Bio-cage™: A Novel innovative low-cost solution for sludge thickening – results from 52 Southern Water Sites
Veesam, M1 and Thomas, P.2, 1Southern Water, UK, 2AFECO, UK
(free)
Sludge thickening is vital to any utility dealing with tonnes of sludge movements across the operating
region. Significant haulage and operational benefits are connected with improving the sludge dry solids
concentration. A trial Bio-cageTM at Southern Water’s Coldwaltham wastewater treatment works
increased the dry solids by over 2% and reduced the average tankering from 10 to 4 tankers per month
thus majorly reducing the haulage costs by £8k with a return on investment of just over a year. This
extremely successful trial led to surveying several sites across Southern Water and carrying out an
initial program of Bio-cageTM installation across 52 sites that offered an attractive return on investment
of less than 3 years. At West Hoathly wastewater treatment works, Bio-cageTM proved to be a great
success with a deferred capital spend of over £400k, as a direct replacement for a drum thickener. The
data assessed from the sites showed an average tankering reduction of 28% in 2017/18.
This paper aims to discuss the results of these Bio-cageTM installations which have greatly contributed
to reducing Southern Water’s tankering budget and carbon emissions. It will also look in more detail at
the data from 2017/18 to investigate the site factors which have the largest effect on the performance
of the Bio-cageTM.
Keywords
Carbon reduction, Innovation, Opex reduction, Optimisation, Sludge thickening,
