3.0 Introduction

Treated municipal wastewater sludges that are regulated under the 40 CFR Part 503 rule are generated during primary and secondary wastewater treatment as well as in domestic septic systems [56]. Depending on the regulatory requirements for a specific biosolids beneficial-use option together with transportation considerations, sludges may undergo various steps of processing before being applied to land. The four major sludge-processing operations that occur at the wastewater treatment plant are

• Thickening

• Stabilization

• Conditioning

• Dewatering

This chapter reviews these processing operations and their impact on the various biosolids beneficial use and disposal options.