Food industries still depend to a large extent on potable water in conducting their routineoperations. Equipment cleaning, in particular, is a water intensive process which results inconsiderable volumes of wastewater. Considering the high environmental impact and increasingcosts for water treatment before discharge, they are exploring alternatives to minimize their waterwaste production. Optimization of cleaning recipes towards less use of water and chemicals orreplacing the necessary volumes with process water recovered from various effluent streams byreverse osmosis (RO) filtration, are some of the main routes explored. However, the success andcost efficiency of any of these strategies depends on good process control and efficient evaluationof safety aspects, which ideally should be done based on real-time measurement techniques.
First aim of this thesis was to show how spectroscopic techniques combined with chemometricmodeling techniques may be used to achieve a solution for a non-destructive - preferably real-time -monitoring system over the hygiene and microbiological level of different surfaces involved indifferent production processes. More specific, the scenario of monitoring hygienic status ofconveyor belts under slaughterhouse processing conditions.
An algorithm based on Wilks ratio statistics applied on fluorescence recordings was developed anddemonstrated in pilot-scale for its potential to monitor online hygienic status of conveyor surfaces.Strong background interferences and changes in surface physical properties due to processingconditions are identified as main challenges. The algorithm is designed to neutralize suchinterference and high potential for reaching a valid monitoring solution is expected when usingmore advanced fluorescence spectrophotometers.
The second aim was characterization of RO membrane fouling to map and potentially optimizeperformance and cleaning strategies. Several industrial-scale RO membranes used for recovery ofprocess-water from whey ultrafiltration permeate have been examined for their fouling tendency. Atthe end of a complete cleaning-in-place (CIP) protocol, biofouling appears to be the main issue inmost RO-elements. Significant yeast contamination was found on the membrane permeate surfacesof these particular elements. Microbiological analysis performed on RO permeate streams indicatedthat minimal loads of microorganisms pass into the permeate streams, however being inactivated byUV treatments proceeding the RO units. Therefore, the identified biofouling appears to haveprimarily technological and economic implications, whereas the process water streams a havesuitable quality for reuse.