FOOD PROCESSING WASTE STREAM UTILIZATION

Transcription

1 ENHANCING RESOURCE EFFICIENCY AND SUSTAINABILITY IN FOOD PROCESSING: FOOD PROCESSING WASTE STREAM UTILIZATION CHRISTOPHER SIMMONS, PHD FOOD SCIENCE & TECHNOLOGY ENERGY EFFICIENCY CENTER UNIVERSITY OF CALIFORNIA, DAVIS

2 Waste Heat Recovery GOAL Find opportunities to recover waste heat in food processing and develop applications for that recovered heat.

3 Waste Heat Recovery Tomato processing example: Tomato water hot condensate from evaporation step of paste production. Condensed water (Tomato water) ( F) EVAPORATOR

4 Waste Heat Recovery Reusing the cooled tomato provides further energy savings. 236,800 kwh/season $35,520/season ELECTRICITY SAVED WASTEWATER TREATMENT 29,400 kwh/season $4,305/season ELECTRICITY SAVED WELL WATER PUMPING 176,400 kwh/season $22,050/season ELECTRICITY SAVED WASTE HEAT RECOVERY TO OFFSET STEAM PRODUCTION How many MMBTU? FACILITY SAVINGS = $???/SEASON *California Energy Commission. Industrial Water Energy Nexus Assessment: Campbell Soup California Tomato Processing Facility. Sacramento:California Energy Commission, Print.

5 Waste Heat Recovery CONCEPT Use tomato water waste heat as part of the hot break. Chopped tomatoes at 75 F Hot steam HEAT EXCHANGER Crushed tomatoes at 200 F Condensate

6 Waste Heat Recovery Cooler tomato water Hot steam Chopped tomatoes at 75 F HEAT EXCHANGER Chopped tomatoes at 120 F HEAT EXCHANGER Chopped tomatoes at 200 F Less hot steam/water Hot tomato water EVAPORATOR Tomato juice Tomato paste

7 Waste Heat Recovery Modeling heat transfer in first stage of a 2-stage hot break process: Hot tomato water Inputs: 1. Tomato temperature 2. Tomato flow rate 3. Tomato water temperature 4. Tomato water flow rate 5. Type of heat exchanger 6. Heat exchanger heat transfer coefficient and area Cool tomato water Image: Allegheny Bradford Hot chopped tomatoes Cool chopped tomatoes

8 OBJECTIVE 2 MODELING 1 ST STAGE OF 2-STAGE HOT BREAK Effectiveness-NTU method: KNOWN Calculated from facility data and heat exchanger properties Number of transfer units (NTU): NTU = UA C min Heat capacity rate ratio: = C min C max Maximum heat transfer rate (W): q max = C min T TW,in T CT,in DETERMINE Effectiveness: ε(ntu, C min C max ) = q q max Heat transfer rate: q=mc p ΔT Heat capacity rate: C=ṁc p OUTPUT Heat transfer rate to tomatoes (energy savings), q Temperature of tomatoes at end of first stage, T CT,out Time to heat tomatoes in first stage, t

9 Waste Heat Recovery Cool tomato water 44.6 C Image: Allegheny Bradford Hot tomato water 32.7 kg/s 74 C Hot chopped tomatoes 40.3 C Cool chopped tomatoes 73.5 kg/s 26.7 C Modeling results: >9 million kwh recovered over 2250 hr season Offset 10.6 million kwh of natural gas energy in boilers $217,000 in natural gas savings/season

10 Waste to Energy GOAL Enhance conversion of agricultural and food processing residues into renewable energy.

11 Waste to Energy Anaerobic Digestion: Converting waste organic matter to biofuel Biogas Methane Carbon dioxide Food processing waste Digester Residual biomass and water

12 Waste to Energy Anaerobic digestion is a complex network of microbial activity. There are many potential points of inhibition. We can use recent advances in metagenomics to understand and design more robust and functional digester communities.

13 Waste to Energy Example: finding bacteria and enzymes for high-solids deconstruction of rice straw: Xylanase activity Endoglucanase activity thermophilic mesophilic Thermophilic community has more xylanase and endoglucanase activity than mesophilic community.

14 Waste to Energy

15 Relative abundance (%) Waste to Energy All other phyla Fungi Bacteroidetes Proteobacteria Mesophilic enrichment Thermophilic enrichment Firmicutes Actinobacteria Mesophilic enrichment Thermoph enrichme

16 Waste to Energy Cellobiohydrolases with carbohydrate binding module 2 are overrepresented in thermophilic community Thermophilic community Mesophilic community

17 Waste to Energy Example: Using microbial communities for wastewater treatment, electricity generation, and desalination: Simultaneous -wastewater treatment wastewater electricity generation - -water desalination exoelectrogenic bacteria + - anode cation exchange membrane saline water anion exchange membrane cathode

18 Solid Waste Management GOALS Develop new applications for agricultural and food processing solids wastes. Turn waste streams into co-products. Advance sustainable waste management and agriculture.

19 Solid Waste Management Inactivate plant pathogens and weed seeds in soil via passive solar heating and microbial activity. Replaces need for soil fumigants. Adds nutrients to soil. Biosolarization

20 Solid Waste Management Induce microbial activity with waste biomass soil amendment: + + Field soil Stable green waste compost Agricultural or food processing organic residues

21 Solid Waste Management Plastic tarp Soil Acid fermentation: -Lactic acid -Butyric acid -Acetic acid

22 Solid Waste Management Inactivation of black mustard seeds: Combination of soil microbial activity and passive solar heating is significantly more effective than heating alone.

23 Solid Waste Management NON-SOLARIZED CONTROLS Nonmetric multidimensional scaling 2D representation of community similarity. Similar communities appear closer together. AMENDED SOIL NATIVE SOIL S = 100% soil C = 100% compost SCW = 90% soil + 8% compost + 2% wheat bran n=5

24 Solid Waste Management Amended soil shows enrichment of potentially beneficial bacteria following solarization. Azotobacter beijerinckii enriched in amended soil (10.5% of total community). Azotobacter species can secrete phytohormones. Not detected in native soil after solarization.