Exhaust emissions usually containsignificant amounts of variousodorous components. The perceived odour is due to theeffect of all compounds in the mixtureand depends upon the concentrationand odorous qualities of thecomponent compounds.
Therefore, it is logical that an odorous gas samplebe characterised in two ways.1. Analytical expression, wherebythe components are identified andtheir concentrations are measured2. Sensory expression, where thehuman response to the odorousmix is measured.
GC/MS Analysisreveals the compositionof the odorous mix butwill not be able todetermine the humanresponse.
There are a number of products on the market claiming thatodour emissions can be „neutralised‟ by the addition of certaincomponents into the air stream Traditionally, these types of products are split into twobroad categories Odour Masking Neutralisers Agents
What do the suppliers of these products claim? “we do not mask, we neutralise!” “encapsulation & absorption” “unique blend of essential oils” “treat all odours with one spray!” “CHEAP AS CHIPS! ”
Based on these vague and grandioseclaims, the facility operator wouldmostly out of desperation due topressure from regulators and thecommunity purchase these products.Is it any wonder, then, that FacilityOperators opt for the ‟QUICK FIX‟and „cheap as chips‟ solution?
Quite a few dollars later, itdoesn‟t take long for theoperator to feel disappointmentand then anger that the “quickfix” doesn‟t really work.Herein a vicious cycle begins
What are these productsand how do we distinguishbetween them? Do they work, and if not,why are they used withsuch regularity?
Essential Oil Blend Essential Oils, terpene & emulsifier formulationsthe products Surfactant Induced Absorption Technology Various types of surfactants & blends thereof (Odourless) Surfactant Induced Absorption Technology + Essential Oil Blend Formulation based on a combination of the first two above
Surfactant Inducedthe products Absorption Technology (Site Specific Formulations – fragranced & odourless) Various types of surfactants & blends thereof Masking Agent Aromatic oils, perfumes & fragrances (mainly bubble-gum, musk, citrus and rose types)
Laboratory investigationA simulated stack and odorous air generator was setup at the ANSTO Laboratories at Lucas Heights. Airsamples were subsequently transported to the Centrefor Wastewater Treatment‟s Odour ResearchLaboratory at the University of New South Wales.
Manifold inserted into „stack‟ – raw odour is thenPermeation Raw Odour challenged with sprayed SampleDevice „Stack‟ Collected products collection
Sampleiscollected Odour generating device (Permeation) „Raw Odour‟ is pumped into the „stack‟
Spray system is turned on and theSample nozzles spray the odour neutraliseriscollected Odour neutraliser is introduced into the stack 5 mins after the Raw Odour Raw odour is introduced into the stack
Synthetic Sewage Odours 78% Removal With Water aloneOlfactometry (ODU) 90% Removal With SIAT (Odourless) 66% Removal With SIAT + Essential Oil Blend
Sulphur Dioxide – Initial 85% Reduction with water alone 95% Reduction with SIAT (Odourless)Dynamic Olfactometry (ODU) 93% Reduction with SIAT & Essential Oil Blend 87% Reduction with Masking Agent
Sulphur Dioxide – 24 Hrs Later 25% Reduction of SO2 after 24 hrs in Tedlar bag 73% Reduction with Water aloneDynamic Olfactometry (ODU) 95% Reduction with SIAT 95% Reduction with SIAT + Essential Oil Blend 78% Reduction With Masking Agent
Sulphur Dioxide – Comparison SO2 Levels increased 25% 24 hrs after treatment SO2 Levels remained the same 24 Hrs after treatmentDynamic Olfactometry (ODU) SO2 Levels decreased 33% 24 Hrs after treatment SO2 Levels Increased 39% 24 Hrs after treatment
On-Site Investigations –Sewage Treatment Plant – Tuncurry, Forster The misting system remained off and a section of the inlet works were covered - Raw Odour samples were collected Exposed inlet works – existing misting system already using a odour neutralising agent The misting system was turned off and Raw Odour samples were collected
On-site: Sewage Treatment Plant 83% reduction with water alone 88% reduction with Essential Oil BlendDynamic Olfactometry (ODU) 83% Reduction With SIAT & Essential Oil Blend 18% Reduction with Masking Agent
Foundry (Ferrous) Cooling LineTo nozzles Stack Cherry picker was used Control unit & to reach exit of stack pump Sampling point 3 #1.5 nozzles installed in stack Solution tank 700 mm stack diameter Fan Cooling mould(s) Odour control application device
Foundry (Ferrous) 8.5% Reduction with Essential Oil 3.2% Blend Reduction with Masking 60.6% Reduction Agent with SIAT & Essential Oil Blend 99.3% 97.9% Reduction Reduction with Site with SIAT Specific SIAT
Poultry Shed 1. Windbreak erected around exhaust fans (Side View) Row of atomising nozzles Dust & odour 3. Top View Exhaust 2. Exhaust fansDust & odour Nozzles 2a. Removal windbreak wall Sampling point
Poultry Shed 62% Reduction with 1.8% Essential Oil Blend Reduction with 79% Reduction Masking with SIAT Agent 73& Reduction with SIAT + Essential Oil Blend 97.8% Reduction with Site Specific Formula
Application EquipmentHigh Pressure System >1000 psi
Application EquipmentLow Pressure System 250 psi
Choice of application equipment and nozzle is integralto the performance of the odour neutralising agentApplication of odour neutralisers should be limited toatomisation. Odour Neutralising agents fail toperform in the liquid phase, and in most instances willnot work in scrubbers.
Outcome:Masking Agents are not suitable for use in industrial odourcontrol applications at any time. Masking Agents have little or no effect on complex odourmixtures. Olfactometry revealed that masking agents to donot have an “additive” effect on the malodour beingchallenged. Masking Agents are ideal for low level, simple andtransient odours – such as in a hotel lobby or lavatory Masking Agents consistently failed to perform in “real-life”.
Outcome:Essential Oil Blends have succeeded in some instances buttheir effects are highly inconsistent “Essential Oil Blends” may assist in the reduction ofodours in some instances. Essential Oil Blends so not show any consistency inremoval efficiency and their application can best bedescribed as “luck of the draw” Some Essential Oil Blends have resulted in a significantreduction on sewage odours – provided the odours are fromdomestic sewage
The bulk of “odour neutralisers” assessed over theyears have a high concentration of essential oils. The SIAT products have some low concentrationoils which contain functional groups and surfaceactive agents
Some companies professing to be“odour control specialists” andenvironmentally friendly are usingessential oils as a “technology” to treatmalodours. Our research has revealedthat the use of essential oils is not veryenvironmentally friendly when youconsider that trees need to be choppeddown, squeezing out the oil and usingthis oil to reduce odours at an industrialsite.
Although the results showed some reduction andsome success when using Essential Oil Blends, it mayfinally be about time to move away from these types ofproducts. For example, if we look at rosemary oil, thechemical make up includes components such asgeraniol, citronella and pine. Different batches of oilsfrom different parts of the world have these componentsat different concentrations. There is no consistency inthe raw product being used by formulators.
The research suggests that a cleaner morescientific approach is via the use of aroma andnature identical chemistries and surfactantbased technology.The components in the mix seem to be reliableand there was no evidence to suggest thatapplication of such products „mask‟ themalodour.This is very heartening and requires furtherstudy.
17 years of research into these products have revealed the following:The difference between odour neutralisingagents and masking agents lies in the FACTthat some Odour Neutralising Agents do work –albeit inconsistently depending on the odoursourceMasking Agents are NOT Odour NeutralisingAgents and can best be described as „creativeperfumes‟.
17 years of research into these products have revealed the following: Odour Neutralising Agents can safely be considered inany odour control application – BUT should be the last onthe operator‟s list Odour Neutralising Agents are not suitable as a standalone treatment for industrial odour control applications. There is no such thing as “broad-spectrum” or a “cure-all” odour neutralising agent.