AWWA ACE95247 ✓ Most Recent

The forthcoming Disinfectant/Disinfection By-Product (D/DBP) Rule has directed the attention of many utilities on NOM removal as a key factor in minimizing the formation of disinfection byproducts. For utilities which practice conventional treatment, meeting the required TOC removal may require the reevaluation of existing coagulant strategies with emphasis on enhancing coagulation. Addition of higher coagulant dosages with or without the addition of acid and/or addition of powdered activated carbon (PAC) for rapid removal of organics will contribute to increase the volume of residuals to be treated prior to ultimate disposal. Along with the increased volume, increased removal of NOM will have a profound impact on the quality and characteristics of the residuals generated. Our recent research has shown that incorporation of higher amounts of NOM in the sludge matrix can significantly alter residual characteristics, resulting in decreases in sludge dewaterability. This decrease in sludge dewaterability could ultimately increase the cost of sludge handling and disposal. To identify the mechanism(s) responsible for poor dewaterability of sludges generated under enhanced coagulation, research focused on examining changes in both sludge macro and micro properties. Evaluation of sludge macro-properties included determination of sludge dewatering characteristics such as specific resistance and cake solids concentration, while sludge microproperties consisted of evaluation of particle size distribution, floc density, aggregate volume index (AVI) and characterization of organic matter incorporated into the sludge matrix. See more