the Syctom site, and ELLONA’s mathematical models enable the continuous delivery of source identification with both qualitative and quantitative data. The continuous odour monitoring system has improved Syctom’s understanding of the processes that affect odour, including specific events and the volume of waste being handled for example. In addition, the availability of trustworthy transparent data has provided reassurance to local residents.
Explaining the value of the insights that the
ELLONA solution delivers, Bara says: “The monitoring system has confirmed the main odour sources that we have on-site; in particular, it has demonstrated that odours arising from waste truck movements are more important than we initially expected. To-date, the measurement
network has helped us to identify and implement the most effective mitigation measures. That work is currently ongoing, but we expect the system to show us that these measures have enabled odour improvement, for the benefit of our staff and local residents.” Looking forward, now that the concept has been proven, the plan at the Green Star site is to further lower odour nuisance by implementing odour mitigation measures and identifying those which are the most successful. As time passes, the constituents of household waste are likely to change, but with the monitoring system in place, Syctom will be able to respond accordingly to any changes in odour generation.
ELLONA
April 2023 Instrumentation Monthly
www.ellona.io
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