Sewage-to-energy could cut costs and reduce greenhouse gas emissions

MOST people flush the toilet without thinking twice about where the contents end up, but the National Agricultural Research and Extension Institute (NAREI), having recently conducted a study on “bioenergy (biogas) from sewage system” has indicated that it should be seen as a resource rather than waste.

The study was part of an investigation of Bioenergy utilisation in Guyana including environmental and economic impacts done by NAREI’s Chief Executive Officer (CEO), Dr. Oudho Homenauth and Dr. Clairmont Clementson.
The research, which was aided by Research Assistants, Lalita Gopaul and Vickram Persaud, has found that the conversion of sewage into energy could not only cut costs but reduce greenhouse gas emission.

According to the report, an average household of four persons can produce about 40 gallons of waste water which contains one pound sludge. Approximately 14.8 tonnes of sludge can be produced daily from a population of 118,363 (Georgetown’s population in 2012).

The report stated that one tonne of sludge can produce approximately 270 cubic meters of biogas so, with Georgetown’s population, 1,458,084 cubic meters of biogas can be produced annually replacing 1622 barrels of liquefied petroleum gas.
While this will be a success for the country, there are some challenges involved. For one, the Guyana Water Inc. (GWI)’s sanitation manager hasstated that sewage sludge is generated after the treatment of sewage, therefore, the major impediment to its utilisation is the lack of a treatment facility.

There is also a lack of sewage networks in Georgetown. Currently, only five per cent of the city’s population has access to the system, and the installation and use of such a system may require a fee which residents may not agree to pay.
Additionally, the manager opined that GWI may have a challenge in getting residents to understand how the system works and why it is beneficial to use instead of septic tanks. Another challenge to the utilisation of sewage sludge would be the setting up of sewerage networks in places other than the city.

In rural parts of Guyana, there is no connection to the main sewage system. Residents, schools and other institutions commonly utilise a septic-tank system to manage their sewage. Settled solids are digested anaerobically while excess liquid usually in a clear state is drained via an outlet into a drain field.

According to the report, there is usually a vent attached to the tank where biogas escapes. On a small scale, biogas from septic systems can be used for cooking and lighting. To overcome these potential challenges faced by the GWI require political will, funding and skilled persons to carry out such projects.

GWI is partnering with the Caribbean Regional Fund for Wastewater Management and the Inter-American Development Bank (IDB) to develop sewerage networks in the city, the town of Bartica and in the new housing schemes, through collaboration with the Central Housing and Planning Authority.

Furthermore, there are plans within GWI’s five-year development strategy to build a treatment facility at Tucville and another where local septic tank sludge collectors can treat their waste before releasing it into the Atlantic.
After these facilities are up and running, sludge would then be available to be used to produce biogas.