Day 2 :
Hong Kong Baptist University, China
Time : 09:00:09:25
Jonathan W C Wong is currently a Professor in the Department of Biology at the Hong Kong Baptist University and the Directors of Sino-Forest Applied Research Centre for the Pearl River Delta Environment (ARCPE) and Hong Kong Organic Resource Centre. He received his BSc (Hons.) and MPhilfrom the Chinese University of Hong Kong and his PhD in environmental science from Murdoch University, Western Australia. His major research areas include anaerobic digestion and composting of organic wastes for energy and biomass production and waste separation and recycling. He has a cumulative funding of over HK$70 million and published over 350 papers in journals and conference proceedings. He was awarded the Medal of Honor (MH) and Justice of Peace (JP) by the Hong Kong Government for his valuable contribution to the promotion of environmental protection and to the wellbeing of the public.
Nearly one third representing about 1.3 billion tons/year of food produced for human consumption is lost or wasted globally and is mostly landfilled. This landfilled waste emits greenhouse gases, produces contaminated leachate and uses valuable land. Therefore, diverting the food waste for biological treatment such as composting would reduce the environmental impact and produce value added product. However, collecting the food waste from domestic sector is a challenge when the centralized-composting is targeted. In contrast, small-scale decentralized composting at the community level is a viable option to obtain the organic wastes of good quality suitable for composting. Food wastes are ideal substrates for composting as they can produce good quality compost due to the very little concern of contaminants. However, the composting process of food wastes is a bit complex than other organic wastes due to the generation of organic acids during the rapid degradation of easily available organic matter. Accumulation of organic acids acidifies the composting mass and cause failure and emission of acidic odour. In addition, significant quantities of protein and fat contents also create odour and operational problems, respectively. Addition of alkaline compounds are generally practiced to control the pH however, this practice results in ammonia emission and nitrogen loss from the composter resulting in the production of compost with low nutrient content affecting its marketing value. Emission of odour reduces the acceptance of composting as the treatment technology in urban settings. Another critical issue of these composters is that the fed-batch mode of feeding and the mixing affects the retention of composting mass in the reactor for sufficient period time that leads to production of immature compost requiring further curing. Therefore controlling the acidity and odour, reducing the nutrient loss and achieving a stable operation are the keys for the successful decentralized composting. Addition of lime at 2-4% is effective to neutralize the acids generated during food waste composting but the nitrogen loss was about 44% of the total nitrogen. Alternatively, addition of zeolite at 5-10% showed a similar effect and also reduced the nitrogen loss by 34% compared with lime. In addition, zeolite accelerated the composting reduced the salinity and odour. During the entire operation, the odour intensity was <2 D/T. Use of effective oil degrading bacterial consortium effectively improved the physical structure of the composting mass in the reactor that promoted rapid composting. Mature composts could be obtained within 4 weeks with the bacterial inoculation and alkaline addition. Furthermore, addition of inorganic salts to induce struvite formation was shown to reduce the nitrogen loss but controlling the salinity is the challenge. Thus, an integrated approach of inoculating effective microorganisms to breakdown the oil/lipid and alleviating the acidity and odour through alkaline/struvite agents is an effective approach. However, a balance must be maintained to achieve the desired results. This presentation will share the approaches to overcome the challenges and the success achieved with the community-level food waste composters.
Tohoku University, Japan
Time : 09:25-09:50
Takashi Nakamura completed his MA Sc in Metallurgy from Kyushu University, Japan in 1974, PhD in Metallurgy in 1979 from the same university. He became Lecturer in Kyushu Institute of Technology (1977), Associate Professor (1981) and Professor (1991). In 1998, he was appointed as a Professor at Institute for Advanced Materials Processing, Tohoku University and from 2001 to till date he is a Professor at Institute of Multidisciplinary Research for Advanced Materials, Tohoku University.
Word of “Urban mining” is one of important message to achieve a sustainable development in future.If any recovery system is not taken into consideration, critical metals will dissipate all over the land in the future. In the case of WEEE, however when Cu, Au and Ag are collected for recycling, rare metals can also begathered with them. If critical metals are separated from WEEE by proper technique and are accumulated for reservation, we can consider them as resources. A possibility of critical metals recycling was shown in this presentation that could have a self-supporting economical system by devising the collection system and by changing the recycling system related with a commercial transaction.WEEE are dismantled and crushed to various parts in first step after collecting. There are many methods for dismantling such as hand-picking and for crushing such as shredding. Sorting techniques are applied to separate each material for example iron & steels, non-ferrous alloys including aluminum and copper and plastics. These sorting techniques are not only real sorting processes but include gravity separation, magnetic separation and so on which are mainly used for processing of old minerals. Also in the case of metallurgical production with its intrinsic potential of smelting, extraction, enrichment and separation methods, related technology and process flow sheets each with their own selectivity and yield play an important role in the context of minor rare metals.