Multivariate monitoring of a biological wastewater treatment process: a case study at Melbourne Water's Western Treatment Plant

Biological wastewater treatment is a complex, multivariate process, in which a number of physical and biological processes occur simultaneously. In this study, principal component analysis (PCA) and parallel factor analysis (PARAFAC) were used to profile and characterise Lagoon 115E, a multistage biological lagoon treatment system at Melbourne Water's Western Treatment Plant (WTP) in Melbourne, Australia. In this study, the objective was to increase our understanding of the multivariate processes taking place in the lagoon. The data used in the study span a 7-year period during which samples were collected as often as weekly from the ponds of Lagoon 115E and subjected to analysis. The resulting database, involving 19 chemical and physical variables, was studied using the multivariate data analysis methods PCA and PARAFAC. With these methods, alterations in the state of the wastewater due to intrinsic and extrinsic factors could be discerned. The methods were effective in illustrating and visually representing the complex purification stages and cyclic changes occurring along the lagoon system. The two methods proved complementary, with each having its own beneficial features. (C) 2003 Elsevier B.V. All rights reserved.

Do squash players accurately report use of appropriate protective eyewear?

Self-report surveys are a common method of collecting data on protective equipment use in sport. The aim of this study was to assess the validity of self-reported use of appropriate protective eyewear by squash players. Surveys of squash players' appropriate protective eyewear behaviours were conducted over two consecutive years (2002 and 2003) at randomly-selected squash venues in Melbourne, Australia. Over the two years, 1219 adult players were surveyed (response rate of 92%). Trained observers also recorded the actual on-court appropriate protective eyewear behaviours of all players during the survey sessions. Eyewear use rates calculated from both data sources were compared. The self-reported appropriate protective eyewear use rate (9.4%; 95% CI 7.8, 11.0) was significantly higher (1.6 times more) than the observed rate (5.9%; 95%CI 4.6, 7.2). This suggests that players may over-report their use of appropriate protective equipment, though some may have incorrectly classified their eyewear as being appropriate or suitably protective. Studies that rely only on self-report data on protective equipment use need to take into account that this could lead to biased estimates.