Back River Egg-Shaped Digester

Construction of two three-million gallon egg-shaped concrete digesters including modifications. Each cast-in-place concrete tank is founded on a pile cap with 177, 24-inch square precast concrete piles beneath it. The tanks each contain a liquid-ring compressor for gas mixing, a vertically-mounted draft-tube mixer in the center and a sludge recirculation system with piping and injection points at several levels of the tank. Work included a closed-loop gas recovery piping system to withdraw gas from the headspace and use it as fuel for the boilers and gas for the gas mixers. Steam injectors control the temperature of the recirculating sludge and undigested sludge. The work included all the associated underground utilities and central utility upgrades, as well as the complete commissioning of the vessels and the digestion process.

Water Industry Excellence Coordinator: Chris Collins | | 410.337.6911

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