PROJECT DESCRIPTION
BACKGROUND
The presence of biological and bacterial contaminants in wastewater from poultry processing prevents water re-circulation, resulting in significant environmental and economic impacts. In order to re-use poultry chiller water it is necessary to have a process which both removes the bacteria and also the organic loading of the water. The SafeQuest Macron Loop was developed in the US to allow significant amounts of water recirculation. The Macron Loop is a mechanical filtration and ozone disinfection process that continually treats a stream of water from poultry chiller baths. The Macron filter removes fats and protein contaminants at 400 US gallons per minute down to a particle size of 25 microns. After filtration, ozone is dissolved into the water to kill contaminating bacteria and oxidise organic matter. The motivation for the LIFE project was to build on development work on ozone disinfection already carried out in the US and investigate the use of similar water treatment systems in the Europe. In Europe the scale of operation and the ligislative constraints for the poultry industry are different to those in the US. In the European industry broilers are generally air chilled, not water chilled. In the UK the only significant use of water for cooling is in turkey processing. Therefore, BOC and Bernard Matthews Ltd agreed to investigate the application of the technology at Bernard Matthew's Holton turkey processing plant.
OBJECTIVES
The objective of the project was to assess the feasibility of combining filtration and ozonation to decontaminate wastewater from poultry processing. Decontaminated water was to be re-circulated, resulting in a reduction of water usage and a reduction in effluent discharges. The benefit if this was achieved would be that significant amounts of water could be saved, with an equivalent reduction in the discharge of effluent. It may also have been possible to reduce bacterial loading in the finished poultry, thereby reducing the incidence of food poisoning.
RESULTS
The original plan to use ozone for chiller bath water sanitisation was not achievable because of the results of parallel development work on the filtration system which is required in combination with ozone addition. The large amounts of water found to be required during the filter cleaning cycle could not be provided at the factory chosen, and anyway, would have cancelled out any water saving benefits achievable by switching off the make up water. A separate issue was the unexpected finding that the process water contained concentrations of inorganic components in excess of the potable water specifications, which would not be affected by ozone. The most significant were nitrates, potassium and phosphates. For both the final effluent and the maturation tank water, tests with the ozone pilot plant showed that ozone's performance in sterilisation is good but 100% bacteria kill was not achieved in all circumstances, particularly for water with high organic loadings. Even for the final effluent, which had relatively low organic loading, ozone did not fully break down the organic components present. The conclusion therefore was that while full bacteria kill is achievable with ozone, removal of the inorganic compounds and complete breakdown of organic material is not possible. The effluent from the ozone treatment process could be used in a "grey water" treatment system for uses for which sanitised but not potable water is acceptable. Practical constraints meant that this option was not pursued at the site used for testing. There is unlikely to be a future for a Macron Loop type system in Europe unless the current legislation is changed. Conversations with the Ministry of Agriculture, Fisheries and Food (MAFF) confirmed the requirement for potable applies in this case, although it was argued that the recycle system is internal to the equipment, and so a non-potable water stream could be returned to the chillers, as it is in the US. Ozone addition alone will not return the final effluent to potable water standards. Investigation of other treatment systems suggested that reverse osmosis might be a suitable treatment option. The original plan to use ozone for chiller bath water sanitisation was not achievable because of the results of parallel development work on the filtration system which is required in combination with ozone addition. The large amounts of water found to be required during the filter cleaning cycle could not be provided at the factory chosen, and anyway, would have cancelled out any water saving benefits achievable by switching off the make up water. A separate issue was the unexpected finding that the process water contained concentrations of inorganic components in excess of the potable water specifications, which would not be affected by ozone. The most significant were nitrates, potassium and phosphates. For both the final effluent and the maturation tank water, tests with the ozone pilot plant showed that ozone's performance in sterilisation is good but 100% bacteria kill was not achieved in all circumstances, particularly for water with high organic loadings. Even for the final effluent, which had relatively low organic loading, ozone did not fully break down the organic components present. The conclusion therefore was that while full bacteria kill is achievable with ozone, removal of the inorganic compounds and complete breakdown of organic material is not possible. The effluent from the ozone treatment process could be used in a "grey water" treatment system for uses for which sanitised but not potable water is acceptable. Practical constraints meant that this option was not pursued at the site used for testing. There is unlikely to be a future for a Macron Loop type system in Europe unless the current legislation is changed. Conversations with the Ministry of Agriculture, Fisheries and Food (MAFF) confirmed the requirement for potable applies in this case, although it was argued that the recycle system is internal to the equipment, and so a non-potable water stream could be returned to the chillers, as it is in the US. Ozone addition alone will not return the final effluent to potable water standards. Investigation of other treatment systems suggested that reverse osmosis might be a suitable treatment option.
