Presentation Transcript

1. Presented by Ray Hamilton, PE, BCEE AMEC Environment & Infrastructure Inc., Denver, CO Process Modeling and Mass Balance Analysis using KBC WaterTracker® Software for Wastewater Discharge Improvements and Water Conservation at a Colorado Sugar Refinery PWO Industrial Wastewater Seminar Golden, CO April, 11, 2014
2. Outline History of Sugar Refineries in Colorado Overview of Sugar Processing Existing Wastewater Disposal System New Regulatory Environment Mass Balance Model Development Existing System for Calibration Proposed System Summary and Questions
3. Sugar Refineries in Colorado Colorado “Sandwiched” Between Utah and Nebraska 1890s - Sugarbeets grown in Colorado shipped to Utah or Nebraska for processing 1899 – Colorado’s first sugar refinery opened in Grand Junction Early Colorado Plains Sugar Refineries 1900 – Rocky Ford and Sugar City in the Arkansas River valley of SE Colorado
4. Sugar Refineries in Colorado (cont.) Production Moves to the Front Range 1901 First Front Range sugar refinery opens in Loveland 1903 new sugar refineries in Windsor and Greeley 1904 Fort Collins and Eaton 1905 Sterling and Brush 1906 Fort Morgan Boom and Bust leads to 23 Colorado sugar refineries
5. The Sugarbeet Sugarbeet has Three Parts Central Root – stores sugar Taproot – supplies moisture and minerals Top – Photosynthesis provides energy Sugar in Two Forms Monosaccharide sugar, C6H12O6 disaccharide sugar C12H22O11 Ideal Beet is 2 Pounds and >17% Sugar
6. Composition of a Typical Sugarbeet
7. The Sugar Refining Process Beet Washing Removes dirt and other field debris Slicing Produces “cossettes” Diffusion Hot water soaking produces “juice” Still contains other beet products and impurities
8. The Sugar Refining Process (cont.) Liming and Pressing High pH precipitates impurities Filtration separates impurities Recarbination and Filtration Lowers pH Removes dissolved lime Precipitates calcium carbonate Second filtration removes calcium carbonate
9. The Sugar Refining Process (cont.) Acidification and Filtration Sulfuric acid to balance and bleach Third filtration produces “standard liquor” Sugar content of standard liquor + 50% Evaporation and Condensation Series of evaporators to drive off water Condensers cool and recycle water
10. The Sugar Refining Process (cont.) Crystallization Super saturated solution put under vacuum to crystallize sugar Separation Centrifuge spins out sugar Filtrate is “molasses” Purified sugar dried and packaged
11. Typical 1900 Era Sugar Refinery Source: Silver Wedge: The Sugar Beet Industry In Fort Collins, SWCA Environmental Consultants, 2003
12. Wastewater Discharges at Sugar Refinery Major Sources of Wastewater Mud from beet washing Condenser water Pressed calcium carbonate Boiler blow-down to ash pond Historic Discharge to Unlined Ponds Evaporation and seepage Integral part of water rights adjudication
13. Typical Flow Patterns at Sugar Refinery Campaign Driven – September to April
14. Regulatory Concerns Discharge to Groundwater Groundwater standards apply Total coliform standard – as if water supply High Mn++ levels in ash Source well water above TDS standard Potential nitrite/nitrate problems Pond Seepage to South Platte River Alluvial Flow Water Rights Issues Ignored
15. Regulatory Concerns (cont.) CDPHE Applied Surface Water Standards to Groundwater Discharge South Platte River standards EC/TDS/SAR limits controlled by downstream bean farmers New ammonia limits Measured as Weighted Average of In-Pond Values and Pond Influent Flows Seepage does not equal influent - biasing mass based parameters (BOD5 and TSS) No credit for effects of filtering through pond bottom
16. Client Concerns Water Rights High Cost of Treatment Low Hanging Fruit PCC Press eliminated all liquid discharge to PCC pond Mud Press significantly reduces flow to mud pond How Much More Can be Saved with Water Recycling and Water Conservation?
17. Mass Balance Approach Simplest Mass Balance Unfortunately It’s not that Simple
18. Mass Balance Inputs – External to Process Beets: Sugar, TDS, TSS, N, H2O Water Supply (wells and ditch): TDS, N-NO3, H2O Stormwater/Snow Runoff: TDS, TSS H2O Coal: TDS, TSS, N, S, Mn
19. Mass Balance Inputs – Internal to Process SO2 and Sulfamic Acid: S, TDS, N Gypsum TDS, S Limestone, Soda Ash & Caustic TDS, TSS, S
20. Mass Balance Outputs Evaporation Mud, condenser, and ash ponds Granulator drier Seepage Mud, condenser, and ash ponds Discharge Flue gas Pressed mud
21. Mass Balance Outputs (cont.) Products Processed Sugar Molasses Pressed PCC (animal feed byproduct)
22. Mass Balance Software
23. WaterTracker Top Level View
24. WaterTracker Process Level View
25. Recycle Alternatives Modeled Separate Fly Ash from Bottom Ash Closed Loop Condenser Circuit with Cooling Tower Mud Press Enhancements Internal Redirection of Process and Waste Streams
26. Results of Water Recycling and Conservation
27. Questions and Answers Questions Ray Hamilton – 303-975-2195 or ray.hamilton@amec.com