Sunday, March 28, 2010

Trench Peacefare

This one trick pony has expanded his repertoire. As loyal readers should know, the people of Mali suffer from completely unnecessarily high rates of giardia, dysentery and explosive diarrhea because the raw sewage from their “traditional latrines” flows out into the streets and the entire population is exposed to the dangerous pathogens which cause these illnesses and continue the positive feedback loop by making their way into other people’s mouths. Sewage is both a danger to public health and also a necessary byproduct of human life itself, and so this blog’s eponymous hero is busy spending the prime years of his youth and your tax dollars building modern latrines equipped with concrete floors and soak pits: a rudimentary septic tank technology appropriate for cultures in this harsh Sahelian climate with few financial resources and building materials.

In the flat center of Sanadougou where I live, the water table lies almost perfectly uniformly between 7.5 meters below ground level at the peak of hot season and 4 meters below ground level after the groundwater has been recharged by 4 months of rainy season. In the center of Sanadougou where about 3,800 of the 4,400 permanent residents live, development-minded villagers have been digging soak pits 1 meter deep and varying in diameter (usually about 1 to 1.5 meters) depending on the number of people in their households and the volume of wastewater generated by their respective nyegens. Since the pathogens originating in wastewater can usually seep up to half a meter through hard-packed soil and sedimentary rock, the water table should never come closer than 2.5 meters to the sewage generated by these modern latrines and thus the groundwater consumed through wells and pumps should be adequately protected from direct contamination by human fecal matter.

However, even within the demarcated borders of Sanadougou there are some places where the soak pit is an inappropriate technology. Namely, there is an outlying neighborhood called Filablena which is significantly lower in elevation than the rest of the town and sits around a couple of large seasonal ponds. Here the water table varies between 5 meters below ground level at the peak of rainy season and 1.5 meters below ground level after rainy season.

The wells here are so shallow, and with less rock they are cut into nothing but soft soil which is much more permeable and conducive to groundwater flows. The pressure in a well is somewhat less than within the soil, so the water levels of wells are slightly higher than the water table; in Filablena during rainy season, the well water surface is only slightly less than a meter below ground level.

If we built 1 meter deep soak pits here like we have in the rest of Sanadougou, soak pits would in fact exacerbate the water sanitation problem by directly polluting the groundwater with raw sewage. That contaminated groundwater would then eventually make its way to people’s wells from which they get the bulk of their drinking water. The absolute worst-case scenario would be that contaminated water makes its way into the seasonal ponds and – though it probably wouldn’t be as obvious as the ones which form behind "traditional latrines" – render them into gigantic seasonal cesspools.

In Filablena we are just beginning to introduce a specialized technology: the infiltration trench. An infiltration trench serves the same function as a soak pit in that it contains the wastewater emitted from “traditional latrines” underground so that it cannot serve as a fertile breeding environment for filth flies and mosquitoes and cockroaches and a vector for all sorts of disease. It has to be able to store roughly the same volume of wastewater as a soak pit, but in an environment where the water table is prohibitively high an infiltration trench must be dug at a much smaller depth. In truth, the volume of a soak pit is only really important so long as it briefly stores wastewater before in seeps into the surrounding soil and rock; what is much more important is the surface area which determines the rate of discharge into the ground where it is safe and isolated from human water and food supplies. Where there has not been a lot of room to maneuver, we have solved this problem by simply reducing the depth of our soak pits and increasing the diameter accordingly.

Infiltration trenches take that ideal of minimal depth and maximum surface area even further. First I found a group of Filablenakaw interested in rebuilding their nyegens, measured their dimensions and assigned them lengths of plastic piping between 4 and 6 meters in length. Then we took an afternoon and pierced holes in them; we took a dozen large nails and placed their ends in the fire until they became red hot, and with protective work gloves we held pliers to hold the hot nails and melted lines of holes down the length of the pipes. With these hole-ridden pipes, wastewater should flow out over a more evenly distributed area and facilitate more rapid and less concentrated wastewater seepage into the soil.

Instead of small circular pits, Filablenakaw have been digging 4- to 6-meter long trenches which begin about 20 centimeters and eventually expand to a maximum depth of no more than 50 centimeters. We fill them in with rocks in such a way that the plastic pipe is on a gradual incline downwards and wastewater flows all the way down. Then we fill them with more rocks to keep the pipe stable, and cover the end of the pipe with a large flat rock to protect it from closing up.

Eventually we’re going to cover the trenches all up with plastic sheeting and cover them with the dirt that was dug up in the first place so that the sewage is contained underground, people and animals can walk over them without falling in, and every year or so homeowners can open up their infiltration trenches to inspect them and clean them as necessary.

However, there are some negative aspects of this process which make the construction of an infiltration trench an unattractive option. The biggest down point of this technology is that burning holes in the plastic pipes produces noxious fumes and is fairly harmful to anyone who isn’t wearing a respirator – I covered my face with soaking wet handkerchiefs while doing this work, and even then I came down with really bad headaches. Infiltration trenches also require more than 6 times as much plastic piping and sheeting than your average soak pit – but the plastic materials are so cheap compared to the cement that goes into the nyegens that the cost of an infiltration trench cannot be prohibitively expensive to anyone who is building or revamping an entire nyegen. Nevertheless, in communities sitting atop extremely high water tables, infiltration trenches are the most practical, cost-effective technology available for sound wastewater management. It is unlikely that we will be able to completely sanitize Filablena's latrines with such infiltration trenches, but my hope is that the few models which we are building will serve as an example for the entire community to one day safely contain their waste underground and away from the rest of the water supply - insh'allah.

Monday, March 15, 2010

This is Why UNICEF and NGOs Should Stop Giving People Free Mosquito Nets

Madu Bigmeat: What are you doing?

Gajuma: I am cutting up a mosquito net.

M: I can see that. But why?

G: I am making rope.

M: You can make rope out of old rice bags, you can make rope out of cotton or grass or even old rope. Why - of all things - are you making rope out of a precious mosquito net?

G: This mosquito net was free.

M: Do you have another mosquito net?

G: No.

M: Are you going to buy another mosquito net?

G: Of course not! The doctor gives them to pregnant women for free!

M: Is your wife pregnant?

G: Of course not! She is 70 years old! She is too old to have another child.

M: Then you're never going to get another free mosquito net! Why on Earth are you destoying this one?!?!?!

G: It doesn't matter - my sons have wives. And soon they will have more children. And the doctor will give them another mosquito net.

M: Yeah, that new mosquito net - if they ever get it - would be for the mother and her infant child to protect themselves from malaria. No doctor is ever going to give you a new mosquito net!

G: Yes, but when my sons' daughters get new mosquito nets, they will give them to me because I am an old man.

M: And are you going to sleep under them?

G: No, I will use them to make more rope.

Floccing Shit

Madu Bigmeat: So things are going fairly well with my newest round of latrines and soak pits… But I dunno, James Brown II… should I be focusing the whole time on wastewater management? Should I return to teaching people how to treat their well water?

James Brown IV: Sorry man, I think you’ve got us cats confused!!! I’m the fourth James Brown you’ve had hanging round this gwa!

Madu: James Brown IV?!?!?! Damn, son. I’ve been going through you cats so fast that I’ve lost track.

James Brown IV: Whatchoo talkin’ bout, Madu?

Snoop Dogg: I think you should break him the bad news, being his master and all.

Madu: You see, James Brown IV, due to the low content of vitamins and minerals in a diet of millet goop and peanut oil, the townsfolk of Sanadougou are suffering from acute malnutrition – especially the children. One of the most important things which Malians are lacking from their diet in sufficient quantities is protein. And so, James Brown IV, it is quite common for my malnourished neighbors to hunt other people’s cats when they wander around at night– hence the suffix after your last name.

James Brown IV: But… but… why?!?! Why would anyone want to eat a cute little kitten like me? There’s hardly any meat on these bones!!!

Madu: You’re right, but the fact that there is meat on those bones – and not enough of it on the bones of all the children here in Mali. That’s why you’re inevitably going to get eaten.

James Brown IV:

Mdu: Yeah, the fact of the matter is that all animals raised in this society – whether they be cows, goats, chickens, dogs or cats – are eventually destined for the food bowl. It’s been hard, but I’ve come to terms with this. And I’ve come to accept that both of you will also one day be eaten by my malnourished neighbors… though in the meantime, I’m going to give you all the tender love and care that I can.

Snoop: That’s the truth, fo’ sure!

James Brown IV: If only it didn’t have to be like this!!! If only!!!


Al Gore: There is in fact logic to that assertion, for it in indeed possible to address the root cause of this pet-eating behavior amongst the local populace.

Madu: Al Gore!!!! What in tarnation are you doing here?!?!?! There is no way that your academic brainpower can solve this problem.

Al: Your claim is lacking in foundation, for there exist sound methods of improving the nutritional content of the typical Malian diet and therefore obviating the demand for feline and canine proteins.

Madu: Shove it up your converter box, Al. There simply isn’t enough water to grow any food here in substantial quantities beyond millet and peanuts. And if anyone gets their hands on any money, they’re going to blow it on tea and sugar and toys. Unless you’ve got a solution that requires no water and no money, then it’s not going to fly.

Al: There are in fact a multitude of species of plants edible to humans and possessing a plethora of nutritious elements which can be grown in environments with little to no water. For example, one such species, among the most promising of crops to be disseminated for the objective of improving nutrition in the developing world, is the Moringa oleifera – a tree native to the foothills of the Indian Himalayas commonly known as the “moringa”.

For millennia Indians have eaten the pods of the Moringa – which they call “saragwa” and is consumed fried and in sanbars and curries. In addition, the moringa leaves can be cooked like spinach and are even more nutritious, containing significant amounts of Vitamin A, Vitamin C, protein, calcium, iron, phosphorus and potassium. If each Malian child were to drink a serving of moringa leaves crushed into powder and stirred with water into a beverage – perhaps with a little sugar or lemon for taste – it would be the nutritional equivalent to eating an orange, a carrot, a banana and drinking a glass of milk.

James Brown IV: So you’re saying that if these kids eat these leaves, they’ll have their protein and won’t want to eat my cute little self?

Al: Well, there is no certainty that Moringa oleifera alone can serve as a causal factor in such a momentous behavioral change; however, if this species could be cultivated to such an extent that the present nutritional deficiencies in Malian culture were abated then it is reasonable to surmise that the demand for feline protein would reduce significantly.

Snoop: And dogs?

Al: Yes, improved nutrition would probably reduce the demand for canine protein as well.

Snoop: Y’know, I think this solar panel pinhead over here’s got some sense in him. Everyone here eats their toh with baobab leaves in the sauce – adding moringa leaves wouldn’t be such a big change in their habits!

Okay, so this tree’s nutritious – I get it. But why should people farm these trees to eat the little leaves and pods when they could grow oranges and bananas and carrots instead?

Al: Unlike all of the crops which you just mentioned, moringa is a relatively easy and cheap crop to cultivate. After sugarcane, oranges, bananas and carrots are amongst the most water-intensive crops that are grown in this country – and in addition to intensive irrigation during the dry months and even during rainy season, they require much intensive fertilization and maintenance. Oranges and especially bananas do not start bear fruit until many years have passed since planting.

Alternatively, moringa requires little to no irrigation to be a productive crop. Of course, irrigation is linked to extremely high rates of growth and the bearing of pods and leaves, but Moringa will sprout pods and leaves even with no precipitation or irrigation. If it receives no moisture at all for extremely lengthy periods of time it will shed its leaves and go dormant, feigning the appearance of death, but in fact it will remain alive to blossom upon the receipt of the next rainfall.

Madu: Is that it?

Al: No, Moringa oleifera also serves additional benefits to most that lie adjacent to it – with the notable exception of corn. Moringa is a nitrogen-fixing legume – which means that it fosters cultures of bacteria on and around its roots which take nitrogen and convert it into ammonia, enriching the nutritional content of the soil and thereby improving the yields of adjacent and/or subsequent garden crops.

Madu: Alright, fine. Now that’s it with the benefits of moringa – right?

Al: Your assumption is erroneous, for Moringa oleifera can also serve to assist in the treatment of water for drinking purposes and even in wastewater treatment, because the seeds of the plant contain a cation which is polarized and can therefore assist in flocculation.

Snoop: Fuck you too, man.

Al: You see, if particles of polluting matter are suspended in a solution, it is often because they are of the same usually negative charge and hence do not aggregate together – or rather, they do not “floc”. But certain polarized substances can catalyze these colloids to floc into the noun form – a floc – and accumulate sufficient weight to sink down to the bottom.

Moringa seeds contain so many of these aforementioned cations that if they are crushed into a fine powder with a mortar and pestle, they can serve as practical flocculants for use even in a non-monetary economy or those where commercial flocculants such as aluminum chloride or polyaluminum sulfate are otherwise unavailable on the market.

So what you’re saying is, if there’s little bitty poo particles in someone’s well, if you add moringa seeds then they’re going to form big pieces of poo and settle on the bottom of the well? How is moving the poo from the top of the well to the bottom of the well going to make it more sanitary?

Even if the entire body of water is not potable, since the vast majority off well water is taken from the top of the well, or if someone fills a cup from the top of the water jug it is almost certainly from the top of the water jug, the process of flocculation per se will reduce the total quantity of fecal particles consumed by that individual.

Madu: So I should just quit it with the chlorine treatment and just start filling my water filter with moringa seed powder?

Al: If you possess the means, it would be advisable to do both, for flocculation in fact expedites chlorination and renders it more effective overall. Sodium hypochlorite – bleach – purifies water only by killing and removing pathogens such as bacteria and amoebas; however, it is limited by the overall mass of pollutants suspended in the body of water at hand. If each particle of sodium hypochlorite can kill and remove exactly one unicellular pathogen, and if the number of bleach particles is greater than or equal to them number of pathogens, then chlorination is an adequate method of water purification. However, if the number of pathogens exceeds that of bleach particles, then the population of pathogens can be lessened but not annihilated and can even grow resistant over time. Flocculation increases the efficacy of chlorination by floccing the pathogens together into a lesser number of larger, heavier particles.

Madu: So this moringa tree thing, all I have to do is plant the seed, maybe I should water it a little if I’d like but I don’t really have to, and the tree that grows out of it improves nutrition, it improves the yields of all of the other plants in its garden, and it can even make drinking water treatment more effective. Is there anything that this tree cannot do?

Al: To my knowledge, it remains unable to encourage Malians to wash their hands before eating and sharing their fecal matter through the common food bowl.