Researching a sustainable solution for aquaculture industry

By Associate Professor John Lau Sie Yon

Aquaculture activities have been growing rapidly in recent decades to fulfil the global demand for protein sources as population growth increases. However, water pollution has also increased as a consequence as massive amounts of wastewater from aquaculture effluents and feed residues is produced from these aquaculture activities.

Aquaculture wastewater can be a major environmental concern as it contains high levels of nutrients such as nitrogen and phosphorus, as well as organic matter and suspended solids. Discharging aquaculture wastewater into the environment can expose water bodies to the risk of eutrophication, and conventional wastewater treatment to mitigate this risk can be extremely costly.

This predicament has led researchers to look increasingly towards microalgae as an answer. Microalgae have a huge potential to be an effective and sustainable solution for treating aquaculture wastewater.

Microalgae are capable of removing excess nutrients from wastewater through a process known as nutrient uptake. As the microalgae grow, they absorb nutrients such as nitrogen and phosphorus from the water, converting them into biomass. This can help to reduce the nutrient load in the wastewater, which can benefit the aquatic ecosystem’s health.

In addition to nutrient removal, microalgae can also help to improve water quality by reducing the levels of organic matter and suspended solids in the wastewater. As the microalgae grow, they produce oxygen through photosynthesis, which can help to increase dissolved oxygen levels in the water. Adequate supply of dissolved oxygen ensures high degradation efficiency of the organic particles by aerobic bacteria into by-products. This is also critical for the health of aquatic animals as low levels of dissolved oxygen can be harmful or even lethal.

Microalgae-based wastewater treatment has several advantages over traditional treatment methods. Firstly, it is a more sustainable approach as it relies on natural processes rather than chemical treatments that can be harmful to the environment. Secondly, both the wastewater treatment cost and microalgae biomass production cost can be reduced. Thirdly, microalgae can be harvested and used for various applications, such as biofuels, animal feed, or even food for humans. This can provide additional income streams for aquaculture farmers and make the overall operation more profitable.

Owing to their fast growth rate and high lipid content, microalgae species such as Chlorella and Scenedesmus are deemed to be highly potential as alternative renewable feedstock for biofuels. Biofuels such as biodiesel can be produced via the extraction and transesterification of the lipids. The biomass left can then be further processed to produce bioethanol.

On the other hand, microalgae are also rich in carbohydrates, proteins, pigments, vitamins, and minerals, which are a promising food source for humans and animals, with essential antioxidant, immune boosting, as well as anti-inflammatory properties. The carotenoid pigments, particularly beta-carotene and astaxanthin, are vital to aquaculture in enhancing the health, colouration, growth, and survival rate of aquatic organisms.

Research into microalgae-based wastewater treatment is ongoing, with scientists exploring different species of microalgae, optimal growing conditions, and the potential benefits for different types of aquaculture operations. Some researchers are also investigating the potential of using microalgae in combination with other wastewater treatment technologies, such as biofilters or constructed wetlands.

Recently, Curtin University Malaysia has been expanding its research interests into the field of aquaculture. This includes a new research project funded through a grant from the Curtin Malaysia Research Institute (CMRI) being carried out by postgraduate student Jessica Ling Siew Kiong under a supervisory team led by Associate Professor John Lau Sie Yon.

This project intends to study the potential of hybrid cultivations of prawn and microalgae in a recirculating aquaculture system (RAS). The final goal is to fabricate a complete prototype for a prawn-microalgae integrated recirculating aquaculture system approaching zero-waste emissions.

In conclusion, microalgae have the potential to be an effective and sustainable solution for treating aquaculture wastewater. As research continues to explore the possibilities of this innovative approach, the team at Curtin University Malaysia is eager to discover even more exciting and beneficial applications for microalgae in aquaculture and environmental management. The team is also looking for collaborations in this field and invites other researchers pursuing similar research to get in touch with them.

Associate Professor John Lau Sie Yon is the Associate Dean of Research and Development an Associate Professor in Chemical and Energy Engineering at Curtin Malaysia’s Faculty of Engineering and Science. He is an accomplished researcher who has secured numerous research grants for his research, as well as published and co-authored a significant volume of journal publications, book chapters and conference papers. His research interests include enzyme technology for various applications, microalgae integrated RAS design, chiral compounds separation using enzymatic membrane reactor, biomass conversion for industry applications, aptamer mediated biosensor for pathogen detection, and nano-vehicles for targeted drug delivery. Associate Professor Lau can be contacted by email at johnlsy@curtin.edu.my.