CORDIS

Hydrogen sulphide (H2S), a toxic, foul-smelling and highly corrosive gas, is a major challenge in wastewater collection systems where it causes the premature deterioration of sewer pipes, wells, pumps, motors, and other assets. In addition to accelerated asset deterioration, the gas also poses significant worker safety concerns, and “rotten-egg” odour nuisances with a severe negative impact on the quality of life for affected residential areas. It is estimated that the annual worldwide direct cost of asset corrosion in the wastewater industry exceeds €1.4 trillion.

To avoid the negative effects of hydrogen sulphide, water utilities spend a significant share of their operating budgets on mitigation initiatives including the dosing of neutralization agents (chemicals), but as the gas is notoriously difficult to measure in the harsh environments found in sewer systems, mitigation actions are often inefficient. Without a clear overview of the real-time development of hydrogen sulphide in complex sewer systems, utilities often dose chemicals in excess and are forced into making long-term asset management decisions on an uninformed basis.

Existing sensor solutions typically measure hydrogen sulphide in the gas phase only, however, the data collected by these sensors does not provide a full overview of the challenge, as they often underestimate hydrogen sulphide levels and as they are unsuitable for deployment in many sewer environments.

Based on the extensive knowledge in developing, constructing and applying microsensors, Unisense has developed a cost-effective and robust sensor for continuous monitoring of liquid-phase hydrogen sulphide in wastewater collection systems. Built for long-term deployment in extreme environments, the novel iMEC sensor enables utilities to map the development of hydrogen sulphide in sewer systems in real time. Using this approach, the sensor technology enables utilities to; cost-optimise chemical dosing strategies to reduce operating costs, locate the source of hydrogen sulphide development in complex sewer networks for efficient mitigation, and make long-term planning decisions on an informed basis to increase the lifespan of assets.

The liquid-phase measurements of the iMEC sensor represents a radically new approach to hydrogen sulphide monitoring in the wastewater industry, and the overall objective of the iMEC project is thus to overcome prominent barriers of entry that may hinder the market uptake of the new technology. Furthermore, Unisense aim to mature the technology and its production processes, and clearly demonstrate the sensor’s value-added benefits through large-scale demonstrations and product certification.