Water Online

September 2017

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

Issue link: https://wateronline.epubxp.com/i/861825

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Page 16 of 38

Treatment Augmentation In concert with the analysis of existing treatment capabilities, bench-scale testing was completed at the DeCew Falls plant to identify modifications to the existing treatment which the Region could implement relatively quickly if toxins were detected at the plant. Based on the results of the bench-scale study, operating with an enhanced coagulation dose of the existing plant coagulant (alum) was selected as the preferred short-term solution that used the existing infrastructure, and a range of potential polymers was screened. The polymer investigations identified a product which could assist in forming a fast-settling, heavy floc to promote better settling of cyanobacterial cells and prevent re-suspension of the sludge. Once a preferred polymer was selected, logistical considerations such as the availability of supply, location for injection, make-down system requirements, and regulatory approvals for implementation of a new chemical system were addressed, and the Region prepared to enact treatment augmentations, if necessary. Recognizing that further fine-tuning of plant operations may be required under changing water quality conditions throughout a cyanobacterial event, a training program for the Region's staff was incorporated in the bench-scale studies. Increasing the Region's in-house capacity to develop and carry out jar test plans will provide greater flexibility in determining the appropriate response and implementation for subsequent events, including continued examination of coagulant, chlorine, and polymer doses. Monitoring Implementation, Response Readiness, And A Cyanotoxin Framework Within the 2016 cyanobacterial season, a tiered monitoring plan was implemented by the Region of Niagara, and while cyanotoxins were only ever detected upstream of the DeCew Falls treatment plant (never at the plant itself ), the Region was ready to use existing chlorination capabilities to manage dissolved toxins and had obtained approvals from the regulator to implement a polymer system for augmented removal of cyanobacterial cells, should it have become necessary. The Region successfully navigated the potential pitfalls of gathering data about a cyanobacterial event, analyzing the data to understand the implications, and preparing a treatment response plan. A teamwork approach to communication, monitoring logistics, implication analysis, and decision execution was integral to the process, and included O&M staff, summer interns, quality and compliance staff, the Region's laboratory staff, Public Health officials, the local conservation authority, university researchers, and other municipalities. Ultimately, a monitoring and response framework was developed to support the Region in managing potential cyanobacterial impacts going forward. While circumstances might differ between events or evolve throughout the duration of an event, the framework will allow the Region to obtain needed and actionable information, understand the current treatment capabilities and augmentation options, and have the in-house training to further fine-tune the treatment parameters. By ensuring that tiered monitoring and response measures are in place, issues such as sample frequencies and locations, preliminary treatment set-points, and media release timelines will be addressed ahead of time, allowing the Region's staff to focus on critical questions rather than laboratory logistics during future events. n 14 wateronline.com n Water Innovations MICROBIALCONTAMINANTS Silvia Vlad is a water treatment engineer in CH2M's Toronto, Canada office and holds a Masters of Applied Science from the University of Waterloo, where her thesis focused on the treatment of the cyanotoxin anatoxin-a in drinking water. Silvia is delighted to be part of an industry that strives towards a resilient global water supply through ambitious policy initiatives, open communications, and effective engineering solutions. About The Authors Literature Scan Chlorination Goals and Tradeoffs DeCew Falls WTP performance observations Standard intake chlorination: Intake chlorination for cyanotoxin oxidation: Chlorination post-filter for cyanotoxin oxidation: Monique Waller obtained her Master's degree in civil engineering from the University of Toronto in 2008, after which she joined CH2M's Kitchener office. Monique has supported a range of municipal drinking water treatment and distribution projects, including water quality and optimization studies, environmental assessments, and hydraulic modeling of water distribution systems. Quirien Muylwyk, MASc., P.Eng., is the National Practice Leader for Water Quality with AECOM. Quirien has more than 20 years of experience in strategic planning for regulatory compliance and growth, the design and construction of new works, and process optimization for municipal water systems. Her work has focused on making the link between performance inside the treatment plant and performance in the distribution system, all with the purpose of promoting public health. • Avoid cell Iysis • Maintain pretreatment performance • Address zebra mussels • Consider DBP formation • Oxidize dissolved microcystin-LR released following cell lysis • Oxidize dissolved microcystin-LR remaining post- filtration

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