On the nose
It’s an unmistakable aroma and one that your tenants will have plenty to say about. Arian Bahramsari reports.
An unpleasant smell emanating from garbage rooms, bin chutes and loading bay areas is not the lingering impression you want to give to residents, visitors or clients. It can also lead to disputes between neighbours and even some allergic problems for building occupants.
According to environmental campaigner, author, broadcaster, science journalist and sustainability researcher Tanya Ha, Australians produce about 2.25 kilograms of waste each per day. Imagine a high-rise tower with around 500 apartments – that means more than a tonne of rubbish produced in a day. Odour control management needs to be more than simply installing an automated air freshener in garbage rooms and bin chutes.
ODOUR REMOVAL RESOLUTIONS
From simple proactive steps to sophisticated resolutions, there are several approaches that facility managers can use to overcome odour challenges.
Prevention is obviously the best step. Here are some common and effective tactics to successfully manage garbage smell:
- Arranging more frequent service from the bin hauler company
- Although it may seem obvious to some, scheduling frequent trips from your garbage hauling party, regardless of compactors being full or not, can make a great difference.
- Frequent sanitising in targeted area
- Regularly disinfecting, sterilising and cleaning trash chutes, compactors and other waste receptacles can minimise negative impacts of bad smells and improve comfort and enjoyment of a space.
- Providing compactors and bins with appropriate covers/lids
- Applying lids on the top of the compactors can also be very effective. Covers capture the gas before it is released into the area.
- Upholding bin chutes’ exhaust fans
- Maintaining exhaust fans mounted in the vent stack, which create a partial vacuum in the chute and extract fumes and odours, is also an imperative consideration to remove smells. These fans are normally located on the roof of the building and a weatherproof cowl is generally fitted at the top of the vent stack.
- Creating negative pressure in garbage rooms via HVAC (heating, ventilation and air-conditioning) optimisation
- Tune up the trash room’s ventilation system and confirm that adjacent areas are positively pressurised in relation to the odour source. The constant exhaust can create a negative pressure in the garbage room, chute and shafts. The negative pressure would prevent odour migration back into the halls and outside of the garbage room. A well-maintained HVAC system can also stop dust blowing out into the faces of residents/clients/cleaners when they open the chute to dispose of garbage. Facility managers should also note that the air transported by mechanical ventilation systems can move odours from their source into an area where people complain.
- Installing a garbage cooler system
- Cooling systems usually maintain the garbage storage area’s temperature below 10 degrees Celsius and they will slow down odorous molecules’ activity dramatically. Having said this, while cooling systems may partially rectify the odour problem, nevertheless their maintenance cost and energy consumption can leave a lot to be desired.
- Installing air freshener units
- It may seem the quickest and easiest way to neutralise trash odours, but it’s not the right way to go. There is a wide range of perfume dispersal equipment in the market, but such products only mask the issue. Indeed, in most cases after applying these machines, the scent is a mixture of garbage and perfume.
- Deploying odour control technologies using photolysis, oxidation, ozonolysis and catalysts
- There are numerous forms of odour removal machines on the market using these methods. Some systems use a single-engineered technique, while others apply a combination of methods.
ODOUR CONTROL TECHNOLOGIES
Ultraviolet germicidal irradiation technology
In this method the air is forced through ultraviolet (UV) germicidal irradiation. Essentially, UV light is a short-wavelength light just beyond the blue/violet part of the electromagnetic spectrum that our eyes can detect. UV is classified into three wavelength ranges:
- UV-C, from 100 nanometres to 280 nanometres (called germicidal UV)
- UV-B, from 280 nanometres to 315 nanometres, and
- UV-A, from 315 nanometres to 400 nanometres.
UV-C or germicidal UV (usually around 250 nanometres) is the most effective bandwidth of UV light in destroying microorganisms in the air. In this way, UV light can damage the DNA structure and chemical bonds of volatile organic compounds (VOCs), which cause odours.
The hindmost step of this method could be an appropriate filtration, which removes the microorganisms and dead remains.
There are two major reasons that justify applying filters with UV-C odour control systems. First, according to an article published in 2015 in the journal, Environmental Science and Technology, UV treatment alone can push bacteria into a dormant state instead of killing them, and in some cases, the bacteria can later revive and proliferate. Second, dead organisms may become food for new produced bacteria and airborne particles.
ODOUR REMOVAL FILTER TYPES
Filters used in UV-C systems can be activated carbon, HEPA (high efficiency particulate air) or any other type. HEPA filters remove microscopic particles down to 0.3 microns such as smoke and volatile organic compounds (VOCs) while activated carbon (carbon filtration) has pores sized from six to 20 microns to which chemical contaminants become attracted and trapped within.
Photocatalytic Oxidation Technology (PCO)
Photocatalytic oxidation is a process where ultraviolet light irradiates onto a catalyst, which converts water in the air into a form that turns odorous molecules and VOCs into harmless substances and non- odorous molecules.
The catalyst used in this method is normally a thin film of semiconductor such as titanium dioxide. The energy from an ultraviolet light photon excites the electrons on the catalyst’s surface. Electrons then are released and interact with water molecules floating in the air. They bind with oxygen to become hydrogen peroxide, hydroxyl radicals (which are highly reactive and short-lived), and hydroxides. These final products attach themselves to specific organisms and attack them. The harmful VOCs are oxidised and turned into water and carbon dioxide.
The disadvantage of this process is that photocatalytic purifiers also produce tiny amounts of ozone, which is, in itself, a toxic air pollutant. There is some uncertainty over whether what is produced by photocatalytic air purifiers could pose a greater risk to human health than the pollutants they are designed to remove.
These systems apply UV light to promote oxygen molecules and break these apart into individual atoms. The unstable oxygen atoms attach to other oxygen molecules and form a triatomic form of oxygen (ozone). Ozone then is dispersed into the area that needs treating.
Ozone is highly inclined to bond to pollutant microorganisms in the air and neutralises the aromatic molecules causing the smell. Carol James, founder of InspiredLiving.com explains how ozone removes odour. Once the ozone (O3) molecule meets a contaminant, one of its atoms attaches itself to it and leaves two other atoms behind as pure oxygen (O2). Both the contaminant and the atom are destroyed.
Basically, if the O3 molecule does not find a contaminant in its environment, it will attack itself to change its configuration of O3 back to O2 (normal oxygen) in 20 to 30 minutes at room temperature and normal humidity.
It is highly recommended not to breathe in heavy amounts of ozone and it is imperative that nobody is in the room when the purifier is on.
It is worth mentioning that there is a difference between UV-C technology and ozone generators. Ozone generators use UV light to form ozone, which then eradicates pollutants, while in UV-C technology, the germicidal UV-C kills pathogens directly.
There are some other complementary technologies to resolve garbage odour.
- Ionizer purifiers – These systems benefit from using electrically charged liquid ions to neutralise odorous contaminants. The liquid ions attract pollutants electrostatically and turn them into newly formed heavy particles, which fall into the collection plate.
- Plasma-injector odour control technology – This recent technology relies on high- speed oxidation by applying plasma (oxygen radicals, hydroxyl radicals, ions, ozone) within a plasma reactor.
Another option is using sample collector equipment (an olfactometer) and conducting odour analysis for in-depth examination. Evaluating the smell in a laboratory can gauge the odour intensity and identify the best resolution method. Facility managers can hire experts to examine the smell in their buildings and deploy a pilot odour removal system before applying a permanent solution.
Arian Bahramsari is a facility manager at Docklands-based Facility Management Victoria.
This article also appears in the December/January issue of Facility Management magazine.
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