The food waste problem has been deteriorating in Hong Kong. In 2022, 3,353 tonnes of food was sent to landfill everyday which equals 233 double-decker buses. In Hong Kong, food waste accounted for one-third of all solid waste. Food waste mainly comes from households, which accounted for 68%, while the remaining 32% comes from companies and industries. In the household, each Hong Kong resident is estimated to produce 71 kg of food waste every year. About 778 tonnes of food waste were generated from commercial and industrial sources such as restaurants, hotels, wet markets, food production and processing industries. Supermarkets and wet markets dispose of a total of around 43 tonnes of edible food daily. Among all food waste in Hong Kong, only 4.6% was recycled and the others were thrown away to landfill. The only three landfills operated which are in Tuen Mun, Tseung Kwan O and Ta Kwu Ling are full. [1] Not only does the food waste problem happen in Hong Kong, but also in the entire world. According to the United Nations Environment Programme, nearly 570 million tons of household food waste is produced which is 11% of global food production. As the food waste problem is getting more serious, it is crystal clear that an efficient way to handle food waste is needed. [2]
Some of the food was collected from the commercial sector and donate to the needy. However, most of Hong Kong’s food waste is sent to the landfills and some of them may be collected through various kind of pilot scheme on food waste collection, such as O-Park which transforms food waste into energy and compost. [1] O-Park adopts anaerobic digestion and composting technologies to recycle source separated food waste into biogas and compost. The biogas will be used to generate electricity. O-Park can recycle 2000 tons of food waste each day and produce 14 million kwh of surplus electricity generation each year, fertilizer is a by-product. 4200 tons of greenhouse gas emission can be reduced each year.[3] Table 1.1 shows a comparison of different common food waste treatment methods available in Hong Kong.
The situation of antibiotic resistance in the past few years has remained a significant concern worldwide. The overall trends indicate that antibiotic resistance continues to grow and pose challenges to healthcare systems. Antibiotic resistance has been on the rise for many commonly used antibiotics.
AMR causes lower effectiveness of antibiotics. However, alternative antibiotics to deal with the same disease are hard to find, thus the world is running out of effective antibiotics. [4] Antibiotic resistance has been on the rise for many commonly used antibiotics. Take K. pneumoniae, a common intestinal bacterium that can cause life-threatening infections, as an example, it has a high resistance against 4 major antibiotics cephalosporins, aminoglycosides, fluoroquinolones and carbapenems. From the data, K. pneumonia has a more than 50% resistance to major used antibiotics on India and South America. [5] It means that many antibiotics do not work in more than half of the patients treated for K. pneumoniae infections due to resistance.
As the food waste problem is becoming more serious, black soldier flies are one of the best solutions to relieve the situation. Black soldier fly is non-pest which does not transmit any disease. Ingesting food scraps for life, black soldier flies can reduce food waste harmlessly. Also, the food waste will not stink since black soldier flies decompose toxic bacteria with functional antimicrobial peptides (AMPs). [6] Moreover, black soldier flies can consume twice its body mass each day.[7] and they can eat any type of organic waste. Using black soldier fly to handle food waste produces less greenhouse gasses and is more environmentally friendly. Comparing other food waste treatments, using black soldier flies as a solution can give a higher output with a lower energy consumption under a controlled growing environment. [8] And then, the shell of it also can be collected and used to make the biodegradable plaster.
Figure 1: Antimicrobial activity of black soldier fly
Figure 2: The living condition of black soldier fly in it’s life cycle
According to the existing municipal solid waste collection and disposal system in Hong Kong, the per-liter charge for designed garbage bags is set at $0.11. Using black soldier flies to consume food waste can greatly reduce money from dumping waste and practice food waste reduction. In addition, the cost will be low since once the system starts to work, 1kg of black soldier flies larvae can consume about 1kg of food waste every day. At the same time, the transportation fee and rental cost can be significantly reduced because each housing estate can set up its own system. The whole process is easily conducted and effective. Not only can it create great benefits by becoming chitosan and fertilizer, but black soldier flies also benefit the whole world and even the next generation as well. Moreover, the carbon footprint will be reduced, and the food waste problem can be solved. Therefore, the system can definitely attain ‘low cost, high benefits’.
Furthermore, the Black soldier flies’ shell can be used to make plaster. After some chemical processes, the shells become a piece of gel which is suitable for making plaster, which is biodegradable. The expression of antimicrobial peptides from our E.coli system can further improve the function of this environmental-friendly plaster to become antiseptic.
By Black soldier flies, we hit Sustainable Development Goals 12, Ensure sustainable consumption and production patterns. The high efficiency of black soldier flies is shown at converting organic waste into valuable biomass. By utilizing black soldier flies in waste management systems, we can reduce the amount of organic waste going to landfills which achieve “Responsible Consumption” and promote circular economy principles as plasters would be a daily product which is necessary for everyone, achieving “Production”. Our project contributes to changing unsustainable consumption and production patterns, including through the easing the food waste problem, setting up a circular economy model, and innovative design of antimicrobial black soldier fly plaster to move towards more sustainable patterns of consumption and production. [10]
Figure 3: how black soldier fly convert the waste into protein
At the same time, we are achieving Sustainable Development Goals 3, Ensure healthy lives and promote well-being for all at all ages. The goal aims to reduce the global maternal mortality ratio; end the epidemics; reduce mortality from non-communicable diseases, etc. [11]
We have organised a series of activities to present our project to primary students, secondary students, teachers and the public to let them know the importance of both SDGs and how we achieve it. Activities include assembly, workshops, leaflet distribution, online questionnaires, competitions etc.
We have introduced our project and also SDGs to all students in school via morning assembly.
We have organized workshop to promote our project and SDGs to primary school student.
A competition has been organised in Baptist Lui Ming Choi Secondary School to further promote our project and let students know how our project meet both SDGs.
A food waste collection booth has been set in Carmel Pak U Secondary School. This encourages students to recycle food waste to achieve the SDG together.
Our team collaborates with the HongKong-CUHK iGEM team and the HK-SKHLPSS iGEM team to have a primary school workshop at SKH Chu Oi Primary School (Lei Muk Shue). We have taught the primary students about the structure of DNA and experimented on how to extract the DNA from a banana. Meanwhile, we have introduced our project and promoted one SDG (Ensure sustainable consumption and production patterns) to them. In the workshop, we also emphasize on plastics recycling. All plastics used in the workshop were collected and sent to recycle bins. This workshop has satisfied the primary students' curiosity about biotechnology and raised their attention to plastic problems.
Our team collaborates with HongKong-CUHK iGEM team to study the degradation rate of our plaster. Our biodegradable plaster normally take around 7 weeks to be completely degraded in soil. For the HongKong-CUHK igem team, their team focuses on complete biodegradation of mixed plastic waste with mixed enzymes, so our team sent our plaster to them and see would our plaster be degarded faster with their mixed enzymes.
Our team and HongKong-CUHK iGEM team, both of us have designed questionnaires about our projects and SDGs concerned. We published questionnaires together in our IG account and also invited our students and the public to complete them. That can encourage more people in different schools to complete the questionnaire and catch their attention to the SDGs concerned.
Reference
[1] E. Environmental Protection Department, "Food Waste Challenge", Environmental Protection Department, 2023. [Online]. Available: https://www.epd.gov.hk/epd/english/environmentinhk/waste/prob_solutions/food_waste_challenge.html
[2] M. Niall, "The Enormous Scale Of Global Food Waste", Statista, 2021. [Online]. Available: https://www.statista.com/chart/24350/total-annual-household-waste-produced-in-selected-countries/
[3] O'Park, "Waste-to-energy", O'Park, 2022. [Online]. Available: https://www.opark.gov.hk/en/process.php
[4] Antimicrobial resistance – World Health Organization https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance
[5] Antibiotic Overuse and Resistance – Thermofisher https://www.thermofisher.com/procalcitonin/wo/en/antibiotic-stewardship/antibiotic-overuse-resistance.html
[6] Hadj Saadoun, Jasmine, Anna Valentina Luparelli, Augusta Caligiani, Laura Ioana Macavei, Lara Maistrello, Erasmo Neviani, Gianni Galaverna, Stefano Sforza, and Camilla Lazzi. 2020. "Antimicrobial Biomasses from Lactic Acid Fermentation of Black Soldier Fly Prepupae and Related By-Products" Microorganisms 8, no. 11: 1785
[7] S. Brian, "Hungry Hungry Hermetia", Science Friday, 2019. [Online]. Available: https://www.sciencefriday.com/educational-resources/hungry-hungry-hermetia/#:~:text=What %20these%20guys%20do%20best,feat%20on%20a%20regular%20basis.
[8] Kim, Chul-Hwan, JunHee Ryu, Jongkeun Lee, Kwanyoung Ko, Ji-yeon Lee, Ki Young Park, and Haegeun Chung. 2021. "Use of Black Soldier Fly Larvae for Food Waste Treatment and Energy Production in Asian Countries: A Review" Processes 9, no. 1: 161.
[9] Jing Xia, Chaorong Ge and Huaiying Yao, "Antimicrobial Peptides from Black Soldier Fly (Hermetia illucens) as Potential Antimicrobial Factors Representing an Alternative to Antibiotics in Livestock Farming" Animals (Base1l). 2021 Jul; 11(7): 1937.
[10] Goal n.12 of the 2030 Agenda for Sustainable Development aims to ensure sustainable consumption and production patterns, United Nations, 2023. [Online]. Available: https://sdgs.un.org/topics/sustainable-consumption-and-production
[11] Related Topics on Goal n.7, United Nations, 2023. [Online]. Available: https://sdgs.un.org/goals/goal3