Practical proposal for restoring water quality of the Pasig River
Our research subject is "Practical proposal for restoring water quality of the Pasig River." In the beginning, I will explain the present situation. This is the Pasig River, which flows through Metro Manila. Water pollution load is rapidly increasing there because of the population movement from the rural area. As a result, water quality of the Pasig River is highly polluted. Figure 1 shows the BOD production rate of water pollution load. According to this graph, the domestic wastewater load is dominant.
Figure 2 shows the population rate of human waste disposal in Metro Manila. 3.49% of the population use sewerage line. 87.82% of the population use septic tank. But many septic tanks are not working efficiently. Therefore, wastewater load from septic tanks causes water pollution of the Pasig River. And the other, 8.69% of the population, doesn't have a toilet. Most of people who have no toilet must throw human waste away into rivers or creeks. So, it is necessary to solve a problem of the human waste disposal for restoring water quality of the Pasig River.
In the Philippines Waste disposal is a serious problem, too. The clean air act was enforced in 1999. This act forbids burning waste material. There are some dumping sites in Metro Manila. However, they are already full. As a result a lot of waste material is left all over Metro Manila. There are two possible solutions considered. One is building other dumpsites. The Metro Manila Development Authority (MMDA) is looking into the possibility of building an offshore dumpsite in Manila Bay. However, it is possible that these planning dumpsites will be full someday. The other solution is recycling/reusing waste material. Some activities to recycle/reuse waste material are now appearing. Non-biodegradable waste material can be sold to junk dealers. Biodegradable waste material is transformed into compost. They dispose of both biodegradable and non-biodegradable waste; however, they don't dispose of human waste.
Then, what kind of proposal should be made for restoring water quality of the Pasig River? Figure 3 shows Japanese GDP from 1950 to 1995. These circles show GDP of each country in Southeast Asia. Philippine GDP is almost equal to Japanese GDP in 1950's. Therefore, they can't afford to invest money in restoring water quality of the Pasig River soon. Probably, it will take more than 50 years for the Philippines to catch up with developed countries like Japan. It's a very long time. Because of this fact, it is necessary to propose a new idea that doesn't need an expensive infrastructure.
Photo 1 and photo 2 show "New-Type Toilet" called Bio-toilet. The septic tank is replaced by a composting chamber filled with sawdust. After using the toilet, the push of a button activates a spiral screw, and the sawdust is turned over. In a composting chamber, aerobic bacteria decompose human waste. After half a year, sawdust and human waste become compost. The merits of using Bio-toilet are no water is required and the cost of installation is relatively cheap. This means that introducing Bio-toilet to the Philippines is a very practical proposal for restoring water quality of the Pasig River.