Cities test plant-based filters with connected air monitoring
A city is tendering plant‑based air purification units with IoT monitoring, showing how public buyers are linking green infrastructure to data-led services.
A city is tendering plant‑based air purification units with IoT monitoring, showing how public buyers are linking green infrastructure to data-led services.
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Published on 14th November 2025, Obshtina Shumen’s Urban Air Purification Device Installation contract notice seeks suppliers for two plant‑biofiltration units, pairing living filters with IoT monitoring. The project points to a growing interest in air-quality solutions that combine physical infrastructure, real‑time data and planned maintenance.
The municipality wants contractors to deliver and install two air purification devices that use plant biofiltration. According to the notice, the units are designed to enhance urban air quality by reducing particulate matter, a pollutant that features prominently in many recent public‑sector clean‑air projects.
Crucially for technology and service providers, the devices must integrate Internet of Things (IoT) functionalities for monitoring and maintenance. That requirement signals an expectation that the units will not be simple stand‑alone structures, but connected assets that can feed back information on performance and condition.
This blend of nature‑based intervention and digital oversight puts the contract at the intersection of green infrastructure and air‑quality‑monitoring‑as‑a‑service. Suppliers that can combine plant‑based systems with sensors, connectivity and maintenance regimes will recognise the model from a growing number of indoor air and industrial filtration contracts.
Obshtina Shumen’s move sits alongside a wave of recent contracts that seek not only cleaner air, but also richer data on pollution. Ports, state environment agencies and city administrations are modernising monitoring networks, often tying equipment supply to software, training and support.
In June 2025, LUČKA UPRAVA PLOČE published an Air Quality Measurement Station Procurement covering a container‑type station for continuous monitoring of multiple pollutants and meteorological parameters at a port site, complete with associated software. By August 2025, LUČKA UPRAVA ZADAR had followed with an Air Quality Monitoring Equipment Supply tender for two monitoring stations and five sensor stations, aimed at building a reliable system for continuous monitoring and accurate emission analysis.
State‑level environment bodies are also refreshing their fleets of instruments. The State Environment Agency’s Optical Measuring Devices Procurement, issued in July 2025, sets up a framework for supplying optical devices to measure PM2.5 and PM10 dust concentrations at 29 air‑quality stations, replacing outdated equipment and including initial training for operators.
Mobility and flexible deployment are another clear theme. MESTNA OBČINA KRANJ’s Mobile Air Quality Monitoring notice from August 2025 seeks calibrated sensors installed on a vehicle, with LTE‑M connectivity and maintenance services. In the same month, the City of Zrenjanin launched a Mobile Air Quality Monitoring Lab tender under the EU funded Blue Sky project, covering a lab unit, sensor devices with solar panels and consumable materials.
In September 2025, Institut lázeňství a balneologie, v. v. i. went to market for a Mobile Air Quality Station that will deliver automatic air‑quality and meteorological measurements in spa landscapes, bundled with installation, training and warranty service.
Some buyers are looking across environmental media. In July 2025, Ypourgeio Perivallontos kai Energeias issued a Monitoring Pollution Equipment contract notice covering specialised systems for both air and marine pollution, including measuring stations, unmanned vehicles and advanced mapping tools to improve data management and evaluation.
Within this wider push for denser and smarter monitoring networks, Obshtina Shumen’s use of connected, plant‑based devices looks like a small but aligned step: using one piece of infrastructure to deliver both mitigation and actionable data.
The Shumen contract’s emphasis on IoT‑enabled monitoring and maintenance mirrors a trend in indoor air and ventilation procurements, where hardware supply is increasingly bundled with rental options, digital ordering systems and ongoing support.
In July 2025, TeeSe Botnia Oy Ab signalled plans for an Air Purifier Rental Service, using a framework agreement to offer indoor air purifiers and related services as a complete package for its owner communities. The prior information notice is explicitly about identifying interested service providers ahead of a future competition.
The same month, Max‑Planck‑Gesellschaft z.F.d.W. launched a Market Exploration for Filter Systems combining air ionisation with conventional dust filtration in central ventilation systems, aiming to cut energy use while maintaining air quality. That exercise underlines growing interest in hybrid technologies and long‑term operating costs, not just upfront purchase.
By August 2025, Tuomi Logistiikka Oy had gone further with an Air Purifiers Procurement that offers both rental and purchase options to tackle indoor air problems across multiple municipal services. And in November 2025, Aarhus Kommune used a prior information notice on Air Purifiers Procurement to test requirements for units designed for heavy‑smoking citizens, detailing performance in individual rooms of at least 115 m³ and larger areas of at least 190 m³ in nursing homes and housing facilities.
Health‑sector buyers are also specifying filtration systems with clear operational outcomes. The contract notice from Mnogoprofilna Bolnitsa za Aktivno Lechenie - Dobrich AD, published in September 2025, covers Health and Safety Devices Supply with three lots for mobile filtration systems and a destratification system to secure healthy and safe working conditions.
Meanwhile, Oulun kaupunki’s October 2025 Air Ventilation Filters Procurement goes beyond the supply of filters to include an electronic ordering system, initial surveys and annual property inspections for Oulu Facility Services.
Taken together, these procurements suggest that public buyers now often expect filtration and purification to come with associated services: data, digital tools, operational support and lifecycle maintenance. Obshtina Shumen’s insistence on IoT‑ready, maintainable plant‑biofiltration units fits neatly into that pattern.
The Shumen notice also highlights the role of vegetation and green infrastructure in clean‑air strategies. Other municipalities are taking related paths, especially in tackling dust and particulate pollution in urban spaces.
In August 2025, Obshtina Lovech issued a Green Infrastructure Project in Lovetch seeking a contractor to develop and build green infrastructure to reduce secondary dust emissions and improve air quality in urban areas, under a project applying for funding from the Environmental Program 2021–2027. Obshtina Kardzhali followed in October 2025 with a Green Infrastructure Development contract for green infrastructure and mobile irrigation systems, again aimed at mitigating secondary dust pollution through an Environmental Program grant.
Alongside physical works, some authorities are investing in communication to build public support. Obshtina Pleven’s June 2025 contract for Publicity for Air Quality Project focuses on explanatory signs, a portable information banner, press conferences and media publications to raise awareness of project activities.
Other buyers are approaching air protection through energy and odour control. Gmina Żychlin’s July 2025 project on Renewable Energy Installations in Żychlin links air protection to the installation of photovoltaic systems, solar collectors and pellet boilers in residential buildings, framed around environmental sustainability and the circular economy. Skellefteå kommun’s July 2025 Activated Carbon for Odor Control agreement focuses on reliable deliveries of activated carbon to reduce odours at a wastewater and biogas facility.
Obshtina Shumen’s choice of plant biofiltration adds another strand to this mix: using vegetation‑based systems directly as purification devices and, through IoT integration, folding them into a monitoring and maintenance regime.
The scale of Shumen’s contract – two devices – is modest, but the specification is revealing. It links living infrastructure to particulate‑matter reduction and requires connected monitoring and maintenance functions.
For suppliers of air‑quality‑monitoring‑as‑a‑service, the notice offers a clear signal that even small urban projects are looking for solutions that unite hardware, data and support. The next key step will be how the municipality applies the devices in practice, how it uses the data they generate, and whether similar plant‑based, IoT‑enabled systems appear in larger follow‑on procurements.
Across recent tenders – from mobile monitoring labs and container stations to indoor filter frameworks and green‑infrastructure builds – public buyers are building out both their measurement capabilities and their interventions. Obshtina Shumen’s contract shows how even targeted procurements can become part of that broader shift towards cleaner, better‑understood air.
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