Food Waste to Biogas Technology

Transcription

1 Food Waste to Biogas Technology Environmental Management Division Ir Dr. Anthony MA 10 Dec 2016 Food Waste Problem in Hong Kong Food Waste: 3,641 tonnes/day Over 1/3 of Total MSW Yard Waste & Others: 515 tonnes/day Total MSW: 9,782 tonnes/day Extracted from Monitoring of Solid Waste in Hong Kong Waste Statistics for

2 Food Waste Arising from C&I Sources The amount of food waste arising from C&I sources, such as restaurants, hotels, wet markets and food production & processing industries has increased steadily. Extracted from Monitoring of Solid Waste in Hong Kong Waste Statistics for C&I Food Waste Generation in Mainland China produces 50,000,000 tonnes/year food waste (137,000 tonnes/day) Food waste accounts for ~70% of China's mounting garbage 4

3 Food Waste Management Strategy Extracted from EPD website 5 Design of Biogas Pit 6

4 Organic Waste Treatment Facilities (OWTF) Biogas Electricity generation 200 tonnes food waste per day Complicated Logistics OWTF in Siu Ho Wan Initial capital investment: HK$1.5 billion Running cost: HK$72.4 million/year (HK$992 per tonne food waste) Compost for landscaping or agricultural application Wastewater treatment 7 Organic Waste Treatment Facilities (OWTFs) HK Government is planning to build 5-6 OWTFs between 2014 and 2024 with a total recycling capacity of about 1,300 1,500 tonnes per day Undergoing EIA 300 tonnes/day By 2017 Drawbacks of OWTFs: Even with 6 OWTFs, can only handle 50% of total food waste Lack of suitable sites for OWTFs Huge investment 200 tonnes/day by 2016? Extracted from A Food Waste & Yard Waste Plan for Hong Kong , February

5 Food Waste Recycling Pilot Plant at Sheung Shui A 2-year ITF project commenced in 2014 with support from CityU, Towngas, Associated Engineers, Ltd., Hong Kong Organic Waste Recycling Centre Ltd., Green Technology Consortium Ltd., WIT Holding Ltd., Sunway Environmental Technology Co. Ltd., VTC, EPD After 1 year s laboratory study, a pilot plant of 50 kg/day was set up at Sheung Shui in September Project Team Project Coordinator Dr. Anthony Ma Deputy Project Coordinator Dr. Vinci Lee Engineering Design Lab & Pilot Studies Pilot Plant Operation External Microbiological Expert External Gas Utilization Expert Billy Cheung William Lo Wong Kin Wai Cheuk Chun Yeung Dr. Susana Wu Dennis Tang Barry Bi Ho Chi Tung Alan Lam Dr. Patrick Lee (CityU) Towngas 10

6 Natural Bacterial Decomposition of Food Waste 11 FTR Food Waste Total Recycling System (patented) Food waste slurry Biogas( m 3 ) 1. Auto Food Waste Separator 1 tonne Food Waste 3. Food Waste Decomposition Bioreactor 4. Biogas Production Bioreactor 5. Membrane filtration 2. Ultrasonic System First Step Waste Oil Solid Residue Nutrient Solution Third Step Recycle Water Biodiesel Eco Fish Feed Second Step

7 Specialized Microbes for Food Waste Decomposition Lactobacillus Production of lactic acid Lactococcus Production of lactic acid during glucose fermentation Leuconostoc Fermentation of sugars to lactic acid, ethanol or acetate Decomposition Bioreactor 13 Specialized Microbes for Biogas Production Methanofollis Anaerobic bacteria use CO and H 2 to produce methane Methanosaeta High affinity for acetatemethane producer Methanosarcina Anaerobic methanogens Methanogenesis Bioreactor 14

8 Biogas Generation from Methanogenesis 15 Compare Biogas with Town Gas / Natural Gas Biogas vs Other Combustible Gases Items Biogas (HKPC Pilot Plant) Town Gas Natural Gas CH 4 (%) H 2 (%) trace trace-0.02 Chemical Composition CO 2 (%) CO (%) Nil H 2 S (ppm) Nil (after purification) Nil - Others (%) Physical Properties Calorific Value (MJ/M 3 )

9 Recycling of Food Waste to Valuable Resources Protein-rich Solid Residue Analysis Item Unit Dried Sludge Fish Feed for 鱸魚 Fish Feed for 羅非 Moisture g/100g Total Carbohydrates g/100g Protein g/100g Total Fat g/100g Ash g/100g Crude Fibre g/100g Cost HKD/kg Recycling of Food Waste to Valuable Resources Floatable Oil Biodiesel Food Waste Decomposition Food Waste Nutrient Solution Methanogenesis Biogas ( m 3 ) Solid Residue Eco Fish Feed 18

10 Merits of the Developed System Patented pretreatment to ground and separate digestible organic substances from the trash instead of complicated waste sorting; Generation of valuable recyclable products to maximize financial return; High specific yield of methane per kg of food waste ( m 3 biogas per tonne of organic); High methane concentration reaching approx. 80%, minimizing the biogas purification cost; Other than the trash, 100% of the organic fraction is converted into reusable products, leaving no residual waste; Much stable and robust 2-stage biological process, requiring minimal level of operator attendance; Compact system with minimal space requirement. Thank you! 20