Pump stations

The function of the pumping station is to lift the wastewater a number of meters to push the flow further. The stations are built both above ground and underground. The stations are designed for the current flow requirements. Capacity requirements vary from small systems for individual houses to very large installations.

To keep the relative humidity level under control, many pumping stations today are heated to between 15° – 20°C, all year round with direct-acting electricity. It is often unnecessary! Reducing the heating to 5-10°C can save a lot of money!

However, when the heat is lowered, the relative humidity increases unless the amount of water in the air is reduced. Airwatergreen dehumidifiers are built with a technology that allows them to dehumidify the air energy efficiently regardless of the temperature. Even at low temperatures down to minus degrees!

Corrosion

Corrosion is an electrochemical reaction on metals exposed to corrosive gases and/or high relative humidity (RH). This can lead to high maintenance costs and reduced lifespan of key components.

Hydrogen sulphide emitted from the sump is an example of a common corrosive gas in pumping stations. Hydrogen sulphide is also a health hazard and the bad smell is a source of great irritation for local residents. Bad smells are best managed with our carbon filter Blackbox in combination with our dehumidifier FLEX in our Odorless Climate solution, which ensures that the carbon has dry air to work in. Corrosion in pumping stations is typically due to:

• High relative humidity
• Hydrogen sulphide from the sump
• Other corrosive gases from the sump

Right moisture level A moisture level below 55% relative humidity (RH) reduces the risk of corrosion and mold. Airwatergreen dehumidifiers can maintain the right relative humidity level at the prevailing temperature. See the Mollier diagram where the condensation (saturation) curve is given as 100% RH at different temperatures.

Energy saving with dehumidification

The following calculation is based on a bachelor thesis from Uppsala University. Here, the energy consumption of a small pumping station was measured in two cases. The pumping station has a floor area of about 5.8 m2.

• In the first case, a heating element was kept at 18°C in the pumping station and the relative humidity varied freely.
• In the second case, a condensing dehumidifier was used, FLEX Integrate was kept at 50% RH and the temperature was allowed to vary freely above 5°C.

The figure below shows energy consumption values for a pump house with temperature data in 2015. The blue line shows the values for the pump house with an element keeping the temperature at 18°C. The red line shows the energy consumption values for a condensing dehumidifier. The result shows that with a condensing dehumidifier the energy consumption for one year is 513.8 kWh and with an element 3101.57 kWh. The energy consumption when a condensing dehumidifier is used instead of radiators is 83.0% lower!

The adjacent figure shows the energy consumption of a pumping station where the relative humidity level is controlled over a whole year.

The blue line shows the energy demand when heating with a radiator and the red line shows the energy demand when using a condensing dehumidifier to control the climate and keep the relative humidity at a stable level.

As shown in the figure, our dehumidifier needs a fraction of what an electric element requires. Heating using a typical electric heater consumes just over 3,200 kWh per year. An Airwatergreen FLEX dehumidifier consumes on average less than 350 kWh in a normal sized pumping station. This provides significant energy savings and also eliminates renovation costs due to rust and mold!

The red line shows the lower energy consumption when a FLEX dehumidifier maintains the same climate.

The installation is easy as we don’t need to make any holes in the walls or run long ventilation pipes. The dehumidifier can be mounted on a FLEX wall bracket (accessory) to keep the floor free in the station building. An ordinary 1-phase 230V plug is sufficient to supply electricity to a FLEX. The easiest way to remove the water is with a hose to the sump or other drain.

Bad smell in and around pumping stations

Bad smells come from the sump and enter the superstructure. This affects the working environment and can lead to complaints from nearby residents. Examples of gases that emit odors are:

• Hydrogen sulphide
• Ammonia
• Merkaptans
• Sulphur dioxide
• Methane

Working environment

The amount of hydrogen sulphide in the air in a pumping station can affect the health of those working in pumping stations. The health effects are linked to the concentration of hydrogen sulphide in the air. To be allowed to work for 8 hours, the Swedish Work Environment Authority has guidelines that the level must be kept below 5 ppm of hydrogen sulphide in the air.

Our solution – Odour-free climate

Our BLACKBOX carbon filter can adsorb gases that cause corrosion and odor problems from hydrogen sulfide, ammonia and mercaptans. Our Odorless Climate solution, which combines dehumidification with the carbon filter, keeps the relative humidity below 70%. This ensures that the activated carbon can focus on capturing the harmful gases. This makes the activated carbon last much longer, resulting in lower maintenance costs.

Odorless climate set-up

To address the challenges associated with bad odors in pumping stations, we recommend our solution odor-free climate, which includes the Blackbox carbon filter is included.

The air is sucked directly from the sump. This creates a negative pressure in the sump. Air dried by FLEX is therefore sucked down from the superstructure into the sump and mixed up.

This reduces the relative humidity level in the air before it passes through the carbon filter.