Lower carbon footprint

Many of Cambi’s clients and their consultants have estimated the reduction in carbon footprint by introducing THP compared to their previous sludge and waste management practices. Various independent papers and articles summarize the analysis:

  • In 2011 Aecom and China’s Ministry of Housing and Urban Development, studied “International best practice of sewage sludge management”. The study included carbon footprint
    analysis of 15 technical routes for sludge treatment and utilization, showing thermal hydrolysis as the lowest carbon footprint.
  • For the Cambi project at Davyhulme sludge centre, Manchester, UK, United Utilities estimate a yearly reduction of 32,000 t CO2e.

  • Northumbrian Water (NW) conclude that for its Bran Sands Cambi Project: “Overall, when reduced natural gas consumption, cogen benefits (including avoided imported electricity), transport and other energy savings are taken into account, the project is estimated to reduce NW’s carbon footprint by up to 50,000 t CO2 per year.

  • For Cardiff and Afan plants Welsh Water calculate a 37,000 t CO2e/year, 15% reduction over their previous AD + drying project. 

  • In Washington DC, DC Water documented its “... overall greenhouse gas (GHG) inventories for 2007 and 2008 and show how the proposed digestion upgrades will reduce the utility’s overall inventory by an estimated 28 to 39 percent or 46,816 to 73,340 MT of CO2e per year.

  • Thames Water hired independent consultant Entec to analyse the effect of CambiTHP and concluded: “…advanced digestion in conjunction with dewatering and taking the cake to    agriculture offers the most appropriate process route for Thames Water Utilities Ltd. Of the two advanced digestion techniques that have been commercially proven (Thermal Hydrolysis and   Acid Phase Digestion), Thermal Hydrolysis offers lower cost, more energy and fewer GHG [Green House Gas] emissions across the whole process route. Furthermore, Thermal Hydrolysis   produces a much superior cake product that should help to maintain the agricultural route (still the Best Practicable Environmental Option in most circumstances) open.”

  • Dr. Bill Barber, then United Utilities’ Biosolids Expert, concludes: “For Class A processes, the lowest carbon footprints (after composting) are associated with advanced pretreatment prior to MAD. Thermal hydrolysis can further reduce carbon impact due to improved dewatering which in turn reduces downstream processing requirements and transport when compared to similar processes.”