THE HEAVY-METAL CONTENT OF ACTIVATED-SLUDGE USED AS ORGANIC FERTILIZER

It has been determined that activated sludge from the Kotlas Pulp and Paper Plant possesses a number of valuable properties and can be used as nontraditional organic fertilizer and as a melioration agent to improve the physical chemistry and fertility of soils in Arkhangel'sk Oblast. At the same time, the widespread use of the activated sludge has been restricted because of its significant content of heavy metals, particularly mercury. Further study is needed as io possible changes in soil properties as a result of long-term use of the sludge and the nature of any aftereffects, and more detailed investigation of the behavior of the heavy metals is required.