Main results from the desktop study for the meat sector are:
- Red meat processing is significant to the Australian economy and large quantities of potable-quality water is used in meat processing, mainly for washing yards, unloading areas, stock floors, equipment and product.
- Average water use in Australian meat processing plants has reduced from 16.6 kL per tonne of hot standard carcass weight (tHSCW) in 1978 to 9.4 kL/tHSCW for 2008/09.
- Results from a survey in 2011/12 show that the average water use in Australian meat processing plants has dropped further to 7.2 kL/tHSCW with a range from 2.8 kL/tHSCW for small plants to 8.6 kL/tHSCW for large plants. Large plants use more water per head because they have additional processing operations such as rendering.
- Benchmarking the water use of Australian meat processing plants with other countries shows that small plants in Australia without on-site rendering are comparable to world standards. It is difficult to make a direct comparison with large plants in other countries because of the wide variation of on-site operations in each country.
- Generally, regulations allow recycled water of potable quality to be used in meat processing areas where the water comes into contact with the product. However, for meat product that is exported, some countries do not allow any recycled water to be used if the water comes into contact with the product.
- Reverse osmosis (RO) is often used to de-ionise bore water for boiler feed and hot-water systems and large quantities of the retentate (brine) are generated. Managing and disposing of this brine is a problem because of the high concentration of dissolved solids and ions.
- A number of advanced technologies are available (and are being developed) that could be used to remove most of the dissolved solids and ions from the brine. However, these technologies (e.g. forward osmosis, vacuum membrane distillation, RO-nanofiltration integration, electrodialysis bipolar membranes, electrodialysis and electrodialysis reversal) may be costly.
- Effluents from processing red meat are high in N and contain moderate amounts of P. Therefore, these effluents should be treated prior to disposal. Physical and biological systems are available to recover nutrients and energy from these effluents. Improved efficiencies could be gained through appropriate separation of waste streams at their source.
- There are existing processes to remove fat, oil and grease from effluents in meat processing. However, there is a gap in knowledge and research is needed to determine the effects of different fat levels in effluents on anaerobic digestion. Furthermore, new processes should be considered such as:
- a) two-stage anaerobic treatment with a separate vessel or pond for initial hydrolysis and acidogenesis
- b) high-rate anaerobic system-inverted sludge blanket reactor for high fat effluents.
- Overall, the Australian meat processing industry is making good progress in using appropriate technologies to treat wastewater for reuse and recycling. However, further opportunities could be captured by adopting some of the emerging technologies and using the tools developed from this project.