Cargill Pleased with LWT Automated Dredging System for Agricultural Sludges

LWT and Cargill worked jointly to design and install a system to remove solids from one of our process lagoons on a continuous and automated basis. A basic description follows:

Solids are removed from the lagoon with a Pit Hog™ dredge that can be operated either fully automated, or manual mode remote from on shore. The dredge travel and lateral movement is automated by a rail system that is mounted on the ends of the pond. This system allows the unit to make "sweeps" including all forward, reverse and lateral movement covering the entire pond without an operator. The control system tracks the location of the unit along the reverse cable and laterally along the rail. This dredge unit has several options including automatic bottom sensors to maintain the auger location at a set distance from the bottom of the pond. The pump and the entire system are designed to handle up to 3" solid spheres.

The dredge travel function is linked to a mass flow density meter that monitors the solids content of the slurry. The meter provides feedback to a control system which then controls the speed of travel into the solids. For instance, if the percent solids content increases over the set parameter, the dredge would slow down its travel to increase the amount of water being mixed at the pump. We use this system to load trucks for recycling of the biosolids by land application, and maintain a predetermined solids content.

This system was installed in 1993, and we are quite pleased as the system has met all of our expectations in terms of quality and functional capability.

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