This manual is designed for use in the laboratory phase of courses dealing with microbial aspects of pollution. It attempts to cover the subject area broadly in four major categories: (1) microorganisms in clean and polluted waters, (2) carbonaceous pollutants, (3) nitrogen, phosphorus, iron, and sulfur as pollutants, and (4) sanitary bacteriology. Principles are stressed rather than specific modes of technical applications. Most of the 25 exercises deal with more than one phenomenon to reflect associations as they exist in nature. Although the aquatic environment is emphasized, some consideration of microorganisms in relation to solid wastes and air pollution is included. A brief introductory essay places each topic into the context of pollution where this might not otherwise be obvious. Additional components outlined for individual exercises include materials to be used, procedures, reports to prepare, questions, and literature sources for study of the topic in greater detail. The presentation is at the advanced undergraduate and beginning graduate student level. An introductory course in microbiology (or bacteriology) including laboratory instruction is assumed, as are familiarity with the basic techniques of analytical chemistry and some knowledge of sewage treatment processes. (BL)