Clean Blocks

TU Delft is working with IIT Kanpur to demonstrate the use of clean blocks as a filter to remove particles, organics and nutrient from the drain water of the Barapullah Drain


Working principles

Clean blocks are specially produced drain blocks, consisting of mineral wool cubes that are used to filter sewage and to treat the water by the biological activity within the filters.

This technology focusses specifically on removing turbidity, COD, NH4-N and PO4-P and doesn’t require energy to operate. The filters will be tested as a passive in situ treatment step in the drain when the hydraulic capacity of the drain is sufficient during dry season, and as a pre-treatment of the PAS system on site.

The clean blocks consist of cotton candy made from molten rock with densities 120 – 80 – 45 kg/m3

High porosity > 98%

  • High hydraulic conductivity ≤ 1 m/min
  • High filtration rate
  • Large internal surface area
  • Biofilm formation
Clean blocks of mineral wool cubes

Main goals

  • In-situ drain treatment for overall water quality improvement
  • During dry season
  • With cascades and bio filters
  • Oxygenation and nutrient removal
  • Design focus: TSS or nutrients?

Involved partners