WATER / WASTEWATER
Figure 3: Total cell counts along the water reuse treatment train.
Figure 4: Total cell counts in RO permeate during a plant shutdown of 1 day. After such long interruptions, it took 1.5 days for cell counts to return to baseline levels.
Figure 5: Total cell counts in a RO permeate during membrane scaling. Scaling led to reduced permeate fl ow and rapidly increasing cell counts.
Figure 6: RO permeate quality during process optimisation. To increase membrane recovery, the feed pressure was increased by 20%, resulting in an immediate 20-fold increase in the total cell count.
spikes in RO permeates, while long-term stagnation had lasting negative effects on water quality (fi gure 4). This has direct implications on the treatment operation and highlights the need for additional fl ushing or cleaning steps following stagnation.
Moreover, rapid microbial regrowth indicates that both UF fi ltrates and RO permeates are not biostable, emphasizing the importance of assessing microbial regrowth up to the point of use and preventing stagnation whenever possible.
3. Membrane scaling reduces permeate fl ow and increases bacterial levels
In a dedicated experiment, RO membrane scaling was studied by omitting antiscalant dosing. Shortly after the start of the experiment, a reduction in permeate fl ow was observed, accompanied by a rise in total cell count (fi gure 5).
4. Minor adjustments of membrane operation can have unexpected effects on its performance
At the process optimization stage of the pilot, maximizing the membrane recovery was further investigated. One of the aspects under examination was the membrane performance at different feed pressures. It could be shown that a minor feed pressure increase led to a drastic rise of the total cell counts in the permeate (fi gure 6). Importantly, this phenomenon was not transient. The cell concentrations remained at a high level, demonstrating that operational parameters such as feed pressure can strongly infl uence the microbiological quality of the permeate.
Pilot Outcome
“Pilot testing is of utmost importance to us. By integrating an online fl ow cytometer as a monitoring system, we gain rapid insights into microbiological performance, enabling us to make informed, data-driven decisions with confi dence.”, states
Benjamin Buysschaert, Manager R&D from Ekopak. The pilot system successfully met the client’s key performance indicators, delivering high quality water that complies with local drinking water standards. Importantly, the microbiological data collected during the trial provided crucial insights, helping to identify critical treatment elements, schedule maintenance activities, and understanding the direct impact of operational changes on water quality. The client is very pleased with the outcome of the pilot and has gained the confi dence that innovative solutions are available to achieve his sustainability targets.
Benefi ts
Containerized pilot systems are simple to deploy, require minimal infrastructural adaptations by clients, and enable real-world performance assessments of effl uent streams. This de-risks full-scale implementation by verifying that the treatment design works under all operational conditions. Furthermore, on-site and remote support by experts throughout the entire pilot period allows to closely monitor KPIs and rapidly iterate with process optimizations, an important strength in case of variable feed water properties.
Including an automated rapid monitoring system in the pilot empowered the operators to get an immediate understanding of the microbiological performance of the proposed solution, and a practical tool to further examine critical elements. Silvan Kaufmann, solution programme manager at bNovate, remarks: “We are very happy to have been able to contribute to the success of this pilot with comprehensive and actionable microbiological data. We experienced fi rsthand how much value such containerized pilot installations bring to clients.” As an example, the initial grab sampling campaign provided a comprehensive overview of the microbiological landscape of the whole treatment train, helping to qualify the performance of the membranes and understanding microbial regrowth phenomena in prefi lters and pipes. Several subsequent online monitoring installations helped
understanding the temporal dynamics of the membrane fi ltration units, assessing the effects of prefi lter maintenance, stagnation, scaling and optimization of operational parameters.
About the project partners
Ekopak is a Belgian company specialized in sustainable water management solutions utilizing innovative and environmentally friendly technologies. Ekopak supports businesses in reducing water consumption and dependence on traditional water sources, contributing to a more sustainable future.
bNovate Technologies SA is a leader in the microbiological analysis and monitoring of water. The Swiss company propels industrial microbiology into the digital age with rapid, automated solutions for the global water, food & beverage, pharmaceutical, and cosmetics industries.
Silvan Kaufmann, bNovate Technologies SA
Chem. de la Dent d’Oche 1A, 1024 Ecublens, Switzerland
Tel: +41 21 552 14 21 Email:
silvan.kaufmann@bnovate.com Web:
www.bnovate.com
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