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Malaysian aquaculture is still largely limited to traditional practices such as cage farming which are constantly plagued by various problems affecting their yield. Adopting modern aquacultural practices such as microbubble aeration and bioflocs has the potential to improve our yields and provide better sustainability and food security. Tests have shown that aquaculture stock raised in tanks utilising microbubble aeration will grow bigger and faster than those raised in tanks without microbubbles. Microbubble generation when used in conjunction with bioflocs will lead to greater production yields, thereby creating a more efficient and sustainable aquacultural production system.
Even in the modern day, Malaysia’s aquaculture still largely relies on traditional methods such as cage farming near the sea or river sides and earth ponds which are built on land near sources of brackish or fresh water. Our farmers have stubbornly held on to these practices for generations in spite of being constantly subjected to various challenges affecting their production yields such as water pollution, drastic climate change, disease outbreaks, predation and many other such issues. A recent example is the mysterious mass fish die-off at Teluk Bahang, Penang, with similar cases having also occurred at Jerantut, Pahang and Sungai Gombak.
As these problems grow, it has become clear that our nation needs to adopt modern aquacultural methods and techniques to improve the production and sustainability of our aquaculture. Neighbouring countries such Thailand and Vietnam have already adopted modern methods, which makes Malaysia still lagging behind all the more obvious.
Next to feed, aeration is the most important component in any form of aquaculture as it is the primary source of dissolved oxygen in the water. Sufficient quantities of oxygen in the water will improve the appetite and general well-being of fish and other aquatic life in the water, thereby ensuring that they grow well and remain healthy. Dr. PooBalan Ganesan of the University of Malaya (UM) aims to address the need for better practices in aquacultural farming. Together with his teams, Dr. PooBalan has been continuously working on new methods of improving the dissolved oxygen content in water for aquaculture applications, both fundamentally as well as practically.
“Doing something related to living stock makes me feel excited,” says Dr. PooBalan, “On top of that, this is a society impact orientated work for food security and sustainability.”
Microbubble aeration is one of the methods that Dr. PooBalan tested for implementation in Malaysian aquaculture. Compared to macro-sized bubbles (which are at the millimetre scale), microbubbles (which are at the micrometre scale) tend to stay suspended in the water for longer periods, thus resulting in increased mass transfer between the air and water and higher dissolved oxygen levels. Based on the understanding of bubble formation, Dr. PooBalan’s team developed a microbubble generator and tested it at UM. This generator produces microbubbles at sizes below 200 micrometres, significantly improving the dissolved oxygen content of the water (see Figure 1).
Figure 1: Testing of the microbubble aeration system
To ensure the sustainability and effectiveness of this system, a feasibility study was carried out, monitoring the water quality, performance measurement, durability investigation, and actual culture of different species such as whiteleg shrimp, freshwater prawn (Udang Galah), jade perch and tilapia (see Figure 2) in order to determine the generator’s effectiveness. The results showed that shrimp and fish grew larger and faster when raised in tanks using microbubble aeration compared to animals raised in tanks without this system.
Figure 2: Shrimp and jade perch are reared as part of the feasibility study
Another topic that Dr. PooBalan and his team focused on during their research is the usage of Biofloc technology (BFT). BFT is seen as the new “blue revolution” in aquaculture; a technique that utilises in situ microorganism production to reuse and recycle waste nutrients from the animals and thus create a self-sustaining ecosystem. By creating a working Biofloc, tanks will be able to maintain their own water quality via uptake of nitrogen compounds and will also have a ready supply of supplement feed for aquaculture species. Furthermore, BFT synergizes well with microbubble aeration as the generators will be able to supply the high levels of dissolved oxygen required to maintain the biofloc’s nitrogen cycle and thus ensure that the ecosystems remain healthy.
By creating tanks utilising both bioflocs and microbubble aeration, we will be able to create an efficient, modern aquacultural system that will provide greater yields and is protected from many of the issues plaguing traditional aquaculture. This in turn, will create a more efficient and sustainable aquacultural production system that our country can rely upon.
Asoc. Prof. Ir. Dr. Poo Balan A/L Ganesan
Department of Mechanical Engineering' Faculty of Engineering