Microplastic discharge from a wastewater treatment plant: long term monitoring to compare two analytical techniques, LDIR and optical microscopy while also assessing the removal efficiency of a bubble curtain.

In this study we compare two parallel analytical methods while also testing a microplastics mitigation method. We assess the effectiveness of a bubble curtain to reduce microplastics in a wastewater treatment plant (WWTP)-effluent canal during the course of six months (>70 samples) using two analytical techniques: laser direct infrared (LDIR) and optical microscopy (OM) covering a size range of 0.02 to 5 mm. Comparison of the two analytical strategies shows similar trends, fluctuations, and correlating particle and fibre numbers. However, absolute values of particles differ, and the strategies provide different levels of information: LDIR is capable of identifying the plastic type as well as shape, while OM cannot determine the plastic type. Furthermore LIDR has a lower size limit (10-20 µm) than OM (50 µm). While information obtained by OM in general is far less detailed it is more affordable. This research also shows that the bubble curtain pilot does not have a measurable effect on the particle concentration. Possible effects of the curtain are hidden in the temporal variations. This research also reveals that individual samples show a large variation in particle numbers, illustrating that single measurements might give a poor representation of environmental particle number.

Multiple Sources of the Outbreak of Legionnaires' Disease in Genesee County, Michigan, in 2014 and 2015.

BACKGROUND: A community-wide outbreak of Legionnaires' disease (LD) occurred in Genesee County, Michigan, in 2014 and 2015. Previous reports about the outbreak are conflicting and have associated the outbreak with a change of water source in the city of Flint and, alternatively, to a Flint hospital. OBJECTIVE: The objective of this investigation was to independently identify relevant sources of Legionella pneumophila that likely resulted in the outbreak. METHODS: An independent, retrospective investigation of the outbreak was conducted, making use of public health, health care, and environmental data and whole-genome multilocus sequence typing (wgMLST) of clinical and environmental isolates. RESULTS: Strong evidence was found for a hospital-associated outbreak in both 2014 and 2015: a) 49% of cases had prior exposure to Flint hospital A, significantly higher than expected from Medicare admissions; b) hospital plumbing contained high levels of L. pneumophila; c) Legionella control measures in hospital plumbing aligned with subsidence of hospital A-associated cases; and d) wgMLST showed Legionella isolates from cases exposed to hospital A and from hospital plumbing to be highly similar. Multivariate analysis showed an increased risk of LD in 2014 for people residing in a home that received Flint water or was located in proximity to several Flint cooling towers. DISCUSSION: This is the first LD outbreak in the United States with evidence for three sources (in 2014): a) exposure to hospital A, b) receiving Flint water at home, and c) residential proximity to cooling towers; however, for 2015, evidence points to hospital A only. Each source could be associated with only a proportion of cases. A focus on a single source may have delayed recognition and remediation of other significant sources of L. pneumophila. https://doi.org/10.1289/EHP5663.