Green Technology – Food Waste Purification with Oil-producing Microalgae Supplementary information About the OUHK Research Team, The research team comprises 5 staff and students from the OUHK. Under the leadership of Prof. Ho Kin-chung, Assistant Professor Dr Yau Yiu-hung, Assistant Professor Fred Lee Wang-fat, Assistant Professor Steven Xu Jing-liang and Assistant Lecturer Mr Wong Yee-keung from School of Science and Technology joined the research, along with a group of students studying Bachelor and MPhil degrees in Environmental Studies in the OUHK. Research Methodology and Process From April 2014 to April 2015, the research team will be conducting filtrate sampling and analysis of food waste filtrate samples collected from Olympian City 2 regularly through the ‘Algal Culture Reactor’ set up at the site. The data collected will form the basis for the design of future model for large-scale sewage treatment. Two important principles of environmental protection could be fulfilled through the project, including the cleaning up of sewage and reducing water pollution while promoting the research on renewal energy. This project first stemmed from the huge amount of food waste from restaurants in the shopping centre. In view of this, a food waste decomposer was installed at the Olympian City 2 shopping centre to deal with the issue. The decomposer is able to turn solid waste into organic fertilizer, but the fluid and filtrate become by-products. If not treated properly before discharge, the filtrate could lead to serious water pollution problem affecting the Victoria Habour. In view of this, the School of Science and Technology of the OUHK therefore advised Sino to tackle the issue through algal treatment. As the microalgae can digest Nitrogen and Phosphorus in the sewage, the filtrate in a way becomes the “nutrient” for growing algae which in turn can bring enormous economic value. The team also identified the most suitable species of microalgae for the reactor. The culture and adaption process of microalgae took place at the microalgae laboratory of the Open University to serve as the backup for the onsite treatment of filtrate. After one to five days, the filtrate could be cleaned up by microalgae with acceptable purity standards. Research result Because currently the major sewage treatment works in Hong Kong cannot substantially remove nitrogen and phosphorus from the effluent, there is a potential to cause harmful algal blooms (HABs). Therefore, to treat the food waste filtrate with microalgae can actually enhance the process to secondary or even tertiary treatment. It provides high environmental benefits and enables further improvement of coastal water quality. The research members hope to work out the reactor with economically optimal performance in order to raise the sewage treatment from level 2 to level 3, comparable to the highest standard of water quality resulted from the bacteria treatment by the sewage plant and thus effectively improves the water quality. It also produced the species of microalgae with high diesel quantity. According to the design of food waste decomposer in the Olympian City 2, the carbon dioxide emissions from the food waste treatment process can be fed into the microalgal treatment system, and be utilized by the microalgae for photosynthesis. It kills two birds with one stone. Such a 'zero carbon emissions' process can further reduce 'carbon footprint' and greenhouse gas emissions, and helps mitigate the threat of climate change. Throughout the data collection in six months, the preliminary result showed that 1.215 gram of microalgae could be produced by one litre of food waste filtrate. It led to the production of 316 milligram of biodiesel. In addition, the removal rates of ammonial-nitrogen, nitrate, orthro-phosphate, total phosphorus and total suspended solid in the sewage could be decreased by 88.5%, 49.3%, 54.4%, 36.6%, 34.1%, which reflected the high effectiveness in reducing the sewage pollutants. A great quantity of solid and fluid food waste are produced at shopping malls in Hong Kong every day. Provided that all filtrate of food waste at Olympic City 2 to undergo the microalgae treatment, the emission of carbon dioxide will then be deducted by 12,800 kilogram (equal to the daily absorption of carbon dioxide by 214,115 mature trees). It will bring benefit to combat the climate change problem. Research team’s insight Dr Yau Yiu-hung, one of the research team members and course co-ordinator of OUHK’s environment and safety programmes said that their team took six months to complete stage one of the study and identified the most ideal species of microalgae for treating sewage and producing biodiesel effectively. The experiment took place respectively at the laboratory and the shopping centre with significant result. Since the Algal Culture Reactor was set beside the decomposer at the mall, the researchers could directly conduct the treatment on filtrate and utilize the carbon dioxide emitted from the decomposer. As for the next stage, the team will further study the components of the filtrate, come up with the most optimal conditions, taking into account of efficiency, time for treatment, energy produced, space and economic benefit, to let the microalgae grow properly. Another team member, Dr Fred Lee Wang Fat, Assistant Professor of OUHK’s testing and Certification programmes said, besides refining for algae biofuels, some microalgal species contain some polyunsaturated fatty acids, e.g. docosahexaenoic acid (DHA), which is favorable to the brain development of infants. Possessing the characteristic of polyunsaturated fatty acids, it can also be made into very cost-effective algae nutrition products, and even can be used to produce pharmaceuticals, cosmetics, and food etc. Therefore it has very high development potential. 'The OUHK research team is also actively exploring the possibility from microalgae on producing DHA which helps the brain development of the infants and Omega-6 of fish oil. Dr Steven Xu Jingliang Steven explained, ‘microalgae exist in freshwater and seawater ecosystems. In fact, they are the culprits who caused harmful blue-green algal blooms in Mainland China, and contaminated water supply systems in North America and Australia. In Hong Kong and South China Sea, they are the causative agent of red tides. There are over a hundred species of algae exist in the OUHK algal library. The Open University of Hong Kong, after years of study, has become one of the authoritative research institutes in research area of microalgae organisms. The use of non-toxic microalgae species in sewage treatment associated with biofuel production is a process to convert harm into benefit.' In addition, one of the research team members, Mr. Wong Yee Keung, assistant lecturer, is one of the council members of "Association on Harmful Algal Blooms in the South China Sea". A team led by Mr. Wong recently developed a new "Algal Culture Reactor" and won the championship in the Hong Kong Institute of Engineers (HKIE) Environmental Project Competition 2013–2014. It denotes the remarkable achievement of the OUHK research team in this area over the years.