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[...]Glasgow, Scotland[...]

[...]Saalbach-Hinterglemm, Austria Fine screening systems are an interesting alternative to primary settling tanks when it comes to changing the sludge stabilisation process from aerobic to anaerobic. Compared with a traditional primary clarifier with a retention time of 0.5 to 2 hours, a fine screen achieves the same or better reduction rates, which take effect within a few minutes whilst requiring only a fraction of the space and volume. Energy savings and biogas yield through carbon removal Switching from aerobic to anaerobic sludge stabilisation can reduce aeration costs by around 20–25%. This reduction is achieved through carbon removal, usually through a primary clarifier or, as in the case of Saalbach, using HUBER fine-screen technology prior to biological treatment. This has also resulted in a further positive effect in terms of energy generation through the utilisation of primary sludge, which is used directly for the production of biogas or to increase on-site electricity generation. Seasonal utilisation of the Saalbach sewage treatment plant The municipality of Saalbach, known as a winter sports destination but also enjoying high visitor numbers during the summer, operates a sewage treatment plant at Glemmtaler Landesstraße 554 with a design capacity of 49,000 population equivalents (PE). Due to seasonal fluctuations, its actual utilisation varies between 10 per cent during the off-peak periods and 100 per cent during the peak season. Capacity limits and lack of primary treatment The Saalbach wastewater treatment plant already had two digestion tanks and a combined heat and power (CHP) unit, but no primary treatment. The digestion process had been fed exclusively with mechanically thickened excess sludge. With increasing tourism, particularly during the winter season, the plant approached its authorised capacity of 49,000 PE60 on some days. It was therefore necessary to find a solution to relieve the load on the biological treatment process. Plant expansion to relieve the load on the biological treatment process The first studies for the expansion were carried out in mid-2019. The aim was to relieve the biological treatment process through primary treatment, whilst simultaneously improving the energy balance through biogas production and electricity generation and reducing the energy required for aeration. Lack of space and integration of the mechanical primary treatment The aerial view shows that, nestled between the northern slope, the Glemmtal main road, the Saalach river and the southern slope, there was no space for a primary treatment tank. The plot on the western side was not available. The sketch outlined in red shows where the lifting station, the mechanical primary treatment (drum screen) and a primary sludge thickener (disc thickener) could be integrated into a confined space after the grit chamber and before the aeration stage, and in the immediate vicinity of the digestion tanks. Initial trial operation under winter conditions From mid-February 2020 to mid-March 2020, during the winter season and in freezing temperatures, the first operational trial was carried out using a demonstration unit of the HUBER Drum Screen LIQUID housed in a container with a 0.2 mm mesh. Optimisation of screen surface cleaning for grease-laden sludge Although the first trial run had to be cut short after a short time due to the coronavirus pandemic, it was already apparent that screen surface cleaning was, and remains, the key criterion; this is why the LIQUID screen was fitted with additional air-jet cleaning and a modified high-pressure cleaning system, enabling it to function reliably even with very grease-laden primary sludge. Thanks to the air-jet cleaning system, the drum screen produced a thicker primary sludge than was the case with spray-water screen surface cleaning, which is fed from the finely screened inlet. Second trial run confirms high COD reduction The second trial run took place between December 2021 and March 2022. This demonstrated that COD removal rates of 25–40 per cent (with and without the use of polymers) could be achieved, thereby reducing the load on the subsequent biological treatment stage through the removal of pollutants from the wastewater. Implementation and commissioning ahead of the 2025 World Ski Championships Following the local council’s decision and the granting of a water law permit by the Salzburg Provincial Government, construction of the primary treatment plant, including its integration into the existing system, began in late summer 2024, half a year before the 2025 World Ski Championships. Commissioning took place on 27 January 2025. At the end of the 2025 winter season, the primary treatment system was taken out of service until it was put back into operation during the 2025 summer season, from early June to late September. Operational results during seasonal operation Depending on the proportion of wastewater routed through the primary treatment system, the operational results showed a COD reduction of 26 to 33 per cent (daily composite sample) prior to entry into the biological treatment stage, in both winter and summer operation. It should be noted that this was achieved without the use of polymers. Flexible feeding and control of the C/N ratio Plant manager Josef Ebner and his colleagues are particularly impressed by the flexibility and ease of maintenance of the process: The mechanical primary treatment system is fed on a case-by-case basis and with variable flow rates from a load of around 15,000 p.e. It can be brought into operation within a few minutes. The C/N ratio for denitrification is adjusted to the required value by controlling the volume of influent withdrawn after the grit chamber and passed through the fine screen. Positive effects on energy consumption and electricity generation During peak load periods, the measure implemented leads to a significant reduction in the aeration energy required in the aeration tanks and, at the same time, to an increase in biogas yield, which in turn results in higher in-house electricity generation. Image Gallery Sludge Thickening: Primary sludge from the HUBER Drum Screen LIQUID in the HUBER Disc Thickener S-DISC HUBER Drum Screen LIQUID manufactured in the HUBER production in Berching HUBER Drum Screen LIQUID at the Saalbach WWTP HUBER Disc Thickener S-DISC[...]

[...]Malta The Ta' Barkat sewage treatment works, often referred to as the Malta South STW, is at the heart of Malta’s wastewater management system. It is situated near Xgħajra on Malta’s south-east coast and officially came into operation in 2011. It is the country’s largest sewage treatment works and treats around 60,000 m³ of wastewater every day. This corresponds to around 80 per cent of the island’s total wastewater volume. The plant uses a modern biofiltration process that alternates between aerobic and anoxic environments to efficiently treat the wastewater. Its commissioning has significantly improved water quality at beaches in the south, such as Marsascala and Kalkara. ‘New Water’ project An important feature of Ta’ Barkat is its reclaimed water treatment plant, which allows the water to be used for agricultural irrigation. Here, the already treated water is further purified through ultrafiltration (UF) and reverse osmosis (RO) to such a high standard that it can be used as high-quality irrigation water for agriculture. The result is Class A water, the quality of which, according to the operator Water Services Corporation (WSC), even exceeds the standards set by the Food and Agriculture Organisation of the United Nations (FAO) for the irrigation of food crops. Currently, up to 9,000 m³ of ‘New Water’ is produced daily. However, it is expected that daily production will need to be increased to 20,000 m³/d by 2028. In the long term, the project is intended to cover up to 35 per cent of the agricultural sector’s water requirements. The main objective is to achieve a ‘net-zero impact’ on the natural water cycle by replacing illegal or excessive extraction from wells with sustainable reuse. To protect the downstream ultrafiltration and reverse osmosis plant (UF-RO system), drum filters were originally used as ultra-fine screens downstream of the secondary clarifier. However, these did not provide the necessary purification performance. The TSS values in the effluent from the drum filters were regularly in the range of 20–40 mg/l, leading to high operating costs for the UF membrane and, consequently, plant downtime. For this reason, the operator conducted an in-depth review of alternative technologies for ultra-fine filtration of the treated effluent. Ultimately, it was decided to replace the drum filters with cloth filters in order to ensure a better effluent quality for the operation of the UF-RO system. HUBER solutions in use In January 2024, HUBER SE was commissioned via a local partner to upgrade the plant with a cloth filtration stage. At the WSC’s request, the system was installed in tanks. Following intensive detailed discussions and coordination with all parties involved, three HUBER Pile Cloth Media Filter RotaFilt®, size 2700, were delivered to Malta in November 2024. After more than a year of satisfactory operation, a routine inspection carried out by a HUBER service team in collaboration with the operator identified potential for improvement in the overall functioning of the plant. The aim is to increase plant availability and improve operational performance. This is because the pile fabric filtration stage must also significantly increase its net daily throughput in the course of 2026. Meanwhile, construction work on the expansion of the downstream filtration stages is also in full swing, to ensure the plant is optimally prepared for future requirements.[...]

[...]Totalphütte, Alps, Austria The Totalphütte was originally a site hut for Vorarlberger Illwerke AG and served as accommodation for the construction workers building the Lünersee lake dam. Since 1964, the Austrian Alpine Club has been running the hut as a mountain refuge. Following a number of refurbishments and the reconstruction of the hut – it was severely damaged by a dust avalanche in 2019 – it has since become a popular destination for walkers and those conquering the Rätikon’s highest peak, Schesaplana, at 2,965 m. Wastewater treatment remains an important issue even in high-alpine environments. A HUBER Micro Strainer ROTAMAT® Ro9 screen is in use at the Totalphütte. It treats the wastewater daily from up to 1,000 day visitors, plus a further 150 people who stay overnight at the hut. Seasonal operation presents challenges Due to the short operating period of the sewage treatment plant, keeping the plant running smoothly and reliably is always a major challenge. This makes the pre-treatment of the wastewater all the more important before it is fed into the biological treatment stage. Furthermore, ease of operation of the plant’s machinery is of great importance. The plant must be commissioned at the start of the season in July with just a few simple steps and then decommissioned again in September after a short but intensive period of operation. A straightforward start-up and shutdown procedure was therefore a prerequisite for the plant operator. During our conversation, the hut tenant expressed her delight at how smoothly the entire project had been carried out. She also highlighted that the workload at the sewage treatment plant has reduced a lot since the new HUBER screening system was installed. An efficient solution for mountain regions and similar areas The HUBER Micro Strainer ROTAMAT® Ro9 is simple and flexible to use and easy to transport to any location. At the Totalphütte, it has been reliably reducing the load on the biological treatment system since its installation, as the screen thoroughly removes foreign matter. Thus, a simple helicopter flight has made it possible to clean the water resources in the mountains sustainably and protect the environment.[...]

[...]Bickenbach, Germany The European water sector will face enormous challenges in the coming years. Implementing the new EU‑Urban Waste Water Treatment Directive (UWWTD) and ensuring the sustainable protection of our water resources will be a significant collective task. UWWTD is therefore rightly regarded as a milestone that will shape urban water management across Europe in the long term: stricter requirements for the removal of phosphorus and nitrogen, energy neutrality and, above all, the widespread introduction of the fourth treatment stage. All sewage treatment works with a capacity of more than 150,000 population equivalents (PE) and, in sensitive areas, those with more than 10,000 PE, must retrofit this additional treatment stage by 2045. It is not yet clear how many sewage treatment works in Germany and Europe will actually be fitted with trace substance removal systems. However, it is expected that in Germany alone, around 600 sewage treatment works will be fitted with a fourth treatment stage. To date, over 60 German sewage treatment works have already been upgraded with an industrial-scale fourth treatment stage, including 33 plants in Baden-Württemberg, which, together with Switzerland, has taken on an important pioneering role in this field. A small selection of these successfully implemented case studies is presented in the fact sheets opposite. The projects impressively demonstrate that, from a technological perspective, the successful implementation of an industrial-scale fourth treatment stage is already possible today. It is now up to European policymakers to promptly develop and present a pragmatic solution for the financing of the UWWTD that is acceptable to all parties.[...]