Co-Existence of Free-Living Amoebae and Potential Human Pathogenic Bacteria Isolated from Rural Household Water Storage Containers

This study investigated the co-existence of potential human pathogenic bacteria and free-living amoebae in samples collected from stored water in rural households in South Africa using borehole water as a primary water source. Over a period of 5 months, a total of 398 stored water and 392 biofilm samples were collected and assessed. Free-living amoebae were identified microscopically in 92.0% of the water samples and 89.8% of the biofilm samples. A further molecular identification using 18S rRNA sequencing identified Vermamoeba vermiformis, Entamoeba spp., Stenamoeba spp., Flamella spp., and Acanthamoeba spp. including Acanthamoeba genotype T4, which is known to be potentially harmful to humans. Targeted potential pathogenic bacteria were isolated from the water samples using standard culture methods and identified using 16S rRNA sequencing. Mycobacterium spp., Pseudomonas spp., Enterobacter spp., and other emerging opportunistic pathogens such as Stenotrophomonas maltophilia were identified. The results showed the importance of further studies to assess the health risk of free-living amoebae and potential human pathogenic bacteria to people living in rural communities who have no other option than to store water in their homes due to water shortages.

ENGINEERING GEOLOGICAL AND GEOTECHNICAL CHARACTERISTICS OF LANDSLIDE IN GORNJI HRGOVI, MUNICIPALITY OF SREBRENIK

Natural disasters during May 2014 caused a flood of water outside the unregulated bed of the river Tinja in the local area of Gornji Hrgovi. The flood effect affected the undermining and destruction of the foot part of the slope, reactivation and regressive development of the landslide, which was manifested by further secondary "breaking" of the sliding body towards the hypsometrically top part of the slope and intersection of the primary water pipeline. Gravitational displacement of the colluvial material resulted in significant degradation of the agricultural land surface in the central part of the unstable slope, while in the accumulation zone the accumulated slide mass destroyed the earth road communication. Based on the conducted geotechnical researches, determined engineering-geological and hydrogeological composition and properties of the terrain, the zoning of the terrain according to the degree of stability was performed, important recommendations and conditions of the landslide remediation method were presented.

A Review on Process and Practices in Operation and Design Modification of Ejectors

This work reviews the current operational condition and activities on design modification for different applications of ejectors. Ejectors being a simple mechanical system capable of performing multiple fluid related functions (vacuum generation, pumping, mixing, condensing and heat exchanging), have been an essential part of several industrial processes. Two areas have been emphasized; internal flow and application-based modifications in components of ejectors. The geometry and inlet flow conditions were found to be the prime influencing factor of its performance. The objective and application-based modifications were performed on the primary nozzle, secondary nozzle, mixing chamber, throat and diffuser. The resultant performance was found to be dependent on operational condition and fluid type. This emphasizes the requirement of application-based design selection of the technology. In addition, the flow dynamics of condensing, non-condensing, particle and slurry flow has been studied based on available literatures. The one-point final objective is to identify the usability of primary water jet ejectors for active vapor transport and condensation, to replace vacuum pump and condenser in compact domestic water desalination system.

Fatigue Damage Management According to Performance Based Maintenance (PBM) Concept

A maintenance concept of performance based maintenance (PBM) has been proposed by the current author. According to the PBM concept, inspection results are considered in determining the next inspection schedule. In this study, this concept was applied to fatigue degradation for stainless steel components in the pressurized water reactor (PWR) primary water environment. It is possible to estimate the fatigue life for the PWR water environment from that obtained in an air environment and the parameter Fen, which represents the ratio of the fatigue life in the air and PWR water environments. It was shown that the fatigue life prediction using Fen can be replaced by the crack growth analysis using the growth rate for the PWR water environment. Then, the crack growth was predicted for a thermal loading assuming the growth occurred in the PWR water environment. It was shown that the duration until the next inspection could be optimized based on the inspection results together with the crack growth curve. A long term operation before the inspection resulted in a longer duration until the next inspection.