CASE STUDY OF THE TREATMENT AND RECYCLING TECHNOLOGY DEVELOPMENT

OF MARINE LITTER RELATED TO FISHERY IN JAPAN

by Yasutsugu Yokohama

Director, Shizugawa Nature Center,

Organization to Promote Conservation of Sea and Seashore (Marine Blue 21),
Tokura-Sakamoto 40, Minami-Sanriku-cho, Motoyoshi-gun, Miyagi prefecture, Japan, zip 986-0781,
yokohama@nature.shizugawa.miyagi.jp

INTRODUCTION

The Organization to Promote Conservation of Sea and Seashore was established in 1992 for the purpose to conserve the environment of sea and seashore supporting marine resources and pleasure of people.

In order to attain our purpose we support the voluntary activities cleaning up the beach, and make the map of marine litter distribution in Japan under the support of the Fisheries Agency. Recently, as the accumulation of useless floats made of foam styrene on the beach become serious in areas where the raising of oyster etc. is active, we try to develop the technology to treat and recycle them.

We also make effort to raise public awareness of the importance of sea and seashore by means of lectures on making pressed algae which makes every one notice the existence of various seaweeds beautiful in color and shape which grow on the bottom of the sea and play important functions in the marine ecosystem.

BEACH CLEANING

We investigate cleaning activities on seashores and riversides in Japan under the support of Fisheries Agency every year from 1994. Results obtained for 11 years from 1994 to 2004 are shown in Table 1. The last results obtained in 2005 shows that 16,810 activities were held on seashores and riverside in Japan. The total number of participants in the activities was about 1,320,000, within which about 740,000 was those in the activities on seashores. The amount of marine litter collected on seashores was 377,000m3. This value is equivalent to about 123,000 t.

The amount of marine litter collected on seashores in each of last three years in Japan was around 400,000m3, which was two to three times as large as that in each of four years from 1994 to 1997.

The yearly mean of marine litter collected on seashores for last 12 years from 1994 to 2005 was about 100,000 t. The total amount of marine litter stranded on seashores whole over Japan is estimated to be about four times as large as that actually collected. The yearly mean for last 12 years is estimated to be about 400,000t.

TREATMENT OF USELESS FLOAT MADE OF FOAM STYRENE

Our organization developed an instrument to crush the float to small pieces and compress them. Its test working was made in 2004 under cooperation of local fishery guilds. The test showed us that the instrument could treat about 25 floats (60 cm in diameter and 105 cm in length for each) per hour and decrease the volume to about 5 to 7 %. On the other hand, however, several problems were found. The most serious one of them was the wear of the screw which was essential to crush the float to small pieces and compress them. The wear of the screw was due to contamination of sand, mud and many kinds of organisms from the surface of the float. Another problem was too much load on the motor driving the screw. The cause of this problem was also contamination of sand, mud and organisms.

In order to solute the problems the instrument was improved, and the wear of the screw and the load to the motor were decreased.

Fig. 1 shows the appearance of the improved instrument, and Fig. 2 shows its structure. Photo. 1 shows the process of the treatment of floats. Photo. 1-1 shows the instrument and floats to be treated. Each of those floats is loaded in the crush room of the instrument as shown in Photo. 1-2 and Photo. 1-3. Photo. 1-4 shows the bottom of the crush room, where the screw crushes the float and force crushed material toward the pipe. As the pipe is made taper, crushed material is compressed, and decreased in volume to 5~7 %. The compressed material is excreted from the pipe as shown in Photo. 1-5, and lifted up with a belt conveyer just above a bag as shown in Photo. 1-6. Each of bags, shown in Photo. 1-7, contains material from 30 floats, the weight of which is about 150 kg.

Compressed pieces of foam styrene produced in this system can be used as fuel substitute for petroleum.

The subject to be solved is the further improvement of the system to reduce the effects of impurities since most of floats are attached with various foreign substances as shown in Photo. 1-8.

LECTURE ON MAKING PRESSED ALGAE

As the issue of artificial marine litter is mainly due to the indifference of people to the environment of the sea, raising public awareness is an effective way of reducing marine litter. Activity to make pressed algae using beautiful seaweeds is effective in raising awareness of the importance of the sea as well as the beach cleaning activity.

Although all the land plants have green leaves, seaweeds are colorful than paints. The color variation among seaweeds is the result of the adaptation and acclimation of each species to the light condition at each depth it grows. The colorfulness of seaweeds suggests us that sunlight is essential for seaweeds to live. Pollution of the seawater diminishes the intensity of light penetrating into seawater.

After the experience of making or looking at pressed algae beautiful in color and shape, most of people from children to the aged become aware of the important light breeding seaweeds, and grow to prevent pollution of the sea.

They become also aware of important roles of seaweeds in the marine ecosystem. Communities of seaweeds clean seawater as well as offer spawning grounds, nurseries and foods to various marine organisms. These functions are very large in marine forests, as shown in Photos. 5 and 6, constituted with brown algae of large size. Unfortunately, however, destruction of such marine forests, due to diminishment of light, frequently occurs in Japan.

Pressed algae made in the lecture are different from scientific specimens. Although scientific specimens are not necessary to be beautiful, pressed algae made in the lecture must be beautiful because they must attract people. In the le`cture they draw pictures using colorful seaweeds as shown in Photo. 4.

The lecture on making pressed algae also has the effect to attract people to beach cleaning activity. The beach cleaning activity can be well combined with the lecture on making pressed algae because among marine litter on seashores we can find out many kinds of colorful seaweeds drifted from different depths and stranded on shore.

Table 1. Amount of marine litter collected in Japan for 11 years from 1994 to 2004

Photo 1. The process of the treatment of floats

Photo 2. A lecture on making pressed algae held at an elementary school sponsored by our organization

Photo 3. A beach cleaning by schoolchildren after the lecture

Photo 4. Works of pressed algae made by schoolchildren

Photo 5. A community of Ecklonia cava at a depth of 5m in Shimoda Bay

Photo 6. A community of Sargassum horneri at a depth of 3m in Shimoda Bay

Fig. 1. The appearance of the instrument

Fig. 2. The structure of the instrument