State Water Resources Research Institute Program

Project ID: 2008CT177B
Title: Optimization of Acidogenic Anaerobic Wastewater Treatment with The Potential for Water Reclamation
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2010
Congressional District: 2nd
Focus Categories: Wastewater, Water Quality
Keywords: anaerobic wastewater treatment, acidogenic phase, water reclamation
Principal Investigator: Li, Baikun
Federal Funds: $ 24,421
Non-Federal Matching Funds: $ 50,900
Abstract: With the dense population and the advanced development of industry and agriculture in the Northeastern states, water shortage has become a serious problem in these areas. Long Island Sound regions have experienced eutrophication and groundwater contamination for years. Water reclamation through wastewater treatment is a necessity to meet increasing water demand and protect natural water resources. Compared with costly aerobic wastewater treatment processes, anaerobic treatment can efficiently degrade organic contaminants in an energy-saving fashion. Large molecule contaminants are broken down into small molecule fatty acids in anaerobic treatment, which can be easily removed in further treatment processes for water reclamation. However, the slow growth rate of anaerobic bacteria (especially methanoganeic bacteria), the long retention time, and the low tolerance to operational shocks (e.g. flow rate, pH and temperature) have severely limited the broad application of anaerobic treatment processes. This research will investigate, for the first time, acidogenic anaerobic treatment to shorten the retention time and enhance anaerobic wastewater treatment efficiency. As microorganisms play critical roles in anaerobic systems, this research will also investigate the variation of microbial communities with operational conditions to elucidate the functional anaerobic bacteria for organic contaminant removal. The knowledge gained from this project is critical to enhance anaerobic treatment efficiency and stability, and further contribute to developing novel energy-saving treatment processes for water reclamation and shaping regulatory policy for sustainable water reservation.

The main goal of the proposed project is to improve anaerobic treatment efficiency for water reclamation, and achieve wastewater treatment in a cost-effective, energy-saving and sustainable fashion. To achieve this goal, multidisciplinary research activities will be performed. Specifically, this project will focus on four objectives.

The optimization of anaerobic treatment will be conducted in a continuous flow biofermenter (simulating common wastewater treatment processes) and batch mode serum bottles (simulating the accumulation of acidic fermentation products). The reactors will be inoculated with organic agricultural soil from the farm at the University of Connecticut (UConn). Synthetic wastewater will be used to simulate different wastewater sources. Operational parameters critical for anaerobic treatment will be tested individually at three levels, including organic substrate concentration (1000, 3000, and 8000 mg/L), pH (4.5, 5.5 and 8.0) hydraulic retention time (10, 24, and 100 hrs), and inoculum concentration (1000, 2000 and 5000 mg/L). Each condition will be operated for 40 days to allow anaerobic bacteria to adapt to each condition. The performance of anaerobic treatment will be evaluated by monitoring the following parameters: influent pH, chemical organic demand (COD), redox potential (ORP); effluent pH, COD and ORP; ORP inside the reactor; total suspended solid (TSS); liquid fermentation products (e.g. acetic acid, propionic acid, butyric acid, ethanol, etc.) and biogas (e.g. hydrogen and carbon dioxide). Since liquid fermentation products are still present in effluent, the fermentation types will be evaluated for the feasibility of further treatment for water reclamation.

Along with the engineering operational tests, the microbial communities in the reactors will be characterized by a well developed molecular biology approach--automated ribosomal intergenic spacer analysis (ARISA). ARISA is a rapid method for identifying "fingerprint" of complex microbial communities by using the heterogeneity of the intergenic spacer (IGS) region between 16S and 23S rRNA genes to distinguish strains and closely related species. The microbial community information will be used to determine the functional anaerobic bacteria for organic substrate removal.

Progress/Completion Report, 2008, PDF
Progress/Completion Report, 2009, PDF
Progress/Completion Report, 2010, PDF

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