Waste Water Treatment Plant saves 31 % energy with Atlas Copco 55 kW blower
With a savings goal set at 25 % for the Danish waste water industry, optimizing all parts of the operation, so even the aeration, is of the highest importance. The Waste Water Treatment Plant in Skanderborg, Danmark, recently replaced one of its 75 kW lobe blowers with a new 55 kW Atlas Copco ZS screw blower and were able to reduce their energy consumption by 31%.Up to 70 % of the energy consumed by a Waste Water Treatment Plant (WWTP) consists of low pressure aeration of the waste water, why savings in this part of the process is of paramount importance. Atlas Copco’s ZS screw blowers are on average 30 % more energy efficient than lobe blowers. This has been proven by independent tests by TÜV and by WWTP’s in Scandinavia. “Skanderborg WWTP had problems with their aeration using lobe blowers so we suggested that they should try the Atlas Copco ZS blow¬ers”,says Flemming Broksø, Sales Engineer at Atlas Copco Compressor Technique Scandinavia. Atlas Copco delivered a new 55 kW variable speed drive blower, operating at 0.7 bar(e), to Skanderborg WWTP, replacing a 75 kW lobe blower in one of the aeration process lines. “We chose Atlas Copco as supplier of our new blower as they showed us possible energy savings of 30 % compared to our old lobe blower”says Ivan Andersen at Skanderborg WWTP. During August every year in Skanderborg the traditional Summer Festival takes place. This is the time of the year when the work load is at its highest for Skanderborg WWTP, and where the blowers operate on maximum capacity. During the festival, a test was carried out by Skanderborg WWTP comparing the energy consumption of the two identical aeration process lines. Both lines are equipped with two blowers each – one variable speed drive and one fixed speed. The operations are set up so that the variable speed drive blowers function as the primary blowers and the fixed speed blowers come in when the demand for low pressure air increases. Line 1 1 75 kW lobe blower, variable speed drive 1 75/62 kW (dual speed) lobe blower, fixed speed Total energy consumption: 19 989 kWh Line 2 1 Atlas Copco ZS55VSD-700 screw blower, variable speed drive 1 75/62 kW (dual speed) lobe blower, fixed speed Total energy consumption: 14 492 kW The figures show a total saving of energy for Line 2 including the Atlas Copco ZS screw blower at 31 %. “The Atlas Copco ZS screw blower is working really well, better than expected. It runs smooth and has, besides replacing a bigger lobe blower, lowered the amount of time that the fixed speed lobe blower has to support the VSD blower in its aeration process line”,Ivan Andersen says. “This has given us big energy savings and we are calculating a payback time of the ZS blower as low as only 16 months. We also made it through the Skanderborg Summer Festival without any downtime, and it runs much more silent than the old lobe blower”,he concludes.