WATER QUALIT Y
Costing end-point disinfection in water treatment plants Budgets are tightening, and the responsibility to account fully for all input cost variables in water treatment systems is more important than ever. End-point disinfection offers a useful case study.
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or example: everybody knows that bleach is cheap and chlorine gas is cheaper. But is it really? There is a long-held assumption that the cost of a chlorination programme can be determined by comparing the relative cost of the chemical (R/kg), but recent extensive studies have invalidated this
FIGURE 1 Opex distribution results
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perspective,” explains Peter Buchan, CEO of Control Chemicals. In order to correctly calculate end-point disinfection, it is necessary to consider multiple components, including: • capital expenditure on the dosing equipment, as well as its depreciation and maintenance costs
• t he cost of ongoing training and labour needed to operate that equipment •e nergy/electricity consumption • r isk/safety – insurance and potential injury costs • r aw material/chemical used • performance. One complication arises from the fact that capital expenditure, operational expenditure, labour and training budgets typically fall into different departments or cost centres. “Many of these costs are not immediately obvious,” explains Peter Buchan, CEO of Control Chemicals. “In order to fully assess the total cost of a disinfection technology or system, it can be illuminating to work backwards from the end result – meaning, once the mandated water quality has been reliably achieved, one should then cost out laterally from there. It is remarkable to find that efficacy and performance are often considered in isolation when disinfection systems are specified or budgeted for,” he says. Fortunately, over the past few years, a series of proactive comparative case studies were conducted by a major local municipality, with the results shedding sufficient light on the
