Early warning sign attributes for the safety of drinking water treatment works

A proactive risk management strategy seeks to prevent accidents from taking place and maintain the safety of a system. In this context, the task of identifying and disseminating early warning signs and signals is among the most important. The problem is that warning signs that are present before an accident takes place are often being overlooked and not picked up or identified as warning signs. If these warning signs were responded to, then an accident may be averted. Accidents occuring in the critical domain of a drinking water treatments works can have serious implications for the public health of consumers of the water supplied. Realising and comprehending early warning signs is a major challenge for the domain of systems safety and especially in the domain of a water treatment works. The approaches that are typically used to enhance the realisation, comprehension and dissemination of early warning signs in the water treatment domain in Ireland mainly involves the creation of accident scenarios, the use of monitoring data and procedures for the dissemination of warnings. While all of these approaches are all useful to inform the mental or process models of possible accident scenarios, nevertheless, accidents are still occurring in this domain. Therefore, a new approach to enhance the comprehension of and effective dissemination of early warning signs is required in order to improve safety and proactive risk management strategies. The contributions of this thesis is the provision of a set of attributes associated with the early warning sign concept that provides meaningful data on the early warning signs and allows recipients to better comprehend them. The values of these attributes were customised for application in the water treatment domain. This research proves that early warning signs at a water treatment works received with information on their attributes are comprehended and communicated more effectively and efficiently than the usual pragmatic approach and thereby improves the safety and proactive risk management strategies.

Biomethane production from macroalgae

Irish brown seaweeds have been identified as a potential bio-resource with potentially high specific methane yields. Anaerobic digestion is deemed the most feasible technology due to its commercial viability for handling such wet feedstock. However, the biomethane potential of seaweed is highly dependent on its chemical composition which can vary by species type, cultivation method, and time of harvest. This study aims to investigate and optimize the process for the production of biomethane from Irish brown seaweeds focusing on the key technology bottlenecks including for seaweed characterization, biomethane potential assessment, optimization of long-term anaerobic digestion and suitable pre-treatment technologies to enhance potential gas yields. Laminaria digitata and Ascophyllum nodosum were tested for seasonal variation. From the characterization and batch digestion of L. digitata, August was found to be the optimal month for harvest due to high organic matter content, low level of ash and ultimately highest biomethane yield. The specific methane yield of 53 m3 CH4 t-1 wwt in August was 4.5 times higher than the yield in December (12 m3 CH4 t-1 wwt), with ash content the key factor in seasonal variation. For A. nodosum, the optimal harvest month was October with polyphenol content found to be a more influential factor than ash. The gross energy yields from both species were evaluated in the range of 116-200 GJ ha-1 yr-1. Continuous digestion trials were subsequently designed for S. latissima and L. digitata to optimize the key digestion parameters. Results from mono-digestion and co-digestion with dairy slurry revealed that both seaweeds could be digested at maximum biomethane efficiency to a loading rate of 4 kg VS m-3 d-1. Accumulation of salt in the digesters was a concern for long term digestion and it was reasoned that suitable pretreatment may be required prior to digestion. Various pre-treatments were subsequently tested on L. digitata to enhance the gas yield. It was found that maceration after hot water washing yielded 25% more specific methane and up to 54% salt removal as compared to untreated L. digitata. The experiments undertaken aim to assist in providing a basic guideline for feasible design and operation of seaweed digesters in Ireland.

Prehistoric burnt mound archaeology in Ireland

It is apparent from the widespread distribution of burnt mounds that Ireland was the most prolific user of pyrolithic technology in Bronze Age Europe. Even though burnt mounds are the most common prehistoric site type in Ireland, they have not received the same level of research as other prehistoric sites. This is primarily due to the paucity of artefact finds and the unspectacular nature of the archaeological remains, compounded by the absence of an appropriate research framework. Due to the widespread use of the technology and the various applications of hot water, narratives related to these sites have revolved around discussions of age and function. This has resulted in a generalised classification, where the term ‘fulacht fia’ covers several site types that have similar features but differing functions and age. The study presents a re-evaluation of fulachtaí fia in light of some 1000 sites excavated in Ireland. This is the most comprehensive study undertaken on the use of pyrolithic technology in prehistoric Ireland, dealing with different aspects of site function, chronology, social role and cultural context. A number of key areas have been identified in relation to our understanding of these sites. Previous investigations of burnt mounds have provided little information on the temporality of individual sites. It has been established that appropriate sampling strategies can provide important information about the formation of individual sites, their relationships to each other and to other monuments in the same cultural landscape. The evidence suggests that considerable caution should be exercised with regard to certain single radiometric dates from burnt stone deposits, based on the degree of certainty of the dated sample and its association with pyrolithic activity. Previously regarded as Bronze Age in date, there are now numerous examples of pyrolithic-type processes in earlier contexts, with the origins of the water-boiling phenomenon now considered to be Early Neolithic. A review of recent excavation evidence provides new insights into the use of pyrolithic technology for cooking. This is based on the discovery of faunal remains at several sites, combined with insights gained through experimental studies. The model proposed here is of open-air communal feasting and food sharing hosted by small family groups, as a medium for social bonding and the construction of community. It is also argued that if cooking was the primary activity taken place at these sites, this should not be viewed as a mundane functional activity, but rather one that actively contributed to the constitution of social relations. The formality of the technology is also supported by the presence of possible specialised structures, some of which were used for cooking/feasting while others were for ritualised sweat-bathing. The duration and frequency of activities associated with burnt mounds and the opportunities they provided for social interaction suggest that these sites contributed some familiar frames of reference to contemporary discourse.