District of Columbia Water and Sewer Authority (DC Water)
Washington, DC
Due to potential risks associated with transportation and handling of liquid chlorine, the District
of Columbia Water and Sewer Authority (DC Water), switched to the use of liquid sodium
hypochlorite as the disinfecting agent at the Blue Plains Advanced Wastewater Treatment Plant
(AWTP). The escalating cost of bulk purchased sodium hypochlorite prompted DC Water to
commission a study to evaluate disinfection alternatives that: 1) are compatible with existing
treatment processes; 2) meet all plant effluent disinfection requirements; and 3) reduce life cycle
costs of disinfection.
The study involved a detailed technical, economic and non-economic evaluation of the feasibility
of constructing and operating an onsite sodium hypochlorite generation facility in lieu of bulk
purchase. Economic analyses included capital and O&M costs, life cycle costs over a 30-year
time horizon, and sensitivity of price of bulk sodium hypochlorite and salt, electric power cost,
debt service on life cycle costs.
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Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment | Tags: Capital Savings, Improved Plant Reliability, O&M Cost Savings | No Comments »
Humber Treatment Plant (HTP)
Toronto, Ontario (Canada)
The Humber Treatment Plant (HTP) was experiencing severe settling problems. An opportunity
to improve the performance of the HTP was seized by the plant’s Senior Engineer by developing
and implementing a program of repair, continuous assessment, analysis, and tuning to ensure
optimal operation of the aging infrastructure. Through the strategic utilization of existing inhouse
expertise and resources, a new benchmark of excellence, serving the community through
improved and consistent effluent quality with accompanying odour reductions, was established.
This achievement was accomplished paradoxically using less energy and chemicals, thus,
significantly reducing the Humber’s environmental footprint. The direct delivery of these
services by City staff, while further enhancing in-house knowledge, skill, and stewardship,
eliminated the delays associated with project delivery using external contractors and made it
possible to reap the immediate rewards. The monetary benefits to the City are savings in
operating costs of $550,000 per year and capital savings of $6,000,000.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Capital Savings, Decreased Energy Consumption, Improved Plant Sustainability, Operating Cost Savings, Reduced Carbon Footprint, Reduced Odor Problems | No Comments »
Inland Empire Utilities Agency
Chino, California
Carollo Engineers (Carollo), together with the Inland Empire Utilities Agency (IEUA) developed
an innovative planning tool, OPTIMOTM, which uses optimization algorithms to minimize
operational costs for a complex and interconnected collection, wastewater treatment, and
recycled water system. The model applies mass and energy balances to simulate wastewater flow
routing, treatment, recycle water distribution, and energy demand and supply. The model
accounts for multiple physical and water quality constraints, while maximizing the use of
recycled water and minimizing total system operations and maintenance costs, including power,
chemical, and labor demands. This integrated model is a planning tool for IEUA that simplifies
the complex interactions of their extensive wastewater system to maximize capacity, minimize
costs, and balance risks, while meeting regulatory constraints. This paper presents the
development and application of the model to IEUA, and benefits to other agencies.
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Posted: May 3rd, 2011 | Filed under: 500K-1M, Waste Water Treatment, Water Treatment | Tags: Capital Savings, Improved System Efficiency, Maximize Capacity, Meet Regulatory Constraints, O&M Cost Savings, Reduced Risks | No Comments »