Civil engineer Chris Nganga Kimaru has developed a manhole protector grid (MPG) solution that uses GSM and Sigfox-enabled Internet-of-Things sensors and gateways to continuously monitor sewage flow rates and transmit the data to a management platform as an early warning system.

The MPG solution is positioned inside sewer manholes below the cover slab and above the pipeline. The system alerts authorities to potential blockages, thereby enabling proactive maintenance and reducing the risk of sewage spills.

The MPG can be installed in new and existing sewer manholes across South Africa and other regions facing similar sewage challenges, Kimaru says.

The improper disposal of solid objects and the theft of manhole cover lids for scrap value lead to frequent blockages and sewage spillages. South Africa has about 750 000 manholes.

The MPG approach will enable the country to manage multiple sites simultaneously and facilitate swift attendance to issues, he says.

"The MPG, which is made from durable, non-corrosive materials, can decrease incidents of sewage blockages by up to 70%, thereby leading to significant maintenance cost savings.

"By preventing blockages, the MPG helps maintain well-functioning sewerage networks, which is crucial during climate change-induced events like increased precipitation and flooding,” he states.

The MPG mitigates public health risks by reducing sewage spillages that contaminate water sources and helps protect aquatic ecosystems and soil quality, adds Kimaru.

Additionally, by retaining sewage within the pipelines and ensuring it reaches wastewater treatment plants, the MPG enhances opportunities for water reuse and recycling, which is especially important in water-scarce regions.

“The use of this sewage flow data within the broader water balance analysis will also contribute to municipalities’ task of reducing non-revenue water,” Kimaru says.

Dysfunctional sewerage networks are an issue in many developing countries, including South Africa, primarily owing to vandalism and improper disposal of rubbish, refuse and other unwanted objects into sewer manholes.

The problem the MPG addresses is widespread in developing countries across sub-Saharan Africa, Asia and Latin America. The problem is solvable, and the MPG can be an essential component of manholes during the design and construction of sewerage networks, he notes.

“This will ensure the long-term functionality of sewerage networks is maintained and benefits such as lower maintenance costs, less environmental degradation, better healthcare outcomes and reduced greenhouse-gas emissions are realised.”

“This technology enhances the efficiency and sustainability of sanitation infrastructure, and also optimises the functionality of manholes as a key cog in the wastewater conveyance system. Working sanitation systems contribute to lower water and sanitation infrastructure maintenance costs,” he states.