Disruption of diatom attachment on marine bioinspired antifouling materials based on Brill (Scophthalmus rhombus).

Bioinspired surfaces, due to their nano and micro topographical features, offer a promising approach for the development of novel antifouling solutions. The study of surface topography has gained popularity in recent years, demonstrating significant potential in mimicking natural structures that could be manufactured for application in the marine environment. This research focuses on investigating the antifouling (AF) performance of bio-inspired micro-textures inspired by Brill fish scales, Scophthalmus rhombus, under static laboratory conditions, using two common fouling diatom species, Amphora coffeaeformis and Nitzschia ovalis. In this study, we evaluate six engineered surfaces, inspired by Brill fish scales, fabricated through a 2-photon polymerization (2PP) process, for their potential as antifouling solutions. The investigation explores the settlement behaviour of microfouling organisms, comparing these mechanisms with theoretical models to guide the future design of antifouling materials. A key emphasis is placed on the impact of surface topography on the disruption of cellular response. Our results suggest that cells smaller than 10 µm, exceeding the peak-to-peak distances between surface features, comfortably position themselves between adjacent features. On the other hand, as peak-to-peak distances decrease, cells shift from settling within uniform gaps to resting on top of surface features. Surfaces with sharpened edges demonstrate a more substantial reduction in diatom attachments compared to those with rounded edges. Furthermore, all micro-textured surfaces exhibit a significant decrease in colony formation compared to control samples. In conclusion, this study shows the potential to manipulate cellular responses through topographical features, providing valuable insights for the design of effective antifouling materials. The results contribute to the growing body of knowledge in biomimetic antifouling strategies using a novel marine organism for inspiration to design practical structures that can be replicated.

Establishment of an antifouling performance index derived from the assessment of biofouling on typical marine sensor materials.

Marine biofouling, known as the unwanted accumulation of living organisms on submerged surfaces, is one of the main factors affecting the operation, maintenance and data quality of water quality monitoring sensors. This can be a significant challenge for marine deployed infrastructure and sensors in water. When organisms attach to the mooring lines or other submerged surfaces of the sensor, they can interfere with the sensor's operation and accuracy. They can also add weight and drag to the mooring system, making it more difficult to maintain the desired position of the sensor. This increases the cost of ownership to the point where it becomes prohibitively expensive to maintain operational sensor networks and infrastructures. Furthermore, the analysis and quantification of biofouling is extremely complex as it is based on biochemical methods such as the analysis of pigments such as chlorophyll-a as a direct indicator of the biomass of photosynthetic organisms, dry weight, carbohydrate analysis and protein analysis among others. In this context, this study has developed a method to estimate biofouling quickly and accurately on different submerged materials used in the marine industry and specifically in sensor manufacturing like copper, titanium, fiberglass composite, different types of polyoxymethylene (POMC, POMH), polyethylene terephthalate glycol (PETG) and 316L-stainless steel. To do this, in situ images of fouling organisms were collected with a conventional camera and image processing algorithms and machine learning models trained were used to construct a biofouling growth model. The algorithms and models were implemented with Fiji-based Weka Segmentation software. A supervised clustering model was used to identify three types of fouling to quantify fouling on panels of different materials submerged in seawater over time. This method is easy, fast and cost-effective to classify biofouling in a more accessible and holistic way that could be useful for engineering applications.

Pilot Scale Study: First Demonstration of Hydrophobic Membranes for the Removal of Ammonia Molecules from Rendering Condensate Wastewater.

Hydrophobic membrane contactors represent a promising solution to the problem of recycling ammoniacal nitrogen (N-NH4) molecules from waste, water or wastewater resources. The process has been shown to work best with wastewater streams that present high N-NH4 concentrations, low buffering capacities and low total suspended solids. The removal of N-NH4 from rendering condensate, produced during heat treatment of waste animal tissue, was assessed in this research using a hydrophobic membrane contactor. This study investigates how the molecular composition of rendering condensate wastewater undergo changes in its chemistry in order to achieve suitability to be treated using hydrophobic membranes and form a suitable product. The main objective was to test the ammonia stripping technology using two types of hydrophobic membrane materials, polypropylene (PP) and polytetrafluoroethylene (PTFE) at pilot scale and carry out: (i) Process modification for NH3 molecule removal and (ii) product characterization from the process. The results demonstrate that PP membranes are not compatible with the condensate waste as it caused wetting. The PTFE membranes showed potential and had a longer lifetime than the PP membranes and removed up to 64% of NH3 molecules from the condensate waste. The product formed contained a 30% concentrated ammonium sulphate salt which has a potential application as a fertilizer. This is the first demonstration of hydrophobic membrane contactors for treatment of condensate wastewater.