Synthetic biology is a new interdisciplinary science and cannot be described from a single person or industry. It is also important for us to consider the safety aspect of our project.
We needed to be responsible and thoughtful, so to evaluate that our work is on a good track and has positive impacts on a real world, we talked to and sought advice from various experts in addition to reviewing literature. Our project was influenced by experts in various fields, including industry experts (8, 9), researchers at a university (11) and research institutes (1, 5), startup company (2), administration (3, 7), and sewage treatment plants (4, 6, 10). After talking with them, we understand the phosphorus problems and its market better.
What did we learn from them?
Our goal is to recover phosphorus from the wastwater to prevent it from entering into the environment. We contacted research institutes working to solve the environmental problems caused by phosphorus, an academic researcher investigating the material flow of it, sewage treatment centers where it is removed, industries developing phosphorus absorbent. Through the discussions, we learned the current states of environmental and resource problems caused by phosphorus, technologies to solve them, work of sewage treatment centers, where it is used in the industry and importance of securing biocontainment. These conducts deepened our knowledge on phosphorus itself and provided us opportunities to think about how we can apply our project to the real world. Hearing from experts, we ensured that phosphorus is indeed an important resource and need to find out a way to recover it. Knowing what is happening in the world helped us evaluate our project and review it from a higher standpoint. And we were convinced that eutrophication is an issue to be solved and at the same time, we now know that we need to think about the effects on fisheries when removing the phosphorus from rivers.
How did we act on their feedback?
At first, we thought of recovering phosphorus from the natural environment like rivers and agricultural wastewaters. Some experts said that the recovery rate would significantly be reduced when we used our bacteria to treat water containing relatively low concentrations of phosphorus. Therefore, we changed our application and now consider targeting industrial and domestic wastewaters, where phosphorus is concentrated. By visiting sewage treatment plants and talking to people working there about the activated sludge method, which is the main technology to remove phosphorus from sewage, we learned that there is a room for our E. coli to be implemented. Some researchers and companies have already tried to recycle phosphorus from the environment, but they said it is difficult to make profits. From the viewpoint, we are now aware that developing a cost-effective technology with additional value is needed.
1. Kyushu Environmental Evaluation Association
Kyushu Environmental Evaluation Association aims at solving environmental problems by measuring water/air quality, monitoring ecosystems, and conducting environmental assessment. We had an online meeting with 2 experts from the environment department. We introduced an overview of our project and they made us interesting suggestions; for example, using E.coli that has high proliferative activity or can be constantly active under temperature change might work for our project. Another idea was engineering to improve the efficiency of current technologies in sewage treatment. We also talked about using our bacteria for agricultural wastewater treatment and found it difficult because the wastewater can be easily diluted by rainwater and the chemical properties can be different depending on the crop species. Lastly, we asked questions about the following paper written by the foundation: Yokoyama et al (2011). A change of the species composition of phytoplankton with the variation of nutrient concentration in Hakata Bay. JSCE Magazine,“Civil Engineering”, Vol 67, No.2. Through the discussion, we learned the current situation of sewage treatment and eutrophication in Hakata Bay. It was surprising to know that oligotrophication is a serious problem in coastal water in Japan.
2. Nature Co., Ltd
We visited Nature Co., Ltd which developed a multifunctional water quality improvement device to solve eutrophication problems in dam lakes.
Firstly we asked about details of the device. The target of the device is hypoxic waters in the lower lake, and by using microbubbles, it can improve the oxygen conditions. Then we heard about eutrophication in dams. In dams, water circulation is limited so even the influx of nutrients is small, it is accumulated and can cause eutrophication. Also, the lack of water flow leads to oxygen depletion in the hypolimnion, and nutrients from the layer are released thus accelerate eutrophication. After the introduction of our technology, we found that keeping the cost down is important for implementation.
Through the discussion, we are able to learn about the current state of eutrophication and the technology to solve it. It was interesting to know a different way to cope with the issue.
3. Mr Keigo Okauchi
We interviewed Mr Keigo Okauchi from the Ministry of Land, Infrastructure, Transport and Tourism. He is involved in promoting “Jyunkan Sodachi (Circulatory Growth)“, a project to utilise sewage to produce sewage-based fertiliser.
There are about 40 projects now in Japan, and among them 6 are implemented at sewage treatment plants, with the penetration rate approximately 0.3%. He also introduced us to Saga City Waterworks and Sewerage Bureau, which is working on the project.
4. Fukuoka City Seibu Sewage Treatment Center
We visited a local sewage treatment plant, Fukuoka City Seibu Sewage Treatment Center to know how phosphorus is recovered from sewage.
Fukuoka City has been adopting a biological degradation process. Magnesium ammonium phosphate (MAP) method is used for phosphorus recovery from the filtered water which is produced from activated sludge, and MAP is sold as a phosphate fertilizer. To prevent water pollution caused by eutrophication in Hakata Bay, high concentration of phosphorus in the wastewater needs to be removed, however, MAP does not make money.
We heard that the number of facilities using the MAP method is expected to decrease in the future because the phosphorus concentration of dewatered filtrate will be reduced by the change of the dewatering method to cut the amount of sludge generated by making the moisture content of dewatered sludge lower.
5. Fukuoka Institute of Health and Environmental Sciences
The Fukuoka Institute of Health and Environmental Sciences working to protect the health of the inhabitants and comfortable environment. Division of Water Science is analyzing water pollutants including phosphorus. According to the institute, algae blooms occur in closed, eutrophic lakes/dams and is not a serious problem in Fukuoka Prefecture. Some dams in the prefecture circulate water to prevent algae blooms. In Japan, algae blooms are only frequently seen in densely populated areas such as Lake Biwa or Kasumigaura, so it may be possible to use our plan in these areas. In order to install our technology in the real world, they advised us to make it inexpensive. They suggested we recover phosphorus from rivers in developing countries where phosphorite is not affordable.
6. Saga City Sewage Purification Center
At the Saga City Sewage Purification Center, sewage is converted into resource. It is one of the six wastewater treatment plants that practices the project “Jyunkan Sodachi” (Circulatory Growth. See #3 for details) in Japan. In the center, all of the dehydrated sludge is turned to fertiliser by mixing with YM bacteria and fermenting above 90 deg C for 45 days. Farmers can buy the fertiliser at about a tenth of the chemical ones and it has vitalised agriculture. 1400 tons of fertiliser is produced every year and the entire amount is sold out. Other than sludge composting, the center is adjusting the discharge of the treated water by season, which contributes to Nori (seaweed) cultivation. It is also energy friendly, for power is generated from biogas produced from sewage sludge and covers 40 % of the electricity used in the facility. What is more, CO₂ is separated from the biogas and then used for greenhouse farming. In this way, the center is fully recycle-oriented and is in harmony with agriculture. There are no large factories around the treatment plant and therefore the quality of sewage is good, which might make the sewage-based fertiliser possible. Considering the appropriate applications corresponding to regional characteristics are important.
7. Fukuoka City Hall
Fukuoka City Hall provided us with details about the Hakata Bay Environmental Conservation Plan. Hakata Bay, one of the semi-enclosed bays of Fukuoka, is easily affected by the discharged water from sewage.
In the past, the goal was to remove as much nutrients as possible to keep the water clean, but now changed to maintain appropriate nutrient levels for sustaining marine lives.
In summer, the bay experiences red tides due to the large inflows after the seasonal rain and the temperature suitable for algae proliferation. In winter, on the other hand, lack of nutrients is significant. Therefore, to achieve the goal, nutrient levels are being tried to be adjusted by season in Seibu Sewage Treatment Center.
Despite the increase of wastewater in Fukuoka City with the growing population, the city has managed to keep the environment at a certain level under the plan.
Regarding the device we are developing, they told us that in order to recover phosphorus efficiently, places with high phosphorus concentrations are suitable such as sewage treatment plants or septic tanks, rather than rivers and oceans.
8. Taiheiyo Cement Corporation
Japan’s largest cement supplier, Taiheiyo Cement runs globally, including cement, mineral resources, and environmental businesses. We were interested in “Rintoru”, an inorganic material that absorbs phosphorus, and had an opportunity for an online meeting with Mr. Tsuyoshi Aketo from the company who engages in the development. At the meeting, we found that Rintoru is very interesting and useful. Rintoru is an amorphous calcium silicate hydrate material and has a high chemical affinity with phosphorus. It is applied to decolorize wastewater along with the recovery of phosphorus. Recovered phosphorus material can be used as a fertilizer. Moreover, it has superior settleability, so can be easily collected. Next, we asked him questions about Rintoru, like necessary equipment, business models. We learned that the phosphorus recovery rate is overwhelming compared to other conventional materials because inorganic reactions are relatively rapid. We also heard that the presence of phosphorus in the cement is not preferred.
9. Fukuoka Fisheries And Marine Technology Research Center
We heard from the Fisheries and Oceanographic Technology Center, which is striving for the sustainable development of the fisheries industry through the development of technologies to protect fishery resources and fishing environment in Fukuoka Prefecture.
Necessary nutrients for the growth of phytoplankton, the basic production of the ocean, are nitrogen, phosphorus, and potassium, but since potassium is abundant in the ocean, the amount and balance of nitrogen and phosphorus are important. However, in recent years, the amount of phosphorus has been decreasing in Hakata Bay, and the production of nori seaweed has been hampered by the decrease in phosphorus levels in the seawater, especially in winter in Hakata Bay.
When asked about the device we were developing, he replied, “Phosphorus is removed by biological treatment, but even now the amount of microorganisms is adjusted by artisanal techniques, so I’ve heard that it’s difficult to adjust the amount of phosphorus removed as expected. However, we have heard that it is difficult to control the amount of phosphorus removed as expected, since the amount of microorganisms is currently controlled by artisanal techniques. He said,”We have heard that it is difficult to adjust the amount of phosphorus removal as expected.
Note: Nori (seaweed) is one of Japan’s signature foods, and Fukuoka is Japan’s 3rd largest Nori-producing prefecture.
10. Shin-seibu Sewage Treatment Center
We visited the Shin-seibu Sewage Treatment Center. There we learned that the sewerage system not only cleans the water, but also plays a role in improving the environment and preventing flooding. At the Shin-seibu Sewage Treatment Center, nitrogen is recovered from oxygen-free tank and aerobic tank and phosphorus is collected by adding a coagulant. Sludge is carried to the Seibu Sewage Treatment Center and thereby processed. To protect the ecosystem of tidelands, E. coli in the wastewater is killed using ultraviolet light instead of Sodium hypochlorite. Irradiation for 3 seconds is enough to reduce the number of bacteria.
They commented on our project that currently, the cost of reusing phosphorus as a fertiliser is not cost efficient,and that if phosphorus can be recovered and converted into fertiliser at a low cost, it can be commercialised putting aside the details.
11. Prof. Kazuyo Matsubae
We talked to Prof. Matsubae, who is investigating the material flow of phosphorus. We learned details about the current market, elemental two forms (white phosphorus and red phosphorus) and how phosphorus is used in Japan.
Newly found phosphorus rock reserves often contain relatively high concentrations of radioactive elements and cadmium. High-quality deposits without those pollutants are likely to be depleted in the near future. If we can recover phosphorus using E. coli, she said, purity would be an advantage.
As her study, she is proposing to recover phosphorus from steelmaking slag, for the quantity of phosphorus in the slag is almost equivalent to that of imported rocks. In contrast, a biological solution using E. coli is more suited for wastewater from food processing factories.
Currently, the price of mined phosphorus is cheaper than that of recovered ones. We realised that it is important to have an economical perspective - changes in the social structure (e. g. tax system) are needed before the recovered phosphorus becomes widespread.