Odours are a major issue confronting piggery owners in Australia . Piggeries close to neighbouring houses or towns are facing mounting pressure to reduce odours. Regulatory authorities also wish to ensure that odours from piggeries do not unreasonably affect these receptors. Piggery odours are a by-product of the anaerobic breakdown of organic matter. APL-funded research suggests that 70-80% of odour from conventionally-designed piggeries (i.e. piggeries comprising sheds and effluent treatment ponds) is generated by the ponds (Smith et al. 1999).

The hypothesis of this project is that odour generation from piggeries can be significantly decreased by reducing the surface area of effluent treatment ponds or by eliminating these ponds through alternative treatment processes.

A number of reports were completed as part of the project, including:

• A review of piggery effluent characteristics and solids separation systems.
• A case study evaluation of 14 solids separation systems.
• A desk-top study of the effect of solids separation on overall odour emissions and impacts from piggeries.
• A report detailing the design, commissioning and testing of a solids separation system installed at a piggery on the Darling Downs.
• An evaluation of the odour emissions from the piggery anaerobic pond where the separation system was installed, before and after the commissioning of the separation system.

An extensive literature review of piggery effluent and solids separation was conducted which culminated in a technical review. During this review a number of solids separating devices were identified for further investigation. These systems were further evaluated for their feasibility in removing solids from piggery effluent. The evaluation was conducted in terms of operating performance and cost.

From this review and evaluation of various devices, a solids separation system was recommended that combines the high solids removal efficiency of a settling basin with the benefits of a FAN Ò screw press separator. The system was installed at a 10,500 SPU grow-out piggery on the Darling Downs. Extensive testing of this system was then conducted.

The calculated efficiency of this system at removing solids from the fresh manure is calculated at 42% of the total solids (TS), 45% of the volatile solids (VS) and 24% of the fixed solids (FS).

Although there has been an increase in pig numbers at the site since the initial testing of the system was conducted (nine to eleven sheds), the removal efficiencies of the system mean that the amount of VS entering the pond has reduced by 39%.

The odour concentration measurements taken suggest that both the total odour emission rate from the pond and the amount of odour emitted per kg of VS added has substantially increased (despite the reduction of VS added to the pond). Anecdotal evidence by both staff at the piggery (including the on-site manager) and project officers collecting the odour samples suggest that the odour from the piggery has reduced. However, the results indicate the emissions from the anaerobic pond have increased by more than five times from the anaerobic pond (presumably the largest odour source at the piggery).

It was recommended that further testing of pond odour emissions be undertaken, incorporating simultaneous analysis for odour concentration, odour intensity and odour chemistry (e.g. using an electronic nose).

Australian Pork Limited funded research by Smith et al. (1999) suggested that 70-80% of odour from conventionally-designed piggeries (i.e. piggeries comprising sheds and effluent treatment ponds) is generated by the ponds. Also, the effluent treatment ponds at many existing piggeries are grossly undersized by today's design standards. As a result, they have high organic matter loading rates.

Watts (1999a and 1999b) suggested that because of the significant contribution ponds make to odour from piggeries, decreasing the odour-emitting area of the ponds (without under-sizing the ponds) or eliminating ponds has the potential to substantially reduce odour.

Solids separation removes nutrients as well as solids from the effluent stream, creating better quality water for recycling as flushing water, and reducing the nutrient load of irrigated effluent. Recent work funded by APL (Project No. 1628) has shown that a reduction in the amount of volatile solids has a direct effect on reducing odour emission rates (see Tong Park Pty Ltd Pink Pond Odour Research Study (McGahan et al., 2001)).

As part of this project, an extensive literature review of piggery effluent and solids separation was conducted which culminated in a technical report (Part A Report) - Watts et al . (2002a). A broad range of solids removal systems were investigated for their feasibility (performance and cost) in removing solids from piggery effluent streams (Part B Report) - Watts et al . (2002b).

A third report was completed on the odour reduction benefits of reducing the amount of solids in the effluent stream of piggeries and hence reducing pond volumes (Part C Report) – Watts et. al . (2002c).

The second major component of the project was the development, commissioning and testing of a practical, low maintenance system for removing solids from piggery effluent. This culminated in the Part D Report of the project - McGahan et. al . (2002).

To further investigate the effect of solids separation on reducing odour from anaerobic ponds, measurements of the odour emissions from the primary pond at the piggery where the solids separation system was installed were conducted. The Part E Report of the project (McGahan et. al . 2003) details the first two rounds of odour testing that were conducted as part of the project (before commissioning of the system and 6 months after the commissioning of the system).

This Part F Report summarises all the reports that have been completed for the project and details the three rounds of odour testing that were conducted as part of the project:

• Before commissioning of the system.
• 6 months after the commissioning of the system.
• 12 months after the commissioning of the system.

A copy of the project report is available from:

Australian Pork Limited, Deakin West ACT 2600

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