Legislation in the Netherlands requires routine analysis of drinking water samples for cultivable Legionella species from high-priority installations. A field study was conducted to investigate the presence of Legionella species in thermostatic shower mixer taps. Water samples and the interior of ten thermostatic shower mixer taps were investigated for cultivable Legionella species. In seven cases, Legionella species was found in at least one of the samples. In four cases, Legionella species was detected in the biofilm on the thermostatic shower mixer taps interior, with the highest values on rubber parts, and in five cases in the cold supply water. These results show that thermostatic shower mixer taps can play a role in exceeding the threshold limit for cultivable Legionella species, but the cold supply water can also be responsible. Practical implications: This study showed that contamination of thermostatic shower mixer taps (TSMTs) with Legionella spp. was frequently observed in combination with contamination of the water system. Consequently, a combined focus is necessary to prevent the proliferation of cultivable Legionella spp. in TSMTs. In addition, the results also demonstrated that biofilms on rubbers inside the TSMT had high numbers of Legionella spp., probably because rubber contains relatively high concentrations of biodegradable substrates. Therefore, improvement of the rubber materials is necessary to reduce the proliferation of cultivable Legionella spp. in TSMTs.
Thermal disinfection is probably the oldest water treatment method ever used. Similarly to other disinfection processes, it targets the inactivation of pathogenic (micro)organisms present in water, wastewater and other media. In this work, a pilot-scale continuous-flow thermal disinfection system was investigated using highly contaminated hospital wastewater as influent without any pre-treatment step for turbidity removal. The results proved that the tested system can be used with influent turbidity as high as 100 NTU and still provide up to log 8 microbial inactivation. Further results have shown energy consumption comparable to other commercially available thermal disinfection systems and relatively low influence on the investigated physical–chemical parameters.
MULTIFILE
Fish and vegetable protein sources are relatively underutilized for human consumption in comparison to meat, dairy and egg protein sources. Only part of the available fish proteins is used: fish is to small for human consumption and fish has a high proportion of by-products, up to 50% of fish weight is not used. This project aims to develop products and processes for creating healthy high valued consumer products based upon vegetable proteins and fish/crustacean proteins from by-products or from neglected fish. Three innovative processes are developed:1) Iso-electric solubilization and precipitation of fish/crustacean proteins from by-products,2) Networked vegetable/fish protein textures based upon low moisture extrusion processes3) Fibrous vegetable/fish protein textures produced with high moisture extrusion processes.Two innovative processes are applied:1) Food products with water-oil-water emulsions with isolated fish proteins2) Food products with sous-vide prepared fish fillets in semi industrial context.Different consumer product prototypes will be developed like fish nuggets, fish flakes and fish crackers.The Nuprotex project created successfully two new processes. Hanzehogeschool developed the process for fish protein isolation based upon iso electric solubilization and precipitation. With this process it was possible to recover about 15% weight of additional proteins from fish by-products. Please be aware that the yield of fish fillets from the fish is only about 30% of fish weight. So this is an important increase in food grade proteins! These Isolated Fish Proteins are successfully converted into several consumer prototype products like multiple emulsions for savory liquid products and fish cake/cracker applications. A sous-vide cooking process for fish fillets was developed with respect to microbial safety. It was shown that a microbial safe route could be developed, however further research is necessary to confirm these preliminary results.DIL has developed successfully an high moisture extrusion process for isolated fish proteins, grinded fish by products and vegetable proteins. This semi-finished product is successfully applied by for developing deep fried fish nuggets and fish burgers. DIL produced fish pellets which are suitable for applications as fish feed as is demonstrated in actual trials. Further research must demonstrate the quality of the feed product in actual growth experiments with fish.This project has clearly demonstrated that it is possible to produce with fish by-products added value consumer products. A possible increase of food-grade fish protein of about 15% on fresh weight base of processed fish is possible.
