Water Journal : Water Journal December 2012
operations water DECEMBER 2012 77 this left staff to rely solely on face-to-face communication. It took four days until the safety of every staff member and contractor was confirmed. Aquaforce 5000 Units Deployment In early April, as the city’s water supply relied mostly on emergency bottled water and water transported from the next city, Veolia Environment Foundation provided two temporary water treatment plants. The Aquaforce 5000 is a temporary treatment system that consists of coagulation, settlement, filtration and disinfection steps, and is specifically designed for emergency situations (see Figure 8 for the process diagram). Each Aquaforce 5000 treated about 5m3/hour of water. One Aquaforce 5000 unit was constructed in the central part of the city and the other in the northern part. Both units used water from small rivers as a source. Fuel generators were used to run the units, as electricity was not available when Aquaforce 5000 was first deployed. About 20 volunteers were sent from Veolia Water and its subsidiaries to set up and operate the units. Figure 6 shows the constructed Aquaforce 5000 unit in the northern part of the city. Figure 6. Deployed Aquaforce 5000 unit. Both units started providing non- potable water to residents on 13 April, 2011. In line with Japanese regulation, the produced water had to be tested before it was considered drinkable. It took seven days before the water quality analysis was complete. During this time, many people still came to fill the tanks in their small trucks with non-potable water. Figure 7 shows people distributing water from tanks loaded on their trucks. While the test results for the water quality analysis were being conducted, a further analysis showed the possibility of pathogenic contamination (anaerobic spore-forming bacteria) in the raw water being fed to the Aquaforce 5000 units. Anaerobic spore-forming bacteria is used in Japan to indicate the possibility of Cryptosporidium contamination. It was suspected that, due to the poor sanitation situtation, domestic wastewater was being discarded directly into the river, thus having a detrimental effect on the water quality. According to Japanese drinking water standards, turbidity generally has to be two degrees or lower. However, once the possibility for pathogenic contamination with Cryptosporidium is suspected, the turbidity standard becomes much stricter and decreases to 0.1 degrees or lower. Unfortunately, the Aquaforce 5000 units that were deployed in the city were not designed to produce water with such a low turbidity. By fine-tuning the treatment, the treated water from Aquaforce 5000 reached about 0.15 degrees, but it was difficult to consistently meet the target of 0.1 degree. After several more trials, the team decided to add microfiltration membranes, provided by Veolia Water Solutions & Technologies, to the Aquaforce 5000 unit to consistently produce safe drinking water. Figure 8 shows the new process of the Aquaforce unit with the microfiltration membrane. From May, with this additional step, the system was able to produce water with turbidity of less than 0.01 degree. Desalination Unit Installation In May, construction began on temporary housing for those who had lost their homes. People started moving from the group evacuation centres to more private individual temporary houses where they could cook, wash clothes and take showers. Accordingly, the volume of water consumption increased. The city needed a stable water supply system to distribute water to these houses. In August 2011, two mobile seawater desalination units with a combined capacity of 1,300m3/day were installed to combat the salt concentration of the groundwater and enable water distribution to a wider population. One Year and Six Months After the Catastrophe As the situation in the city improved, Aquaforce units ended their operations in August 2011, five months after the tsunami hit. Desalination units were removed from the city in July 2012, 17 months after the tsunami. With the improvement of the raw water quality of the shallow wells and with temporary pipings, the Minamisanriku residents currently have a constant water supply. However, the measures that have been put in place are not long-term solutions. Much of the equipment and pipelines that have been built after the earthquake are still temporary due to the immediate need to supply water to citizens as quickly as possible. More importantly, the city’s reconstruction plan has not yet been developed. Approximately 60% of Minamisanriku’s buildings were destroyed by the tsunami and the population has decreased to about 15,000 people with close to 5,000 people still living in temporary housing. One of the main reasons for the delay in developing the city’s reconstruction plan is due to the lack of safe locations for rebuilding infrastructure. As the city is surrounded by mountains and the Figure 7. Emergency water supply being distributed by truck. Treated water tank Activated carbon Sand filtration Raw water tank River water Water distribution by buckets and trucks Disinfection Microfiltration (added) Figure 8. Aquaforce 5000 unit’s process and the addition of microfiltration.
Water Journal February 2013
Water Journal November 2012-1