Sludge gives a very big environmental load to the local sea area. Here, attention was paid to micro-bubble technology for application to the purification of sludge. The important point in this technique is to activate the bacteria existing in the area by micro-bubbles. In this study, our objects are to develop a new powerful purification system for sedimentary sludge using a micro-bubble device and liquid for microorganism activation. As the results of our experiments, we succeeded in reducing time to purify the sludge.


It is very important to reduce sedimentary sludge in the ocean. Plans to reduce the sludge are usually dreading or sand covering. Dredging is a simple way and aims to cut off the sludge. But after cutting off, treating the dredged sludge takes much more time and, of course, cost. Sand covering, in general, gives a big load to living organisms and the ecological system. Here, a more efficient way is needed to reduce the sludge while not imparting environmental load in the local sea area. Now, we have micro-bubble technology. Micro-bubbles can change conditions into an aerobic state. If the bubbling stops, the situation changes into anaerobic state, according to recent research. So, we selected a method for decomposing the sludge by microorganisms. Therefore, our research targets purification experiments on oceanic sedimentary sludge by micro-bubbles and microorganism activator.

Experimental Devices

The experimental apparatus consists of two parts, shown in Fig. 1 and 2. The water circulates through two tanks. One tank generates microbubbles. The micro-bubbles have micro-size diameter and high solubility. Microorganism activator is used; this is liquid and mainly comprises Kelp and also includes nutrients and some enzymes. Our used activator is reported to show effective results in purification for grease trap.

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