More Data Crunching

So, today has been a little bit topsy-turvy because the President (of Bangladesh) died yesterday (aged 85) and so there has been an impromtu public holiday...but so impromptu that some places are taking time off, and others aren't.  Thankfully we managed to get the samples over to the icddr,b and had a good chat with Dr Zahid there.

He's got some initial results from the first and second tests (raw sludge and 5 day-matured sludge) and we're seeing a factor 10 reduction in E-Coli and C. Perfringens.  I'll graph the results and get them up asap.

Suman also told me that while they were taking samples, the sludge was so hard it was breaking the (disposable, plastic) spoons they were using to collect material.  What this says about the quality of disposable cutlery here, versus the dryness of the sludge I don't know, but I reckon that's a good result - we can dry sewage slop to a hard cake in 5 days, with a meaningful reduction in pathogens.

I've also been looking at the temperature differences in the three beds, compared to those measured from our weather station (on the top of a bamboo pole next to the site):

This will probably be too tiny to read on the blog, but the green line is the bed that was vented for 12hrs during the day, and closed at night, the red line is the bed that was vented 24/7, and the blue line was our control, the open bed.

The spikes occur in the mornings, between 7am and noon, and the flat-ish bits between them are around 2pm-3am.  This means there is the greatest difference between outside and inside (the roofed beds) in the morning, indicating that they are gaining heat rapidly once the sun rises, and also, they are retaining heat overnight.  The last three or four spikes are where we closed the green-line bed 24/7, so it was basically a greenhouse, and you can see it was retaining more heat at night, and performing marginally better that the open bed during the day.

I'm not sure why the vented bed also improved its performance over the last few days, and I will ask Practical Action if they did anything to the roof during this time.

Anything from the minibar?

If anyone asks, I've got some SOIL SAMPLES in the fridge...

Taking them to the icddr,b later today - they might even have some initial pathogen testing results for us too - so much excitement in 24hrs!

Phase 2 Initial Results

So, I've had the data for an hour or so this evening, and this is what we've got:

We've got some interesting step-up effects going on with the beds with roofs on (red and green lines), whereas the open bed (blue) is tracking the external weather conditions (purple) pretty faithfully.  The weather station is about 15ft up on a bamboo pole, hence it's a few degrees cooler than 6" above the sludge which is where the temperature sensor was hung.

The green line is from the bed where we had it open during the day, and closed at night, and on the 17th we switched to having it closed 24/7 to try and 'bake' the sludge.  It does seem to have lifted it a few degrees above the fully vented approach (red line) for these last few days, but I'm not sure its a conclusive difference.

Also, we hit the magic 55 degrees for a few hours which is pretty exciting!

And check out how closing the roof at night keeps the beds up to 5 degrees warmer than leaving them open...

The more I look at this the more I think I may need to tweak my trendlines...when you look at them individually, the step-up effect is much more pronounced once we closed the roof 24/7...

Anyway, it all looks good to me so far.  More analysis tomorrow.

Hotels and hartals

We've got hartal's Monday, Tuesday and Thursday this week.  Which basically means I can't leave the hotel, or at least definitely not the immediate area.

So, I've been entertaining myself catching up on emails, clearing out all those old ones at the bottom of my inbox, and updating the blog!

What do you think of the new layout?!  I've still got some gremlins to sort out, but it's a bit more glamorous than it was.  I'll keep tinkering over the next few days, so keep checking back to see it's latest incarnation...

UPDATE: Wednesday 20th March

Back in the office today, and waiting for the car to come back that's gone to collect our last round of samples and data from the site.

We've asked the guys from Practical Action to do the sampling for us, and they are going to bring the samples and equipment half-way back to Dhaka, where a WaterAid driver is going to meet them and bring it all back to the office.

 As I've been away from the site for most of this test, I can't wait to see what information we've got on the temperature and weather sensors!  I'm consoling myself that my forced absence means that we've inadvertently done some capacity building with the PA staff, as they now know how to undertake the sampling process and could feasibly do it without our instruction.

It'll still be a couple of weeks before we get the pathogen results back from the lab at the icddr,b so we won't know about pathogen reduction for a while, but it'll be great to see if the higher (anticipated) temperatures have had an effect.

I'll report back with some initial results later today.

Round two - halfway through

Sunday 17th March

Its a public holiday today (one of the 24 they'll have this year!) - to commemorate the birthday of Sheikh Mujibur Rahman, 'Bangabandhu' ('Friend of Bengal').  He is seen as the father of the nation, and his eldest daughter is the current prime minister.  More info here: http://en.wikipedia.org/wiki/Sheikh_Mujibur_Rahman.

Suman has been a trooper and gone down to site today to collect another round of samples (so we can track pathogen decay after 5 days and 10 days) en-route to another project site.  The driver returned to Dhaka with them, and I've just put them in the bath!

 I was going to unpack them and put them in the fridge, but the ice is still pretty thick, so I'll let them melt quietly overnight and drain off any excess water in the morning, before we take them to the icddr,b.

I sketched up a little sampling plan for Practical Action last time I was there, and this gives a pretty good idea of the current site layout (numbers correspond to sampling points):

Computerised version of sampling plan sketch

Apparently, the open bed is the most liquid of the three (open/ roof+vented/ roof+closed at night) and the middle bed, which is open at both ends, is almost dry! It's only been 5days, and they each have 900L of sludge on them, compared to 500L in the previous Phase!  This is Good News.

They are all still dripping a bit at the gate valve, showing water is still draining out of them, and apparently some was also coming out from the end of the reedbed, so the 13th sample was taken too (I suspect this is because the reeds are still very young and the bed is still maturing).

They have been raking every day before 9am, when the temperatures in the bed are closest to outside temperatures (to minimise heat loss when the roofs are removed), and perhaps in the next (and final phase) we will try non-raked versus raked to assess how much impact it has.

We are now trying a 'baking' approach and closing the end of the bed that was being closed just at night, but now keeping it closed 24/7 to assess the temperature gain from having a sealed drying bed.

We've got hartals ('closed doors') tomorrow, Tuesday and Thursday.  They are basically national strikes, making it hard to get out and about, and it's inadvisable to go out after dark in case anything (riot-y) kicks off.  This means I'm making a bid for Faridpur on Wednesday so I can get there again before I leave on Friday!  I'll keep you posted on whether I make it back before the city shuts down!

A Weekend in Dhaka

Friday 15th/ Saturday 16th March

I did my (now) usual Friday walking tour with the Urban Study Group.  I was excited about this one as we were going to see the waterfront - a part of Dhaka I've never actually dared venture to!

Waiting outside Sutrapur Police Station for the group to assemble, you can already see bits of old rubbing up against the new...

 After setting out from the  Sutrapur Police Station we first visited the Reboti Mohan Das Residence, the palatial building built in Neo Classcal style which used to overlook the famous canal of Dhaka the Dholai Khal. Unfortunately, the canal was filled up less than 20 years ago, and is now a barely used road (I'm not sure it actually goes anywhere).

 

Reboti Mohan Das Residence

Reminded me of my red and cream bike at home...

 The house is now used by the Dhaka fire service (or equivalent) and used to home about 60 families of its employees.  In one way it's nice that it's being used, but it would be an incredible tourist attraction too!

We then visited Kalicharan Shaha Street. The most unique feature of the Mohalla is that, it has experienced very little change, most of the buildings from the colonial period have survived so far.

Now a kind of college residence

Internal courtyard of the residence

Detail of relief tiles originally made in Calcutta

Detail of the woodwork

The top of the building says '1915 Mongol Alaya'

We then walked through a market and some paper recyclers!

Recycling in full swing

The dust in the air made it hard to stay for long - we soon started coughing and spluttering - goodness only knows how they tough it out.

The main highlight of the walk was Ruplal House,the waterfront palace, which has been converted into a vegetable/spice market and Lalkuthi.

The market makes it almost impossible to take a full-frontal photo of, but here's one I found from the 19th Century, of what it used to look like:

And bits of it now:

The rusty roofs are the spice market which have taken over the ornamental gardens

The internal courtyard

 The current waterfront:
 

Had a lovely (late) lunch at the American Club with a fellow walker, and crashed out at the hotel after a tiring day in the heat of the city.

Saturday was mainly chilling out at the Nordic Club spa with a friend from the garment industry, getting our nails done and remember what it is to be clean and girly!

Back to poo tomorrow...

A useful day in the office

Thursday 14th March

On Thursday I was working in the WaterAid office, and in the afternoon presented the project to our colleagues there.

It was good to share the project with others, particularly as we now have a growing team working on the project.  We have a new project officer, and a lady working on some of the social aspects of the project.  Along with Suman and Opel, that now makes four in WAB.

It was also useful as Mamun and Dipok from Practical Action joined us, and we discussed several further design developments:

Rubbish Net:  Unlike our previous sludge from Phase 1, this sludge was full of detritus, bits of plastic and general rubbish.  It wasn't obvious when they collected the sludge, but as it settles in the drying beds, the rubbish is floating to the top.  We talked about pouring the sludge into the beds through a coarse net to capture the rubbish, which can then be dumped in a pit on-site to degrade safely.  This may also mean we do not need a splash plate, but we shall see.

Lightweight Roof:  With all the additional framing, the roof is now found to be too heavy, and a more lightweight design is to be explored.  Mamun has spoken with some of the local CNG drivers, and the polythene they use for their windshields is thought to be good - tough and won't rip.  So, amusingly, seeing as this was something we suggested way back in the beginning, it looks like we might end up with a poly-tunnel after all!

Scaling and sizing:  We have sought to develop a modular design that can be scaled up to suit demand.  The beds themselves will be relatively easy to scale, but now we have the reedbed element, we will need to be careful it doesn't get too large.  However, I am not convinced that we really understand what volume of water is draining out of the sludge - reedbeds are based on an average daily flow - and as we have an exponentially dropping flow over time, we used the worst-case first 24hrs.  However, as the reedbed works with a plug-flow, I am now wondering whether we could have used a smaller version, and taken the total expected volume, and divided it by the number of days...The issue then being, what proportion of water drains out and what is evaporated.  perhaps next time, we will focus more on moisture content, and measure the initial moisture content more accurately, along with the total volume drained.

Sludge temperature:  As our initial question was around which roof generated the most heat underneath, we have been measuring air temperature over the sludge, rather than the actual sludge temperature.  We have been assuming that air temperature is a useful proxy.  However, it would be good to now understand more about the actual sludge temperature relative to the air temperature.  Practical Action said they had some sensors they could use, so we might try this for the second half of the test, and definitely for Phase 3.

Volumes of sludge:  The team working in Khulna are keen to bring the drying beds to their town, but before we can do that, it was suggested that they need to get a better idea of what volumes of sludge they will need to be treating, and how often.

Soil testing:  We need to get the now composted material from Phase 1 tested, and arrange for the material from this Phase 2 to be tested too.

So, still more work to do before we get to a final design, but each time we run the test we are learning more, and gaining experience, so I do not think any of our efforts will have been wasted.