RECENT FINDINGS ON BIOSOLIDS CAKE ODOR REDUCTION - MIDPOINT RESULTS OF WERF PHASE 3 BIOSOLIDS ODOR RESEARCH

The Water Environment Research Foundation (WERF) has sponsored three phases of a long-term project entitled “Identifying and Controlling Odors in the Municipal Wastewater Environment.” The current (third) phase focuses on reduction of odors from dewatered biosolids cakes, and is entitled “Biosolids Processing Modifications for Cake Odor Reduction.” This phase encompasses nine research agenda items developed from the results of the prior phase of research (Phase 2), which was completed in December 2003 as WERF Report No. 00-HHE-5T and was entitled “Impacts of In-Plant Parameters on Biosolids Odor Quality.”The current phase (Phase 3) is a minimum two and a half year project, the first half of which is dedicated to testing several of the more promising hypotheses from Phase 2 in the laboratory to help determine the cause-effect relationships of odor generation from biosolids, and to develop odor reduction techniques. It is important to realize that this research project covers the reduction or prevention of odorous emissions from dewatered biosolids cake, not odor control by means of containment or adsorption or absorption of malodorous emissions. In the remainder of the Phase 3 project, we plan to apply promising laboratory findings to biosolids handling processes at one or more wastewater treatment plants (WWTPs), with the goal of achieving significant cake odor reduction in a realistic, full-scale setting.The Phase 3 laboratory results are being used to identify the relative effectiveness of methods for reducing biosolids cake odors, using techniques and measurements of biosolids cake odor production potential that have been developed by the WERF Project Team.Laboratory investigations related to each of the following topic areas were conducted in Phase 3, with the results summarized and discussed in this paper:The role of cations in odor production from anaerobically-digested biosolidsThe effect of digester solids retention time on cake odorsEffects of advanced digestion processes on cake odorsEffects of dewatering processes and associated control parameters on cake odorsEffects of chemical addition on cake odorsAn amendment to the research project was recently authorized to investigate a number of additional chemical, enzymatic, and biological agents (hereinafter “CEBAs”), and that research is getting underway at the time of submittal of the draft manuscript.Plans to demonstrate the most promising research findings at full-scale biosolids digestion and dewatering facilities constitute the final phase of the project. Surveys are being used to contact wastewater treatment facilities that have an interest or need to reduce their biosolids cake odors. The main goal of this last phase of the project will be to match wastewater or biosolids facilities that need to reduce biosolids odors with specific technologies, chemicals, or biological agents, in order to demonstrate the efficacy of promising laboratory findings full scale at a real WWTP.