INFORMATION FOR ENGINEERS DESIGNING UV WASTEWATER TREATMENT

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UV wastewater systems are designed based on the maximum peak instant flow rate.  This flow rate will dictate what options are available.  Flow can enter through channel or piped layouts with gravity flow or pumped effluent.    

Open Channel Horizontal

Open Channel Vertical

Closed Chamber (aka vessel)

Tube System (non contact)

Retrofit - Replacing existing equipment

The UV transmission (UVT %), the amount of light that can pass through, is typically around 65%.  This number will vary based on the quality of the pre-treatment.  The lower the number, the more lamps are required.

A data collection sheet is included below as an attachment.  In addition to the design information, engineers need to understand parts cost, energy cost, and typical service requirements. System location and hydraulic issues need to be addressed.  Items like flow conditioner plates or baffle plates are sometimes required to de-energize the flow.

UV wastewater systems are designed to operate in outdoor conditions.  It is recommended that a shade structure or pole buildings be placed over the equipment for worker safety, protection from rain and snow, system longevity, and heat issues on the controls.   Hoists or cranes may need to be used for larger systems.

Discharge permits vary based on the location.   For typical plants, UV systems are designed to meet a certain dosage.   Traditionally, 30 mJ is used and is calculated at end of lamp life with quartz fouling and is used for 126/100 ml E.coli or <200/100 ml for fecal coliform. Stricter limits require special engineering for pre-treatment solutions and to limit algae growth and other microbes.