What happens to waste water in Heredia, Costa Rica?
As many of you know, one of my specialization areas is the examination of contaminant fate and transport in aquatic systems - streams, rivers, sewage systems, etc. How do these contaminants get there? What happens to them once they're in your water? Do they stay in their present form or do they transform into something more harmful?
Some of the issues surrounding these contaminants are well understood, while others are still emerging as the subject of research. But one thing strikes me very clearly: in the US we spend billions on research and control for trace levels of relatively obscure pollutants while in other parts of the world, routine pollutants are released into the environment in massive amounts. I have seen this same issue in India and China too. It is important to investigate and correct all types of water pollution but some basic improvements abroad could go a long way towards meeting basic public health improvement. Here in Heredia, there are plenty of basic infrastructure improvements needed.
Some shocking statistics: According to the World Health Organization
(2008, http://www.who.int/water_sanitation_health/mdg1/en/index.html) About 2.6 billion people – half the developing world – lack even a simple ‘improved’ latrine and 1.1 billion people have no access to any type of improved drinking source of water. This is one of the greatest injustices of the world.
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Sewage Treatment Plant, UNA Campus, Heredia
Tuesday we visited the sewage treatment plant for the UNA campus in Heredia. This small plant takes all the waste from the campus and passes it through secondary (biological) treatment before releasing the water to the nearby stream. When all is working well, purification steps remove the solids then optimize growth conditions for bacteria so they can decompose the organics, converting them to easily removed solid sludge. But - this whole process is dependent on a healthy population of bacteria. Unfortunately, the science labs on campus have delivered a toxic shock load to the treatment plant and now the plant has failed. They hope to receive new inoculant next week (a fresh load of bacteria that should kick-start the plant back into proper operation) but when we visited, not many systems were operating and the discharge looked as bad as the influent.
But at least UNA is trying. They are doing (mostly) the right things to help keep contamination out of local streams and I'm confidently that ultimately they'll get it right. But not so fast for the rest of Heredia; most homes have either failing septic systems or no treatment at all. We see untreated raw sewage flowing through broken, combined (storm plus sanitary) sewers every day. Laws are in place to address this, but so far they are not effective.
Open sewer during "dry" flow. At least during rain, this gets diluted:
Successful water quality control does not have to be complex or expensive. Last week we visited the Sanchiri Mirador Lodge & Restaurant:
http://www.sanchiri.com/valleyrestaurant.html. Pat posted the beautiful pictures from the porch overlook, but I liked the view behind the scenes. This eco-friendly hotel grows their own organic food and feeds their barnyard animal table scraps from the restaurant. All the human and animal sewage is collected in an anaerobic bioreactor (basically a large septic tank). This process removes 70% of the influent waste load and the byproduct gas, methane, is used to provide fuel for some basic heating purposes. Nice.
Bioreactor and gas piping at Sanchiri:
Finally, I told my students today during their final presentations (where they showed the class numerous pictures of polluted this and that, as assigned) that I am actually in this business because I love the beautiful, clean places of the world. I wish there were more of them, and I'm glad that I work in part to see that there are.
Before the storm, Gulf of Nicoya, near Isla Tortuguero:
- Chuck
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