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Water Quality management

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The vision of sewage treatment has changed significantly over recent years. Next to the tighter consent levels, reduction of CO2 emission and energy consumption has become increasingly important. The idea that energy can be extracted from sewage and waste products can be recovered and upgraded to raw materials has stimulated the development of new technology.

With the use of IntenSieve as pre-treatment, CirTec contributes to the objectives of the Water utilities. IntenSieve relieve the biology and thereby contribute to the energy objectives. The sieved material that is secreted mainly consists of cellulose which has enormous potential as a raw material. Fine screen technology for sewage treatment is far beyond the pilot phase. Large scale installations are in operation and treat sewage while recovering celllose (base material of toiletpaper) as marketable product.

Fine screens are not only used for the treatment of raw influent, they are also applied for screening filtrate from centrifuges. The use of IntenSieve behind overflows in combined sewer systems has proven to be a promising solution. A study CirTec has recently carried out in close cooperation with several Waterboards and consulting companies have demonstrated that.

CirTec Technology

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The technology we use to maintain and manage the water quality are:

Fine Screens

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The advantages of using Fine screen technology include superior performance, compact size, reduced sludge production, and improved effluent quality. Equipment installed by CirTec has proven to be a reliable technology.

Fine screens are applied for/in:

Fine screening of raw wastewater

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As part of a research program, supported by STOWA (Dutch acronym for the Foundation for Applied Water Research), the Dutch Water Authority installed a Salsnes fine screen at its facilities. The operational results of the fine screen are intensively monitored, as well as any changes in the biology with regard to eg. sludge characteristics, denitrification, and biological phosphorus uptake.

The plant is designed to treat the total dry weather flow and may treat capacities up to 500 m3/h under rainy water conditions. The surplus is bypassing the fine screen and is fed directly into the anaerobic selector tank.

The average TSS in the feed is approximately 450 mg/L, but as a result of the first flush, peak concentrations are measured well above 1,200 mg/L.

The WWTW is an activated sludge system with a biological capacity of 29,920 p.e. at 150 g TOC/day (33,000 p.e. at 136 g TOC/day). The hydraulic capacity at DWF is 385 m3/h and at RWF 1,800 m3/h

Cellulose Assisted Dewatering of Sludge (CADoS)

https://youtu.be/UJpL0psxkQw

Wastewater that is discharged into the sewage system contains suspended solids that largely consist of cellulose. Cellulose has its origin in the use of toilet paper. The CADoS technology is designed to separate the cellulose present in the sewage, using a fine screen, and use the screenings for optimization of the dewatering of sludge. The CADoS principle seeks to significantly reduce chemical use for dewatering, reduce energy and achieve lower sludge disposal costs. Furthermore, CADoS leads to higher energy yield from biogas in sludge digestion.

Wastewater that is discharged into the sewage system contains suspended solids that largely consist of cellulose. Cellulose has its origin in the use of toilet paper. The CADoS technology is designed to separate the cellulose present in the sewage, using a fine screen, and use the screenings for optimization of the dewatering of sludge. The CADoS principle seeks to significantly reduce chemical use for dewatering, reduce energy and achieve lower sludge disposal costs. Furthermore, CADoS leads to higher energy yield from biogas in sludge digestion.

Wastewater that is discharged into the sewage system contains suspended solids that largely consist of cellulose. Cellulose has its origin in the use of toilet paper. The CADoS technology is designed to separate the cellulose present in the sewage, using a fine screen, and use the screenings for optimization of the dewatering of sludge. The CADoS principle seeks to significantly reduce chemical use for dewatering, reduce energy and achieve lower sludge disposal costs. Furthermore, CADoS leads to higher energy yield from biogas in sludge digestion.

https://youtu.be/QaWl4wBqu1g

ScreenCap, fine screening WWTP Aarle-Rixtel

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https://youtu.be/TjqJKQHQuqs

As one of the first large-scale sewage treatment plants (WWTPs) in Europe, the Aarle-Rixtel WWTP is equipped with CellCap fine screens. The essence of this innovative concept is the removal of suspended solids from raw wastewater based on particle size. Compared to common separation techniques that work on the basis of density, CellCap fine screens have a significant positive impact on downstream processes. In addition to capturing a different fraction of suspended matter, the BOD:N ratio in the filtrate can be influenced by adjusting the process settings of the sieves.

The Aarle-Rixtel WWTP, one of the WWTPs of Waterboard Aa and Maas, is designed for 340,000 PE and can treat a hydraulic capacity at RWA of 16,000 m3/h. The CellCap fine screens are designed for a hydraulic capacity of 4,000 m3/h which corresponds to approximately 120{4f1e35c07df61488f28768334a6350a7c20f145341bf5f3233e6477760a58c2c} of the DWF.

The Aarle-Rixtel WWTP is constructed in two identical treatment lines that can be operated independently of each other. This set-up makes it possible to make an accurate comparison of the impact of CellCap fine screens on downstream processes. Supported by a network of European partners, a small consortium consisting of a technology developer (CirTec B.V.), a launching customer (Waterschap Aa en Maas), and a knowledge institute (KWR), wants to validate the CellCap technology for this large-scale purification. During a period of 24 months, only the influent of one of the two purification lines will be pretreated with CellCap fine screens. During this period, the downstream processes will be closely followed and monitored. In addition to the operation of the fine screens, attention will be paid to biomass activity, dewatering characteristics, energy consumption, and other process characteristics.

The project, called ScreenCap, for which a European subsidy has been granted from the Eco-Innovation scheme, should be a prelude to further marketing of the CellCap technology.