IMPACT OF HIGH SHEAR SOLIDS PROCESSING ON PRODUCTION OF VOLATILE SULFUR COMPOUNDS FROM ANAEROBICALLY DIGESTED BIOSOLIDS

摘要

The emission of volatile sulfur compounds (VSCs) was evaluated for stored anaerobicallydigested biosolids cakes. This evaluation was conducted on the headspace of anaerobicallystored cakes obtained from two municipal wastewater treatment plants. The objective of thisinvestigation was to determine the impact of high-shear solids processing on VSC productionfrom digested biosolids. Experiments were conducted on biosolids obtained from full-scale lowandhigh-solids centrifuges, and from screw conveyors. The results of this study indicate thatstorage of biosolids obtained from high-solids centrifuges (high shear equipment) can produce 3orders of magnitude more VSCs than biosolids obtained from low-solids centrifuge (low-shearequipment). Similarly, biosolids subject to a combination of centrifugation and screwconveyance (high-shear conveyance) produced as much as 3 orders of magnitude more VSCsthan biosolids that were subject to centrifugation alone. These results verify the impact ofbiosolids shear on VSC production. Preliminary laboratory-scale experiments were alsoconducted to study the impact of biosolids shear and protein amendment on VSC production.These experiments demonstrated that storage of laboratory-sheared or protein amended biosolidsresulted in greater VSC (specifically methyl mercaptan) production than the unaltered control. Amodel was developed that relates increase in biosolids shear during solids processing to increaselabile protein. The subsequent hydrolysis of labile protein results in the formation of VSCs.