• On-line time >99% since installation in March 1997, even with high fat concentrations in the sample stream
• Bio-tower COD loading controlled to maximize operational efficiency
• Bio-tower emissions eliminated - economically and effectively

General Background

Glanbia Plc, Ballyragget, Co. Kilkenny, Ireland.
The effluent produced by this dairy factory is high in milk fats, sugar and protein. These by-products (from the manufacture of various dairy products) must be neutralized before they can be released from the plant. Glanbia uses an aerobic bio-tower to do this through biological oxidation. However, if the carbon load of the waste is too high, the biological environment within the bio-tower is effected and putrefaction (i.e. greatly increased anaerobic digestion) occurs. This lowering of oxidation activity within the tower also reduces the processing capacity of the effluent plant, and causes the release of offensive odors.

Solution

The BioTector 970 was installed in Glanbia’s effluent treatment plant as a carbon load warning system. To monitor the carbon load of effluent entering the bio-tower, the BioTector is programmed to analyze a representative sample (containing all the fats, sugars and proteins from the factory’s main effluent plant) every 30 minutes. These data are then sent to the control room via a 4-20 mA signal, and the carbon load is calculated by integrating the TOC result (measured by the BioTector) with the flow signal (received from a flow meter installed in the waste line). When the incoming carbon load exceeds the capacity of the bio-tower, the plant control system takes the necessary actions to prevent the bio-tower from being destabilized.

The BioTector has succeeded in totally eliminating the release of offensive odors from the bio-tower. It has proved to be highly reliable and has been highly effective in analyzing milk fats and solids.