Water reclamation redesign for reducing Cryptosporidium risks at a recreational spray park using stochastic models

Mark H. Weir, Maria Tereza Pepe Razzolini, Joan B. Rose, Yoshifumi Masago

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Recreational outbreaks associated with sprayparks are well recognized, and may be partly due to the engineering designs used for their water reclamation systems are problematic to control. This work is based on an outbreak of cryptosporidiosis linked to a spraypark in New York State, where it was determined, specifically that the spraypad (the main attraction) was the primary exposure point. We first determined the likely dose the spraypad users were exposed to, then modeled the efficacy of the treatment system and used this to inform a Monte Carlo method to estimate the probability of infection and illness for the users of the spraypad. The current treatment system which consists of; two holding tanks, a dual media filter and chlorine injection as well as two design change recommendations were modeled using three independent Markov chain models. Within the current treatment system design the receiving tank for the treatment train is also connected with a second pipe to the spraypad used to deliver the return (treated) water, this return pipe is acting potentially as a bypass for the treatment train. Based on the risk assessments performed it is recommended that the bypass pipe be removed from the treatment system since in doing so the probability of infection and illness were reduced appreciably. Secondarily including an ozone contactor was shown to slightly reduce the risk further and provide a multiple barrier.

Original languageEnglish
Pages (from-to)6505-6514
Number of pages10
JournalWater Research
Volume45
Issue number19
DOIs
Publication statusPublished - 2011 Dec 1

Keywords

  • Cryptosporidium
  • Markov chains
  • Monte Carlo
  • Risk assessment
  • Water treatment

ASJC Scopus subject areas

  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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