Prague - new and old

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Prague_new.jpg (27236 bytes)

Four 44 m diameter final clarifiers added to existing eight clarifiers (see below).

Side wall depth 4.1 m, uniform bottom slope 8%. Peripheral drive. One-and-a quarter spiral scrapers (at least two full arms would be more appropriate), variable speed control. Maximum peripheral velocity 0.085 m/s.

Flocculation well 10 m dia. Energy Dissipation inlet.

Single weir effluent launder mounted on the inner side of the wall. Stamford baffle.

Maximum operational overflow rate 1,65 m/h, design overflow rate 2 m/h, MLSS around 3 g/l.

weirnew.jpg (9993 bytes)

Weir loading rate was not considered to be a valid parameter for design.

Stamford baffle mounted on launder.


Prague_old2.jpg (32553 bytes)

Eight final clarifiers built in the sixties. 43 m dia, side wall depth 2.3 m.

Note the light cage-type bridges! 

weirold.jpg (4346 bytes)

Inboard double weir launders placed at 2/3 of clarifier radius. Outer, wall mounted launders, were blinded to combat the density current lifting suspended solids over the outer weir.

Prague_old.jpg (30601 bytes)

Traditional small size inlet well, later modified to deep inlet. Plow type, single arm scraper.

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All pictures by courtesy of the Prague Central Wastewater Treatment Plant (UCOV). Special thanks to Mr. Jiri Roskota.

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