Biofouling of aeration equipment is a significant farm management issue and production cost for Australian marine prawn farms. Defouling aeration equipment has a high labour demand and once fouled the energy efficiency of paddle-wheels and other aerating equipment can be markedly reduced, leading to elevated electricity costs and shorter equipment life. The estimated cost of biofouling is a minimum of $1,000 per hectare per crop when considering the additional labour, maintenance and electricity costs that it creates. This cost figure however does not include the impact of aerator fouling on prawn production levels which potentially could be far greater. The industry uses up to 10x aerators per hectare and they consume 70-80% of total farm energy use. It is estimated that at the peak of the production season around 6,000 2hp aerators are in use in ponds across the prawn industry alone.
Ensuring appropriate and timely aerator defouling is conducted is a significant farm issue. Manual defouling is one of the least desired tasks on the farms as it is dirty, laborious and workers are susceptible to multiple skin cuts that are prone to infection. Consequently it can be difficult to maintain staff to undertake this task for any length of time.
There is no data available on the impact of biofouling on the aeration efficiency, for example the oxygen transfer rate, and this information is critical to maximising benefit from mitigation strategies from both a practical and economic stand point.
The relevant industry body, the APFA through the R&D Committee, has assessed prevention of aerator biofouling as a priority issue and has recommended that the project commence as close as possible to the start of the current production season.
The proposed project falls within the Seafood CRC Theme – ‘Aquaculture Innovation’ as the objective is to improve production efficiency.
Final report
Biofouling of aeration equipment is a significant farm management issue and production cost for Australian marine prawn farms. Defouling aeration equipment has a high labour demand and once fouled, the energy efficiency of paddle-wheels and other aerating equipment can be markedly reduced, leading to elevated electricity costs and shorter equipment life. The estimated cost of biofouling is a minimum of $1,000 per hectare per crop when considering the additional labour, maintenance and electricity costs that it creates.
The project was designed to assist the Australian prawn farming industry improve aeration efficiency through providing farms with new information pertinent to cost-efficient management of their aerator fleet. The project focussed on the impact of biofouling on aeration and measures to control its accumulation, though broader aspects of aeration were also considered.
On-farm monitoring of aerators determined a huge variation in aerator electrical performance within and among farms. Around 60% of the electrical use variability among paddlewheels is due to biofouling accumulation. This also means that around 40% of differences among paddlewheels is attributable to mechanical factors such as degree of wear and tear.
The overarching output from the research conducted under this project is an improved understanding and quantification of the problem of biofouling in the use of aerators in marine prawn ponds. Farms are under pressure to become increasingly efficient production systems and the information arising from this project will substantially contribute to the farm knowledge base drawn on to optimise strategies that reduce aerator fleet management costs.
