City of Wyoming Clean Water Plant

The City of Wyoming has requested that the Calvin Senior Design team perform an in-depth, preliminary design for a UV-disinfection system complete with advanced oxidation. Reaeration and plant hydraulics are additional aspects of the project the team will consider. Currently, flow through chlorination at WCWP happens by gravity. However, if UV-disinfection is implemented, an extra pumping station at the plant will be needed. The team will include a pumping station design in the final report. A more in-depth explanation of each aspect of the project is given below.

Disinfection rids wastewater of pathogens and microorganisms by chemical or radiation processes, in which the disinfectant is added, mixed, and allowed time to react. UV disinfection is an alternative to conventional chemical disinfectants used in the wastewater treatment process. UV disinfection consists of ultra-violet radiation in the form of wavelengths (Ho et al, 1998). The UV rays are absorbed by pathogens within the wastewater, inhibiting replication and inactivating the microorganisms. Advantages of UV disinfection include no chemical transportation or safety concerns and minimal worry about disinfection by-products. The team will evaluate and provide a preliminary design for a UV disinfection treatment system suited for the future demands on the City of Wyoming’s Clean Water Plant. A low pressure, high intensity UV lamp system in a closed pipe has been selected for use on site. (Picture courtesy of Clean Water - Oxford)

Advanced oxidation processes are emerging and innovative water treatment processes shown to eliminate elusive compounds of concern often ignored because of low concentrations and low chemical and biological degradability. Compounds targeted for removal include both pharmaceuticals and personal care products (PPcPs) (Huber et al. 2003; Zwiener and Frimmel 2000). The CWP is considering coupling UV-disinfection with advanced oxidation to ensure water quality and meet stricter regulations imposed by Michigan Department of Environmental Quality (MDEQ) and the Environmental Protection Agency (EPA). The team selected ozone/UV system with the goal of providing an effective plant design that eliminates pharmaceuticals and personal care products before discharge into the Grand River.

Reaeration is used to increase the dissolved oxygen (DO) concentration of the wastewater after the water undergoes disinfection by UV rays or chemicals. It is necessary to raise DO levels to an extent that the wastewater is biologically stable and meets effluent requirements. A cascade aeration system will be used in the older chlorine disinfection contact tank because of its ease of use, and relative ease of maintenance, and low cost.

If the ozone advanced oxidation process is implemented in the future, additional reaeration will likely not be needed, as the degradation of ozone will provide enough oxygen content.

New pumps for UV disinfection, advanced oxidation, and reaeration will be needed. The team proposing converting an unused settled sludge pumping station to a new pumping station for the additions to the plant. This pumping house would provide enough head so that the wastewater can flow through the entire plant.

The team performed bench-scale testing to determine the optimal ozone dosage of an ozone-based AOP system for contaminant removal at the CWP and to better understand the ozone/UV advanced oxidation process. Bench-scale testing occurred throughout the month of April. All testing and experimentation took place in the environmental engineering laboratory located inside the Science Building at Calvin College. Water samples collected from bench-scale testing experiments were analyzed at Calvin College using high-pressure liquid chromatography (HPLC).