Naburn Wastewater Treatment Works Refurbishment

Naburn provides sewage/imported sludge waste treatment for the York area. Part of the onsite treatment process involves anaerobic digestion of the biomass utilising sunken digesters with a top entry mixer. Unfortunately over a period of 6-12 months the mixer becomes ragged up with fibrous materials significantly reducing the digester operation and biogas production. In addition to the mixing system the aging heating recirculation system also required updating to meet the new systems operating requirements.

ACWA’s scope involved the design and installation of 1 No Digesters mixing and heating recirculation loop with a compressed biogas mixing system which:

  • 36No Actuated External to Internal biogas lancing for digester mixing
  • Duty/Standby Biogas Compressors
  • Spiral Heat Exchanger with duty/standby recirculation pumps
  • Digester anti-foam suppression system
  • Condensate reduction within Biogas mains
  • Biogas quality monitoring station
  • Biogas Bulk storage, Flare Stack and Transfer to CHP engines

Technical Overview

Design basis:

  • Process, Mechanical, Electrical & Instrument Supply Project
  • Biogas Production 377m3/h/Digester
  • Meets YW Design Specifications

The Benefits

ACWA’s solution is:

  • Reuse of existing concrete (digester) structure with minimal changes
  • Designed to maximise access to and around the digester top
  • Result significantly increased the quality and production of biogas from that single digester
  • Does not require periodic shutdowns for de-ragging purposes