Dear Leonardo,
Really fascinating idea to use feacal sludge and solid organic waste to produce gasoline and diesel. Thanks for sharing your research with us. It would be nice to know how your project has proceeded. Have you made progress regarding your lab test and examination of the feasibility of your idea? Did you manage to obtain funds to explore your innovative proposal further?

I also have some more specific questions regarding your research:
- You mention that you consider a mobile central processing plant; what are the benefits of having it mobile? You are talking about a daily input of about 20 to 80 tons, which sounds like high amounts for a mobile plant?
- You have sketched on a business model for a full project requiring large investments. Have you considered developing a small-scale pilot outside of the lab to test your idea?
- Apart from water, what other sub-products will be generated that cannot be recycled in the process (considering that there should be an accumulation of nutrients)? What does this sub-product look like and what treatment will is require enable a safe reuse?

Looking forward to get some news from your project!

Best regards,
Kim

I would like to update the status of the project.

The experimental part of the project has been delayed because of lack of funding. Right now we are working on a new approach for the concept of the plant, going step by step. First, we will be focusing on sludge gasification.

Nevertheless, if any of you reading this are interested in any of the subjects that were treated throughout the project, please let me know if we can help.

The main topics to discuss could be any of the following:

• Waste gasification
• Plasma torches
• Fischer Tropsch processing
• Syngas production and cleaning
• Bio-crude, syn-crude distillation
• Sludge drying

Hello, My name is Leonardo De Silva Muñoz. I am a Chemical Engineer with a Ph.D. in process engineering. I live in Mexico and have been involved in different alternative energy projects since I finished my Ph.D studies in the National Politecnic Institute of Toulouse, France. I welcome you to the discussion forum about the project: Mobile Waste to Liquid Fuels Conversion Plants, which was funded by the Bill and Melinda Gates Foundation through the Grand Challenges Explorations program (Round 7).

Title of grant: Mobile Waste to Liquid Fuels Conversion Plants
Subtitle (more descriptive title): Development of a faecal sludge and solid waste processing plant for the production of liquid fuels and/or electricity integrated on a mobile platform.
Name of lead organization: Alianza para la innovación en integridad de infraestructura y ductos A.C (AI3D)
Primary contact at lead organization: Leonardo De Silva Muñoz
Grantee location: Cuernavaca, Mexico
Developing country where the research is being tested: Mexico

Short description of the project:
Waste to energy conversion is a promising route for reducing the fossil fuel dependency of the world. Fermentation, chemical processing, pyrolysis and gasification have been the main processes used for transforming biomass and other “burnable” wastes into useful fuels like ethanol, methanol, biogas, bio-diesel, bio-oil, bio-hydrogen etc. Most works on the subject are focused on power generation or on the production of alternative fuels, while few consider the option of producing gasoline or diesel. Here we propose a processing plant that produces gasoline, diesel and electricity using faecal sludge and solid waste as feedstock. The proposed plant will use a gasifier to produce a mixture of hydrogen and carbon monoxide known as syngas and a Fischer-Tropsch reactor that will produce synthetic hydrocarbons that can be refined in order to obtain liquid fuels. Both gasification and Fischer-Tropsch synthesis are performed normally at large scales. Aiming at a small scale mobile processing plant that can transform waste at the source, the main challenge of the project is to prove the technical and economic viability of the proposed plant.

Goal(s):
The goal of this project is to design and construct a small-scale waste treatment plant for faecal sludge and municipal solid waste mixtures based on plasma gasification. The
treatment system will be fitted into a truck in order to make it mobile. The energy needed to operate and transport the plant will come from the waste mixture being treated making it a self-supporting system.

Objectives:
- Harness the energy contained in faecal sludge
- Storing it in the form of a high value fuel
- Turn faecal sludge into something valuable
- Make pit emptying more profitable and safe





Start and end date: November 1st, 2011 - October 31, 2012
Grant type: Grand Challenges Explorations, Round 7 (GCE R7)
Funding for this research currently ongoing: The technical tasks of project are in pause. We are working for funding from the BMGF in order to continue the project.
Research or implementation partners: Corrosion y Protección Ingeniería, Institute of Physical Sciences, UNAM.

Results so far:
The first phase of the project consisted in a theoretical approach by modelling the gasification and Fisher-Tropsch reactors and through an energy and mass balance in order to estimate the mass and energy flows for different mixtures of solid waste and faecal sludge. Available technologies were also identified for the different steps of the process.

The overall energy and mass balance of the modelled process showed that it is possible to produce hydrocarbons from the gasification of Faecal Sludge and Municipal Solid Waste (MSW) mixtures, with a liquid products yield from 10 to 55 litres per metric ton of waste.

The gasoline and diesel production rate depends on several variables such as waste mixture composition, oxygen flow rate, gasifier temperature and gasifier efficiency.
With the developed model, several scenarios with different water content and overall system efficiency were tested. Oxygen input was always optimized in order to get a self supporting system (the higher the oxygen feed, the more waste is burned, which is one of the energy inputs in the system). In the real scale, oxygen feed can be controlled through a variable speed compressor, blower or air pump that delivers air into the gasifier. The water content in the mixture can be controlled by changing the proportion between solid waste and faecal sludge being fed into the gasifier.

Results have shown that in general, the higher the water content in a waste mixture, the higher the energy input required for the waste gasification. Mixing Faecal Sludge with MSW reduces the water content per ton of waste, which reduces the energy requirements of the gasifier. The higher the MSW content in the mixture, the higher the yield per metric ton of waste.

We have not yet a detailed economic study because the different technologies are not yet commercially available at the scale we intend to use them. The final dimensions of the system are also not determined yet. We have to do some experimental tests first in some of the parts of the process in order to have an estimate on size, weight and cost for the tested technologies.





Business Model
• Target capital cost: 750,000 USD/plant
• Target time to investment return: 3 to 6 years
This could need:
• 20 to 40 tons per day of mixed MSW and Faecal Sludge
• Central (mobile) processing plant
• Optional satellite supplying vehicles (300 m radius)

Main challenges / frustration:
We had some trouble with the analysis of faecal sludge samples. Some samples were lost due to inappropriate handling. Also, obtaining quotes on certain equipment such as plasma torches and Fischer-Tropsch reactors, were difficult to get, taking several weeks in some cases, or not getting them at all from some suppliers.

Current state of affaires and outlook:
We are about to start the second phase of the project where real data will be obtained by performing experimental testing of the proposed Fischer-Tropsch reactors, the gas cleaning systems and most probably the electricity generation module using syngas and light hydrocarbons as fuel. These tests will demonstrate the feasibility of producing liquid hydrocarbons for different possible gas compositions that could be obtained from a gasifier for a given waste mixture, as well as the syngas cleaning system size and performance requirements in order to allow the FT reactor and the electricity generation system work properly. The tests will be performed at a lab scale. Size and weight of the systems being tested will be estimated for a prototype scale plant.



Links, further readings, etc:

Documents in SuSanA library: www.susana.org/en/resources/library/details/1744
(includes presentation and paper at FSM-2 Conference in Oct. 2012)

- The video of my presentation at the FSM2 Conference: