Land Application of Domestic Sludge in Cold Climates

Abstract

Aerobically digested sludge from the Fairbanks sewage treatment plant was worked into the soil on several plots at the University of Alaska in the summer of 1978. Some of the sludge had been air dried for up to six months prior to application while some was taken directly from the thickener. Applications varied from 12 to 100 tons of solids/acre. For sludge applied in July and August, the fecal coliform count decayed by several orders of magnitude by the middle of September.. There was no significant movement of fecal coliform bacteria either vertically or laterally. Lime was used to raise the pH of one plot to 12, completely killing the fecal coliform bacteria within several days. The nutrient distribution demonstrated the potential for enriching soils by sludge addition. The main purpose of the study was to investigate the feasibility of this concept for remote military sites. Air drying followed by land application may represent a viable means of sludge disposal.