1 / 21

Feasibility Study of Decentralized Blackwater Treatment: Culmination of the Methanogenesis Chronicles

Feasibility Study of Decentralized Blackwater Treatment: Culmination of the Methanogenesis Chronicles. Kris Bruun Email: Kris.Bruun@Colostate.edu Thesis Defense March 31 st , 2009 Colorado State University Civil and Environmental Engineering Department. Research Intent.

kezia
Download Presentation

Feasibility Study of Decentralized Blackwater Treatment: Culmination of the Methanogenesis Chronicles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Feasibility Study of Decentralized Blackwater Treatment: Culmination of the Methanogenesis Chronicles Kris Bruun Email: Kris.Bruun@Colostate.edu Thesis Defense March 31st, 2009 Colorado State University Civil and Environmental Engineering Department

  2. Research Intent • Determine whether implementation of a decentralized blackwater treatment system in conjunction with individual home graywater recycling systems is economically feasible as compared to current municipally operated centralized wastewater treatment layout.

  3. Decentralized Wastewater Treatment (discuss w/ Neal) • Define • Differentiate between BW and Graywater • Benefits of decentralized treatment

  4. Process Diagram (modify for final present)

  5. Anaerobic Digestion • Process in which volatile organic material is broken down by bacteria in an oxygen-free environment to yield off gases, primarily consisting of Methane and Carbon Dioxide. • Three Stages: • Hydrolysis and Fermentation • Liquefaction of cellulose, protein, and lipid compounds • Acid Stage • Organic acids are converted by acetogens to acetic acid • Methanogensis • Methane-generating micro-organisms generate CH4 (60-80%) and CO2

  6. Digestion & Methane Production • Optimization Techniques: • Temperature • Thermophilic (130-150oF) vs Mesophilic (93-98oF) • Higher Temps = Busier Bugs • pH • Optimum range~ 6.8-7.2 • Solids Retention Time • Longer retention = more extraction from the reaction

  7. Digester Operation • Blackwater (BW) Characteristics: • COD = 4,000 mg/l • VSS = 3,000 mg/l • TSS = 3,000 mg/l • Complete Mix Digester Operation: • Temperature = 95 oF (35 oC) • SRT = HRT = 20 days • OLR = 3 kg VSS/m3-d

  8. Estimating Flow Rates • G-WATER Model • Water usage is based on a Fort Collins Utilities study conducted in January 2001 • 10% consumed • BW = (Toilets + Dish Washing)*90% = 61 gal/house/day • Indoor Water Usage (model inputs):

  9. Digester Calculations

  10. Scenarios Overview • Energy Generation • On-site reciprocating engine/micro-turbine • Thermal energy recovery (heat exchanger) • Natural Gas Supplementation • Supply biogas to individual homes • Hot water heater operation • Digester Heating • Reduce natural gas consumption • Maintain optimal digester temperature

  11. Evaluated Scenario #1 • Electricity Generation • On-site generator, voltage regulators, transfer switch, biogas storage, and gas purification

  12. Evaluated Scenario #2 • Natural Gas Supplementation • Biogas storage and gas purification

  13. Evaluated Scenario #3 • Strictly Digester Heating • Gas purification

  14. Evaluated Scenario #4 • Aerobic Treatment • Aeration equipment and sludge dewatering

  15. Summarization of Evaluated Scenarios

  16. Equivalent Monthly Costs • Assumptions: • Loan interest rate of 7% • System Design Life of 20 years • Household sewer connection fee of $1,500

  17. Equivalent Monthly Costs

  18. Centralized WWTP Rate Schedule • Treated Volume = 400 gal/house/day = 12,200 gal/house/month

  19. Centralized WWTP Cost Comparison • Total Monthly Fee = $41.29 (per house) • Equivalent Number of Houses for Decentralized Treatment Layouts: • Energy Production~ 493 houses • Natural Gas Supplementation~ 426 • Digester Heating~ 396

  20. Future Work • Future development vs current infrastructure • Lifecycle costs • Environmental impacts • Reduced greenhouse gas emissions • Etc. • Water reuse

  21. Acknowledgements and Questions • Sybil Sharvelle Assistant Professor, Research Advisor Civil and Environmental Engineering Department, CSU • Larry Roesner Professor Civil and Environmental Engineering Department, CSU • Scott Glick Professor Department of Construction Management, CSU • Dan Zimmerle Power Systems R&D Manager, Professor of Mechanical Engineering Engines and Energy Conversion Laboratory, CSU

More Related