The viability of sludge dewatering on small-to-medium unmanned satellite works to reduce whole life costs and indirect carbon footprint
Sims, J. and Foster, D., Huber Technology, UK PRESENTATION ONLY
(free)
Improving sludge treatment whole life cost savings by way of dewatering on satellite sites
• In order to optimise methane production and sludge quality for disposal, the UK has seen a trend towards large, regional sludge reception facilities with some form of Advanced Anaerobic Digestion (AAD) (e.g. with Enzymic or Thermal Hydrolysis pre-treatment).
• These facilities involve significant CAPEX and it is more economically viable to have only a few of these huge capacity sites and bring in sludge from outlying satellite works.
• The transportation costs incurred by such sludge movement are significant and obviously get higher if the sludge is thinner and if the satellite sites are a long way from the AAD plant.
• Some water companies are already using satellite site sludge dewatering to reduce volumes for transport followed by “re-wetting” at the AAD site to give the required feed thickness.
If practical and if the payback period is acceptable, upgrading satellite sites to include some form of volumetric reduction of the sludge being produced:
• Can significantly reduce the whole life cost of the plant as a result of reduced transportation costs,
• Can reduce the indirect carbon footprint of the AAD plant as a result of fewer lorry movements (against which the increased power consumption etc. at the satellite sites is insignificant),
• Can help the water company achieve it’s AMP6 goal to improve efficiency (by reduced OPEX). Dewatering is likely to only be favored over thickening or optimizing the existing set-up if the overall whole life cost saving is significant and if the payback period is sufficiently short (3-7yrs).
