Softening makes water more expensive

Softening makes water more expensive

The supply of water for municipalities can be an expensive affair. Mainstockheim is realizing this right now: in order to comply with the eu directives on water hardness, around 1.5 million euros in investments will be needed in the coming years. At the council meeting on thursday evening, sven muller from the planning office baurconsult provided information on the possibilities of sulfate reduction.

In the past years, mainstockheim has already invested a lot of money in its own water supply: the wells, which supplied soft but nitrate-rich water, had to be abandoned because they were no longer up to technical standards. For this purpose the deep well was rehabilitated and another one was drilled. These wells produce water that is low in nitrates but high in sulfates. There are no more health concerns, but the sulfate leads to a high water hardness, which in mainstockheim is around 40 degrees german hardness.

However, this quickly causes pipes and household appliances to calcify during cooking. As a result, many households in mainstockheim have a private water softening system in their cellar. According to the latest EU directives, drinking water may only contain a maximum of 250 milligrams of sulfate per cubic meter; water from mainstockheim contains almost twice that amount. Although the municipality has a temporary exemption that will remain in effect for another nine years, there is still a need for action.

And the engineering firm commissioned to solve the problem with a nano-filter system. The water from the two wells is forced through filters that remove the sulfate as well as some of the calcium and magnesium from the drinking water. The end result is drinking water with a hardness of 12 to 13 degrees. For every ten liters of water filtered, eight liters are added to drinking water and two liters of highly concentrated sulfate are added to the main river. The technicians have no reservations about discharging this water into the river, since the two liters per second discharged are matched by a flow volume of the mains of around 45 cubic meters per second, and sulfate is also a natural substance.

The three variants presented differ mainly in their design and technical equipment. While variants 1 and 2 are double-equipped in most technical areas, such as two filter lines, variant 3 has them only once. This is particularly problematic in the case of technical problems and maintenance, as the regulations require "redundant" plant components, i.E. At least in duplicate.

The costs for the first two variants, which differ only in the construction method, amount to about 1.5 million euro each, variant 3 costs about 1.2 million euro. In addition, there are annual operating costs of around 44,000 euro for the first two and around 37.500 euros for the third variant, which would increase the price by around 50 cents per cubic meter if water consumption remained the same.

However, there are advantages, because on the one hand the private water softening plants become superfluous, the load of the clear plant is reduced by it, the consumption of detergents sinks and pipes calcify hardly more.

For the council, the fulle of information was a bit rough, so that in the end they only agreed to take over variants 1 and 2 for further official discussions. The next steps, such as setting a budget year for the construction of the plant and possible financing solutions, have been postponed.