Modern odour control for the modern dairy

The team at Hydroflux have encountered a wide variety of odours across the various municipal and industrial projects we have completed. Those of us left with a sense of smell have a high appreciation for the level of control put in place in Australian dairy manufacturing.

Dairy manufacturers have many challenges to overcome to keep their product pure and untainted because of the speed at which product can go off, given the right (or perhaps wrong) conditions.

Once processed, any residual product and clean-in-place (CIP) waste is sent to the wastewater treatment plant (WWTP), which can become a significant source of odour. Dairy manufacturers have become adept at putting in place controls to ensure these odours are minimised, masked, contained and treated.

Although these traditional odour control methods have been around for a long time, and are proven, these systems have a lot of drawbacks. Activated carbon absorption systems require expensive media replacement and disposal; liquid scrubbers use large volumes of expensive chemicals and produce yet more effluent; and biofiltration systems take months to start working, take up a large area of land and again produce more effluent to treat.

Neutralox photoionisation odour control systems are a modern, compact and robust alternative that addresses the poor and typically unmanageable odour produced at industrial wastewater treatment plants and in their sludge tanks.

Unsurprisingly the older technologies are rapidly being phased out overseas, particularly in Europe — and now this low-energy and sustainable odour control process that is specifically designed to replace the older unsustainable and expensive technologies is available here in Australia.

Photoionisation systems are incredibly compact, they operate without chemicals, they do not produce effluent and they do not work by absorption alone. They also work the moment they are turned on and can be turned on and off as needed.

A pilot study on a Neutralox photoionisation system was recently conducted at a dairy in Western Sydney. The aim of the study was to determine the reduction in odour and reduced sulfur compounds from the air emanating from the raw wastewater pump well and the DAF sludge tank.

The focus of this study was the incoming effluent pit and the sludge tank — two sources of odour notorious for turning heads that provided an excellent opportunity to establish the effectiveness of the Neutralox System on strong dairy odours.

The system was operated for several weeks with a noticeable difference in odours in the area. Samples of air were tested and analysed by Airlabs Environmental. The Neutralox pilot unit is fitted with an internal fan that draws air through the unit from the source at a rate of up to 200 m³ per hour.

Source	Inlet	Outlet
Sludge tank (Ou)	2300	230
Wastewater sump (Ou)	3100	100

Additional tests were conducted on ammonia and reduced sulfur compounds with the following results.

Compound	Inlet	Outlet
Ammonia (ppm)	1.9	0.24
Hydrogen sulfide (ppm)	1.7	0.07
Carbonyl sulfide (ppm)	<0.02	<0.02
Carbony disulfide (ppm)	<0.033	<0.02
Methyl mercaptan (ppm)	0.45	<0.02
Indole	0.11	0.032
Skatole	0.067	<0.02

The Neutralox Photoionisation process is a physical-chemical off-gas treatment process for control of odours originating from waste, sewage and sludge treatment processes. The technology is based on the application of UV-light and catalysts.

Neutralox Photoionisation units essentially consist of a stainless-steel housing, dust-filter, UV compartment and catalysts.

The first stage of the process is to remove particulate matter from the air via a fine dust filter. A pressure sensor is installed in the system that monitors the pressure drop through the dust filter. When the pressure drop reaches a set level, an alarm is activated, and the dust filter needs to be cleaned or replaced.

The contaminated air then passes through the UV compartment where UV light initiates catalytic enhanced chemical reactions resulting in a significant reduction of odour as the linkages of odour molecules are broken by the UV light.

The reaction between UV light and naturally occurring constituents within the air also creates additional oxidants which further degrade or otherwise eliminate odours.

The reaction is then enhanced by photocatalysts. The catalyst provides further degradation of odorous compounds and prevents the release of oxidants into the atmosphere.

The downstream fan ensures extracting the polluted air from the odour source by keeping the whole system under negative pressure conditions.

Diagram of the NEUTRALOX Photoionisation process.

The housing of the Neutralox Photoionisation units is manufactured in stainless steel AISI 304 and consists of an insulated double wall. The units are easily accessible from the front and/or back side through removable maintenance doors.

“I am excited at the opportunity Neutralox Systems will provide our clients to confidently manage their odours with a modern, compact, chemical-free solution,” said Mathew Pugh, Director of Hydroflux Industrial. “The system utilises UV light and catalysts to break down odorous compounds in air in a highly efficient and compact process.

“However, of most appeal is the low power demand. With a compact size and no air restrictions, the system can use smaller fans than are required with bio filters, carbon adsorption filters and scrubbers.

“I am particularly pleased with the results of the trial which have shown the effectiveness of the Neutralox technology on dairy odours, which consist of a variety of odorous substances that can be difficult to manage.”

For more information please click here or if you would like to conduct trials at your site, please contact us.

About the Hydroflux Group

The Hydroflux Group comprises seven companies based in Australia and the UK, providing design and build, equipment, processes and operational services in water and wastewater treatment. Hydroflux Industrial specialises in industrial wastewater treatment including designing and constructing plants and supplying equipment across all sectors. Hydroflux Industrial is a wholly owned subsidiary of the Hydroflux Group.

Image top right: A Neutralox System in Europe.