B-Sludge Advanced Sludge Treatment

The B-Sludge system is a flexible and advanced solution for the treatment of organic sludge, from diluted to dewatered streams. Designed to handle a wide range of Total Suspended Solids (from 1% to over 30%), it equalises sludge concentration through mechanical pre-treatment, ensuring optimal conditions for downstream processes. The pre-treated sludge is then processed via hydrothermal carbonisation (HTC), maximising efficiency and performance, before undergoing solid–liquid separation through a filter press that operates without the use of polyelectrolytes.

Managing sewage sludge is a complex challenge. With B-Sludge, every treatment stage is engineered to work together, improving overall process efficiency, reducing environmental impact, and unlocking new value from waste. Explore how each step contributes to a more sustainable sludge management model.

CHARACTERISATION AND PRE-TREATMENTS

Before any treatment begins, it is essential to fully understand the sludge being processed. Sludge characterisation provides this insight through a comprehensive analysis of its origin and physico-chemical composition, carried out in our laboratory. This step acts as our guiding compass. It enables us to design and configure plant modules with precision, optimise chemical consumption, anticipate sludge behaviour in subsequent processes, and prevent operational inefficiencies. The result is a more efficient, reliable, and cost-effective treatment process, delivering measurable savings and improved overall plant performance.

Once the sludge has been fully characterised, it undergoes a series of targeted pre-treatments designed to maximise its treatability and minimise operating costs. Key pre-treatment steps include thickening and turbo-dissolution, which ensure the sludge is perfectly prepared for the downstream processes, improving efficiency and overall plant performance.

Thickening concentrates suspended solids, reducing sludge volume and achieving a solids content of up to 10–12%. By removing a significant portion of free water, the process delivers tangible benefits:
  • Reduced footprint: Less sludge to treat downstream means more compact and less impactful plants.
  • Lower energy consumption: Smaller sludge volumes require less energy, translating into operational savings.
  • Enhanced downstream performance: Thickened sludge is easier to handle and process, improving efficiency across all subsequent stages.

Turbo-dissolution is a pre-treatment technology, ideal for sites handling pre-dewatered sludge while optimising costs and transport frequency. Using available on-site technical water, the process adjusts sludge to a controlled liquid concentration, typically around 12% Total Suspended Solids (TSS). Key benefits:
  • Optimised for downstream recovery – prepares sludge for subsequent stages.
  • Stable and homogeneous – ensures consistent performance in downstream processes.
  • Efficient HUBs – enables centralised treatment and economies of scale.

HTC: TURNING SLUDGE INTO A RESOURCE

Hydrothermal Carbonisation (HTC) is a key stage in the B-Plas process for upgrading sewage sludge. This thermochemical treatment, carried out at 180–200°C under autogenous pressure, transforms sludge into hydrochar – a carbon-rich biomass with high energy content.

The technology uses a series of sequential reactors in an alternating batch configuration, enabling continuous treatment while maintaining process efficiency. A dedicated heat exchanger further optimises energy use, making the process both sustainable and effective.

  • Solids and COD solubilisation – improves treatability and downstream processing.
  • Volume and mass reduction – reduces sludge by up to 80%.
  • Enhanced solid–liquid separation – modifies the colloidal structure without polyelectrolytes, achieving high dry matter content.
  • Bioavailable carbon – releases carbon into the liquid fraction, supporting biogas and volatile organic acid production.
  • Energy efficiency – exothermic reactions and heat recovery minimise energy consumption.
Fully integrated into the B-Plas process, HTC ensures effective and sustainable sludge pre-treatment, maximising overall system yield and creating new opportunities for by-product valorisation. It represents a concrete step toward circular and decarbonised sludge management.

Ensuring effective treatment and optimised processes starts with detailed sludge analysis. Using our in-house laboratory or certified external partners, we characterise sludge samples before and after HTC treatment. This data-driven approach allows us to customise the B-Plas solution for each site, ensuring maximum efficiency and performance based on the specific characteristics of the sludge.

SOLID-LIQUID SEPARATION

The HTC treatment modifies the rheological properties of the sludge, enhancing solid–liquid separation through a filter press without the use of polyelectrolytes.
This stage is critical for the overall efficiency of the B-Sludge module, enabling significant volume reduction and the recovery of valuable resources.


Supplied by Diemme Filtration, the filter press applies high mechanical pressure (up to 15 bar) to the filter plates, retaining solids while efficiently draining water enriched with bioavailable COD from the HTC phase.

Key benefits:

  • Superior filtration efficiency: Post-HTC sludge has a more aggregated, less colloidal structure, enabling excellent filtration without additional conditioning agents.
  • Significant volume reduction: Sludge is reduced by up to 80% compared to traditional separation methods, thanks to HTC solubilisation and high dry content.
  • Resource recovery: The pathogen-free liquid fraction, rich in COD, can be reused in biological stages or as a chemical substitute within industrial processes.

Fully integrated into the B-Plas process, the filter press ensures effective and sustainable sludge treatment, maximising overall system efficiency, reducing waste volume, and opening new opportunities for by-product valorisation. Output materials are then characterised in our in-house laboratory or via certified external partners, completing the process.

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