A Comparative Whole Life Costing of Sand and AFM Used as Filtration Media for Drinking Water

An independent report for

Highlands and Islands Enterprise July 2013

Prepared by Consultants 

Oakdene Hollins

registered to

ISO 9001:2008 and ISO 14001:2004

Executive Summary

This work has been commissioned by the Highlands and Islands Enterprise (HIE).  The purpose of this study is to carry out a comparative whole life cycle costing (WLC) for sand that can be used by SME’s in the development of their own WLC for use in presenting to water utilities or engineering professionals.

Currently, sand is widely used for drinking water and waste water management and for the purposes of this first attempt at producing a ‘tool’ for SME’s we have compared sand with Activated Filter Media (AFM) sand substitute where sand would normally be used in mechanical water treatment and adsorption applications.   It is recognised that some costs have not been included such as pacification and site specific costs, but the aim is to have an accepted early stage methodology which SME’s can use to ensure that they don’t waste with their own time or the time of their potential customers.   This approach aims to support the recognition of potential disruptive and useful technologies which could improve operation and make substantial savings across the water and waste water sector. 

Interestingly, this exercise has result in highlighting that AFM could be a disruptive and innovative product for consideration. The company is the process of having AFM along with competitor products independently verified for performance.  The report is therefore a useful precursor in supporting the design of the testing process.,

Results from this early stage WLC approach have show that the installation of AFM in place of sand was calculated to save in the region of £192,000 per year in a typical water treatment plant (WTP), annualised over its projected life of 50 years.  Initial one-off costs of removing sand from filters and replacing with AFM paid back within an estimated eleven months.

Table 1: Whole life cycle costing for sand and AFM filter media, average per year.

 

 

SAND (£000s) AFM (£000s)
Operating costs (per year)
Media £11.2 £0.4
Chemicals £376 £193
Energy £1.6 £0.2
Sludge disposal £9 £13
TOTAL £398 £207
One-off costs
TOTAL    £183

The most significant cost of for a WTP is the addition of chemicals.  It is the 25% reduction in PAC and chlorine and the 75% possible reduction in powdered activated carbon use which has the greatest impact on the economic viability of using AFM.  Further technical analysis is required to substantiate this for WTP, and the independent testing will also provide validation and verification of these claims.

A model has been produced alongside this report which enables the assumptions behind this analysis to be altered/changed.  This model could be further developed and used to further inform how a change in the assumptions in this report can affect any cost savings realised from the use of AFM or other similar products, but this should now be discussed with experienced operations staff within a water utility. 

 

A full copy of the the report is available on request.

Latest Articles