June 17, 2013
Daniel conducting preliminary experiments to modify the Bligh and Dyer procedure.
My research project here will be to analyze and determine if the fermentation of fecal sludge is the right and most efficient way to approach biodiesel. I will do this by quantifying the amount of lipid in the fecal sludge at every step of fermentation. In other words, we are going to take a new batch of fecal sludge and follow it through different stages of fermentation. Lipid samples obtained from each of these steps can be further analyzed and will give us an array of lipid types which will characterize the fermentation steps. By looking at the array and length of lipid in the fecal sludge, we can determine if fermentation improves the quantity and quality of lipid produced.
It has to be noted that fecal sludge contains 97-99% water. Therefore the first step of the experiment is on the distribution of lipid in the solid and liquid layer. Early results from this experiment showed that a good portion of the lipid exists in the liquid. This means that any attempt to filter or remove the liquid portion out will result in a significant loss in lipid yield obtained. Also discovered was that lipid content varies from sample to sample, even though they are from the same batch. Early results showed that the amount of lipid in each sample varies significantly. The cause of this variation will need to be further investigated.
The color of lipids in the chloroform layer. Note the difference of the three samples, left to right: total layer, liquid layer, and solid layer.
Based on these early experiments, it is concluded that the Bligh and Dyer extraction method would be the most appropriate in extracting lipid from samples of fecal sludge. This decision was determined due to the relatively low amount of solvent that was needed, compared to the Folch extraction method. Furthermore, the amount of lipid is far less than 2% of the volume of the sample (Note: Bligh and Dyer has a lower efficiency in extracting lipid from samples that contains more than 2% lipid).
Daniel with his first successful extraction.
The Bligh and Dyer extraction method utilizes the three solvents that are partially miscible in each other; water, methanol, and chloroform. The first step of this method is to create a monophasic solution of chloroform, methanol, and water with ratio of 1:2:0.8. This monophasic solution is intended to take the lipid out of the solid while the sample is being homogenized. The ratio is then raised to 2:2:0.8 to create a phase separation and further improved by adding weak salt solution to increase polarity, raise the ratio to 2:2:1.8 and create a two phase solution where the lipid would be in the lower chloroform layer.
As you can see, things are going great here in Kumasi.
June 4, 2013
In the last couple days, I’ve tried all kinds of new food. There’s a dish called “Red Red”, that is sold in a lot of “Chop Bars”, which are street food vendors. The “Red Red” dish is made up of red beans with onion powder, palm oil, rice, and fried plantain. There’s some sort of fish sauce that is optional, which I think is always good to have. The dish is pretty good, especially the fried plantain. I swear, I could eat just fried plantains for lunch.
Biweekly meeting of the Kumasi team at the fermentation site.
You can also get “fast food” in these Chop Bars and by fast food I mean fried rice with chicken. Each dish cost less than 5 Cedis (USD2.50), so I can’t complain. PROTIP: Even if you are a foodie (like I am) and you really want to try new things, don’t just say yes to everything. When the shopkeeper asked if I wanted something that I didn’t know the name of I just said yes and she gave me the spiciest food I have ever had. I was crying on the side of the Kumasi street while I was eating the food, it was that spicy.
I also attend the biweekly Kumasi Team meeting, where some of my colleagues reported on their progress. A lot of the teams have been making progress. As for me, I finished writing a report regarding transesterification of phospholipid and the effect that phospholipid has on the general biodiesel making process. My next project is to figure out how to get a lipid sample from the fermenter so that it can be sent to the states for further testing. The challenge is that the lipids in the fermenter have been diluted and we can only approximate it to be around 0.1 to 0.05% v/v. We need to send around 500ml to 1L lipid samples to the States for testing, so it is my job to figure out how to extract these lipids from approximately 1000L or 5000L of solution from the fermenter. The suspended solids and microorganism complicates the problem even further. This will be a nice challenge, I’ll see what ideas come to my mind in the next couple days
May 30, 2013
Today, I get to visit the lab in KNUST. It never occurred to me that a research lab could be so small. It has a limited amount of equipment. It has one weight scale, two big heating plates, some glassware, two ovens, and a rotovap. A rotovap! I was really excited about the rotovap. I don’t know why, but it seems like the rotovap is the fanciest equipment in the lab, and will probably be the most useful.
May 28, 2013
Today I visited the fermentation site. It is located close to the landfill and ponds where the fecal sludge is dumped. These ponds are far from an ideal treatment facility. In fact, these ponds are connected to the sea, so the fecal sludge that is dumped in these ponds is poured into the sea with little to no treatment. The fermentation site is built to address this problem. Although it is a pilot site, we hope that one day, this fermentation site could be a applied to all incoming sludge.
The fermentation site serves as the first step in the biodiesel making process. We are using yeasts and other microbial to produce fatty acids. The main research here is to determine the optimum residence time for this sludge, since we want to produce and extract the long chain fatty acids after acidogenesis, but before methanogenesis occurs.
Train of digesters.
As you can see in the pictures, there are two trains of digesters, each train consists of six digesters. Each digester could hold more than 10,000L of fecal sludge. Incoming trucks unload their fecal sludge into the receiving tanks. These tanks serve as the first step to filtration in order to prevent plastics from getting into the holding vessel. From the holding vessel it is transferred to the digesters at a rate of 5000L/day. Since each digester holds 10,000L and there are six digesters, the maximum residence time is twelve days. From the digesters, it is moved through other filtration units, which filters the sludge to improve the water quality before it is dumped.
Samples are taken every day in order to read the composition of each digester and the composition of the incoming fecal sludge. This is one of the biggest challenges that we face here. Fecal sludge comes from different places at different times. We have no control on how long that sludge has been sitting in septic tanks, or how long it has been fermenting in other places before coming to the site. Therefore, the composition of the feed varies quite a bit.
I haven’t had a chance to see the lab yet, but I look forward to see and starting work in the lab.
May 23, 2013
At last I arrived in Ghana. The 15 hour flight from SFO to DBX (Dubai) and the 12 hour layover from DBX to ACC really sucked the energy out of me. First thing I noticed is the heat. I didn’t think it would be that hot when I looked at the average temperature online, but trust me, it is hot. I wanted to look professional so I wore a three layer suit and it was a big mistake.
At the airport I met with Tim Wade and Bob Armantrout from Waste Enterprisers. They are really nice people. From the conversations I had with them, I realized they hadn’t developed anything new for the biodiesel project because their focus has been on the conversion of lipids in the fecal sludge to biodiesel. It sounds like they want me to identify the lipids contents and composition within the fecal sludge. I couldn’t wait to see what’s in store for me for the next 3 months.
Neighborhood where Daniel is living in Kumasi, Ghana.