SECTORS. WASTEWATER SEWAGE TREATMENT PLANT IN OSAN, SOUTH KOREA Background: The environmental agency in Osan, South Korea, operates the local sewage treatment plant and monitors the sewer system. The municipal wastewater generated by a local settlement is collected in a tank and pumped to a basin situat- ed higher up. From there, it then flows to the sewage treatment plant by the force of gravity. To achieve this, three submersible pumps are installed in the pumping station. Together they achieve a delivery rate of 200 cubic meters per hour. Challenge: In order to prevent interrup- tions in operation and malfunctions in the pumping station as a result of block- ages and coarse matter such as textiles, wood and plastic, twin-shaft grinders produced by a Korean manufacturer were installed. However, these worked unre- liably, so the Osan Environment Agency looked solution that could be used in the narrow shaft. for an alternative Solution: The operators opted for the XRipper XRP twin-shaft grinder. This XRipper has a compact design and is therefore also suitable for installation in narrow shafts. It was inserted into a six-meter-deep shaft. The advantages at a glance: • Compared to its predecessor, the XRipper handles higher wastewater quantities reliably and runs more quietly. • The shredding tools (Ripper rotors) in the interior of the grinder are made of a single block of special steel. The mono- lithic design means that torque is trans- mitted evenly along the entire length of the shaft to the rotors. This makes high- er loads and more powerful shredding possible. • The grinder reduces even stubborn impurities such as wet wipes and other hygiene items to an unproblem- atic size. This protects the wastewater pump and prevents downtime due to blockages and interruptions for main- tenance work. • The QuickService design allows direct and quick access to the functional unit. This involves lifting the drive unit together with the Ripper rotors up and out of the housing. When changing parts, only a few individual parts need to be replaced. • The plant’s own staff can perform all the work on-site. At the same time, the XRipper is always ready for operation and does not incur additional costs due to long downtimes. In another pumping station, one with an open sewer, another preexisting unit was replaced by the XRC version of the Vogelsang XRipper, which is specially designed for such applications. NIGG SEWAGE TREATMENT PLANT IN ABERDEEN, SCOTLAND Background: Kelda Water Services Grampian (KWS Grampian) has a 28-year contract to design, build, operate and maintain several sewage treatment plants in northeast Scotland. One of these, the Nigg sewage treatment plant in Aberdeen, treats the wastewater of around 250,000 people. ing costs were too high – not something the operators could tolerate long-term. Maintenance of the grinder proved to be difficult; in-house technical teams were unable to carry it out. As a result, the grinder often had to be overhauled out- side the plant, which was time-consum- ing and costly. Challenge: Some years ago, KWS Grampian installed a twin-shaft grinder in the intake of the sewage treatment plant at its Nigg site to protect the down- stream pumping equipment and increase the efficiency of the screen. The company was satisfied with the performance of the grinder per se, but the ongoing operat- Solution: Since several Vogelsang rotary lobe pumps were already in use on-site, the company was already familiar with Vogelsang’s QuickService concept. Therefore, this customer finally decided to replace its existing systems with the Vogelsang XRipper XRC186-520QD SIK. The advantages at a glance: • Due to their design, the Ripper rotors of the grinder can be replaced in a few minutes. • With its sturdy design and powerful drive at low speed, the unit has high- er torque, providing better shredding performance at a lower rate of power consumption. • After just 12 months, the company was able to reduce maintenance costs by 60 percent – with maximum avail- ability. 360° | 25