WASTEWATER

By Rick Lallish

When operating a belt filter press, alignment is critical for proper operation and safety. What system normally accomplishes this operation?

A. Tension-alignment system

B. Belt tracking system/automatic sensing arm

C. Integrated SCADA controls

D. This is manually controlled by the press operator

Answer: B. Belt filter presses can achieve excellent dewatering when operating properly. Belt tension and alignment are critical for keeping both belts in proper alignment and maintaining necessary tension. If the belt tracking system fails, the belts may travel off the tracks/wheels, and unit failure may occur. This is prevented by a system of automatic sensing alarms that limit the travel of each belt to the left or right. Tension is important as well, as increased belt tension may result in higher cake percent solids but possibly cake extruding from the sides of the unit. Also, increased belt tension may decrease belt life. More information may be found in the WEF textbook, Wastewater Treatment Fundamentals II – Solids Handling and Support Systems, Chapter 5.

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DRINKING WATER

By Drew Hoelscher

How many repeat bacteriological (total coliform) samples should an operator collect if a routine bacteriological sample is total coliform positive?

A. 1

B. 2

C. 3

D. None. Repeat samples are only required if the sample tests positive for E. coli

Answer: C. Routine and repeat bacteriological samples are collected from approved sample site locations throughout the distribution system and analyzed for total coliform. Typically, utilities monitor total coliform every month by collecting the appropriate number of routine samples throughout the sampling period. If a routine sample tests positive for total coliform, the operator must collect three repeat samples within 24 hours of being notified. Repeat samples must be collected from the original site, within five service connections downstream, and within five service connections upstream from the original site. An alternative sample location can be proposed to the governing agency if it is likely to better represent a pathway for contamination.

About the authors

Rick Lallish is water pollution control program director and Drew Hoelscher is program director of drinking water operations at the Environmental Resources Training Center of Southern Illinois University Edwardsville.