JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
This study was conducted to determine the effect of iron and aluminum on odor generation from anaerobically digested and dewatered sludge cakes. Blended primary and waste activated sludge samples obtained from 12 different wastewater utilities was batch digested in the laboratory for 30 days at 37 o C, conditioned, dewatered and the organic sulfur odor generation potential measured. In addition to sulfur gas analysis, all sludge samples were analyzed for total and volatile solids, Fe and Al concentrations in the solids, mono and divalent cations in solution and soluble biopolymer (proteins and polysaccharides). A correlation between iron and peak organic sulfur gas concentrations in the headspace of incubation vials was found. Following anaerobic digestion, a significant increase in solution protein occurred and correlations between solution protein, ammonium production, percentile volatile solids reduction and iron content in sludge were observed. These data suggested that iron plays an important role in anaerobic digestion and in odor generation from dewatered sludge cake. Aluminum reduced the odor potential for sludges that were high in iron, suggesting that proteins associated with aluminum are resistant to degradation following shear.
Abstract-To attain scalable performance efficiently, the HPC community expects future exascale systems to consist of multiple nodes, each with different types of hardware accelerators. In addition to GPUs and Intel MICs, additional candidate accelerators include embedded multiprocessors and FPGAs. End users need appropriate tools to efficiently use the available compute resources in such systems, both within a compute node and across compute nodes. As such, we present MetaMorph, a library framework designed to (automatically) extract as much computational capability as possible from HPC systems. Its design centers around three core principles: abstraction, interoperability, and adaptivity. To demonstrate its efficacy, we present a case study that uses the structured grids design pattern, which is heavily used in computational fluid dynamics. We show how MetaMorph significantly reduces the development time, while delivering performance and interoperability across an array of heterogeneous devices, including multicore CPUs, Intel MICs, AMD GPUs, and NVIDIA GPUs.
Trimethylamine, (CH 3 ) 3 N, (TMA), odors are often associated with limed and polymer conditioned sludges. This odor has a fishy smell and can be a nuisance to the community surrounding a wastewater treatment plant or land application site. Several factors are thought to determine the amount of TMA generated from limed biosolids. These are, the presence of cationic polymer, the polymer dose, the time between addition of polymer and lime stabilization, shear imparted on the sludge in the dewatering process and dewatered cake solids concentration. All of these were investigated in this study. The results showed that TMA could be generated from sludge that did not contain polymer but the concentrations were low compared to sludge conditioned with cationic polymer.As the polymer dose increased, the TMA increased. Shear also showed to play an important role for TMA production. In addition to higher shear increasing the polymer demand, shear in itself can increase TMA generation. However, the most important factor in generating TMA was the time between conditioning and liming. If this time was minimized, little TMA was produced, even at high polymer doses. Data also suggests that methanogens play an important role in the breakdown of TMA.iii Acknowledgements
To be systems thinkers, we must easily and comfortably integrate human subsystems into complex systems. We can diagram dyadic and triadic human relationships to better analyze, design, and implement complex systems containing human subsystems. Trust and distrust are separate but linked state variables. Trust is fragile and distrust is robust because they fit differently into the system structure of the dyadic relationship. Key considerations for trust in the organization include risk and experience. From a systems perspective, we must design into the organization and our dyadic relationships the structure needed to increase trusting and trustworthy behaviors and to reduce opportunistic behaviors. These behaviors are bound together in feedback loops that define the structure of our relationships. We determine that structure using system dynamics tools. These tools provide the needed understanding of trust to identify steps for changing the relationship or organizational system structure that leads to changed behavior.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.