Sewage as an energy source

Optimizing necessary operational costs to treat sewage of a large city. The challenge was not simple, but the solution was "in-house", made it possible by the installing a cogeneration power system. 
Turning sludge into eletricity

A treatment plant that generates its own energy

The AMBIENT - Environmental Services of Ribeirão Preto S / A, a company of the GS INIMA Brazil group, still in the 1990s, became responsible for the sewage treatment of Ribeirão Preto, São Paulo. Generating water, sludge and gas, as is expected in structures of this kind, the treatment plant offered a potential that the company would like to see turning into reality: becoming a source of energy to supply its own operation. 

When sewage becomes electric power

Ribeirão Preto is one of the main cities of the state, located in the Southeastern Region of Brazil, the most populous in Brazil. There, AMBIENT treats an average of 135 million liters of sewage per day, generated by a population of approximately 700 thousand inhabitants

In addition to investments in technology directly related to the treatment of collected sewage, AMBIENT has always realized, in its own raw material, an opportunity for operational improvement. In 2011, an idea consolidated as a fundamental resource to achieve this kind of evolution: the implementation of a system that uses the product of sewage treatment as an energy source.  The solution found was a power cogeneration system. 

The project is doubly ecological. First, it uses biogas as fuel in the engines, avoiding the emission of methane into the atmosphere. Second, because biogas is a source of energy which use doesn't cause depletion of natural resources, allowing a clean energy production. With the project implementation, the company nowadays generates about 50% of the energy used by the treatment plant.

In very simplified terms, the project uses the cooling water from the motors to heat the sludge through heat exchangers, this system causes the sludge of the digester to be heated to approximately 35ºC, thus improving the efficiency of organic matter degradation, in addition to contributing to the generation of more biogas. 

To execute the project, AMBIENT acquired two SFGLD560 generator sets, which are part of the portfolio of Siemens. Together, the two engines provide 1.5 MW of power. The electricity generated from biogas, produced in the sewage, is used to attend the treatment plant itself, allowing a reduction of expenses with the network electricity.


Ambient Environmental Services

Sewage treatment

Sewage treatment 135 million Of liters/day.

Equivalent to a population of 700 thousand inhabitants

Ambient Environmental Services

Biogas power generation system

SFGLD560 Generators

1.5 MW

Ambient Environmental Services

Biogas power generation system


Of the energy consumed in the station operation

Turbine Portfolio

Conventional Energies

The generation of electric energy can be done through diverse sources of energy, and in most times a rotating equipment activates an electric generator. Siemens has in its line of products rotating equipment for these kind of activations.