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 2014 ” 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 2014 ” 3 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
Food Waste Management Strategy Extracted from EPD website 5 Design of Biogas Pit 6
Organic Waste Treatment Facilities (OWTF) Biogas Electricity generation 200 tonnes Complicated food waste Logistics per day OWTF in Siu Ho Wan Wastewater • Initial capital investment: HK$1.5 billion treatment • Running cost: HK$72.4 million/year Compost for landscaping or (HK$992 per tonne food waste) agricultural application 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 Drawbacks of OWTFs: • Even with 6 OWTFs, can only handle 50% of total food waste 300 tonnes/day • Lack of suitable sites for By 2017 OWTFs • Huge investment Undergoing EIA ? 200 tonnes/day by 2016 Extracted from “ A Food Waste & Yard Waste Plan for Hong Kong 2014 – 2022 ” , February 2014 8
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 2015 9 Project Team Project Coordinator Dr. Anthony Ma Deputy Project Coordinator Dr. Vinci Lee External External Gas Pilot Plant Engineering Lab & Pilot Microbiological Utilization Design Studies Operation Expert Expert Billy Cheung Dr. Susana Wu Barry Bi Dr. Patrick Lee Towngas William Lo Dennis Tang Ho Chi Tung (CityU) Wong Kin Wai Alan Lam Cheuk Chun Yeung 10
Natural Bacterial Decomposition of Food Waste 11 FTR Food Waste Total Recycling System (patented) Food waste slurry Biogas(130-160 m 3 ) 1. Auto Food Waste Separator 3. Food Waste 1 tonne Food Decomposition Bioreactor Waste 5. Membrane 4. Biogas filtration Production Bioreactor 2. Ultrasonic System Third Step Nutrient Solid Waste Oil First Step Solution Residue Recycle Water Biodiesel Eco Fish Feed Second Step
Specialized Microbes for Food Waste Decomposition Lactobacillus Production of lactic acid Lactococcus Production of lactic acid during glucose fermentation Decomposition Bioreactor Leuconostoc Fermentation of sugars to lactic acid, ethanol or 13 acetate Specialized Microbes for Biogas Production Methanofollis Anaerobic bacteria use CO and H 2 to produce methane Methanosaeta High affinity for acetate- methane producer Methanogenesis Bioreactor Methanosarcina Anaerobic methanogens 14
Biogas Generation from Methanogenesis 15 Compare Biogas with Town Gas / Natural Gas Biogas vs Other Combustible Gases Biogas Items Town Gas Natural Gas (HKPC Pilot Plant) CH 4 (%) 70-80 28.2-30.7 87-97 H 2 (%) trace-0.006 46.3-51.8 trace-0.02 CO 2 (%) 15-25 16.3-19.9 0.1-1 Chemical CO (%) Nil 1-3.1 - Composition Nil H 2 S (ppm) Nil - (after purification) Others (%) - 0-3.3 5-10 Physical Calorific Value 28-32 17 36-40 (MJ/M 3 ) Properties 16
Recycling of Food Waste to Valuable Resources Protein-rich Solid Residue Analysis Fish Feed for Fish Feed for Item Unit Dried Sludge 鱸魚 羅非 Moisture g/100g 8.3 8.15 8.01 Total Carbohydrates g/100g 20.5 17.2 46.9 Protein g/100g 39.9 45.5 31.3 Total Fat g/100g 17.7 16.3 5.73 Ash g/100g 13.6 12.9 8.07 Crude Fibre g/100g 4.03 1.71 7.26 Cost HKD/kg - 15 9 17 Recycling of Food Waste to Valuable Resources Floatable Oil Biodiesel Food Waste Decomposition Methanogenesis Nutrient Solution Food Waste Biogas (130 – 160m 3 ) Solid Residue Eco Fish Feed 18
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 (130-160 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
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