The resuspension potential method: Yarra Valley water's novel approach to routine mains cleaning

Routine cleaning of water mains is frequently employed by water utilities around the world as a means of managing common water quality issues. When employed correctly, water mains cleaning can be effective in removing loosely deposited sediments and bio-films that cause water discolouration, coliform regrowth and unpalatable tastes and odours. Despite its long history in the water industry, water supply practitioners continue to use highly subjective mechanisms to identify when, where and how much to spend on their mains cleaning programs. This paper discusses the benefits of using the Resuspension Potential Method, an objective means of planning and implementing mains cleaning, to achieve an optimum outcome for both the water company and its customers. Since 2005, Yarra Valley Water has undertaken Resuspension Potential Method measurements in 13 of its water quality zones to gain a better understanding of sediment accumulation rate in the zones over time. Ultimately the information will be used for more effective planning and proactive implementation of the mains cleaning programme.</jats:p

Prevalence of Methicillin-resistant Staphylococcus aureus in the Surgical Wards of the Port-of-Spain General Hospital, Trinidad and Tobago

Objective: Methicillin-resistant Staphylococcus aureus (MRSA) is associated with soft tissue infections in surgical patients. In severe cases, it may result in pneumonia, septicaemia and osteomyelitis. Limited data are available with regard to its prevalence and associations in the Caribbean. This study aimed to assess the prevalence of MRSA in patients hospitalized in the surgical wards of the Port-of-Spain General Hospital (POSGH), Trinidad and Tobago, and determine associated risk factors. Methods: Over the period of April 1 to August 1, 2013, all patients from the surgical wards of the POSGH who had had wound swabs taken were identified. Demographic data included duration of hospital stay, surgical and medical history, antibiotic use and type of wound swab. Microbiological reports were then retrieved and analyses done. Results: A total of 153 patients had wound swabs taken. There were 38 patients (24%) infected with Staphylococcus aureus, with 15 (39.5%) growing MRSA. Increased susceptibility to MRSA was associated with age, gender, ethnicity, duration of hospital stay, co-morbidities, previous antibiotic use, previous surgery and the type of wound (p &lt; 0.05). Conclusion: The prevalence of MRSA in the surgical wards of the POSGH was 39.5% of Staphylococcus aureus isolates. Risk factors included the age range of 60–69 years, patients with co-morbidities, hospital stays of longer than one week, previous surgery and prior use of antibiotics. We recommend more awareness of this problem in the practice of Caribbean medicine to improve infection rates.</jats:p

Combining Evapotranspiration and Soil Apparent Electrical Conductivity Mapping to Identify Potential Precision Irrigation Benefits

Precision irrigation optimizes the spatiotemporal application of water using evapotranspiration (ET) maps to assess water stress or soil apparent electrical conductivity (ECa) maps as a proxy for plant available water content. However, ET and ECa maps are rarely used together. We developed high-resolution ET and ECa maps for six irrigated fields in the Midwest United States between 2014–2016. Our research goals were to (1) validate ET maps developed using the High-Resolution Mapping of EvapoTranspiration (HRMET) model and aerial imagery via comparison with ground observations in potato, sweet corn, and pea agroecosystems; (2) characterize relationships between ET and ECa; and (3) identify potential precision irrigation benefits across rotations. We demonstrated the synergy of combined ET and ECa mapping for evaluating whether intrafield differences in ECa correspond to actual water use for different crop rotations. We found that ET and ECa have stronger relationships in sweet corn and potato rotations than field corn. Thus, sweet corn and potato crops may benefit more from precision irrigation than field corn, even when grown rotationally on the same field. We recommend that future research consider crop rotation, intrafield soil variability, and existing irrigation practices together when determining potential water use, savings, and yield gains from precision irrigation.</jats:p