Everyone wants to see re-invigorated urban shorelines. They look great, they inspire, and they support an enriched marine environment.
However, a long-standing problem is that conventional seawalls and breakwaters built in coastal areas usually use concrete and granite boulders that are ineffective at supporting marine organisms.
But a game-changing approach developed at City University of Hong Kong (CityU) can potentially transform ports and coastal conurbations.
Scientists in Hong Kong are creating new eco-friendly marine structures that support the settlement and growth of marine organisms and lower sea temperatures to enhance biodiversity.
The proposed green technological breakthroughs have earned the State Key Laboratory of Marine Pollution (SKLMP) at City University of Hong Kong (CityU) the prestigious Gold Award at the Hong Kong Green Innovations Award as part of the 2022 Hong Kong Awards for Environmental Excellence.
Creative Take on Seawalls
The CityU team has revolutionized the concept of seawalls with a two-fold innovation.
First, an eco-friendly concrete mix comprising 40% waste materials has been developed. The mix includes fly ash from the incineration of sludge and dredged marine sediment typically taken from routine maintenance carried out on regional shipping lanes. This concrete mix’s high compressive strength (39 MPa) and low surface pH (about 10) are crucial for sea defense structures and marine larval settlement.
Second, microhabitats such as grooves, holes and crevices embedded in the CityU team’s innovative eco-tiles offer refuge for marine life and shade that can lower temperatures during low tide in summer. Twelve-month trials conducted in Hong Kong waters demonstrate that these eco-tiles reduce the average surface temperature by 2°C and increase biodiversity by 80% compared to conventional seawalls.
Commercializing Green Tech
In addition, a CityU start-up called afterNATURE is working on a range of eco-engineered products such as eco-tiles, eco-panels, tidal pools, and eco-blocks.
A crab living inside one of the eco-tiles. (Image credit: CityU)
These products have already been adopted at numerous local seawalls in Hong Kong and have gained traction in coastal restoration projects in South Korea, mainland China and the United States.
“Utilizing waste materials in our eco-tiles minimizes cement usage and reduces the carbon footprint. Transforming waste into useful products for ecosystem restoration also helps reduce waste disposal and extends the service life of landfills,” said Kenneth Leung Mei-yee, Chair Professor in the Chemistry Department and Director of the SKLMP at CityU.
Growing Partnerships
The prize-winning research is a collaboration between City University of Hong Kong, Hong Kong Metropolitan University, and The Hong Kong Polytechnic University.
In addition to winning the Gold Award at the Hong Kong Green Innovations Award, the team's eco-tile invention has received several international accolades: the Special Prize (Prize of the Korea Invention Promotion Association), the Gold Medal with Congratulations from the Jury at the 48th Geneva International Exhibition of Invention in Geneva, Switzerland, and the Gold Medal in the Asia International Innovative Award at the Asia International Innovative Invention Exhibition, held in Hong Kong, China.
Kenneth Leung’s research has attracted global attention. City University of Hong Kong (CityU) has been endorsed by the United Nations to initiate a ten-year Global Estuaries Monitoring (GEM) Program (www.globalestuaries.org) under Leung’s direction to collect and study environmental pollutants in the estuaries of major cities around the globe to formulate a long-term policy for promoting clean estuaries.
