Contaminant Removal Considerations for Anaerobic Digestion. National Composting Conference Halifax 2014

Transcription

1 Contaminant Removal Considerations for Anaerobic Digestion National Composting Conference Halifax

2 FITEC- High Solids Wet AD Systems Finsterwalder Umwelttechnik (FITEC) established in 1997 is an engineering company specializing in AD. 2 Main Areas of Focus: Removing physical contaminants before digestion. Design of self cleaning digester tanks. FITEC has designed and built 9 AD s across Europe, UK and China with a range in capacity from 6,000 to 70,000 t/a. 2

3 Yield and Dr. Digester Services Yield Energy was founded in 2007 to represent FITEC in NA. Focused on selling specialized contaminant removal and de-packaging systems for AD. Dr. Digester Services Feedstock audits & strategies Feasibility studies Dr. Digester operational support and biological system optimization. 5-10% Overs 90-95% Organics 3

4 AD: Is An Integrated Solution Improve nutrient management. Recover nutrients, organic matter. Increase farm gate revenues. Reduce GHG emissions. Produce a renewable energy or fuel. Increase organics diversion rates. Improve the economics at WWTP s. 4

5 AD: Is Taking Many Forms Agricultural based digesters. Urban or municipally based digesters. Co-digestion at waste water treatment plants. Centralized de-packaging or pre-processing facilities. POD s: Points of Digestion. 5

6 Develop a value equation for feedstocks Tip Fee: Fee paid per tonne to disposal facility. Energy Potential: Biogas yield per tonne, methane concentration. Quality: % contaminants/non-digestible, particle size, % residual. Variability: Weekly, monthly and seasonality. Contract Terms: Term length, volume guarantee, quality guarantee. Proximity: Trucking costs. Added costs: Separately collect organics. 6

7 System Design Criteria Look into how the chemical & physical composition of different feedstock will impact the AD process. Biological stability is determined by retention time and organic loading rate. Mechanical stability is determined by how well the equipment has been integrated and ability of system to handle contraries. AD systems can take significant time to recover from biological disturbances! 7

8 Management of sinking and floating contraries No pre-treatment equipment can remove all forms of physical contraries in just one step The equipment or systems chosen can dramatically affect your water balance. When looking at contraries removal think about how a system manages both the heavy and light fractions of the waste stream. 8

9 9 What goes in must come out!

10 Integration and operational experience Not a plug and play situation with pieces of equipment. Most equipment manufacturers don t design integrated solutions for AD systems. No matter what type of conditioning or pretreatment equipment is chosen, it will create a dirty slurry. Contrary removal technologies will increase energy consumption. 10

11 Financial Costs Tipping fee revenue losses during downtime for cleaning. Energy revenue losses during downtime. Energy revenue losses during ramp up cycle. Labour costs for digestion tank cleaning. Increased treatment and disposal costs of the extra process water. Reputation is affected when you turn away suppliers. 11

12 Increased water consumption Balancing act between water consumption & loosing organics in the overs. Smaller screen sizes (< 15mm) results in more organics being separated along with the contaminants. Larger screen sizes (>15mm) use less water: better for batch processing & package separation but will let more contaminants through. 12

13 Budget for support services Remember what you re good at and stick to it. Consider that a poorly operating plant can have an emotional and financial drain on 2 businesses. Example: 500 kw annual program 18 $0.16 kwh = 112,500 kwh to payback Equals 18 days of operating at 50% Approx. 2.7% of revenue Our service successes have been in the range of 30% gas yield improvements not including feedstock changes. 13

14 Specialized Operational Support Feedstock Strategy & Verification Monitoring, Tracking & On-going Support Feedstock & In-situ Digestate Analysis Biogas Plant Nutrient Supplements for bacteria BioTip: Biological Process Simulation Mass Balance Calculation 14

15 Production of clean digestate Digestate is an excellent liquid fertilizer it will typically have higher nutrients and lower odour than liquid dairy manure. Can separate out a solid fibrous fraction as well when beneficial eg. animal bedding material or composting solids). Long term sustainability of biogas industry will depend significantly on producing clean digestate. In UK some AG sectors are threatening to ban the land application of digestate because of too much contraries in the finished digestate applied to land. 15

16 In Summary Reliable partnerships are key. Successful integration of components. Requires a proven systems approach. Monitor process, manage biology and operate stable digester. Produce clean digestate. Key to success robust AD installation and reliable, consistent feedstock supply 16

17 THANK YOU! Tom Ferencevic Technical Services & Sales Phone: (289)