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Municipalities can save operating expenses, eliminate pollution problems and increase the convenience of their waste management program by recycling their sewage sludge slurry in agricultural soils.
Sewage sludge slurries have from 2 to 10-percent solids depending on the treatment plant design and operation procedures. Sewage slurries with more than 8 percent solids are difficult to pump because of high friction in the pipe lines and pump mechanism. Sewage slurries can be applied to agricultural fields by gravity flow and sprinkler irrigation systems, as well as by tank trucks that either broadcast spray on, or inject the slurry into, the soil. The direct application of sewage involves the handling or transportation of large quantities of water. This is a seasonal activity at best that cannot be carried out during the winter, during rainy periods or when agricultural practices conflict with sludge slurry applications.