Project description:Efficacy of a high pressure jet device for excess sludge reduction in a conventional activated sludge process: Pilot-scale demonstration
Project description:Understanding microbial community diversity is thought to be crucial for improving process functioning and stabilities of wastewater treatment systems. However, current studies largely focus on taxonomic groups based on 16S rRNA, which are not necessarily linked to functioning, or a few selected functional genes. Here we launched a study to profile the overall functional genes of microbial communities in three full-scale wastewater treatment systems. Triplicate activated sludge samples from each system were analyzed using a high-throughput metagenomics tool named GeoChip 4.2, resulting in the detection of 38,507 to 40,647 functional genes. A high similarity of 75.5% to 79.7% shared genes was noted among the nine samples. Moreover, correlation analyses showed that the abundances of a wide array of functional genes were associated with system performances. For example, the abundances of overall nitrogen cycling genes had a strong correlation to total nitrogen (TN) removal rates (r = 0.7647, P < 0.01). The abundances of overall carbon cycling genes were moderately correlated with COD removal rates (r = 0.6515, P < 0.01). Lastly, we found that influent chemical oxygen demand (COD inf) and total phosphorus concentrations (TP inf), and dissolved oxygen (DO) concentrations were key environmental factors shaping the overall functional genes. Together, the results revealed vast functional gene diversity and some links between the functional gene compositions and microbe-mediated processes.
Project description:Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L-1). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers. 18 samples; Triplicate PHB-enriched bacterial communities recovered from activated sludge were exposed to nanoparticle (TiO2 or Ag) or AgNO3 (as a silver control) or were not exposed to an nanoparticles (control) to determine if the naoparticles affected PHB production.
Project description:Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L-1). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers.
Project description:Landfill leachate water is often treated in a biological processing step. In most cases a stable operation of the industrial scale plants is controlled by sum parameters such as process relevant ion concentrations, dry matter concentration and dissolved oxygen concentration. A deeper understanding of the current status of the individual cell or the biocoenosis would help to understand malfunctions or the reason for inefficient plant performance. In a simple batch experimental setup, samples of two different conditions have been generated to unravel bacterial proteome changes in response to medium term lack of oxygen supply and landfill leachate addition. The first condition was an activated sludge sample condition from an industrial scale landfill leachate treatment plant with the process stages of nitrification and denitrification. After 45 days without aeration and with addition of leachate and carbon sources as fed batch, the second sample (condition 2) was taken. A comprehensive LC-MS/MS based protemic screen was performed aiming for the identification and quantification of waste water specific bacteria proteomes. To this end, a novel combination of two protein extraction methods has been established meeting the requirements for LC-MS/MS anaylsis. Around 600 proteins were identified of which 90 % were quantified in at least 3 replicates. Numerous essential proteins to maintain the cell redox homeostasis are overexpressed in the condition 1 which was aerated with oxygen and stressed by the ultrafiltration compared to condition 2, which was not aerated in a lab experiment. In addition, heat and cold shock proteins and two proteins related to the apoptosis of organisms (spermidine/putrescine transport system and apoptosis-inducing factor) were identified.
Project description:Metaproteomic studies of full-scale activated sludge systems require reproducible protein extraction methods. A systematic evaluation of three different extractions protocols, each in combination with three different methods of cell lysis, and a commercial kit were evaluated. Criteria used for comparison of each method included the extracted protein concentration and the number of identified proteins and peptides as well as their phylogenetic, cell localization and functional distribution and quantitative reproducibility. Furthermore, the advantage of using specific metagenomes and a 2-step database approach was illustrated. The results recommend a protocol for protein extraction from activated sludge based on the protein extraction reagent B-Per and bead beating.