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14

of grey water, since the relatively low concentrations of dissolved nutrients in the water

were not considered problematic for the application at Papyro-tex.

As the treated grey water from the “Hjortespringbadet” is to be applied in a closed process

at Papyro-tex, no immediate occupational health problems are anticipated, since there is no

physical contact in relation to using the grey water.

A review of the logistic situation at the enterprises of scenario 2 showed that there was a

need for only minor indoor changes corresponding to expenses of approx. 95.000 DKK for

establishment of the necessary facilities to collect and distribute the grey water at both

enterprises. The necessary outdoor construction works, however, are extensive, including

establishment of wells, drain pipes, pressure pipes, equalizing tanks and treatment system.

Working expenses amounts to 32.600 DKK corresponding to a net present (loss of) value of

–4.100 DKK concerning the initial expenditures. If the total amount of grey water from the

“Hjortespringbadet”, corresponding to 7.700 m 3 /year, could have been recycled the result

would have been a net present value of 82.000 DKK per year during a depreciation period

of 20 years. It should be noted that the initial expenses will remain almost unchanged and

that the working expenses will increase only very little in case the extra amount of water is

to be treated, too.

On this background it can be concluded that in case of no particular circumstances, which

might raise the installation expenses or the treatment expenses during the establishment of a

grey water collecting system, it would be economically profitable to establish and run such

grey water exchange systems, provided that they are situated in the neighbourhood (at a

distance of up to approx. 500 m). The main condition is however that the price of water of

the municipality is sufficiently high (20 DKK or more per m 3 exclusive of VAT and water

tax) and that a minimum of 4.000 – 5.000 m 3 /year of grey water can be exchanged. Furthermore,

it is important to ensure that no occupational health problems will arise for instance

as a result of microbiological after-growth in the recycling systems.

When making future plans for common water consuming systems it would be obvious to

prepare the sewer system in a way which makes it possible afterwards to collect the grey

water without having to make expensive changes of the existing installations. It is furthermore

recommended to locate the grey water producers in areas allowing potential grey

water consumers to exploit the available grey water resource.

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