New Trash Rack Cleaning Technology from Bavaria for One of Europe’s Largest Reservoirs

The original trash rack cleaning machine had kept the intake free of debris at Buško Blato (aka Buško Jezero) – one of the largest European man made reservoirs – for around 50 years. Nevertheless, over recent years, it had become increasingly prone to problems, and was struggling to cope with the growing challenges. Hence, a new, significantly more powerful rack cleaning rake machine was required – and was provided by MUHR. Already installed, it heralds a new era in the technical operation of the facility. Cleaning efficiency has been improved with the new system by a staggering 125 %, even though it is currently still in the mandatory trial phase.

Buško Blato Hydropower System Relies on Modern Trash Rack Cleaning

In the early 1970s, the Buško Blato reservoir was constructed at great expense as an integral part of a high-capacity hydroelectric power system. Located just a few kilometres away, Orlovac hydroelectric power plant is fed by the Buško Blato reservoir – or Buško Jezero, as it is also known. It is one of the largest man made reservoirs in Europe covering a total area of just under 60 km² with a volume of 782 million cubic metres. The complex infrastructure of canals, dams and pumping stations has enabled Buško Blato to remain an important fixture for water regulation in the area and, above all, for energy production in the region.

Modernising the Buško Blato Hydropower System

The original trash rack rake machine was installed over 50 years ago to ensure the unimpeded flow of headwater from the intake at the reservoir into the power house. Over this period, it kept the trash rack more or less free of any debris. Nevertheless, Marko Knezevic, Managing Director of MUHR Croatia, explained that, “Despite regular maintenance, the system had begun to show signs of age and wear over the years. Occasional malfunctions, particularly in the electromechanical raking unit, ultimately increased the risk of potential machine breakdowns.” Knezevic’s description of the initial situation with the original equipment shows how this necessitated the modernisation project with the Bavarian hydraulic engineering specialists at Erhard Muhr GmbH, headquartered in Brannenburg, who ultimately took of full responsibility for project implementation. Marko Knezevic also pointed out that the high proportion of manual labour it demanded meant it had long since ceased to meet modern-day standards: “The machine required manual operation, the screen baskets needed to be emptied by hand and the debris required transportation by trolleys to a place a whole 50 metres away.” Hence, the expert, added: “Basically, modernisation of the system was long overdue.”

Complex Logistics for Cross-Border Installation

In recent years, operators had faced an additional environmental problem that had exacerbated the situation. The screen had been becoming increasingly clogged up with organic material from a fast-growing, invasive aquatic plant, and the old machine had no longer been able cope. Ultimately, a host of factors had made replacement of the trash rack cleaner an urgent necessity, and the performance demands and capabilities placed on the new machine were now significantly higher than those for its over 50 year-old predecessor.
In July 2024, the client and the supplier – MUHR, signed the contract for the refurbishment of the trash rack cleaner. The project was devised in multiple phases, covering the entire production and installation cycle – from planning through to final commissioning. “In particular, it should be noted that the dismantling of the old plant, transport preparations, cross-border transport – including customs clearance to Bosnia and Herzegovina, and on-site assembly using a mobile crane, were all carried out – following factory inspection and approval in Brannenburg – in less than a month. This required close coordination between mechanics, electricians, hydraulics engineers and programmers,” Marko Knezevic told us, as he outlined the scope of the challenges for the logistics management process.

Engineering Solutions for Demanding Site Conditions

During project implementation, structural adaptation of the existing infrastructure, and the new, even more demanding operating conditions, both presented significant challenges for the MUHR team: “The challenge began with the new machine’s higher dead weight, larger surfaces subject to snow and wind loads, as well as additional forces caused by an integrated hydraulic crane for lifting large pieces of driftwood out of the water. For this reason, extended analyses of all additional load cases were carried out on top of the usual structural calculations,” Knezevic explains. The structural modifications were made on the basis of the operator’s rack drawings, so for a real imaging during commissioning tests, an underwater drone was used to confirm the perfect fit and correct positioning of the claw unit on the rack. Another critical issue was the on-site space constraint. The lack of space necessitated a carefully coordinated installation plan. Furthermore, particular attention had to be paid to the integration of the new and enhanced workplace safety features, such as multiple emergency stop buttons (ESD), radio remote control infrastructure and presence detection sensors.

New Trash Rack Cleaner Increases Cleaning Capacity by 125 %

The new Buško Blato trash rack cleaner is currently in operational use in a mandatory trial phase to verify its stability, reliability and the full integration of all functions. The machine offers significantly improved technical performance in line with current requirements. Marko Knezevic: “The rake width has been increased from 1600 mm to 2500 mm, meaning a significantly larger raking area is covered per stroke. In combination with higher drive speeds, cleaning time per cycle has been reduced by 20 %, so the new machine is both faster, and removes considerably more floating debris in a single rake stroke. This has increased the hourly cleaning volume by around 125 %.” In addition, the new system is fully automated, remotely controlled, requires minimal manual intervention and offers a significantly raised level of safety. The system guarantees the operator more reliable, powerful and higher-quality equipment, and in turn contributes significantly to the operational safety of the entire hydropower set-up.

MUHR Delivers Integrated Hydraulic Engineering Solution

The fact this long-established Bavarian company bid successfully in the tender process is further proof of its expertise and high quality. MUHR is known to guarantee reliability for demanding hydropower applications, and to be able to provide a fully integrated solution encompassing the mechanical, electrical and control components of any project. MUHR offers equipment and systems that ensure full compliance with technical specifications, a high degree of integration, state-of-the-art safety standards and high-quality manufacturing. Furthermore, the company has experienced, highly specialised technical staff working in every project phase – design and project management, mechanical specialists and fitters, electricians, hydraulics engineers and programmers for control integration. A key reason for the selection of this supplier was their broad technical expertise. For MUHR, a challenging Balkan project has become yet another successful reference job on the company’s long list of international achievements. As regards the Buško Blato reservoir, the new trash rack cleaning machine heralds the start of a new, modern era in hydropower utilisation.