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No-Des is an innovative no-waste flushing system which combines effective Sediment and Bio-Film removal with high-speed water recycling, including filtration and re-chlorination
About
NO-DES flushing differs from conventional flushing in two key aspects: FLUSHING METHODOLOGY The No-Des high-speed flushing methodology is both high-velocity and uni-directional. The unit is connected to the network via two hydrants. The filter chambers and hoses are then slowly filled, the system pressurized, and the air bled. Once the NO-DES unit is full, an inline valve between the two hydrants is closed making the NO-Des unit part of the network loop. The onboard pump speed is then increased against the normal direction of mains flow until the water reaches the desired velocity of (1.5 – 1.8m/s). The open-loop is then flushed until an outlet turbidity reading of <1Ntu is achieved. WATER RECYCLING As the water from the main enters the unit it passes through a set of 1-micron filters, before being re-chlorinated and injected back into the main. The treatment process ensures that the water re-entering the main meets and often exceeds local water quality targets.
Key Benefits
Use of the NO-DES methodology as part of an ongoing mains cleaning programme results in a broad range of customer, regulatory and business benefits, including: • Improved ODI performance due to the zero discharge during flushing process • No loss of supply and low customer impact • The ability to control pressure and velocity eliminates pressure loss and water hammer, reducing potential mains damage • Increases flow velocity within the main removes bio-films and eliminates nitrification more effectively than conventional flushing techniques • The flow direction can be reversed to improve scouring effect • Continual water quality monitoring (pressure turbidity and chlorine) • Will achieve 1-micron absolute filtering • Improved PR as a result of no visible water wastage • The system can be used to support both planned and reactive AWS activities, with the localised treatment capability providing greater network flexibility and service resilience.
Applications
Flushing of water mains between 75mm and 450mm in diameter.