Biofilter Refurbishment

Melbourne Water Eastern Treatment Plant

The performance standards for the biofilter beds at Melbourne Water Eastern Treatment Plant’s (ETP) were not being met due to the organic media becoming severely degraded to the point that it was impeding flow. A drop in foul air extraction and an increase in asset deterioration resulted from this degradation. The biofilter consists of five separate “Blocks” that each contain six “Cells” to treat a combined flow of 195,200 m³/hr (54,222 L/s) of air.

Bioaction was contracted to refurbish the biofilter at the ETP site and recommended the beds be refurbished with Hanit Raised Aeration Flooring and FiltaMin media. Due to its superior air flow design and corrosion resistance, Melbourne Water chose to replace the flooring of each cell with the Hanit Flooring system and fill four blocks with like for like organic media (wood chip) while one block was filled instead with FiltaMin media.

The scope of works for the project included:

  • Removal of the expired and contaminated media as hazardous waste
  • Cleaning, repairing and sealing the cells
  • Removal of existing flooring for recycling
  • Supply and refilling four blocks with like for like organic media
  • Supply and refilling Filtamin media in the remaining block
  • Commissioning
  • 3rd Party Performance testing

Decommissioning revealed a number of damages to the HDPE lining, access doorways and precast concrete walls that Bioaction’s installation team swiftly rectified to minimise the impact on the installation timeline.

With all necessary repairs completed, the Hanit Riased Flooring System installation was extremely successful, requiring only a small labour crew and standard power equipment resulting in a quicker construction time. To fill the cells, Bioaction hired local, knowledgeable and experienced machinery contractors.

Although the like-for-like organic media reduces the volume of gas with the Hanit Raised Flooring, Performance testing revealed that FiltaMin media outperformed conventional Biofilter organic media types. The results in lowering H2S when combined with the Hanit Raised Aeration Flooring technology far exceeded performance expectations.

Biofilter Refurbishment 1
The organic media had decompose to >25% of its original volume
Biofilter Refurbishment 2
Installation of the modular Hanit Raised Flooring system using traditional power tools
Biofilter Refurbishment 3
Filling the biofilter with FiltaMin in bulker bags proved highly successful, safe and efficient

ETP Gas Reduction Results

Hydrogen Sulphide57%99%
Carbonyl Sulphide31%55%
Methyl Mercaptan99%93%
Ethyl Mercaptan0%99%
Dimethyl sulphide93%68%
Dimethyl disilphide91%13%

Melbourne Water has offered good positive feedback and is interested in using FiltaMin to replace the organic media in the remaining four blocks. This will lessen corrosion in the treatment plant, cut down on refurbishment cycles, and lower H2S gas emissions in order to comply with regulatory requirements.

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