Use of biofilm to seed the new activated sludge process at Liverpool WWTW
Black, J. and Molloy, R., United Utilities, UK
(free)
Abstract
This paper describes the seeding technique and results for the process commissioning of the new Sequencing Batch Reactor at Liverpool Waste-water Treatment Works (WwTW). This process replaces the existing secondary treatment: a Biological Aerated Flooded Filter (BAFF), and is the main component of the £200m project to upgrade United Utilities’ second largest waste-water treatment works.
Typically activated sludge is imported from other WwTWs to seed a new process. In the case of Liverpool WwTW there was thought to be a high risk that an imported microbial population would fail to adapt to the influent load, which is known to contain a high proportion of trade effluent as well as fluctuating salinity concentrations. Instead, biosolids from the existing BAFF process were used to seed the new plant.
Process modelling (BioWIn) was used to predict the theoretical microbial growth rates based on seeding with conventional activated sludge. These results were compared with the actual growth rates achieved. The seeding process using BAFF biosolids compared favourably with predicted growth from an imported sludge. In addition the elimination of the need for tankers to import activated sludge resulted in significant financial savings to the project.
Keywords
Process Commissioning, BioWin, Bioflm, Activated Sludge, Sequencing Batch Reactor, Biological Aerated Flooded Filter (BAFF)
Introduction
This paper describes the seeding technique and results for the process commissioning of the new Sequencing Batch Reactor at Liverpool Waste-water Treatment Works (WwTW). It focusses on the innovative technique of using seed sludge from the existing BAFF (biological aerated flooded filter) rather than importing seed sludge from another waste-water treatment works.
