Water monitoring sensors in industrial, municipal and environmental monitoring are advancing our understanding of science, aid developments in process automatization and control and support real-time decisions in emergency situations. Sensors are becoming smaller, smarter, increasingly specialized and diversified and cheaper. Advanced deployment platforms now exist to support various monitoring needs together with state-of-the-art power and communication capabilities. For a large percentage of submersed instrumentation, biofouling is the single biggest factor affecting the operation, maintenance and data quality. This increases the cost of ownership to the extent that it is prohibitive to maintain operational sensor networks and infrastructures. In this context, the paper provides a brief overview of biofouling, including the development and properties of biofilms. The state-of-the-art established and emerging antifouling strategies are reviewed and discussed. A summary of the currently implemented solutions in commercially available sensors is provided and current trends are discussed. Finally, the limitations of the currently used solutions are reviewed, and future research and development directions are highlighted.

Soil moisture is a key parameter of the climate system as it relates to plant transpiration and photosynthesis and impacts land–atmosphere interactions. Recent developments have seen an increasing number of electromagnetic sensors available commercially (EM) for soil volumetric water content (θ). Their use is constantly expanding, and they are becoming increasingly used for agricultural, ecological, and geotechnical applications and climate research, providing decision support and high-resolution data for models and machine-learning algorithms. In this study, a soil moisture sensor network consisting of 10 Sense Cap capacitance-based sensors is evaluated. Analytical performance of the sensors was determined based on laboratory and field measurements with dielectric permittivity (ε) standards and soil media substrates. Sensor response normalisation to standards of known ε was found to reduce intersensor variability and provide robust estimates of θ in soil samples with known θ. Cross-comparison with a time-domain reflectometry (TDR) instrument carried out in two soil media demonstrates good agreement between the two probes throughout the tested range. The data communication performance of the network was evaluated in terms of packet drop rate at different ranges and sampling frequencies. It was noticed that the drop rate increased with distance from the gateway, while sampling frequency had no effect. Sources of errors associated with probe installation were identified and recommendations are provided for sensor deployment. The off-the-shelf all-in-one solution provided by Sense Cap is low cost, user friendly and suitable for implementation at temporal and spatial scales once the identified shortcomings are addressed. The evaluation presented aims to aid stakeholders and users involved in soil and land management practices including crop production, soil conservation, carbon sequestration and pollutants transport.

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.

Low-cost multispectral optical fluorometer for in vivo and in vitro Chl a detection and quantifictaion.

Soil moisture is an essential parameter for irrigation management, transport of pollutants and estimation of energy, heat, and water balances. Soil moisture is one of the most important soil spatial-temporal variables due to the highly heterogeneous nature of soils which in turn drives water fluxes, evapotranspiration, air temperature, precipitation, and soil erosion. Recent developments have seen an increasing number of electromagnetic sensors available commercially for soil volumetric water content (θ) and their use is expanding providing decision support and high-resolution data for models and machine learning algorithms. In this context, two demonstrations of in-situ LoRaWAN sensor networks are presented. The 1st one is from a grassland site, Johnstown Castle, Wexford Ireland where a network of 10 low-cost soil moisture (SM) sensors has been operating for 12 months. The 2nd network has been operating for 6 months at a peatland site (Cavemount Bog, Offaly, Ireland) which is currently undergoing a rehabilitation process through re-wetting. At this site, in addition to SM sensors, ultrasonic sensors are used for continuous measurement of the water table at 7 locations. For both sites, the analytical performance of the SM sensors has been determined in the laboratory, through calibrations in liquids of known dielectric permittivity and through field validation via sample collection or time domain-reflectometry instrumentation (TDR). Experiences and recommendations in deploying, maintaining, and servicing the sensor networks, and data management (cleaning, validation, analysis) will be presented and discussed. Emphasis will be placed on the key learnings to date and the performance of the low-cost sensor networks in terms of collected data. Small-scale sensor networks like these are expected to bridge the gap between the low spatial resolution provided by the satellite-derived products and the single point/field measurements. Within the project, the sensor network will provide spatial observations to complement existing fixed point measurements. It will allow researchers to investigate SM dynamics at field scale in response to different soil types, soil density, elevation, and land cover.

There is a pressing need to monitor, measure, understand and mitigate causes of anthropogenic activities on our aquatic environments. In situ water monitoring sensors are vital tools for decision support and risk mitigation, pollution source tracking, and regulatory monitoring. To be fit-for-purpose, sensors must withstand the challenging marine environment and provide data at an acceptable cost. If networks of sensors are to become not only a reality but common place, it is necessary to produce reliable, inexpensive, rugged sensors integrated with data analytics.In this context, this work presents the design, development and testing of an affordable, robust and reliable optical sensor for continuous measurement of chemical and physical parameters in aquatic environments. Sensor electronics are housed in a marine grade watertight housing; the optical components are mounted inside a custom designed 3D-printed optical head which joins with the sensor housing.The sensor uses multiple optical detection modes (absorption, scatter and fluorescence) over a broad spectral range (280 nm to 850 nm) to measure parameters like turbidity, fluorescent dissolved organic matter (fDOM), Chlorophyll a (Chl a) and petroleum. Sensor analytical performance was established in the laboratory using analytical standards and in the field by comparison with a commercially available multi- parameter probe. The laboratory and field trials demonstrate that the sensor is fit-for-purpose and an excellent tool for catchment monitoring where rainfall-impacted soils can cause ecological disruption in the surface water. The sensor provides high frequency time-series data with unattended operation in-situ for extended periods of times.