This publication presents a methodological model for odour control solutions and applications for diffuse sources, which impact surrounding communities and thereby generate risks to business operations. The problem is described, and definitions are provided for the points to be considered in the proposal and implementation of solutions that include technologies to enable the effective application of neutralising products. Finally, the results and the actual application of this methodology in an industrial environment at a company in the South of Chile are presented.

Sergio Canales ¹

¹ The Synergy Group- Av.americo Vespucci 2296, Conchalí, Santiago, Chile scanales@tsgchile.cl

Competing interests: The author has declared that no competing interests exist.

Academic editor: Carlos N Díaz.

Content quality: This paper has been peer reviewed by at least two reviewers. See scientific committee here

Citation: S. Canales, Diffuse sources: treatment with EcoCatalysts. Odour neutralisation method using organic catalysts, Ist International Seminar of Odours in the Environment, Santiago, Chile, www.olores.org

Copyright: 2015 olores.org. Open Content Creative Commons license., It is allowed to download, reuse, reprint, modify, distribute, and/or copy articles in olores.org website, as long as the original authors and source are cited. No permission is required from the authors or the publishers.

Keyword: Odour neutralisation, immission, atomisation curtains, organic catalyst, odourant gases, oxygenation, solubilisation.

Download presentation

Abstract

This publication presents a methodological model for odour control solutions and applications for diffuse sources, which impact surrounding communities and thereby generate risks to business operations. The problem is described, and definitions are provided for the points to be considered in the proposal and implementation of solutions that include technologies to enable the effective application of neutralising products. Finally, the results and the actual application of this methodology in an industrial environment at a company in the South of Chile are presented.

1. Introduction

Recently, discussion regarding the impact of some industrial odours on surrounding communities has taken on increasing prominence on the national stage. In this context, industries now have the opportunity to develop strategies to optimise their processes to minimise their odour emissions and, consequently, lessen the annoyance to neighbours.

In some cases, despite having optimised and improved their processes, some companies are unable to reduce their emissions to the point that they are no longer a problem. In this scenario, they should consider containment and odour elimination technologies. For this case, we will discuss the implementation methodology of an Odour Control System through the atomisation of an active agent into the environment for a production plant with diffuse sources and a known impact on their surroundings.

2. Problem Determination

Good detection of the root cause of an odour allows the definition of the operational scope that different systems and technologies associated with odour control might have, as well as the definition of their constraints and possibility of success. We understand the relevant variables to be as follows:

1. Annoyance: frequency and time of complaints. This allows us to understand the operational performance curve of odours leaving the plant and impacting people.
2. Location and distance of the immission (to the area receiving annoying odours).
3. Wind direction and speed.
4. Geographical condition surrounding the production process and the immission. It is important to know if there are any natural barriers or amplifying elements that generate changes in the behaviour of the odour plume.
5. Offensiveness: or potential annoyance, concentration and characterisation of odour (including the different types of gases that make it up).
6. Type of production process and associated products, together with their frequency of odour generation.
7. Odour sources, which can be provisional or fixed (by definition all those that can be funnelled) or diffuse (open to the atmosphere without the possibility of a pipe or confinement).
8. Once the odour sources are determined, we must analyse their height (above the ground) since this can expand the distance and the area of the final impact.

For the purposes of analysis, we have the following actual data from a recent installation and troubleshooting exercise from a company located in the South of Chile.

Recurring complaints were generated mostly from 16:00 to 0:00, including demonstrations by the community outside the company. The recurrence of complaints generated an escalation to the respective Health Service, which arrived at the location and requested concrete actions that would solve the problem within a maximum period of 30 days.

Two immission areas were detected, included in the normal complaints, and were located in a North-Eastern area. The first corresponds to a high-traffic road located 375 meters from the source, and the second is associated with a residential area of less than 300 houses within a range of 2,500 to 4,000 metres.

The wind patterns towards the odour impact area coincides with the usual hours of complaints, varying in intensity; the lower the speed, the greater the concentration of odour perceived in the immission area since odourant gas fails to dilute and disperse, remaining compact within the gas plume as it is carried away.

The surrounding geographical area does not have any natural barriers or elements that generate resistance or deformation to the passage of the odour plume.

The descriptors of output odours are fecal, indole, skatole, sulphurates and ammoniacal.

The production process is seasonal (9 out of 12 months of the year) for the generation of Industrial Waste Water and sludge, while odour is present throughout the year, a by-product of Industrial Waste Water treatment.

The main sources of odour emissions are Industrial Waste Waterpools (diffuse source) and a digester that must be open, as it cannot befunnelled, so mitigation measures will be the same as for a diffuse source.

The pool of Industrial Waste Water is located at a height of 4 metres above the ground and the digester at 20 metres.

Figure 1. Definition of odourant sources; Emission Area 1: Industrial Waste Water treatment pools; Emission Area 2: Digester.

3. Type of Solution Applied

The problem is generated by two diffuse sources. The best alternative solution to odour problems was established as the continued atomisation through high pressure systems. The operational logic is as follows.

1. We should dilute the principal active concentratedsubstance with water to then be sprayed into the air via atomisation.
2. The type of spray should be very thin and light. It is vital that the drops of product diluted in water do not precipitate and neutralise airborne odour in a liquid gas phase, to then evaporate into the air and move with the wind, continuing neutralisation in a gas phase.
3. The use and quality of water is relevant for the success of the neutralisation function. The water conditions, to begin with, must not have any odour, there must be an adequate flow for the continuous loading of systems, and which is not heavy.
4. The output of the product diluted in water is done through nozzles, which should be located at an appropriate distance and height for the proper functioning of the system.
5. Hoses are supported by poles capable of withstanding their weight and the water that circulates inside towards output of the product from the nozzles.

The description of the problem provides indications to establish the strategic location of the system, as shown in Figure 2.

The concept of efficient product use is important. The installed system allows for automatic activation according to certain parameters to solve the problem, since we understand that the production process generates odour, and themovement of the plume to places where it does not generate annoyances should not be considered a solution, therefore the system must be switched off. The installed perimeter curtain covers a distance of 370 metres.

Figure 3 shows the installation scheme in the Digester.

Figure 2.Industrial Waste Wateratomisation curtain installation scheme

Figure 3.Atomisation curtain installation scheme in the Digester

Discussing neutralisation is a key element, because of its implications. This contrasts with other products on the market that simply mask odours by saturating the area around the source and lose their effect because of the wind, spreading aromas not in accordance with the production process that is being treated, and failing to address the real problem. The population´s association of the presence of perfumes to the occurrence of an actual problem is natural.

Both systems are set to operate at the times of the most complaints every day of the month, subject to the automatic activation of the sensors set according to the specific conditions of the impact generated by this plant.

4. Definition of the product to use

The first item to be evaluated is the composition of the odourant gases, it is important to remember that odour, conceptually, is the result of a mixture of gases, perceived by the sense of smell. The analyses and composition of these gases indicate that we must atomise a product which is effective in the removal of indole, skatole, sulphur and ammonia compounds, with this understanding, our definition and experience indicate that our product, Ecosystem Plus, should be used. This product is an Organic Biocatalyser, which accelerates and improves the chemical and biological reactions produced by decomposing material. It contains biologically derived catalysts, chemical substances that change the surface and protein chains that act as platforms for reactions and stimulating factors of conventional biological oxidation.

The action principles of Ecosystem Plus are:

• Oxygenation: traps oxygen and creates micro bubbles that increase the amount of dissolved oxygen.
• Catalyst: reduces the amount of power required to make biological or chemical reactions to occur, it increases the natural decomposition process by more than 100 times.
• Solubilisation: Through the breaking of molecular chains.

Benefits of Ecosystem Plus:

• Reduces and eliminates odours quickly and effectively.
• Significantly reduces the levels of H₂S, NH₃, Mercaptans and VOC's.
• Accelerates the degradation of waste, improving the quality of wastewater.
• Increases the level of dissolved Oxygen, as well as the removal of BOD, COD, TSS and fats.
• It is not toxic, caustic or corrosive; it is 100% biodegradable and harmless to humans.

Having defined the odour control system and neutralising product, the only thing left to do isset their dilution. The field tests indicated that for the level of odour that emanates from both sources, and given the distance verified using olfactory panels in the immission, it was decided to dilute 1 litre of product concentrate based on 0.25% v/v.

The following equations explain the chemical interaction of the product with the odourant gas.

1. R-NH₂ + H₂S.R-NH₃ + SH-
2. R-NH₃ + SH- + O₂ + H₂O.R-NH₃ + SO₄^2- + OH
3. R-NH₃ + SO₄^2- + OH-.R-NH₂ + SO₄^2- + H₂O

Where:

R-NH₂ = Ecosystem Plus Compound, which contains and acts as a vehicle of an amino group.

H₂S = hydrogen sulphide in gaseous form.

O₂ = atmospheric oxygen.

SO₄^2- = a sulphate ion.

H₂O = water

OH = hydroxyl ion

SH = sulphur ion

It can be seen that in this reaction, the sulphur ion is captured by an amino group which is decomposed to ion sulphate as long as there is atmospheric oxygen. Therefore the original amino group remains intact until the end of the reaction, acting as a catalyst.

5. Conclusions

The results of this establishment of an odour control solution were successful, allowing for the improvement in the surroundings of the productive plant.

1. Community complaints were reduced to zero, making the operation sustainable and the authorities eliminated restrictions on the company´s operations.
2. The odour level dropped drastically even under 50 metres from the emission sources.
3. The odour panels, unaware of the moments in which the system was on or off, concurred 100% of the time on thepresence of odour at a distance of 4,000 metres from sources when the system was turned off, as well as the disappearance of the odour when it was on.
4. The atomised product, when due to wind conditions falls inside of the pool and makes contact with the wastewater, generates a surface seal that begins to eliminate and significantly reduce odourant gas at the source.
5. Where there are no added fragrances, given theodourlessness of the active substance, the externalities associated with the suspicion of "masking" and not treating the odouris precluded.
6. Currently, progress is being made in the stage of evidence analysis to initiate the addition of this product to the Industrial Waste Water treatment process within the pools with the aim of increasing the efficient use of this organic catalyst. It aims to project savings in electrical energy generated through the reduction of the time required for aeration, to demonstrate that the additional cost of these applications in the production process, allows this solution to technically have a negative differential cost for the company in question.

References: 100% of this material was extracted from the existing historical record in the Case Library of The Synergy Group Chile, specialists in odour engineering.