Looking at wastewater as a resource might come as a new concept in developing countries with a centralized wastewater infrastructure and treatments.
The AP Infrastructure article, “Tapping the power of wastewater,” focuses on the advantages of tapping wastewater’s potential to generate renewable energy to be used back in current sewage treatment systems.
The article says that existing sewage treatment plants consume up to 3% of global power and 20% of power use on public utilities. However, some countries are beginning to use wastewater’s potential to generate renewable energy to their advantage.
According to the article, a standard wastewater treatment consumes around 50% of its entire power needs during aerobic activated sludge treatment by aeration.
However, an alternative technology is available to harvest wastewater’s energy converting it to gas, which is quite similar to how India’s biodigester works.
The energy generated from wastewater can then be used to power wastewater treatments plants, making them energy self-sufficient. In case of a power surplus, treatment plants can sell it back to the grid, helping reduce their utility bills.
In developing countries like India, biogas digesters are common in small agricultural communities and used as home-based biogas for cooking and generating energy. Biodigesters also addressees the country’s two major problems – energy and sanitation.
The article mentions two countries already employing this technology, Copenhagen, Denmark and Turku, Finland. Both have energy-positive wastewater treatment plants, which harvest the intrinsic thermal and chemical power of wastewater.
Converting the chemical energy of wastewater can double the energy supply than consumed, but using both thermal and chemical energy, energy supplied can be up to nine times higher than consumed, the article says.
An alternative energy producer in Missouri, Roeslein Alternative Energy, has enhanced the anaerobic digestion of wastewater to produce two bioproducts – pipeline-quality renewable natural gas and the remaining biosolids fertilizer.
According to Energy.gov, the plant uses a technology incorporating biomass char within the digester to capture and absorb carbon dioxide and other contaminants. It is an important step to upgrade biogas to renewable natural gas before passing through the pipes. The company also partners with livestock farmers to source livestock waste and biomass, which the plant converts to pipeline quality renewable natural gas.
Climate change, population growth, increased urbanization, and industrial activities stretch our water supplies and water infrastructure capacity.
Uptake of new wastewater technologies that view wastewater as a resource can be an excellent solution to climate change.
The process reduces waste by recycling it, cuts back GHG emissions in the process, and boosts power supply through renewable natural gas.
Governments, urban planners, and decision-makers should start re-thinking wastewater as a resource and invest in the technology and infrastructure to tap its potential.
The video below shows how the Kakola heat pump plant process warm wastewater and provides heat for 12,000 Turku residents.
PHOTO CREDIT: Turku City Hall by Markus Koljonen (Dilaudid) – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4484878