Contaminants in sludge: implications for management policies and land application

Abstract

Policies on sludge (or biosolids) management vary widely, particularly when decisions must be made on what to do with the final product. This paper examines the two principal rationales with which such decisions are made, and through which scientific knowledge is included in the process. These rationales are risk analysis (risk assessment and management), and the criterion of sustainability. Both are found to be potentially arbitrary due to the difficulty in defining the individual constituents necessary to relate environmental phenomena to environmental policy. To place the difficulties in a practical context, this paper presents research results from three recent projects concerned with contaminants in sludge (phosphorus, flocculant polymers, and polymer-surfactant aggregates), and uses the findings to exemplify the dilemma encountered in policy making. A path forward is proposed.