Abstract |
The disposal of pulp and paper mill sludge in a manner which has minimal effect on the environment has become a serious problem. Four methods of disposal were evaluated, namely: (1) incineration in an air entrained dryer-incinerator, (2) burning in hog fuel boilers, (3) incorporation into soil as an amendment, and (4) hydromulching for soil stabilization. Other possible uses are discussed. Burning sludge in incinerators costs between $11 and $13/dry ton, including all prior dewatering steps. Sludge can be made available at various degrees of dewatering at costs of from $7 to $20/dry ton. Incorporation into farm soil offers the possibility for disposal of large quantities of sludge. At low levels (100-200 tons/acre) crop yields are satisfactory, provided adequate nitrogen is added. A high level incorporation (600 tons/acre) requires a year of fallow preceding crop planting. Sludge alone or in combination with bark can be used as a hydromulch in establishing grass stands on steep embankments. |