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An economic analysis of ultraviolet (UV) disinfection versus chlorine disinfection at the Brookfield Fox River Water Pollution Control Center (FRWPCC) / by David Grassl.

by Grassl, David.

Sewage -- Purification

Water -- Purification -- Adsorption

Sewage disposal plants

Costs and Cost Analysis

320 leaves : ill. ; 29 cm.

Advisor: Dr. Francis Mahuta.

Introduction and background -- Literature review -- Methodology -- Results and discussion -- Conclusion and recommendations -- Wastewater treatment plants contributing cost data -- References -- Bibliography -- Appendix A) FRWPCC Wisconsin permit discharge elimination system (WPDES) permit B) FRWPCC Fact sheet C) Material safety data sheet (MSDS) for chloroform D) Natural resources (NR) 605 E) Ultraviolet transmittance (UVT) testing results F) FRWPCC total suspended solids (TSS) concentrations for January 2003 through January 2004 and probability plots G) Ultraviolet disinfection design request for Trojan Technologies, Inc H) Ultraviolet disinfection design request for Wedeco UV Technologies I) Ultraviolet Disinfection plant cost data and curves J) Ultraviolet disinfection plant cost calculations and assumptions K) Ultraviolet disinfection system selection by Trojan Technologies, Inc L) Ultraviolet disinfection system selection by Wedeco UV Technologies M) FRWPCC chlorine disinfection cost calculations N) Net present value (NPV) calculations O) FRWPCC hazardous waste generation P) Racine Wastewater Treatment Plant (WWTP) discharge monitoring report (DMR) for fecal coliforms.

This Capstone Design involves an economic analysis of ultraviolet (UV) versus chlorine disinfection at the Brookfield Fox River Water Pollution Control Center (FRWPCC). The purpose of this project was to determine if it is economically feasible for the plant to modify their existing chlorine disinfection system to UV disinfection.

In order to determine the feasibility of switching disinfection technologies, an extensive literature review was conducted to make sure that the UV disinfection includes the characteristics of an appropriate disinfecting agent. After the literature review, ultraviolet transmittance (UVT) testing was conducted over a one-week time period so two manufacturers, Trojan Technologies, Inc. and Wedeco UV Technologies, could recommend an UV disinfection system. Next, multiple wastewater treatment plants (WWTPs) in the state of Wisconsin were contacted to determine the initial capital and annual operation and maintenance (O&M) costs associated with their systems. These costs were then put into cost curves according to the average plant flow rate to estimate similar costs for the FRWPCC.

Upon estimating the costs from the cost curves, they were compared to the system selections by the two manufacturers and to the current chlorine disinfection costs experienced by the FRWPCC. Through UVT testing it was determined that the wastewater to the disinfection process at the FRWPCC had a minimum of 70% UVT. With the UVT and permit requirements of the plant, Trojan Technologies, Inc recommended the Trojan UV4000 Plus, which is a medium-pressure, non-contact type reactor with lamps parallel to flow.

The system as a total of 108 lamps and costs $616,200. Wedeco UV Technologies recommended the Wedeco TAK 55, which is a low-pressure, high-intensity, non-contact type reator with lamps parallel to flow. This system operated with 432 lamps and costs $820,500. From the cost curves it was estimated that for the FRWPCC it would cost $714,000 in initial equipment with O&M costs of $6,750; $10,700; and $5,700 for energy/electrical requirements; lamp replacements; and chemicals, maintenance, and lamp cleaning, respectively.

The costs estimated from the cost curves were close to the costs estimated by the two manufacturers, suggesting that the cost curves were an accurate representation of the actual costs. In comparing the net present value (NPV) of the baseline chlorine disinfection to UV disinfection, it was found that the existing system was $236,481, while modifying the system to UV disinfection was $1,849,664.

Looking the payback period, it was determined that the costs per year exceeded the savings per year for UV, yielding no payback period. Finally, from a pollution prevention aspect, UV disinfection eliminated chloroform as a hazardous waste, but introduced a minimal amount of mercury hazardous waste. At the same time, UV disinfection requires more electricity than chlorine disinfection requiring the consumption of more coal at the local power plant and the associated air emissions.

In this analysis, it was determined that UV disinfection is not economically viable at this time due to the existing costs for chlorine disinfection and the estimated costs for UV disinfection but should be considered from a safety aspect for the community and plant operators.

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