TY - THES A1 - Yotov, Nikola Vladislavov T1 - Development of programmes to investigate the antimicrobial efficacy of domestic dishwashers N2 - Dishwashers have undergone a drastic change both in design and programme variation since their conception. Trends in water and energy conservation, as well as the public perception of topics such as environment protection, have pushed for a dishwashing service that delivers highly efficient cleaning while remaining ecologically friendly. Over the years, different methods have been used to assess the combined effects of different factors that play a role in the antimicrobial efficacy of domestic dishwashers. However, the extent of their individual capabilities remained unknown, as no factor could be tested separately with the commercially available settings. With the aid of a dishwasher with programmable parameters, a method was developed that would allow for the testing of the different factors in a way that separates their microbicidal activities from one another as much as possible. The work of cleaning agents was excluded from any trials, as they are expected to only benefit the microbial reduction. Furthermore, the methodology used in this thesis work presents an opportunity to investigate the energy consumption levels of different steps in traditional dishwashing processes and find potential targets for future reduction in water and energy usage. The study discovered that mechanical action, water quantity and the duration of the main cleaning cycle induce an equal reduction of around 4 logarithmic steps, when tested at room temperature. The main source of energy consumption during these experiments was found to be the spray arm pump with values 0.06 and 1.27 Wh per minute for the lowest and highest setting tested, respectively. The temperature increases caused the largest change in both logarithmic reduction and energy consumption. The highest achieved logarithmic reduction occurred during tests with a cleaning temperature of 75 ℃, with the value being roughly doubled to that of the tests at room temperature. The energy consumption values also drastically increase to a mean of 37 Wh during the heating part of the cycle. Overall, this method shows potential for discovering a combination of settings that can reduce the general energy consumption while retaining the antimicrobial efficacy of current programmes. KW - Microbiology KW - Domestic hygiene KW - Dishwasher KW - Mikrobiologie KW - Haushaltshygiene Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:1383-opus4-13238 ER - TY - THES A1 - Mooren, Timo T1 - Sample Collection Method for a Dispenser-Integrated Germ Detection System in the field of Hand Hygiene N2 - This bachelor thesis validates a demonstrator that had a sample collection method for a dispenser-integrated germ detection system in the field of hand hygiene. In addition, the temperature of the hand was analysed; this was taken from previous work by T.Mooren. The first task was to validate a different spray nozzle. Eight nozzles were analysed by their spray patterns and ranked. Further experiments were carried out with the highest ranked spray nozzle. Subsequently, an attempt was made to prove whether bacteria could be washed off. This was done with an experimental setup to simulate washing off the palm of the hand, realised in the frame scope of this work. Calibrated glass slides with and without bacteria were used to enable localisation of the same bacterial areas before and after. Afterwards, this procedure was expanded to analyse the behaviour of soap and foam bacteria. The drip tray was changed to obtain a high number of bacteria into the sensing device. An excellent visual representation had to be achieved, so a mini-microscope was used in the demonstrator. This mini-microscope was able to capture and display images of the washed-off bacteria sample generation visually. Different lenses and that securitisation versions were tested for the microscope. Within this, the resolution of the pixels could be improved. Also, the comparison between two different objectives were evaluated. A complete electronic system was then integrated into a disinfection dispenser. This included a Raspberry-Pi and microcontroller for programming and controlling the system. Other components were the mini-microscope, a pump, LED-strips, two-infrared sensors for temperature measurements and an LCD-screen for visualisation. Finally, a fully functional system was presented to the funding agency the VDI/VDE-IT and to the employees of Ophardt Hygiene AG. The system was able to wash bacterial samples from a hand or a slide and display them visually with a microscope; the temperature of the hand was taken too. This 1st demonstrator of the project will be set up soon for Ophardt Hygiene AG employees to test at the building entrance in order to valuate long-term stability and user-friendliness. Data for the further project phases will be collected and determined there. KW - Germ detection system KW - Keim Erkennung Y1 - 2022 ER - TY - THES A1 - Geurts, Nick T1 - Photodecompostion of Sodium Dodecyl Sulfate Using a UV/H2O2 Reactor with Ultraviolet-C Light Emitting Diodes N2 - Anionic surfactants are used in many common household products, such as dishwashing detergents or soaps. Sodium dodecyl sulfate (SDS) is one of the most prominent surfactants and can cause substantial damage to the environment. Removal from wastewater is therefore a significant problem. This thesis investigates the photochemical decomposition of SDS using ultraviolet-c light emitting diodes (UV-C LEDs) and hydrogen peroxide. The experiments were performed with a surfactant concentration of 10 mg L which is actually found in wastewater after hand washing. Direct exposure to UV radiation to destroy organic compounds is generally seen as inefficient and consumes a large amount of energy. Adding hydrogen peroxide significantly increased the destruction rate due to the UV-induced formation of hydroxyl radicals. It was also investigated how the effectiveness of the reactor can be further increased. The use of a photocatalyst (titanium dioxide) improved the removal efficiency of SDS substantially. The data generated in this work indicates that using UV-C LEDs in a UV/H2O2 reactor works, and the process was significantly more efficient than only UV radiation. The ease of handling the diodes and implementing them into the reactor offers a significant advantage over other light sources. The standard SDS determination method is known to be very time-consuming. Therefore, a new approach was developed. This technique works faster than the commonly used one and has a low standard deviation. Photodecomposition of the investigated impurity is possible. In the future, development will concentrate on the realisation and system integration of UV/H2O2 reactors, as a common technology in the product family of OPHARDT Hygiene AG. KW - Advanced oxidation processes KW - Hydrogen peroxide KW - Sodium dodecyl sulfate KW - Titanium dixoide KW - UV-C LEDs Y1 - 2022 ER - TY - THES A1 - Terhardt, Isabel T1 - Nachhaltiger Sonnenschutz für die Haare: Produktentwicklung und experimentelle Methodenfindung zur Bewertung der Lichtschutzwirkung N2 - Human hair is significantly affected by UV radiation. UVA and UVB radiation in particular cause hair to become drier and more porous, making it more prone to structural damage. These effects can be attributed to the breakdown of the hair protein keratin. Suitable in vitro and ex vivo models were used to demonstrate the degradation of hair keratin by UV radiation and to illustrate this visually using real strands of hair. The aim of this work was to develop physically effective protection for hair against UV radiation and to demonstrate the protective effect of such sunscreen products on hair keratin using a specially developed methodology. In line with the current trend toward “skinification” concepts and formulation approaches from facial care were transferred to the hair care sector. For this purpose, a sun protection spray with modern oil-soluble and water-soluble UV filters was developed. Particular attention was paid to the optimal solution of the UV filters in an aqueous O/W emulsion and the subsequent sprayability of the emulsion in order to be able to apply the product evenly to the hair. The aspect of sustainability also played an important role in the selection of raw materials and the manufacturing process. In vitro tests were performed on specially manufactured keratin-containing agarose plates, irradiated with UV light, and then evaluated photometrically using a BCA assay. The samples treated with the product showed a significantly higher keratin content compared to untreated samples, indicating a protective effect against UV-induced keratin degradation. In addition, ex vivo tests on real hair strands confirmed a positive effect of the product treatment on the appearance and feel of the hair. The methodology developed represents an innovative approach to investigating the protective effect of hair sunscreen products on hair keratin and provides a basis for further research and product development. However, adjustments and optimizations of the formulation are necessary for standardization of the methodology. KW - Hair photoprotection KW - UV induced hair damage KW - Keratin degradation KW - In vitro hair model KW - Keratin agarose plate KW - Protein quantification KW - BCA assay KW - Sunscreen for hair KW - Hair fiber protection KW - UVA UVB irradiation KW - Photostability KW - Cosmetic formulation KW - Sprayable emulsion KW - Sustainable hair care KW - Film former KW - Color fading KW - Hair photodegradation KW - Ex vivo model KW - Protein loss KW - Biomimetic substrate KW - UV exposure assay KW - Spectrophotometric analysis KW - Statistical analysis ANOVA. Y1 - 2026 ER -